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Reg. No. : ..................................... Name : ..........................................
Third Semester B.Tech. Degree Examination, November 2009 (2003 Scheme) Branch : Production 03.305 : FLUID MECHANICS AND HYDRAULIC MACHINES (PU) Time : 3 Hours
Max. Marks : 100
Instruction : Answer all questions from Part A and any one question from each Module of Part B. PART – A 1. Prove that fluid pressure at a point has the same magnitude in all directions. 2. Differentiate between static, differential and dynamic pressures. 3. Explain the reasons for the coefficient of discharge of a venturimeter to be greater than that of an orificemeter. 4. Write the uses of a draft tube in reaction turbines. 5. What are the causes and effects of cavitation in a turbine ? 6. What are the factors to be considered for the selection of a hydraulic turbine ? 7. Explain the uses of air vessels. 8. Which type of pump is used for pumping muddy water ? Why ? 9. Explain the working of a gear pump. 10. Explain the principle of operation of a hydraulic ram.
(10Ă—4=40 Marks) P.T.O.
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PART – B MODULE – I 11. a) Describe the working of Bourdon’s pressure gauge with the help of a neat sketch. b) A venturimeter with a 15 cm diameter at inlet and 10 cm throat is used for measuring the flow of oil of specific gravity 0.8. The oil mercury differential manometer shows a gauge difference of 20 cm. Calculate the discharge through the orifice assuming the venturimeter to be horizontal. 12. a) The variation of velocity of flow through a flat plate is given by u = 0.9y + y3. Find the shear stress at y = 0.5 m and 0.7 m. Assume the viscosity of the fluid to be 1.3 N-s/m2. b) A cylindrical tank of diameter 1 m and depth 0.3 m contains water to half its depth. At what horizontal acceleration will the tank start spilling water ? What will be the maximum pressure at the bottom of the tank when the water starts spilling ? MODULE – II 13. Draw the velocity triangles at the inlet and outlet of a radial curved vane. Derive the expression for the efficiency of the radial curve vane. 14. a) Explain the classification of hydraulic turbines. b) Starting from fundamentals, derive the relation for maximum hydraulic efficiency of a Pelton wheel. MODULE – III 15. A single acting reciprocating pump is used to raise a liquid of specific gravity 1.2 through a vertical height of 12 m from 3 m below pump axis to 9 m above it. The plunger has a diameter of 125 mm and stroke of 225 mm. The suction and delivery pipes are 75 mm diameter and having lengths 3.5 m and 14 m respectively. There is an air vessel placed on the delivery pipe near the pump axis. If separation takes place at 0.8 bar below atmospheric pressure, find :
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a) the maximum speed with which the pump can run without separation b) power required to run the pump if there is no slip for the pump and the coefficient of friction is 0.02. 16 a) Explain the operating characteristic curves of a centrifugal pump. b) The diameter of a centrifugal pump which is discharging 0.04 m3/s of water against a total head of 21 m is 0.42 m. The pump is running at 1600 r.p.m. Find the head, discharge and ratio of powers of a geometrically similar pump of diameter 0.25 m which is running at 3200 r.p.m. (3×20=60 Marks)
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