Sunday, May 10, 2020

I Am Close With Damon - 971 Words

Since the age of fifteen, I have been dating my boyfriend, Damon, whose family has accepted me as their own. Last year, Damon’s step-brother Elijah had a wonderful little girl named Korra. She is now 11 months old and beginning to exhibit signs of development that we have been exploring in our class work. Since I am close with Damon’s family, I have been able to see at least once a week and watch her develop and learn new things, allowing me to compare her to one of our recent chapters, which was development. I have noticed that Korra is showing Secure Attachment when with her mother, Jessica. When Korra is with her, she is a very happy baby who is willing to be around others that she recognizes and is not afraid to play with her toys; but when her mother leaves she begins to panic and cry out for Jessica to come back. This weekend we had a party for Damon’s youngest sister, and she had many friends over to play and celebrate. When Jessica left Korra with Damonâ €™s sister and her friends, Korra became scared and began to cry for her mother; and when mom returned, Korra was happy and no longer crying. The text book refers to secure attachment as â€Å"in their mother’s presence they play comfortably, happily exploring their new environment† (Meyers Dewall, 2014). Korra is a direct reflection of this statement of the book, depicting that she has a healthy relationship with her mother. The Stranger Anxiety Korra exhibits when her mother leaves is very typical for aShow MoreRelatedViolence In Films Essay720 Words   |  3 PagesViolence In Films In this essay I am going to compare 3 scenes of violence from 3 different genres and analyse their certifications and effects on young people and whether children are finding ways of viewing secretly, or are being allowed to see, too much violence in films, T.V or through any other median. 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Wednesday, May 6, 2020

Hydraulic Design of Small Hydro Plants Free Essays

Version 2 STANDARDS/MANUALS/ GUIDELINES FOR SMALL HYDRO DEVELOPMENT Civil Works – Hydraulic Design Of Small Hydro Plants Lead Organization: Sponsor: Alternate Hydro Energy Center Indian Institute of Technology Roorkee Ministry of New and Renewable Energy Govt. of India May 2011 AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  1 1. GUIDELINES FOR HYDRAULIC DESIGN OF SMALL HYDRO PLANTS This section provides standards and guidelines on the design of the water conductor system. We will write a custom essay sample on Hydraulic Design of Small Hydro Plants or any similar topic only for you Order Now This system includes; head works and intake, feeder canal, desilter (if required), power canal or alternative conveyance structures (culverts, pipelines, tunnels, etc), forebay tank, penstock and surge tank (if required) up to the entry of the turbine, tailrace canal below the turbine and related ancillary works. 1. 1 HYDRAULIC DESIGN OF HEAD WORKS In general head works are composed of three structural components, diversion dam, intake and bed load sluice. The functions of the head works are: Diversion of the required project flow from the river into the water conductor system. Control of sediment. Flood handling. Typically a head pond reservoir is formed upstream of the head works. This reservoir may be used to provide daily pondage in support of peaking operation or to provide the control volume necessary for turbine operation in the water level control mode. This latter case would apply where the penstock draws its water directly from the head pond. Sufficient volume must be provided to support these functions. There are three types of head works that are widely used on mini and small hydro projects, as below: Lateral intake head works Trench intake head works Reservoir / canal intakes Each type will be discussed in turn. 1. 1. 1 Head Works with Lateral Intakes (Small Hydro) Head works with lateral intakes are typically applied on rivers transporting significant amounts of sediment as bed load and in suspension. The functional objectives are: To divert bed-load away from the intake and flush downstream of the dam (the bed load flushing system should be operable in both continuous and intermittent modes). To decant relatively clean surface water into the intake. To arrest floating debris at intake trashracks for removal by manual raking. To safely discharge the design flood without causing unacceptable upstream flooding. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  2 The following site features promote favourable hydraulic conditions and should be considered during site selection: The intake should be located on the outside of a river bend (towards the end of the bend) to benefit from the spiral current in the river that moves clean surface water towards the intake and bed load away from the intake towards the centre of the river. The intake should be located at the head of a steeper section of the river. This will promote removal of material flushed through the dam which may otherwise accumulate downstream of the flushing channel and impair its function. Satisfactory foundation conditions. Ideal site conditions are rare, thus design will require compromises between hydraulic requirements and constraints of site geology, accessibility etc. The following guidelines assume head works are located on a straight reach of a river. For important projects or unusual sites hydraulic model studies are recommended. A step by step design approach is recommended and design parameters are suggested for guidance in design and layout studies. Typical layouts are shown in Figures 2. 2. 1 to 2. 2. 3. 1. 1. 2 Data Required for design. The following data are required for design: Site hydrology report as stipulated in Section 1. 3 of this Standard giving: – Qp (plant flow) – Q100 (design flood flow, small hydro) – Q10 (design flood flow, mini hydro) (data on suspended sediment loads) – Cw – H-Q Curves (W. L. rating curves at diversion dam) Topographic mapping of the site including river bathymetry covering all head works structure sites. Site geology report. 1. 1. 3 Site Selection: Selection of the head works site is a practical decision which involves weighing of several factors including hydraulic desiderata (Section 2. 2. 1/1. 0), head optimization, foundation conditions, accessibility and constructability factors. Given the importance of intake design to the overall performance of the plant it is recommended that an experienced hydraulic engineer be consulted during studies on head works layout. 1. 1. 4 Determination of Key Elevations: AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  3 For the illustrative example: Qp = 10. 0 m3/s Determine V0 = 0. 5 Q0. 2 (= 0. 792, say 0. 80 m/s) (= 12. 5 m2) A0 = Q ? V0 A0 H= (= 1. 77 m, say 1. 80 m) 4 Assume L = 4H (= 7. 08 m, say 7. 0 m) ye = greater of 0. 5 yo or 1. 5 m (= 1. 80m) yd = L. S (= 0. 28 m) NOL = Z0 + ye + yd + H NOL = 97. 5 + 1. 80 + 0. 28 + 1. 80 (=101. 38m, say 101. 50 m) Sill = NOL – H (= 99. 7m) Crest of weir or head pond NOL = 101. 5 m Height of weir = 4. 0 m These initial key elevations are preliminary and may have to be adjusted later as the design evolves. 1. 1. 5 Head Works Layout The entry to the intake should be aligned with the river bank to provide smooth approach conditions and minimize the occurrence of undesirable swirl. A guide wall acting as a transition between the river bank and the structure will usually be required. Intake hydraulics are enhanced if the intake face is slightly tilted into the flow. The orientation of the intake face depends on river bank topography, for straight river reaches the recommended values for tilt vary from 10o to 30o depending on the author. When this angle becomes too large the intake will attract excessive amounts of sediment and floating debris. It is recommended that the sill level of the intake is kept sufficiently higher than the sill level of the under sluice. The under sluice should be located adjacent to the intake structure. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  4 For development of the head work plan, it is recommended that the following parameters be used for layout: Axis of intake should between 100 ° to 105 ° to axis of diversion structure The actual inclination may be finalized on the basis of model studies. Divide wall, if provided, should cover 80% to 100% of the intake. Assume flushing flow equal to twice project flow then estimate the width and height of the flushing gate from orifice formula,: Example should be in appendix. Qf = 0. 6 ? 0. 5W2 Where: Qf = flushing flow W = gate width H = gate height (= 0. 5W) Yo = normal flow depth as shown in 2. 2. 1. 1/2. 0 Sill should be straight and perpendicular to the flow direction. In the sample design (Fig. 2. 2. 1. 1) the axis of the intake = 105 ° Qf = 2. 0? 10. 0 = 20m3/s ? 20. 0 = 0. 6 ? 0. 5 W2 ? W = 2. 8 m (say 3. 0m) and H = 1. 5 m. 1. 1. 6 Flood Handling, MFL and Number of Gates. For small hydro a simple overflow diversion weir would be the preferred option if flood surcharge would not cause unacceptable upstream flooding. For purpose of illustration, the following design data are assumed (see Figure 2. 2. 2): Design flood, Q100 = 175 m3/s A review of reservoir topography indicated that over bank flooding would occur if the flood water level exceeded 103. 0 m. Select this water level as the MFL. This provides a flood surcharge (S) of 1. 20 m. Assume weir coefficients as below: Gate, Cw = 1. 70 – – – sill on slab at river bottom. Weir, Cw = 1. 0 – – – – – – -ogee profile. Assume gate W/H ratio = 1:2 H = 4. 0 m ? W = 4. 8 (say 5. 0 m) MFL. = NOL + 1. 50 (= 103. 0m) Qgate = Cw. W. (MFL – ZS)1.. 5 Qweir = Cw. Lw. S1. 5 Capacity check for MFL = 103. 0 m No. of Length of Overflow QG Gates Section (m) (m3/s) 0 35. 0 0. 0 1 29. 0 109. 6 QW (m3/s) 82. 8 68. 6 QT (m3/s) 82. 8 178. 2 175 AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  5 Therefore one gate is sufficient. Where: MFL = Maximum flood level (m) NOL = Normal operating level (m) S = flood surcharge above NOL (m) W = width of gate (m) H = height of gate (m) ZS = elevation of gate sill (m) = weir coefficient (m0. 5s-1) Cw QG, QW, QT = gate, weir and total flows The flow capacity of the sediment flushing gate may also be included in calculating flood handling capacity. 1. 1. 7 Diversion structure and Spillway Plains Rivers: Stability of structures founded on alluvial foundations typical of plains rivers, is governed by the magnitude of the exit gradient. The critical gradient is approximately 1. 0 and shall be reduced by the following safety factors: Types of foundation Shingles / cobbles Coarse sand Fine sand Safety factor 5 6 7 Allowable Exit Gradient 0. 20 0. 167 0. 143 Also diversion structures on plains rivers will normally require stilling basins to dissipate the energy from the fall across the diversion structure before the water can be returned safely to the river. Design of diversion weirs and barrages on permeable foundation should follow IS 6966 (Part 1). Sample calculations in Chapter 12 of â€Å"Fundamentals of Irrigation Engineering† (Bharat Singh, 1983) explain determination of uplift pressure distributions and exit gradients. Further details on structural aspects of design are given in Section 2. 3. 3 of this Standard. Mountain Rivers: Bedrock is usually found at relatively shallow depths in mountain rivers permitting head works structures to be founded on rock. Also the beds of mountain rivers are often boulder paved and are much more resistant to erosion than plains rivers. Therefore there may be no need for a stilling basin. The engineer may consider impact blocks on the downstream apron or simply provide an angled lip at the downstream end of the apron to â€Å"flip† the flow away from the downstream end of the apron. A cut-off wall to bed rock of suitable depth should AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  6 also be provided for added protection against undermining by scour. The head works structures would be designed as gravity structures with enough mass to resist flotation. For low structures height less than 2. 0 m anchors into sound bedrock may be used as the prime stabilization element in dam design. Stability and stress design shall be in accordance with requirements of Section 2. 3. 3 of this Standard. 1. 1. 8 Sediment Flushing Channel To be reviewed The following approach is recommended for design of the flushing channel: Select flushing channel flow capacity (Qf) = 2? Qp Estimate maximum size of sediment entering the pocket from site data or from transport capacity of approaching flow and velocity. In case of diversion weir without gates assume sediment accumulation to be level with the weir crest. (Assume continuous flushing with 3? Qp entering the pocket, for this calculation). Establish entrance sill elevation and channel slope assuming an intermittent flushing mode (intake closed) with Qs = 2Qp, critical flow at the sill, supercritical flow downstream (FN ? 1. 0) and a reservoir operating level 0. 5m below NOL. Determine slope of channel to provide the required scouring velocity, using the following formula which incorporates a safety factor of 1. 5: i = 1. 50 io d 9/7 i0 = 0. 44 6 / 7 q Where: io = critical scouring velocity d = sediment size q = flow per unit width (m3/s per m) Verify that flow through pocket in continuou s flushing mode (Qs = 3Qs) will be sub critical, if not lower entrance sill elevation further. Determine height of gate and gate opening based on depth of flow at gate location and corresponding gate width. Increase the above theoretical gate height by 0. 5 m to ensure unrestricted open channel flow through the gate for intermittent flushing mode and a flushing flow of 2 Qp. For initial design a width to height ratio of 2:1 for the flushing gate is suggested. 1. 1. 9 Intake/Head Regulator: In intake provides a transition between the river and the feeder canal. The main design objectives are to exclude bed-load and floating debris and to minimize head losses. The following parameters are recommended: Approach velocity at intake entrance (on gross area) 0. 20 Ve = 0. 5 Q p m / s For trashracks that are manually cleaned, V should not exceed 1. 0 m/s. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  7 Convergence of side walls 2. 5:1 with rate of increase in velocity not exceeding 0. 5 m/s per linear m. †¢ Height of sill above floor of flushing channel (ye) = greater of 1. 5m or 50% flow depth. †¢ The floor of the transition should be sloped down as required to join the invert of the feeder canal. Check that the flow velocity in the transition is adequate to prevent deposition in the transition area. If sediment loads are very high consider installing a vortex silt ejector at the downstream end of the transition. Provide coarse trashracks to guard entry to the head gate. The trashrack would be designed to step floating debris such as trees, branches, wood on other floating objects. A clear spacing of 150 mm between bars is recommended. Trashrack detailed design should be in accordance with IS 11388. †¢ The invert of the feeder canal shall be determi ned taking into consideration head losses through the trashrack and form losses through the structure. Friction losses can be omitted as they are negligible: V2 Calculate form losses as: H L = 0. 3 2 2g Where: V2 = velocity at downstream end of contraction. Calculate trashrack losses as: 4/3 V2 ?t? H L = K f ? ? . Sin? . 2g ?b? Where: Kf = head loss factor (= 2. 42 assuming rectangular bars) T = thickness of bars (mm) B = clear bar spacing (mm) ? = angle of inclination to horizontal (degrees) V = approach velocity (m/s) 1. 1. 10 References on Lateral Intakes and Diversion Weirs. IS Standards Cited: IS 6966 (Part 1) IS 11388 USBR (1987) Singh, Bharat Nigam, P. S. Hydraulic Design of Barrages and Weirs – Guidelines Recommendations for Design of Trashracks for Intakes Design of Small Dams Fundamentals of Irrigation Engineering Nem Chand Bros. Roorkee (1983) Handbook of Hydroelectric Engineering (Second edition) †¦.. pages 357 to 365 Nem Chand Bros. – Roorkee (1985) 1. 1. 11 Other References: Bucher and Krumdieck Guidelines for the Design of Intake Structures for Small Hydro Schemes; Hydro ’88/3rd International Conference on Small Hydro, Cancun – Mexico. Bouvard, M. Mobile Barrages and Intakes on Sediment Transporting AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  8 Razvan, E. 1. 2. Rivers; IAHR Monograph, A. A. Balkema – Rotterdam (1992) River Intakes and Diversion Dams Elsevier, Amsterdam (1988) SEMI PERMANENT HEADWORKS (MINI HYDRO) For mini hydro projects the need to minimize capital cost of the head works is of prime importance. This issue poses the greatest challenge where the head works have to be constructed on alluvial foundations. This challenge is addressed by adoption of less rigorous standards and the application of simplified designs adapted to the skills available in remote areas. A typical layout is shown in Figure 2. 2. 3. 1. 2. 1 Design Parameters Hydraulic design should be based on the following design criteria: Plant flow Qp) = QT + QD Where: QT = total turbine flow (m3/s) QD = desilter flushing flow (= 0. 20 QT) m3/s QFC = feeder canal flow (= 1. 20 QT) m3/s QF = gravel flushing flow (= 2. 0 QP) Spillway design flow (SDF) = Q10 Where: Q10 = flood peak flow with ten year return period. 1. 2. 2 Layout ? To be reviewed Intake approach velocity = 1. 0 m/s Regulator gate W/H = 2 Flushing channel depth (HD) = 2H + W/3 Flushing channel m inimum width = 1. 0 m Assumed flushing gate W/H = 2, determine H from orifice equation, as below: Q f = 0. 53? 2 H 2 . 2 gY1 Y1 = HD for design condition Where: W width of gate (m) H = height of gate (m) Yi = upstream depth (m) = depth of flushing channel (m) HD Select the next largest manufactures standard gate size above the calculated dimensions. 1. 2. 3 Weir AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  9 Determine weir height to suit intake gate and flushing gate dimensions, as shown in Figure 2. 2. 3. For weirs founded on permeable foundations the necessary structure length to control failure by piping should be determined in accordance with Section 2. 2. 1/4. 1 of this Standard. A stepped arrangement is recommended for the downstream face of the weir to dissipate hydraulic energy. The height of the steps should not exceed 0. 5 m and the rise over run ratio should not less than 1/3, the stability of the weir cross-section design should be checked for flotation, over turning and sliding in accordance with Section 2. 3. 1. 1. 3 TRENCH INTAKES Trench intakes are intake structures located in the river bed that draw off flow through racks into a trench which conveys the flow into the project water conductor system. A characteristic of trench intakes is that they have minimum impact on river levels. Trench intakes are applied in situations where traditional headwork designs would be excessively expensive or result in objectionable rises in river levels. There are two quite different applications: on wide rivers and on mountainous streams, but the basic equations are the same for both types. The trench intake should be located in the main river channel and be of sufficient width to collect the design project flow including all flushing flows. If the length of the trench is less than the width of the river, cut off walls will be required into each bank to prevent the river from bypassing the structure. Trench weirs function best on weirs with slopes greater than 4%-5%, for flatter slopes diversion weirs should be considered. The spacing between racks is selected to prevent entry of bed load into the trench. The following terms are sometimes used in referring to trench intake designs. Trench weir, when the trench is installed in a raised embankment. †¢ Tyrolean or Caucasian intakes, when referring to trench intakes on †¢ mountainous streams. Features: AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  10 1. 3. 2 Design Parameters The following design parameters are suggested for the dimensioning of trench weirs. †¢ Design Flows: The following design flows are recommended: Bedload flushing flow (from collector box) = 0. 2 QT †¢ Desilter flushing flow = 0. 2 QT †¢ Turbine flow = 1. 0 QT †¢ Total design flow †¢ = 1. 4 QT Dimensional Layout AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  11 The following factors should be considered in determining the principal dimensions: length, breadth and depth of a trench weir: Minimum width (B)= 1. 25 m (to facilitate manual cleaning) Length should be compatible with river cross section. It is †¢ recommended that the trench be located across main river channel. Maximum width (B) ? 2. 50m. Trashrack bars longer than about 2. 50 m †¢ may require support as slenderness ratios become excessive. Invert of collector box should be kept a high as possible. †¢ †¢ Racks à ¢â‚¬ ¢ †¢ †¢ †¢ The clear spacing between bars should be selected to prevent entry of bed-load particles that are too large to be conveniently handled by the flushing system. Generally designs are based on excluding particles greater than medium gravel size from (2 cm to 4 cm). A clear opening of 3. 0 cm is recommended for design. A slope across the rack should be provided to avoid accumulation of bed load on the racks. Slopes normally used vary from 0 ° to 20 °. Rectangular bars are recommended. Bar structural dimension shall be designed in accordance with Section 2. 2. 1/5. 0 of this Standard. An appropriate contraction coefficient should be selected as explained in the following sub-section. Assume 30% blockage. Spacing between racks is designed to prevent the entry of bedload but must also be strong enough to support superimposed loads from bedload accumulation, men and equipment. This issue is discussed further in Subsection 2. 2. 3 / 2. 0. 1. 3. 3 Hydraulic Design of Trench Intake The first step in hydraulic design is to decide the width of the trench intake bearing in mind the flow capacity required and the bathymetry of the river bed. The next step in hydraulic design is to determine the minimum trench breadth (B) that will capture the required design flow. The design approach assumes complete capture of river flow, which implies, that river flow is equal to plant flow for the design condition. Hydraulic design is based on the following assumptions: Constant specific energy across racks. †¢ Effective head on screen is equal to base pressure (depth) †¢ Approach velocity is subcritical with a critical section at the entry to the structure as shown in figure 2. 2. 3/1. The set of equations proposed is based on the method given by Lauterjung et al (1989). †¢ First calculate y1: AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraul ic Design Of Small Hydro Plants /May 2011  Ã‚  12 2 y 1 = k. H0 3 – – – – – – – – – – – (1) Where: y1 = depth at upstream edge of rack Ho = the energy head of the approaching flow k = an adjustment factor (m) m) (-) k is a function of inclination of the rack and can be determined from the following table: Values of k as a Function of Rack Slope (? ) Table: 2. 2. 1/1 ? = 0 ° 2 ° 4 ° 6 ° 8 ° 10 ° 12 ° k = 1. 000 0. 980 0. 961 0. 944 0. 927 0. 910 0. 894 ? = 14 ° 16 ° 18 ° 20 ° 22 ° 24 ° 26 ° k = 0. 879 0. 865 0. 851 0. 837 0. 852 0. 812 0. 800 Then calculate the breadth of the collector trench from the following equations (2) to (4) 1. 50 q – – – – – – – – – – – – – – (2) L= E1. E 2 C. cos? 3/2 . 2gy 1 Where: L = sloped length across collector trench (m) E1 = blockage factor E2 = Eff ective screen area = e/m C = contraction coefficient ? = slope of rack in degrees y1 = flow depth upstream from Equation 1. (m) q = unit flow entering intake (m3/s per m) e = clear distance between bars (cm or m) m = c/c spacing of bars (cm or m) Assume E1 = 0. 3 (30%) blockage. â€Å"C† can be calculated from the following formula (as reported by Raudkivi) Rectangular bars: ?e? C = 0. 66 ? ? ?m? ?0. 16 ?m? .? ? ?h? 0. 13 Assume h = 0. 5 y1. This formula is valid for 3. 5 – – – – – – – – – – – – – (3) h e 0. 2 and 0. 15 0. 30 m m Finally, the required breadth (B) can be determined as below: B = L cos ? – – – – – – – – – – – – -(4) AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  13 1. 3. 4 Hydraulic Design of Collector Trench Normally a sufficient slope on the i nvert of the trench is provided to ensure efficient flushing of bed-load particles that would otherwise accumulate on the invert of the trench. A suitable scouring slope can be estimated from the following equation: Ss = 0. 66 d 9 / 7 6/7 qo Where: d = sediment size (m) qo = flow per unit width (Q/B) at outlet of trench (m3/s per m) Ss = design slope of trench invert. The minimum depth of the trench at the upstream and is normally between 1. 0m to 1. 5 m, based on water depth plus a freeboard of 0. 3 m. For final design the flow profile should be computed for the design slope and the trench bottom profile confirmed or adjusted, as required. A step-by-step procedure for calculating the flow profile that is applicable to this problem can be found in Example 124, page 342-345 of â€Å"Open-Channel Hydraulics† by Ven. T. Chow (1959). In most cases the profile will be sub critical with control from the downstream (exit) end. A suitable starting point would be to assume critical flow depth at the exit of the trench. 1. 3. 5 Collector Chamber The trench terminates in a collector box. The collection box has two outlets, an intake to the water conductor system and a flushing pipe. The flushing pipe must be design with the capacity to flush the bed-load sediment entering from the trench, while the project flow is withdrawn via the intake. The bottom of the collection box must be designed to provide adequate submergence for the flushing pipe and intake to suppress undesirable vortices. The flushing pipe should be lower than the intake and the flushing pipe sized to handle the discharge of bed load. If the flushing pipe invert is below the outlet of the trench, the Engineer should consider steepening the trench invert. If the trench outlet invert is below the flushing pipe invert, the latter should be lowered to the elevation of the trench outlet or below. The deck of the collector box should be located above the design flood level to provide safe access to operate gates. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  14 1. 3. Flushing Pipe The flushing pipe should be designed to provide a high enough velocity to entrain bed-load captured by the weir. A velocity of at least 3. 0 m/s should be provided. If possible, the outlet end of the pipe should be located a minimum of 1. 0m above the river bed level to provide energy to keep the outlet area free from accumulation of bed load that could block t he pipeline. 1. 3. 7 References on Trench weirs CBIP, (2001): Manual on Planning and Design of Small Hydroelectric Scheme Lauterjung et al (1989): Planning of Intake Structures Freidrich Vieweg and Sohn, Braunswchweig – Germany IAHR (1993): Hydraulic Structures Design Manual: Sedimentation: Exclusion and Removal of Sediment from Diverted Water. By: Arved J. Raudkivi Publisher: Taylor Francis, New York. Chow (1959): Open- Channel Hydraulics Publisher: McGraw-Hill Book Company, New York. 1. 4 RESERVOIR, CANAL AND PENSTOCK INTAKES The designs of reservoir, canal and penstock intakes are all based on the same principles. However, there are significant variations depending on whether an intake is at the forebay reservoir of a run-of-river plant or at storage reservoir with large draw down or is for a power tunnel, etc. Examples of a variety of layouts can be fond in IS 9761 Hydropower Intakes – Criteria for Hydraulic Design or Guidelines for Design of Intakes for Hydropower Plants (ASCE, 1995). The features common to all designs are shown in the following sketch: AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  15 The objectives of good design are: To prevent entry of floating debris. †¢ To avoid formation of air entraining vortices. †¢ To minimize hydraulic losses. †¢ 1. 4. 1 Control of floating debris To prevent the entry of debris a trashrack is placed at the entry to the intake. For small hydro plants the trashrack overall size is determined based on an approach velocity of 0. 75 m/s to 1. 0m/s to facilitate manual raking. Trashracks may be designed in panels that can be lowered into place in grooves provided in the intake walls or permanently attacked to anchors in the intake face. The trashracks should to sloped at 14 ° from the vertical (4V:1H) to facilitate raking. The spacing between bars is determined as a function of the spacing between turbine runner blades. IS 11388 Recommendations for Design of Trashracks for Intakes should be consulted for information about spacing between trashracks bars, structural design and vibration problems. Also, see Section 2. 2. 1/5 of this Standard. 1. 4. 2 Control of Vortices First of all the direction of approach velocity should be axial with respect the intake if at all possible. If flow approaches at a significant angle (greater than 45o) AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  16 from axial these will be significant risk of vortex problems. In such a situation an experienced hydraulic engineer should be consulted and for important projects hydraulic model studies may be required. For normal approach flow the submergence can be determined from the following formulae: S = 0. 725VD0. 5 S D V = submergence to the roof of the gate section (m) = diameter of penstock and height of gate (m) = velocity at gate for design flow. (m/s) Where: A recent paper by Raghavan and Ramachandran discusses the merits of various formulae for determining submergence (S). 1. 4. 3 Minimization of Head losses Head losses are minimized by providing a streamlined transition between the entry section and gate section. Minimum losses will be produced when a streamlined bellmouth intake is used. For a bellmouth intake the transition section is formed with quadrants of ellipses as shown in the following sketch. The bellmouth type intake is preferred when ever the additional costs are economically justified. For smaller, mainly mini hydropower stations, simpler designs are often optimal as the cost of construction of curved concrete surfaces may not be offset by the value of reduction in head losses. Details on the geometry of both types are given †¢ Bellmouth Intake Geometry Geometries for typical run-of-river intakes are shown below: A gate width to height of 0. 785 (D): 1. 00 (H) with H = D is recommended. This permits some reduction in the cost of gates without a significant sacrifice in hydraulic efficiency. There is a second transition between the gate and penstock, rectangular to circular. For a gate having H = D and W= 0. 785D the flow velocity at the gate will be equal to the velocity in the penstock so no further flow acceleration is produced in this section. A length for this transition of 1. x D should be satisfactory. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  17 The head loss co-efficient for this arrangement in Ki =0. 10 Details for layout of bell mouth transitions connecting to a sloping penstock are given in IS9761. †¢ Simplified layout (Mini-Hydro): For smaller/mini hydro project s intake design can be simplified by forming the transition in plane surfaces as shown below: The head loss for this design (Ki) = 0. 19V2/2g. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  18 . 4. 4. AIR VENT An air vent should be placed downstream of the head gate to facilitate air exchange between atmosphere and the penstock for the following conditions: †¢ Penstock filling when air will be expelled from the penstock as water enters. †¢ Penstock draining when air will enter the penstock to occupy the space previously filled by water. The air vent (pipe) must have an adequate cross section area to effectively handle these exchanges of air. The following design rules are recommended: Air vent area should the greater of the following values Where: (m3/s) AV = 0. 0 Ap or QT AV = 25. 0 (m2) AV = cross-section area of air vent pipe AP = cross-section area of penstock (m2) QP = turbine rated flow ( ? QT of m ore than one turbine on the penstock) The air vent should exhaust to a safe location unoccupied by power company employees on the general public. 1. 4. 5 PENSTOCK FILLING A penstock should be filled slowly to avoid excessive and dangerous â€Å"blowback†. The recommended practice is to control filling rate via the head gate. The AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  19 ead gate should not be opened more than 50 mm until the penstock is completely full. (This is sometime referred to as â€Å"cracking† the gate. ) 1. 4. 6 REFERENCES ON PENSTOCK INTAKES: †¢ 1. 4. 7 Indian Standard Cited. IS 9761: Hydropower Intakes – Criteria for Hydraulic Design OTHER REFERENCES †¢ Guidelines for Design of Intakes for Hydroelectric Plants ASCE, New York (1995) †¢ Validating the Design of an Intake Structure : By Narasimham Raghavan and M. K. Ramachandran, HRW – September 2007. â₠¬ ¢ Layman’s Guidebook European Small Hydro Association Brussels, Belgium (June 1998) Available on the internet. †¢ Vortices at Intakes By J. L. Gordon Water Power Dam Construction April 1970 1. 5. TRASHRACKS AND SAFETY RACKS 1. 5. 1 Trashracks: Trashracks at penstock intakes for small hydro plants should be sloped at 4 V: 1H to facilitate manual raking and the approach velocity to the trashracks limited to 1. 0 m/s or less. Use of rectangular bars is normal practice for SHP’s. Support beams should be alignment with the flow direction to minimize hydraulic losses. Detailed trashrack design should be done in accordance with IS 11388. 1. 5. 2 Safety Racks: Safety racks are required at tunnel and inverted siphon entries to prevent animals or people who may have fallen into the canal from being pulled into these submerged water ways. A clear spacing of 200 mm between bars is recommended. Other aspects of design should be in accordance with IS 11388. 1. 5. 3 References on Trashracks IS11388 – â€Å"Recommendations for Design of Trashracks for Intakes†. ASCE (1995) –â€Å"Guidelines for Design of Intakes for Hydroelectric Plants†. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  20 DRAWINGS: AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  21 AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  22 2. HYDRAULIC DESIGN OF WATERWAYS The waterways or water conduction system is the system of canals, aqueducts, tunnels, inverted siphons and pipelines connecting the head works with the forebay tank. This Section provides guidelines and norms for the hydraulic design of these structures. 2. 1 2. 1. 1 CANALS Canals for small hydro plants are typically constructed in masonry or reinforced concrete. Several typical cross section designs are shown below: AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  23 Lined canals in earth, if required, should be designed in accordance with Indian Standard: IS 10430. A further division of canal types is based on function: – Feeder canal to connect the head regulator (intake) to the desilter – Power canal to connect the desilter to the Forebay tank. 2. 1. 2 Feeder Canals 2. 1. 2. 1 Feeder canal hydraulic design shall be based on the following criteria: = Turbine flow (QT) + Desilter flushing flow (QF). Design flow (Qd) AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  24 2. 1. 2. 2 Scouring velocity: A sufficiently high velocity must be provided to prevent deposition of sediment within the canal. This (scouring) velocity can be determined from the following formulae: d 9/7 S C = 0. 66 6 / 7 n = 0. 015 q 1 1 ? VS = . R 2 / 3 . S C/ 2 n Where: Sc = Scouring slope d = Target sediment size (m) q = Flow per unit width (Q/W) (m/s/m) R = hydraulic radius (m) Vs = scouring velocity (m/s) n = Manning’s roughness coefficient 2. 1. 2. 3 Optimization: The optimum cross section dimensions, slope and velocity should be determined by economic analysis so as to minimize the total life time costs of capital, OM and head losses (as capitalized value). The economic parameters for this analysis should be chosen in consultation with the appropriate regional, state or central power authorities these parameters include: – Discount rate (i) – Escalation rate(e) – Plant load factor – Service life in years (n) – Annual O+M for canal (% of capital cost) – Value of energy losses (Rs/kWh). Also see Section 1. 7 of this Standard. The selected design would be based on the highest of Vs or Voptimum. . 1. 2. 4 Freeboard: A freeboard allowance above the steady state design water level is required to contain water safely within the canal in event of power outages or floods. A minimum of 0. 5 m is recommended. 2. 1. 3 Power Canals: Power canal design shall be based on the following criteria a) Design flow = total turbine flow (QT) b) Power canal design should be based on optimization of dimensions, slope and velocity, as explained in the previous section. For mini-hydro plants Q 2. 0 m3/s optimal geometric design dimensions for Type 1 (masonry construction) can be estimated by assuming a longitudinal slope of 0. 04 and a Manning’s n value of 0. 018. Masonry construction would normally be preferred for canals with widths (W) less than 2. 0 m (flow area = AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  25 2. 0 m2). For larger canals with flow areas greater than 2. 0m2, a Type 3, box culvert design would be preferred – based on economic analysis. c) Freeboard: A freeboard allowance above the steady state design level is required to contain water safety within the canal in event of power outages. The waterway in most SHP’s terminates in a Forebay tank. This tank is normally equipped with an escape weir to discharge surplus water or an escape weir is provided near to the forebay tank. For mini-hydro plants a minimum freeboard of 0. 50 m is recommended. The adequacy of the above minimum freeboard should be verified for the following conditions: †¢ Maximum flow in the power canal co-incident with sudden outage of the plant. †¢ Design flow plus margins for leakage losses (+0. 02 to +0. 05 QT) and above rated operation (+ 0. 1QT). †¢ Characteristics of head regulator flow control. The freeboard allowance may be reduced to 0. 5 m after taking these factors into consideration. The maximum water level occurring in the forebay tank can be determined from the weir equation governing flow in the escape weir. 2. 1. 4 Rejection Surge Designs which do not incorporate downstream escape weirs would be subject to the occurrence of a rejection surge in the canal on sudden turbine shutdown, giving above static water levels at the downs tream end, reducing to the static level at the upstream (entry) end of the water way. Methods for evaluating water level changes due to a rejection surge are explained in Section 2. 2. 2 / 7. 0 of this Standard. . 2 AQUEDUCTS Aqueducts are typically required where feeder or power canals pass over a gully or side stream valley. If the length of the aqueduct is relatively short the same channel dimensions as for the canal can be retained and there would be no change in hydraulic design. For longer aqueducts design would be based on economic analysis subject to the proviso that flow remains sub critical with NF ? 0. 8 in the flume sections. The following sketch shows the principal dimension of aqueduct entry and exit transitions and flume section. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  26 The changes in invert elevation across the entry and exit structures can be calculated by Bernouli’s equation as below: †¢ Entry transition – consider cross – section (1) and (2); V2 V2 Z 1 + D + 1 = Z 2 + d + 2 + hL 2g 2g and 2 †¢ b? V ? hL = 0. 10 ? 1 ? ?. 2 ? B ? 2g Z2 can be determined from the above equations, since all geometrical parameters are known. Flume – Sections (2) to (3) The slope of the flume section is determined from Manning’s equation 2 †¢ ? Vn ? ( S ) = ? 2 / 3 ? . A Manning’s n = 0. 018 is suggested for concrete channels. ?R ? Some designers increase this slope by 10% to provide a margin of safety on flow capacity of the flume. Exit transition – consider cross section (3) and (4): V2 V2 Z 3 + d + 3 = Z 4 + D + 4 + hL 2g 2g AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  27 and 2 b? V ? hL = 0. 20 ? 1 ? ?. 3 ? B ? 2g Z4 can be determined from the above equations, since all geometrical parameters are known. The same basic geometry can be adapted for transition between trapezoidal canals sections and rectangular flume section, using mean flow width (B) = A/D. . 3. INVERTED SYPHONS 2. 3. 1 Inverted syphons are used where it is more economical to route the waterway underneath an obstacle. The inverted syphon is made up of the following components: †¢ Entry structure †¢ Syphon barrels †¢ Exit structure †¢ Entry Structure: Hydraulic design of the entry structure is similar to the design of reservoir, canal and penstock intakes. Follow the guidelines given in Section 2. 2. 2/2. of this Standard. †¢ Syphon barrels: The syphon barrel dimensions are normally determined by optimization ? V? ? does not tudies, with the proviso that the Froude Number ? N F = ? gd ? ? ? exceed 0. 8. Invert elevations are determined by accounting for head losses from entry to exit of the structure using Bernouli’s equation. For reinforced concrete channels a Manning’s â€Å"n† value of 0. 018 is recommended. The head loss coefficients for mitre bends can be determined from USACE HDC 228. 2. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  28 AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  29 Exit structure: The exit structure is designed as a diverging transition to minimize head losses; the design is similar to the outlet transition from flume to canal as discu ssed in Subsection 2. 2. 2/2 of this Standard. The following sketches show the layout of a typical inverted siphon. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  30 2. 3. 2 Reference on Aqueducts and Inverted Syphons â€Å"Hydraulic Structures† By C. D. Smith University of Saskatchewan Saskatoon (SK) Canada 2. 4. LOW PRESSURE PIPELINES Low pressure pipelines may be employed as an alternative to pressurized box culverts, aqueducts or inverted syphons. Concrete, plastic and steel pipes are suitable depending on site conditions and economics. Steel pipe is often an attractive alternative in place of concrete aqueducts in the form of pipe bridges, since relatively large diameter pipe possesses significant inherent structural strength. Steel pipe (with stiffening rings, as necessary), concrete and plastic pipe also have significant resistance against external pressure, if buried, and offer alternatives to inverted syphons of reinforced concrete construction. Generally pressurized flow is preferred. The pipe profile should be chosen so that pressure is positive through out. If there is a high point in the line that could trap air on filling an air bleeder valve should be provided. Otherwise, hydraulic design for low pressure pipelines is similar to the requirements for inverted syphons. The choice of type of design; low pressure pipeline land pipeline material), inverted syphon or aqueduct, depends on economic and constructability considerations, in the context of a given SHP. Manning’s â€Å"n† Values for selected Pipe Materials Material Welded Steel Polyethylene (HDPE) Poly Vinyl Chloride (PVC) Asbestos Cement Cast iron Ductile iron Precast concrete pipe Manning’s â€Å"n† 0. 012 0. 009 0. 009 0. 011 0. 014 0. 015 0. 013(2) Note: (1) From Table 5. 4 Layman’s Guide Book – ESHA (2) From Ven T. Chow – Open Channel Hydraulics AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  31 2. 5. TUNNELS 2. 5. 1 Tunnels often provide an appropriate solution for water conveyance in mountainous areas. Tunnels for SHP are generally of two types. †¢ Unlined tunnels †¢ Concrete lined tunnels On SHP tunnels are usually used as part of the water ways system and not subject to high pressures. . 5. 2 Unlined tunnels: Unlined water tunnels can be used in areas of favourable geology where the following criteria are satisfied: a) Rock mass is adequately water tight. Rock surfaces are sound and not vulnerable to erosion (or erodible zones b) are suitably protected. The static water pressure do es not exceed the magnitude of the minor field c) rock stress. Controlled perimeter blasting is recommended in order to minimize over break and produce sound rock surfaces. Additionally, this construction approach tends to produce relatively uniform surfaces and minimizes the hydraulic roughness of the completed tunnel surfaces. Design velocities of 1. 5 to 2. 0 m/s on the mean AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  32 cross section area give optimal cross section design. It is normal practice to provide a 100mm thick reinforced concrete pavement over leveled and compacted tunnel muck in the invent of the tunnel. IS 4880: Part 3 provides additional guidance on the hydraulic design of tunnels and on the selection of appropriate Manning’s â€Å"n† values. 2. 5. 3 Lined Tunnels Where geological are unfavourable it is often necessary to provide concrete linings for support of rock surfaces. IS4880: Parts 1-7 give comprehensive guidelines on the design of lined tunnels. 2. 5. 4 High Pressure Tunnels Design of high pressure tunnels is not covered in this standard. For high pressure design, if required, the designer should consult an experienced geotechnical engineer or engineering geologist. For the purpose of this standard, high pressure design is defined as tunnels subject to water pressures in excess of 10m relative to the crown of the tunnels. 2. 5. 5 Reference on Tunnels IS Standards: IS 4880 â€Å"Code of Practice for the Design of Tunnels Conveying Water†. Other References: Norwegian Hydropower Tunnelling† (Third volume of collected papers) Norwegian Tunneling Society Trondheim, Norway. www. tunnel. no Notably: Development of Unlined Pressure Shafts and Tunnels in Norway, by Einar Broch. 2. 6. CULVERTS AND CROSS-DRAINAGE WORKS Small hydro projects constructed in hilly areas usually include a lengthy power canal routed along a hillside contour. Lateral inflows from streams and gullies intercepted by SHP canals often transport large sediments loads which must be prevented from entering the canal. The first line of defense is the canal upstream ditch which intercepts local lateral runoff. The flow in these chains must be periodically discharged or the drain capacity will be exceeded. Flow from these drains is usually evacuated via culverts passing underneath the canal. These culverts would normally be located where gullies or streams cross the canal alignment. The capacity of canal ditches should be decided taking into consideration the average distance between culverts. In the rare cases when distance between culverts is excessive, consideration should be given to diverting AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  33 itch flows across the canal in flumes or half round pipes to discharge over the downhill side of the canal at suitable locations. Culverts are usually required where the canal route crosses gullies or streams. Culverts at these points provide for flow separation between lateral inflows and canal inflows and often present the most economical solution for crossing small but steep v alley locations. It is recommended that culverts design be based on the following hydrological criteria. †¢ For mini hydro projects, 1 in 10 year flood (Q10) †¢ For small hydro projects, 1 in 25 year flood (Q25) Where it is practical to extract the necessary basin parameters, the procedures given in Section 1. 4 should be applied. Otherwise design flows should be estimated from field measurements of cross section area and longitudinal slope at representative cross section of the gully or side stream. A survivable design approach is further recommended with canal walls strengthened to allow local over topping without damage to the canal integrity when floods exceed the design flood values. Detailed hydraulic design should be based on information from reliable texts or design guidelines – such as: â€Å"Design of Small Bridges and Culverts† Goverdhanlal †¢ †¢ 2. 7 2. 7. 1 â€Å"Engineering and Design – Drainage and Erosion Control†. Engineering Manual EM 1110-3-136 U. S. Army Corps of Engineers (1984) www. usace. army. mil/publications/eng-manuals Manufacturer’s guides, notably: – American Concrete Pipe Association www. concrete-pipe. org â⠂¬â€œ Corrugated Steel Pipe Institute www. cspi. ca Power Canal Surges Power canals that are not provided with escape weirs near their downstream end will be subject to canal surges on rapid load rejections or load additions. The rejection surge will typically cause the downstream water level to rise above static level and may control the design of canal freeboard. For load additions there is a risk that the level will fall to critical at the downstream end and restrict the rate at which load can be taken on by the unit. The following formulae taken from IS 7916: 1992 can be used to estimate the magnitude of canal surges. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  34 Maximum surge height in a power channel due to load rejection may be calculated from the empirical formulae given below: For abrupt closure hmax = K 2 + 2 Kh For gradual closure within the period required for the first wave to travel twice the length of the channel: K hmax = + V . h / g 2 Where: hmax = maximum surge wave height, K = V2/2g = velocity head, V = mean velocity of flow, and area of cross sec tion h = effective depth = top width †¢ Maximum water level resulting from a rejection surge at the downstream of a canal: Maximum W. L. = Yo + hmax †¢ Minimum water level resulting from by a start up surge at the downstream end of a canal: Minimum W. L. = YS – hmax Where: Yo YS = steady state downstream water level static downstream water level. The maximum water level profile can be approximated by a straight line joining the maximum downstream water level to the reservoir level. 2. 7. 2 Canal Surges on Complex Waterways: For waterway systems comprising several different water conductor types, the above equations are not applicable. In such cases a more detailed type of analysis will be required. The U. S. National Weather Service FLDWAV computer program can be used to solved for the transient flow conditions in such cases (Helwig, 2002). 2. 7. 3 References IS Standards cited: IS 7916: 1992 â€Å"Open Channel – Code of Practice†. Other References â€Å"Application of FLDWAV(Floodwave) Computer Model to Solve for Power Canal Rejection Wave for Simple and Complex Cases†. P. C. Helwig Canadian Society for Civil Engineering Proceedings, Annual Conference Montreal, Canada (2002). AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  35 3. HYDRAULIC DESIGN OF DESILTERS 3. 1 BACKGROUND Sediment transported in the flow, especially particles of hard materials such as quartz, can be harmful to turbine components. The severity of damage to equipment is a function of several variables, notably: sediment size, sediment hardness, particle shape, sediment concentration and plant head. The control of turbine wear problems due to silt erosion requires a comprehensive design approach in which sediment properties, turbine mechanical and hydraulic design, material selection and features to facilitate equipment maintenance are all considered (Naidu, 2004). Accordingly the design parameters for desilter design should be made in consultation with the mechanical designers and turbine manufacturer. Where the risk of damage is judged to be high a settling basin (or desilter) should be constructed in the plant waterway to remove particles, greater than a selected target size. 3. 1. 1 Need The first design decision is to determine whether the sediment load in the river of interest is sufficiently high to merit construction of a desilter. There is little guidance available on this topic; however, the following limits are suggested by Naidu (2004): Table 2. 2. 3/1. 0 Concentration Suggested Maximum Allowable Sediment versus Plant Head. Parameter Head Maximum allowable sediment concentration Low and Medium Head Turbines ? 150 m High Head Turbines 150 m 200 ppm 150 ppm 3. 1. 2 Removal Size There are also considerable divergences of opinion on the selection of design size for sediment removal. Nozaki (1985) suggests a size range of between 0. 3 mm to 0. 6 mm for plant heads ranging from 100 m to 300 m. Indian practice is to design for a particles size of 0. 20 m regardless of head. Some authors suggest that removal of particles smaller than 0. 20 mm is not practical. The adoption of 0. 20 mm is the design (target) sediment size is recommended for Indian SHP designs. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  36 3. 1. 3 Types of Desilters There are two basic types of desilters: Continuous flushing type Intermittent flushing type Guidelines for design of both types are given in this section. 3. 2. DESIGN CONSIDERATIONS 3. 2. 1 Data Requirements (Small Hydro Plants) It is recommended that a program of suspended sediment sampling be initiated near the intake site from an early stage during site investigations to ensure that sufficient data is available for design. The sampling program should extend through the entire rainy season and should comprise at least two readings daily. On glacier fed rivers where diurnal flow variations may exist, the schedule of sampling should be adjusted to take this phenomenon into account and the scheduled sampling times be adjusted to coincide with the hour of peak daily flow with another sample taken about twelve hours later. While it is often assumed that sediment load is directly related to flow, this is only true on the average, in a statistical sense. In fact it is quite likely, that the peak sediment event of a year may be associated with a unique upstream event such as a major landslide into the river. Such events often account for a disproportionately large proportion of the annual sediment flow. Therefore, it would also be desirable to design the sediment measurement program to provide more detailed information about such events, basically to increase the sampling frequency to one sample per 1 or 2 hours at these times. A five year long sediment collecting program would be ideal. Less than one monsoon season of data is considered unsatisfactory. Some authors suggest that the vertical variation of sediment concentration and variations horizontally across the river be measured. However, on fast flowing rivers inherent turbulence should ensure uniform mixing and sampling at one representative point should be sufficient. The data collected in a sediment sampling program should include: †¢ Mean daily concentration of suspended sediment (average of two readings twelve hours apart) †¢ Water temperature †¢ Flow (from a related flow gauging program) The following additional information can then be derived from collected samples. AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  37 †¢ †¢ †¢ A sediment rating curve (sediment concentration versus flow – where possible) Particle size gradation curve on combined sample Specific gravity of particles. It is also recommended that a petrographic analysis be carried out to identify the component minerals of the sediment mix. It is likewise recommended that experiments be made on selected ranges of particles sizes to determine settling velocities. A further discussion on the subject of sediment sampling is given in Avery (1989) The characteristics of the sediment on a given river as obtained from a data collection program will assist in selection of appropriate design criteria. 3. 2. 2 Data Requirements (Mini Hydro Plants) On mini hydro projects where resources and time may not be available to undertake a comprehensive sampling program, selection of design parameters will depend to a great extent on engineering judgment, supplemented by observations on site and local information. The following regional formula by Garde and Kothyari (1985) can be used to support engineering decision making. 0. 19 ?P ? 0 Vs = 530. 0 P0. 6. Fe1. . S0. 25 Dd . 10 .? max ? ?P? Where Vs = mean sediment load in (tonnes/km2/year) s = average slope (m/m) Dd = drainage density, as total length of streams divided by catchment area (km/km2) P = mean annual precipitation (cm) Pmax = average precipitation for wettest month (cm) Fe = ground cover factor, as below: 1 Fe = [0. 80 AA + 0. 60 AG + 0. 30 AF + 0. 10 AW ] ? Ai = arable land area AA = grass land area (all in km2) AG AF = forested area AW = waste land area (bare rock) 3. 2. 3 Design Criteria The principle design criteria are: 1. The target size for removal (d): d = 0. 20 mm is recommended 2. Flushing flow: QF = 0. 2 QP is recommended 3. Total (design) flow: QT = QP + QF = 1. 2 QP. Where QP is plant flow capacity in (m3/s). AHEC/MNRE/SHP Standards/ Civil Works – Guidelines For Hydraulic Design Of Small Hydro Plants /May 2011  Ã‚  38 3. 2. 4 Siting The following factors control site selection 1. A site along the water way of appropriate size and relatively level with respect to cross section topography 2. A site high enough above river level to provide adequate head for flushing. For preliminary layout a reference river level corresponding to the mean annual flood and minimum flushing head of 1. 0 m is recommended. In principle a desilting tank can be located anywhere along the water conductor system, upstream of the penstock intake. Sometimes it is convenient to locate the desilting basin at the downstream end of the waterway system where the desilter can also provide the functions of a forebay tank. However, a location as close to the head works is normally pref erred, site topography permitting. 3. 3 Hydraulic Design A desilter is made up of the following elements: †¢ Inlet section Settling tank †¢ Outlet section †¢ †¢ Flushing system 3. 3. 1 How to cite Hydraulic Design of Small Hydro Plants, Essay examples

Wednesday, April 29, 2020

Sale of Goods Act 1979 free essay sample

A look at the rights of the consumer and an assessment of proving whether a retailer is liable for faulty goods. The following paper examines whether a retailer, specifically TV World Ltd. is reliable for faulty tv sets, under the Sale of Goods Act 1979. The writer discusses the case study presented where TV World Ltd., a retail business, advertised a new 28 inch stereo television with teletext. The paper continues to examine how Ms. Hardy bought the television set for $300 but after a month it broke down. This paper asserts that Ms. Hardy signed a clause in the sales contract excluding liability under the Sale of Goods Act. The writer looks at a number of points had to be considered before establishing Ms. Hardys legal position. . Under section 12 of the Sale of Goods Act 1979 we can see that the TV World Ltd does have the right to sell the television in question. We will write a custom essay sample on Sale of Goods Act 1979 or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Section 13 ascertains that there is an implied condition that the goods will correspond with the description. Although Ms Hardy saw the TV in operation before he bought it, we can say that it was still bought by description as she was relying on the TV being a stereo model as described. TV World Ltd argues that as Ms Hardy should have realized that it was not a stereo model as she watched the set in the store. As Ms Hardy is just a consumer, she cannot be an expert in televisions and therefore it would be unfair to say that she should have known. We can see this in Beal v Taylor (1967) 3 ALL ER 253 where the plaintiff had inspected the car before she bought but later realized that it was an earlier model. The Court of Appeal held that the plaintiff was entitled to damages for breach of section 13 as she had relied on the description contained in the advertisement. Similar facts are found in the present situation and the goods have not corresponded to their description so TV World Lt d has breached section 13.

Friday, March 20, 2020

buy custom Hamlets Hesitation essay

buy custom Hamlets Hesitation essay Shakespeare wrote an interesting tragedy, Hamlet. The tragic action in the play originates from a flaw of shame and horror which results to the protagonist suffering intensely. In the play, Hamlet that plays the role of the protagonist has a tragic trait in his character and behavior of uncertainty and delay in action. The protagonist faces two kinds of conflicts. First, he has an inner conflict in the mind and his soul and secondly, he has a physical conflict as he collides with his enemies and opponents. However, the sense of the tragic impression lies in the fact of waste. At the end of the play, a wasted talent and an unnecessary suffering comes out clearly. Why did Hamlet hesitate to act after he promised the ghost of his father that he would avenge his murder on his behalf? In the tragic play, the character of Hamlet stands out as different from that of other characters. His character has a characteristic of strength, will, and passion that has a combination of sentiment and thought. He indulges his imagination and thought to reflect upon terrible nature of crime and refining the schemes that he would use in his revenge mission that to put it into immediate action. His passion reflects a will to think carefully instead of acting in an immediate manner. The son of a murdered noble, Hamlet has an obligation to avenge the death of his father with any chance that comes his way. However, he decides to wait and performs the act at the end of the play. Hamlet does not avenge the death of his father immediately because of certain reasons. Hamlet hesitates to kill King Claudius because he suffered from a form of Oedipus complex and for the fact that he had sanity and practical too perform an act of murder. The basic sanity that Hamlet possessed, kept him from committing an immediate act of murder. In society, people grow to believe that those who commit acts of murder have insanity or some form of sickness. The society where Hamlet lives has no exception from that norm. However, his society believes that the son of a murdered noble has the responsibility of finding those who killed his father and his death. Therefore, Hamlet has an obligation to avenge the death of his father. When the ghost of king Hamlet appeared to Hamlet and told him that Claudius killed him by pouring poison in to his ear, he did not act on the word of the specter immediately. Hamlet does not go to kill King Claudius immediately but instead takes time what the ghost had told him. Hamlet contemplates whether the ghost was good or bad judging by the fact that what the ghost had told him had a serious undertaking that could lead to the death of a person. Hamlet does not want to act stupidly just because a ghost told him that Claudius killed his father. This makes him to try to find out whether the ghost told himthe truth. Hamlet engages himself in plans and carries out analyses of situations. When actors came to town, Hamlet implored one of them to perform a play called the murder of Gonzaga that would happen the next day. Hamlet uses the play as a scheme to find out whether his uncle, King Claudius killed his father. The play that Hamlet requested has similarity to the murder that the ghost described, to him. Hamlet wants to capture the conscience of King Claudius through the play. Hamlet considers that if the manor of King Claudius would change with the play then he would know that he killed his father. This clearly shows that Hamlet did not hesitate to fulfill his commandment because of indecision but rather he wanted to ascertain that the ghost had told him the truth and that if he would carry out the revenge then it would have been on the right person. Hamlet had been plagued by self-doubts. This comes out clearly in the second soliloquy where the essence of the true conflict that Hamlet experienced comes out. He has a commitment to avenging the death of his father, but he cannot act on behalf of his father because he had revulsion towards performing the revenge. The self-condemnation that Hamlet has takes several forms. Hamlet engages in a series of imaginary and demeaning insults that highlights him as cowardly. He feels he has not done anything to King Claudius to avenge the death of his father. This makes him feel as if he has no ability to revenge the death of his father. Hamlet failed to suppress his apprehensions of committing murder. This makes him try to focus on a plan that would ensure that King Claudius admits that he killed his father. Hamlet could not find a way that he could use to confront King Claudius and make him agree that he killed king Hamlet. The only way he could do that required him to formulate a plan that would force King Claudius to confess his actions. Hamlet figures out that because he had no way of confronting king Hamlet, he would make him confess his actions by making King Claudius have a guilty conscience. The hesitation that Hamlet had in avenging for the death of his father has a relation with the Oedipus complex that he had. Hamlet loved his mother in a certain manner. This fact presents itself clearly towards the end of the play. Towards the end of the tragic play, Queen Gertrude drank poison and died. Hamlet responded to that by killing Laertes. The mother of Hamlet had died, and it happened that he decided to kill King Claudius at the same time. Hamlet delayed killing King Claudius because he understood why King Claudius wanted his father out of the way. When his mother died, Hamlet decided to kill King Claudius because without his mother he had nothing much to live for because his life had bed ruined. Without his mother, he had no passion to live. Hamlet hesitated to carry out the revenge because he feared that if King Claudius knew that Hamlet wanted to kill him, he would have made plans to make Hamlet appear bad and would instead kill him. Therefore, he had to delay and look for a proper way that he could use to avenge the death of his father once he knew that king Claudius had murdered his father. Committing a murder was a serious crime in the society that Hamlet lived. Hamlet did not want to kill without purpose because that would have led to his own death. Hamlet has intelligence and has a sense of social duty. He wanted to have the support of the society once he avenged the death of his father. The only way that he could have the support of the society and prevent his own death, he had to display a sense of moral integrity. He decided to use the play to have King Claudius show people that he murdered king Hamlet. Once he proved that, the society would support his revenge mission and he would appear the hero, in his society. This showed that Hamlet delayed the revenge because of a sense of social and moral obligation. Hamlet hesitated to perform his revenge because he relied on morals and had a sense of nobility. As a noble man, he had the responsibility to confirm that his uncle had indeed murdered his father, as an action of proving to the society of his actions and more so, as an action of nobility. Nobility, in the sense that he could not just believe words that came from a ghost. In his third soliloquy, to be or not to be, Hamlet questions whether one should live or not, but it happens as a question of whether he should act or not based on the responsibility he has towards the revenge mission. This has governance from reason, as opposed to frenzied motion. Hamlet faces a state of divide between morality, responsibility and societal nobility. His morals do not allow him to kill, yet as a son, he has the responsibility of avenging the death of his father. At the same time, he has to display a sense of nobility to the society judging by the fact that he is the prince. All these facts make him he sitate because he cannot decide the proper action that he can take in the situation he finds himself. This makes Hamlet spent most of his time thinking instead of acting. He wanted his revenge to display him as a hero in every perspective and display King Claudius as an evil man. In conclusion, Hamlet delayed his revenge against King Claudius mainly because of indecision and self-doubts. He wanted to perform a revenge that would be right in every aspect. Despite the fact that Hamlet hesitated, it did not make him a coward. Rather, his hesitation helped display him as honest, moral and noble because he proved that his uncle killed his father. The death of his mother also quickened his action because of his love for her. 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Wednesday, March 4, 2020

President Franklin D. Roosevelt Biography

President Franklin D. Roosevelt Biography Franklin Roosevelt (1882-1945) served as Americas thirty-second president of the United States. He was elected to an unprecedented four terms and served during the Great Depression and World War II.   Franklin Roosevelts Childhood and Education Franklin Roosevelt grew up in a wealthy family and often traveled overseas with his parents. His privileged upbringing included meeting Grover Cleveland at the White House when he was five. He was cousins with Theodore Roosevelt. He grew up with private tutors before attending Groton (1896-1900). He attended Harvard (1900-04) where he was an average student. He then went to Columbia Law School (1904-07), passed the bar, and decided not to stay on to graduate. Family Life Roosevelt was born to James, a businessman and financier, and Sara Sallie Delano. His mother was a strong-willed woman who did not wish her son to be in politics. He had one half-brother named James.On March 17, 1905, Roosevelt married Eleanor Roosevelt. She was the niece to Theodore Roosevelt. Franklin and Eleanor were fifth cousins, once removed. She was the first First Lady to be politically active, involving herself in causes like Civil Rights. She was later appointed by Harry Truman to be part of the first American delegation to the United Nations. Together, Franklin and Eleanor had six children. The first Franklin Jr. died in infancy. The other five children included one daughter, Anna Eleanor and four sons, James, Elliott, Franklin Jr., and John Aspinwall. Career Before the Presidency Franklin Roosevelt was admitted to the bar in 1907 and practiced law before running for the New York State Senate. In 1913, he was appointed Assistant Secretary of the Navy. He then ran for Vice President with James M. Cox in 1920 against Warren Harding. When defeated he went back to practicing law. He was elected Governor of New York from 1929-33. Franklin Roosevelts Nomination and Election of 1932 In 1932, Franklin Roosevelt won the Democratic nomination for the presidency with John Nance Garner as his Vice President. He ran against incumbent Herbert Hoover. The Great Depression was the backdrop for the campaign. Roosevelt gathered a Brain Trust to help him come up with effective public policy. He campaigned continuously and his apparent confidence made Hoovers meager campaign pale in comparison. In the end, Roosevelt carried 57% of the popular vote and 472 electors versus Hoovers 59. Second Reelection in 1936 In 1936, Roosevelt easily won the nomination with Garner as his Vice President. He was opposed by progressive Republican Alf Landon whose platform argued that the New Deal was not good for America and relief efforts should be run by the states. Landon argued while campaigning that the New Deal programs were unconstitutional. Roosevelt campaigned on the programs effectiveness. The NAACP supported Roosevelt who won an overwhelming victory with 523 electoral votes versus Landons 8. Third Reelection in 1940 Roosevelt did not publicly ask for a third term but when his name was placed on the ballot, he was quickly renominated. The Republican nominee was Wendell Willkie who had been a Democrat but switched parties in protest to the Tennessee Valley Authority. War was raging in Europe. While FDR pledged to keep America out of war, Willkie was in favor of a draft and wanted to stop Hitler. He also focused on FDRs right to a third term. Roosevelt won with 449 out of 531 electoral votes. Fourth Reelection in 1944 Roosevelt was quickly renominated to run for a fourth term. However, there was some question over his Vice President. FDRs health was declining and the Democrats wanted someone they were comfortable with to be president. Harry S. Truman was eventually chosen. The Republicans chose Thomas Dewey to run. He used FDRs declining health and campaigned against waste during the New Deal. Roosevelt won by a slim margin getting 53% of the popular vote and winning 432 electoral votes versus 99 for Dewey. Events and Accomplishments of Franklin D. Roosevelts Presidency Roosevelt spent 12 years in office and had an enormous impact on America. He took office in the depths of the Great Depression. He immediately called Congress to special session and declared a four-day banking holiday. The first Hundred Days of Roosevelts term were marked by the passage of 15 major laws. Some of the important legislative acts of his New Deal included: Civilian Conservation Corps (CCC)- hired more than three million men to work on various projects.Tennessee Valley Authority (TVA)- used the Tennessee River to provide electricity for the depressed area.National Industrial Recovery Act (NIRA)- created the Public Works Administration to provide aid to cities for construction and the National Recovery Administration to help businesses.Securities and Exchange Commission (SEC)- corrected abuses which led to the stock market crash.Works Progress Administration (WPA)- hired many people for a variety of projects including in the arts.Social Security Act - Created the Social Security System. One of the election promises Roosevelt ran on was the repeal of prohibition. On December 5, 1933, the 21st Amendment passed which meant the end of prohibition. Roosevelt realized with the fall of France and the Battle of Britain that America could not remain neutral. He created the Lend-Lease Act in 1941 to help Britain by delivering old destroyers in exchange for military bases abroad. He met with Winston Churchill to create the Atlantic Charter vowing to defeat Nazi Germany. America did not enter the war until December 7, 1941 with the attack on Pearl Harbor. Important victories for the US and the allies included the Battle of Midway, the North African campaign, the capture of Sicily, the island-hopping campaign in the Pacific, and the D-Day invasion. With an inevitable Nazi defeat, Roosevelt met with Churchill and Joseph Stalin at Yalta where they promised concessions to Soviet Russia if the Soviets entered the war against Japan. This agreement would eventually set up the Cold War. FDR died on April 12, 1945 of a cerebral hemorrhage. Harry Truman took over as president. Historical Significance Roosevelts terms as president were marked by bold moves to fight two of the largest threats to America and the world: the Great Depression and World War II. His aggressive and unprecedented New Deal programs left a lasting mark on the American landscape. The federal government grew stronger and became deeply involved in programs traditionally reserved for the states. Further, FDRs leadership throughout World War II led to victory for the Allies even though Roosevelt died before the war ended.

Monday, February 17, 2020

Loving Through Understanding and Finding Peace in Peace, Love & Essay

Loving Through Understanding and Finding Peace in Peace, Love & Misunderstanding - Essay Example Diane brings her children, Zoe (Elizabeth Olsen) and Jake (Nat Wolff) with her. Diane surprises her mother, whom she has alienated for twenty years. What is supposed to be a weekend, where Diane only wanted space from her husband and their divorce, became a full week of awakening for all characters. Diane resolves her conflicts her with her children, her mother, and with herself, by understanding that they are all human beings, and by accepting that they all have weaknesses, she can stop judging them and herself and begin loving with peace. Diane is detached from her children, which creates a barrier between them because she misunderstands their maturity and needs. When she brings them to her mother’s house, her children are asking about the reasons. Jake even jokes that their grandmother is dead since they have not seen her since birth and suddenly they have to meet her. Diane finally drops the bad news that she and Mark are having a divorce. Zoe wants to talk about it, but D iane does not say anything anymore. When Zoe asks, â€Å"Are we going to talk about this,† Diane does not answer and prepares to go in the house. With her back on Zoe, the scene indicates detachment from her children’s concerns. Instead of being open to her children, Diane creates a wall between them without even being aware of it. As a result, Zoe and Jake hardly understand what their mother is going through because they do not even know who she is. The conflict between Diane and her kids arises from her treatment of them as children, instead of as adolescents who are already mature enough to know the truth and to know how to cope with their family issues. The irony is that she is doing to her kids, what her mother did to her- to separate herself from her children because of the feeling that they cannot understand their parent’s concerns and needs.  

Monday, February 3, 2020

Computer networks Essay Example | Topics and Well Written Essays - 3500 words

Computer networks - Essay Example Moreover, Cisco devices deliver integration features that will support compatibility and scalability issues with upcoming applications and services. For addressing, network security, again Cisco firewalls are implemented to protect the network from viruses, worms and probes. In summary, Cisco 3845 integrated service router is implemented for exchanging communication from the local area network interface to the WAN interface. The router provides productivity, integration and enhanced features along with Cisco 3845 (ISR) Site-to-Site VPN Support, Cisco 3845 (ISR) Remote Access VPN Support, Cisco 3845 (ISR) Network Admission Control support, Cisco 3845 (ISR) Digital Voice Call support , Cisco Unified Communication Support and Unified Survivable Remote Site Telephony (SRST) support. Moreover, data switches are also acquired from Cisco named as Cisco Catalyst 3750 that provides enhanced features. Moreover, for wireless networks, Cisco Unified Wireless network featuring Cisco Wireless Cont rol System along with Cisco 4400 Series Wireless LAN Controllers are deployed. Furthermore, the wireless network also supports Cisco Clear air Technology. For remote connectivity and scalability, Cisco service mobility engines are installed. For application support, SOAP and XML Support and Context aware Services are available. In addition, for addressing network security, Cisco ASA 5500 Series Adaptive Security Appliances (For Wired Network), AIP-SSM Intrusion Prevention Module and Wireless Intrusion Prevention System (W IPS) (For Wireless Networks) is operational. Fig 1.1 demonstrates the local area network of an organization below: Figure 1.1 (LOCAL AREA NETWORK) Structure and Cabling The current network is constructed on Star topology that is the most widely adopted topology, as it has many benefits when compared to other topologies. By implementing star topology, network engineers can administer and troubleshoot the network more efficiently and effectively. Star topology provid es a one stop monitoring screen that demonstrates activities on the local area network. Likewise, the cost of implementing and managing the local area network is comparatively low, as less resources and low network downtime occurs. Moreover, network security is addressed efficiently, as monitoring of each system or service is carried out