Hydraulics And Hydraulic Machinery Rr220103

Set No. 1

Code No: RR220103

II B.Tech II Semester Supplimentary 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) Explain the term‘s specific energy of a flowing liquid, minimum specific energy, critical depth, critical velocity and alternate depths as applied to non-uniform flow. (b) A river is 30 m wide and has a rectangular shape. At a bridge location the flow width is restricted to 25 m by the piers of the bridge and the river bed is approximately horizontal. Describe the flow, which obtains underneath the bridge with minimum upstream depth when a flood of 450 m3 /s flows in the river. Also determine the upstream depth. [8+8] 3. (a) What is direct method of finding length of water profile in open channel. (b) Water at a velocity of 8 m/s and at a depth of 1 m is flowing through a rectangular channel 8 m wide. Determine whether a hydraulic jump will occur, and if so, calculate the depth of water after the jump and power lost. [8+8] 4. (a) What do you mean by dimensionally homogenous equation? (b) What is meant by hydraulic similarity between a model and prototype. [8+8] 5. A jet of water having a velocity of 20m/sec strikes a curved vane, which is moving with a velcity of 10m/sec. The jet makes an angle of 200 with the direction of motion of vane at inlet and leaves at an angle of 1300 to the direction of motion of the vane at outlet. Calculate [16] (a) Vane angles, so that the water enters and leaves the vane without shock (b) Work done per second per unit weight of water striking the vane. 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]

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Set No. 1

Code No: RR220103 (a) The speed of the wheel and (b) The vane angle at outlet.

7. (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. [10] (b) What are the physical indicators for the presence of cavitation in turbines? [6] 8. (a) What is meant by priming of a centrifugal pump ? What are the different priming arrangements employed for small and big pumping units ? (b) A centrifugal pump works against a head of 30 m and discharges 0.25 m3 /s while running at 1000 rpm. The velocity of flow at the outlet is 3 m/s and the vane angle at outlet is 300 . Determine the diameter and width of impeller at outlet if the hydraulic efficiency is 80 per cent. [8+8] ⋆⋆⋆⋆⋆

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Set No. 2

Code No: RR220103

II B.Tech II Semester Supplimentary 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 are the empirical formulae for determining the value of Chezy‘s constant and what is the relation between Manning‘s constant and Chezy‘s constant. (b) A certain stretch of lined trapezoidal channel has one vertical side wall and the other 450 sloping wall. If it is to deliver water at 30 m3 / sec with a velocity of 1 m/sec, compute bed width and flow depth for minimum lining area. [8+8] 2. (a) What is specific energy curve? Explain it in detail along with a neat sketch. (b) A rectangular channel of width 4 m carries a discharge of 10 m3 /S. Plot the specific energy diagram and use it to find the critical depth and alternate depth to a depth of 0.7 m. What is the specific energy for this depth Assume α = 1.09. Use the following depths of flow for computations and drawing the graph: 0.6, 0.7, 0.8, 1.1 and 1.4 m [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. (a) Explain the terms geometrical, kinematic and dynamic similarities. (b) Give the uses of Buckingham‘s pi theorem.

[8+8]

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. An outward flow reaction turbine has inner and outer diameter of the wheel as 1000mm and 2000 mm respectively. The water enters the vane at an angle of 200 and leaves the vane radially. If the velocity of flow remains constant at 10m/sec and the speed of the wheel is 300rpm, find the vane angles at inlet and outlet.[16] 7. (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. [10] (b) What are the physical indicators for the presence of cavitation in turbines? [6]

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Set No. 2

Code No: RR220103

8. (a) Draw typical characteristic curves for a centrifugal pump at constant speed and explain how the specific speed is determined from these curves. (b) The impeller of a centrifugal pump has 1.2m outside diameter. It is used to lift 1.8 m3 /s of water to a height of 6m. Its blades make an angle of 1500 with the direction of motion at outlet and runs at 200 rpm. If the radial velocity of flow at outlet is 2.5m/s, find the useful H.P and efficiency. [8+8] ⋆⋆⋆⋆⋆

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Set No. 3

Code No: RR220103

II B.Tech II Semester Supplimentary 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) 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. 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 [16] given by: V = 2gH φ H , ρV H 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 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. [10] (b) What are the physical indicators for the presence of cavitation in turbines? [6]

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Set No. 3

Code No: RR220103

8. (a) Why is priming necessary for centrifugal pumps ? What are the various methods of priming a centrifugal pump ? [8+8] (b) A centrifugal pump delivers 10 litres of water per second under a head of 20 m. The speed of the shaft is 1200 rpm. Find its specific speed. ⋆⋆⋆⋆⋆

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Set No. 4

Code No: RR220103

II B.Tech II Semester Supplimentary 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) Show that relation between the alternate depths y1 and y2 in a rectangular channel can be expressed by: 2Y12 Y22 = Yc3 (y1 + y2 ) (b) A trapezoidal channel has a bed width of 5 m, side slopes of 1 upon 1.5 and Manning‘s n = 0.015. Compute the critical slope and the corresponding discharge for a critical depth of 2 m. [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. The efficiency η of a fan depends on the density ρ, the dynamic viscosity µ of the fluid, the angular velocity ω, diameter D of the rotor and the discharge Q. Express η in terms of dimensionless parameters. [16] 5. A jet of water having a velocity of 20m/sec strikes a curved vane, which is moving with a velcity of 10m/sec. The jet makes an angle of 200 with the direction of motion of vane at inlet and leaves at an angle of 1300 to the direction of motion of the vane at outlet. Calculate [16] (a) Vane angles, so that the water enters and leaves the vane without shock (b) Work done per second per unit weight of water striking the vane. 6. (a) Draw the typical layout of hydroelectric power plant and explain its components. (b) What are the types of efficiencies associated with turbines? 1 of 2

[8+8]

Set No. 4

Code No: RR220103

7. (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] 8. (a) Define specific speed of a centrifugal pump. What is its significance.

[8]

(b) A centrifugal pump discharges 1200 lit/minute against a head of 16.5 m when the speed is 1500 rpm. The diameter of the impeller is 35 cm and the power required is 6 h.p. A geometrically similar pump of 45 cm is to run at 1750 rpm. Assuming equal efficiencies, find [8] i. the head developed ii. the discharge and iii. power developed by the 45 cm pump. ⋆⋆⋆⋆⋆

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