Hydraulics And Hydraulic Machinery R05220104

Set No. 1

Code No: R05220104

II B.Tech II Semester Regular Examinations, Apr/May 2007 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Differentiate between: i. ii. iii. iv.

Uniform and non uniform flow. Steady and unsteady flow. Laminar and Turbulent flow. Sub critical and Super critical flow in a open channel.

(b) A rough timber flume (n = 0.012) in the form of an equilateral triangle (apex down) of 1.2 metres sides is laid on slope of 0.01. Calculate the uniform flow rate, which occurs at a depth of 90 cm. [4 × 2=8+8] 2. (a) Explain the terms control section and transitional depth (b) A rectangular channel 10m wide carries a discharge of 40m3/s. If at a section in this channel the depth is 1.5m, how far up string or down string from this section will the depth be 2.0m. Take bed slope = 0.00009 and Manning’s coefficient=0.017. [6+10] 3. (a) Explain the terms geometrical, kinematic and dynamic similarities. (b) Give the uses of Buckingham’s pi theorem.

[8+8]

4. (a) Prove that the force exerted by a jet of water on a fixed semi-circular plate in the direction of the jet, when the jet strikes at the center of the semi-circular plate is two times the force exerted by the jet on the fixed vertical plate. (b) A jet of water of diameter 50mm strikes a fixed plate in such way that the angle between the plate and the jet is 300 . The force exerted in the direction of the jet is 1471.5N. Determine the rate of flow of water. [8+8] 5. Design a Francis turbine for the following data. (a) Gross head available = 80m (b) Losses in the penstocks =15% of gross head (c) Speed = 750 rpm (d) Out put power =340 kw (e) Hydraulic efficiency =94% (f) Overall efficiency = 85% Assume 5% of the circumferential area of the runner is occupied by the thickness of vanes. The velocity of flow remains constant throughout. Assume any missing data suitably. [16] 1 of 2

Set No. 1

Code No: R05220104

6. (a) A turbine develops 7460 KW under a head of 25m at 135 rpm. What is the specific speed. What would be its normal speed and power under a head of 18m. (b) What are the components in governing mechanism of a turbine? (c) Distinguish between unit speed and specific speed.

[6+4+6]

7. (a) Explain the classification of centrifugal pumps. (b) A centrifugal pump 20 cm diameter running at 1450 rpm delivers 0.1m3 /s against a head of 40 m with an efficiency of 90%. Determine its specific speed. Derive the formula you use. [8+8] 8. (a) Explain the classification of hydroelectric power plants based on hydraulic features (b) It is contemplated to develop a run-of-river plant on river Krishna. The flow variation of discharge with head was recorded. Plot the power-duration curve. [6+10] Year 1995 1996 1997 1998 1999 2000 2001 2002 2003 Discharge (cumec) 100 180 215 260 325 370 460 600 700

⋆⋆⋆⋆⋆

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Set No. 2

Code No: R05220104

II B.Tech II Semester Regular Examinations, Apr/May 2007 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) What is critical flow? Derive the condition for maximum discharge for a given value of specific energy. (b) The specific energy for a 6 m wide rectangular channel is to be 5 kg-m/kg. If the rate of flow of water through the channel is 24 m3 /s. Determine the alternate depths of flow. [8+8] 2. (a) Define specific force in open channel applying momentum principle, obtain an expression for specific force. (b) A trapezoidal channel of bed width 6m and side slopes 1:1, carries a uniform flow of 25m3 /s. i. Plot a specific energy curve and find the value of critical depth and minimum specific energy. ii. Calculate the alternate depths and their corresponding Froude’s number for a specific energy of 2.5m iii. Determine the depth alternate to 1.5m iv. Determine the type of flow for y=0.5m and y=2.5m. [8+8] 3. In a 1 in 20 model of a stilling basin, the height of the hydraulic jump in the model is observed to be 0.20 metre. What is the height of the hydraulic jump 1 h.p., what is the in the prototype? If the energy dissipated in the model is 10 corresponding value in prototype? [16] 4. A jet of water having a velocity of 60m/sec is deflected by a vane moving at 25m/sec in a direction at 300 to the direction of jet. The water leaves the vane normally to the motion of the vane. Draw the inlet and outlet velocity triangles and find out the vane angles for no shock at entry and exit. Take the relative velocity at the exit as 0.8 times the relative velocity at the entrance. [16] 5. A Pelton wheel has a tangential velocity of buckets of 15 m/sec. The water is being supplied under a head of 36m at the rate of 20 Lps. The bucket deflects the jet through an angle of 1600 . If the coefficient of velocity of the nozzle is 0.98, find the power product by the turbine. [16] 6. (a) A model turbine 1m in diameter acting under a head of 2m runs at 150 rpm. Estimate the scale ratio if the prototype develops 20 KW under a head of 225 m with a specific speed of 100. (b) What are the physical indicators for the presence of cavitation in turbines? [10+6] 1 of 2

Set No. 2

Code No: R05220104

7. (a) Draw a neat sketch of volute type centrifugal pump and explain the functions of its parts. (b) The following are the test results conducted on a centrifugal pump.

[8+8]

Negative pressure head on suction side 22 cms of mercury. Pressure head on delivery side 1.5 kg/cm2 Difference in level between the gauges 0.5 m S.H.P.of motor 32 H.P Discharge 0.1 m3 /s Diameter of suction and delivery pipe 18 cm Calculate overall efficiency of the pump. 8. (a) Differentiate between firm power and secondary power. (b) Two turbo generators each of capacity 25,000kW have been installed at a hydel power station. During a certain period the load on the hydel plant varies from 15,000kW to 40,000kW, calculate i. ii. iii. iv.

the the the the

total installed capacity load factor plant factor and utilization factor. ⋆⋆⋆⋆⋆

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[4+12]

Set No. 3

Code No: R05220104

II B.Tech II Semester Regular Examinations, Apr/May 2007 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Derive the condition for depth of flow of a most economical circular channel section subject to the condition for maximum velocity. (b) Water flows in a channel of the shape of isosceles triangle of bed width ‘a’and sides making an. angle of 450 with the bed. Determine the relation between depth of flow d., and the bed width ‘a’ for maximum velocity and for maximum discharge condition. Use Manning’s formula and note that d is less than 0.5 a. [8+8] 2. (a) Define specific force in open channel applying momentum principle, obtain an expression for specific force. (b) A trapezoidal channel of bed width 6m and side slopes 1:1, carries a uniform flow of 25m3 /s. i. Plot a specific energy curve and find the value of critical depth and minimum specific energy. ii. Calculate the alternate depths and their corresponding Froude’s number for a specific energy of 2.5m iii. Determine the depth alternate to 1.5m iv. Determine the type of flow for y=0.5m and y=2.5m. [8+8] 3. (a) What do you mean by scale effect? (b) Name and discuss the dimension-less numbers generallyused in fluid flow problems. [6+10] 4. (a) Define the term: impact of jets. Obtain an expression for the force exerted by a jet of water on a fixed vertical plate in the direction of the jet. (b) Find the force exerted by a jet of water of diameter 100mm on a stationary flat plate, when the jet strikes the plate normally with a velocity of 30m/sec. [8+8] 5. (a) Draw the inlet and outlet velocity triangles in the case of a Pelton wheel and explain with usual notations. (b) A Pelton wheel working under a head of 250m develops 120BHP at a speed of 250 rpm. If the overall efficiency is 82% and Coefficient of velocity is 0.975, find the jet diameter, the diameter of the bucket circle, the size of the buckets and the number of buckets required. Assume maximum efficiency condition that the peripheral velocity is 0.46times the velocity of the jet. [6+10] 1 of 2

Set No. 3

Code No: R05220104

6. (a) A model turbine 1m in diameter acting under a head of 2m runs at 150 rpm. Estimate the scale ratio if the prototype develops 20 KW under a head of 225 m with a specific speed of 100. (b) What are the physical indicators for the presence of cavitation in turbines? [10+6] 7. (a) Draw a typical layout and explain the working of centrifugal pump. Also indicate various components. (b) Explain the method of selection of centrifugal pumps through the characteristic curves. [8+8] 8. (a) Write down the application of hydroelectric power plants. (b) The following data is available for a hydropower plant, Available head=140m, catchment area=200sq.km, annual average rainfall=1450mm, turbine efficiency =85%, generator efficiency=90%, percolation and evaporation losses=16%. Determine the following i. Power developed ii. Suggest type of turbine to be used if runner speed is to be kept below 240rpm. [4+12] ⋆⋆⋆⋆⋆

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Set No. 4

Code No: R05220104

II B.Tech II Semester Regular Examinations, Apr/May 2007 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Derive the condition for the best side slope of the most economical trapezoidal channel. (b) Design a concrete lined channel to carry a discharge of 500 cumecs at a slope of 1 in 4000. The side slopes of the channel may be taken as 1:1. The Manning’s roughness coefficient for the lining is 0.014. Assume permissible velocity in the section as 2.5 m/s [8+8] 2. (a) Define specific energy?. Sketch the specific energy curve and explain regimes of flow? Indicate the features of critical flow? Deduce the condition for minimum specific energy and the related expressions in rectangular channels? (b) If y1 and y2 are alternate depths in a rectangular channel show that yc = and hence the specific energy E =

y12 +y1 y2 +y22 . (y1 +y2 )

2y12 y22 y1 +y2

[8+8]

3. The resistance   R, to the motion of a completely submerged body is given by R = ρv 2 ℓ2 φ vℓ .where ρ and g are the density and the kinematic viscosity of the fluid γ while l is the length of the body and v is the velocity of flow. If the resistance to the motion of a one-eight scale air ship model when tested in water at 12 metres per second is 22 kg, what will be the resistance to the motion in air of the airship at the corresponding speed? Kinematic viscosity of air is 13 times that of water and density of water is 810 times that of air. [16] 4. (a) State and explain momentum equation. what are the prarctical applications of it. (b) A jet of water 75mm diameter strikes a curved plate at its center with a velocity of 20m/sec. The curved plate is moving with a velocity of 8m/sec in the direction of the jet. The jet is deflected through an angle of 1650 . Assuming the plate to be smooth. Find i. Force exerted on the plate in the direction of jet ii. Power of the jet and iii. Efficiency of the jet.

[8+8]

5. A Pelton wheel is required to develop 12000 kw when working under a head of 300m. It rotates at a speed of 540 rpm. Assuming the jet ratio as 10 and overall efficiency as 84%, calculate (a) The diameter of the wheel (b) The quantities of water required and 1 of 2

Set No. 4

Code No: R05220104 (c) The number of jets.

[16]

6. (a) What is Thoma’s cavitation factor? What is its significance? (b) A Francis turbine working under a head of 5 m at a speed of 210 rpm develops 75 KW when the rate of flow of water is 1.8 m3 / sec. If the head is increased to 16 m, determine the speed, discharge and power. [8+8] 7. (a) If a centrifugal pump does not deliver any water when started, what may be the probable causes and how can they be remedied? (b) The impeller of a centrifugal pump is 35 cm outside diameter and 17.5 cm internal diameter. The vane angles of the impeller at inlet and outlet are 300 and 250 respectively. The pump runs at 1400 rpm. The velocity of flow through the impeller is constant. Find the work done by the impeller per second per kg of water. [6+10] 8. (a) Explain in detail the components of hydroelectric power plants. (b) Differentiate between Storage and Pondage. Support your answer with a neat sketches. [8+8] ⋆⋆⋆⋆⋆

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