Hydraulics And Hydraulic Machinery Rr

Set No. 1

Code No: RR220103

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2007 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Explain the terms section factor, hydraulic mean depth, wetted perimeter and conveyance. (b) A hydraulically efficient trapezoidal channel has side slopes of 1:1. It is required to discharge 14 m3 /s with a gradient (channel slope) of 1 in 1000. If unlined, the value of Chezy’s C is 45. If lined with concrete, the value is 70. If the cost per m3 of excavation is three times, the cost per m2 of lining, will the lined or the unlined channel be cheaper . [8+8] 2. (a) Derive expressions for critical depth, critical velocity. Also derive condition for minimum specific energy in terms of critical depth. [8+8] (b) The discharge of water through a rectangular channel of width 6 m is 18 m3 /S when depth of flow of water is 2 m. Calculate: i. specific energy of the flowing water. ii. critical depth and critical velocity and iii. value of minimum specific energy. 3. Water flows at a steady and uniform depth of 2 m in an open channel of rectangular cross - section having base width equal to 5 m and laid at a slope of 1 in 100. It is desired to obtain critical flow in the channel by providing a hump in the bed. Calculate hump height and sketch the flow profile. Consider the value of Mannings rugosity coefficient n = 0.02 for the channel surface. [16] 4. Using Buckingham‘s Pi theorem show that velocity through a circular orifice is i h √ µ D given by: V = 2gH φ H , ρV H [16] 5. 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] 6. (a) Differentiate between Reaction turbines and hydraulic turbines. (b) Draw a neat diagram of pelton turbine and explain its working.

[8+8]

7. (a) A hydraulic turbine develops 120 KW under a head of 10 m at a speed of 90 rpm and gives an efficiency of 92%. Find the water consumption and the 1 of 2

Set No. 1

Code No: RR220103

specific speed. If a model of scale 1: 30 is constructed to operate under a head of 8m what must be its speed, power and water consumption to run under the conditions similar to prototype. [10] (b) What are the constant head characteristic curves of a turbine? What is the use to develop them? [6] 8. (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] ⋆⋆⋆⋆⋆

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Set No. 2

Code No: RR220103

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2007 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Show that the discharge in a hydraulically most efficient trapezoidal channel is given by: √ Q = 0.56 C b5/2 S Where c is the Chezy‘s constant, b is bottom width and s is the channel slope. (b) A rectangular channel 4 m wide has depth of water 1.5 m. The slope of the bed of the channel is 1 in 1000 and value of Chezy‘s constant C = 55. It is desired to increase the discharge to a maximum by changing the dimensions of the section for constant area of cross-section, slope of the bed and roughness of the channel. Find the new dimensions of the channel and increase in discharge. [8+8] 2. (a) Show that the discharge formula for a trapezoidal channel having Manning?s coefficient n = 0.0126 and carrying maximum flow is given by : √ z  1/2 Q = 100y8/3 1 + z 2 − S0 2 Where Q is discharge in cubic meters per second, y is depth of flow in the channel of side slope 1 vertical to Z horizontal and S0 is the bed slope of the channel. (b) A field drain of triangular section has side slopes of 1 upon 2 and carries water at a normal depth of 0.75m. Chezy’s C for the channel is 45. Determine the longitudinal slope of the drain for a discharge of 1.2 cumecs. Determine the Froude number and identify the state of flow. Assume α= 1.16. [8+8] 3. Water flows at a steady and uniform depth of 2 m in an open channel of rectangular cross - section having base width equal to 5 m and laid at a slope of 1 in 100. It is desired to obtain critical flow in the channel by providing a hump in the bed. Calculate hump height and sketch the flow profile. Consider the value of Mannings rugosity coefficient n = 0.02 for the channel surface. [16] 4. Prove that the resistance F of a sphere of diameter d moving at a constant speed ν through h ia fluid of density ρ and dynamic viscosity µ may be expressed as F = µ2 [16] φ vdρ ρ µ 5. (a) State and explain momentum equation. what are the prarctical applications of it. [8+8]

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Set No. 2

Code No: RR220103

(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. 6. A Pelton wheel working under a head of 500m has an overall efficiency of 85% and runs at 400 rpm, and developes 7000 kw of power. Taking the bucket speed as 0.47 times the jet speed and assuming Cv = 0.97, find [16] (a) The wheel diameter and (b) The jet diameter 7. (a) What are the conditions for the kinematic similarity to exist between model and prototype? (b) How do you compare the performance of a turbine under different working conditions? [8+8] 8. (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] ⋆⋆⋆⋆⋆

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Set No. 3

Code No: RR220103

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2007 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Discuss the factors affecting Chezy‘s c and Manning‘s n. What are the different values of ‘n’ for different surfaces? (b) Determine the dimensions of an economical Trapezoidal section of an open channel with sides slope 2H:1V laid at a slope of 1 in 1600 to carry a discharge of 36 cumecs assuming chezy‘s coefficient C = 50. [8+8] 2. (a) Discuss the significance and utility of the concept of the specific energy in the study of open channel problems. (b) In a rectangular channel 3.5 m wide laid at a slope of 0.0036, uniform flow occurs at a depth of 2 m. Find how high can the jump be raised without causing afflux? If the upstream depth of flow is to be raised to 2.5 m, what should be the height of the jump? Take Manning?s n equal to 0.015. [8+8] 3. How are various surface profiles in gradually varied flow classified depending on the relative magnitude of actual depth (d), normal depth (do ) and critical depth (dc ). [16] 4. Explain in detail about Rayleigh‘s method of dimensional analysis. What are the practical uses. [16] 5. 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] 6. 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] 7. (a) Where is servo meter used in governing mechanism of turbines? Explain its use? (b) A Kaplan turbine is to develop 2400 KW when running at 240 rpm under a net head of 49m. In order to predict its performance a model of scale 1:5 is tested under a net head of 25m. At what speed should the model run and what power would it develop. Determine the discharge in the model and in full scale turbine if the overall efficiency of the model is 85%. [8+8] 1 of 2

Set No. 3

Code No: RR220103 8. (a) What is meant by priming of a pump. Explain.

(b) A 3-stage centrifugal pump has impellers 37.5 cm dia and 1.8 cm wide at outlet. The outlet vane angle is 450 and the vanes occupy 8% of the outlet area. The manometric efficiency is 84% and the overall efficiency is 75%. What head the pump will generate when running at 900 rpm discharging 60 lps ? What is the input h.p ? [8+8] ⋆⋆⋆⋆⋆

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Set No. 4

Code No: RR220103

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 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 do you mean by most economical section of a channel. What are the conditions for the rectangular channel of the best section? (b) Determine the dimensions of the most economical trapezoidal earth-lined channel (Manning-s n = 0.02) to carry 14 m3 /s at a slope of 4 in 10,000. [8+8] 2. (a) What is Froude number? Show that in an open channel flow minimum specific energy at a given flow and maximum flow at a given specific energy occurs when Froude number is unity. (b) For purpose of discharge measurement, the width of a rectangular channel is reduced gradually from 3m to 2m and floor is raised by 30cm at a given section. When approaching depth of flow is 2m, what rate of flow will be indicated by a drop of 15cm in the water surface elevation at the contracted section? [8+8] 3. Water flows at a steady and uniform depth of 2 m in an open channel of rectangular cross - section having base width equal to 5 m and laid at a slope of 1 in 100. It is desired to obtain critical flow in the channel by providing a hump in the bed. Calculate hump height and sketch the flow profile. Consider the value of Mannings rugosity coefficient n = 0.02 for the channel surface. [16] 4. 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] 5. A jet of water of diameter 50mm having a velocity of 20m/sec strikes a curved vane which is moving with a velocity of 10m/sec in the direction of the jet. The jet leaves the vane at an angle of 600 to the direction of motion of the vane at outlet. Determine [16] (a) The force exerted by the jet on the vane in the direction of motion and (b) Work done per second by the jet. 6. An inward flow reaction turbine has inner and outer diameter of the wheel as 350mm and 750mm respectively. The vanes radial at inlet and the discharge is radial of outlet. The water enters the vane at an angle of 120 . Assuming the velocity of flow to be constant and equal to 3.5m/sec, find [16] (a) The speed of the wheel and 1 of 2

Set No. 4

Code No: RR220103 (b) The vane angle at outlet.

7. (a) What are the requirements of a good surge tank so that the efficiency of hydropower installation is maximum? (b) How is the Kaplan turbine governed? Explain with a neat diagram. 8. (a) What are the different types of pumps ?

[8+8] [4]

(b) State the difference between a turbine and a pump.

[4]

(c) Derive the Euler head equation for a centrifugal pump.

[8]

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