R05220104-hydraulics-and-hydraulic-machinery

Set No. 1

Code No: R05220104

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Give complete classification of the different types of open channel flow. (b) Water flows uniformly at a depth of 1.2 meters in a rectangular canal 3 metres wide laid on a slope of 1 metre per 1000 metres. What is the mean shear stress on the sides and bottom of the canal? Based on the Reynolds and Froude numbers, determine the type of flow in the canal. Take Chezy C as 70 and v = 10−6 m2 /S. [8+8] 2. Explain the phenomenon of hydraulic jump and the significance of froude number. Derive the required equations. [16] 1 scale model was tested in order to determine the resistance of the prototype 3. A 20 ship. The model has a wetted area of 2.75 metre2 . The prototype velocity is 3.50 metres per second in sea water of density 1.04 gm/cc. When the model was moved at the corresponding speed, the total resistance was found to be 3.20 kg. The skin resistance of the model in fresh water is 0.00945 v 1.9 kg/metre2 and that of the ship in sea water is 0.00902 v 1.85 kg/metre2 . Calculate:

(a) The corresponding speed of the model and (b) The total resistance of the ship.

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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. 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) 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) What is meant by priming of a pump. Explain. 1 of 2

Set No. 1

Code No: R05220104

(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] 8. (a) What is meant by flow duration curve and power duration curve? How do you differentiate these? How would you construct such curves? (b) Why hour to hour or day to day fluctuations occur in supply or demand to the turbine? [8+8] ⋆⋆⋆⋆⋆

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Set No. 2

Code No: R05220104

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 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) Write down the uses of hydraulic jump (b) Define rapidly varied flow and gradually varied flow (c) Derive the equation for specific energy curve.

[4+4+8]

3. (a) What do you mean by model testing? What are pre requisites for model testing? (b) Properties of a structure can be calculated by analytical method and by model analysis, which is more suitable. Why? [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. The following data pertain to a Kaplan turbine Power available at shaft=8850kW, Net available head = 5.5m, Speed ratio = 2.1, Flow ratio=0.67, Overall efficiency = 85%, Assuming that hub diameter of the wheel is 0.35times the outside diameter, determine (a) runner diameter (b) runner speed.

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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) What are the various expressions for the manometric head? (b) Explain i. ii. iii. iv.

Impeller horse power Monometric efficiency Mechanical efficiency Overall efficiency.

as applicable to a centrifugal pump. (c) The centrifugal pump running at 750 rpm delivers 60 l/s against a head of 20 m. Find the discharge and head of the same pump when running at 1200 rpm. Compare the power consumed in both cases. [4+4+8] 8. (a) What area the essential stream flow data for water power studies. (b) What is mass curve? Explain the procedure for preparing a mass curve and also its uses. [6+10] ⋆⋆⋆⋆⋆

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Set No. 3

Code No: R05220104

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 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 conditions for the most economical triangular channel section. (b) A sewer pipe is laid on a slope of 1 in 3000 and is to carry 2.5 m3 /s when the pipe flows full. What size pipe should be used if n in Manning formula is 0.015? [8+8] 2. (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] 3. Assuming that the viscous force F exerted by a fluid on a sphere of diameter D depends on the viscosity µ, mass density of the fluid “ρ”, and the velocity of the sphere ν, obtain and expression for the viscous force. [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) Draw the inlet velocity and outlet velocity triangles in case of a Pelton Wheel (b) A 137mm diameter jet of water issuing from a nozzle impinging on the buckets of a Pelton wheel and the jet is deflected through an angle of 1650 by the buckets. The head available at the nozzles is 400m. Assuming coefficient of velocity as 0.97, speed ratio as 0.46, reduction in relative velocity while passing through buckets as 15%, find i. the force exerted by the jet on buckets in tangential direction ii. the power developed.

[6+10]

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) What are the limitations for installing a centrifugal pump above the liquid surface in the sump?

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Set No. 3

Code No: R05220104

(b) A centrifugal pump has to work against a head of 25 m at a speed of 850 rpm. The flow component of the velocity at outlet is 2.5 m/s. The outlet vane angle is 400 . If the discharge of the pump is 0.25 cumec find i. The diameter of the impeller and ii. The width of impeller at outlet. Neglect losses.

[6+10]

8. Explain in detail about high head diversion power plants along with its components? [16] ⋆⋆⋆⋆⋆

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Set No. 4

Code No: R05220104

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 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 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] 2. Derive the dynamic equation for gradually varied flow. Explain the assumptions made. [16] 3. By dimensional analysis obtain an expression for the drag force R on a partially submerged body moving with a relative velocity V in a fluid; the other variables being the linear dimension l , height of surface roughness K, fluid density ρ, and the gravitational acceleration g. [16] 4. 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 (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.

[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) 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] 7. (a) Explain how the discharge, head and power of a pump vary as the speed of the pump is varied.

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Set No. 4

Code No: R05220104

(b) A centrifugal pump discharges 0.15 m3 /s of water against a head of 12.5m, the speed of the impeller being 600 rpm. The outer and inner diameters of the impellers are 500 mm and 250 mm respectively. The vanes are bent back at 350 to the tangent of the exit. If the flow area remains 0.07 m2 from inlet to outlet, find: [8+8] i. the manometric efficiency of the pump ii. the vane angle at inlet. 8. (a) How are the load factor, capacity factor and utilization factor interrelated? What is the significance of diversity factor? (b) Why is it necessary to predict the future load demand? What are the methods of load forecasting? [10+6] ⋆⋆⋆⋆⋆

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