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Reg. No. : ..................................... Name : ..........................................

Third Semester B.Tech. Degree Examination, November 2009 (2008 Scheme) 08.303 : FLUID MECHANICS AND MACHINES (MPU) Time : 3 Hours

Max. Marks : 100

Instruction : Answer all questions from Part – A and one full question from each Module of Part – B. PART – A 1. 2. 3. 4. 5. 6. 7.

State Newton’s law of viscosity. Define absolute viscosity of a fluid. What are the limitations of Bernoulli’s equation ? Explain the Reynold’s experiment. Describe the phenomenon of water hammer. Explain velocity of flow and velocity of whirl and state their difference. Describe a scheme of governing Pelton wheel. Explain the term specific speed as applied to hydraulic turbines. Derive the expression for specific speed. 8. Describe Rayleigh method of dimensional analysis. 9. What is manometric efficiency of a centrifugal pump ? 10. Explain the working of a jet pump. (10×4=40 Marks) PART – B MODULE – I 11. a) A rectangular metal plate of size 20 cm × 10 cm, weighing 1 kg f slides over a smooth long inclined plane of slope 15°. The slope is covered with an oil of viscosity 1.50 poise. Find the terminal velocity of the plate over the inclined plane if the thickness of the oil film below the plate is estimated to be 0.2 mm. b) Two pipes of lengths 2500 m each and diameters 80 cm and 60 cm respectively, are connected in parallel. The coefficient of friction for each pipe is 0.006. The total flow is equal to 250 litres/s. Find the rate of flow in each pipe. P.T.O.

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MODULE – III 15. a) What is an air-vessel ? Describe the function of air-vessel with the help of a neat sketch. Prove that the work saved by fitting the air-vessel to the reciprocating pump is 39.2% in case of single acting reciprocating pump. b) A centrifugal pump having outer diameter equal to two times the inner diameter and running at 1000 RPM works against a total head of 40 m. The velocity of flow through the impeller is constant and is equal to 2.5 m/s. The vanes are set back at an angle of 40° at outlet. If the outer diameter of the impeller is 500 mm and width at outlet is 50 mm determine i) Vane angle at inlet ii) Work done by impeller on water per second, and iii) Manometric efficiency. 16. a) Prove that the manometric head of a centrifugal pump running at speed N and giving a discharge Q may be written as Hmano = AN2 + BNQ + CQ2 where A, B and C are constants. b) A double-acting reciprocating pump, running at 50 RPM is discharging 900 litres of water per minute. The pump has a stroke of 400 mm. The diameter of Piston is 250 mm. The delivery and suction heads are 25 m and 4 m respectively. Find the slip of the pump and power required to drive the pump. (20×3=60 Marks) ————————

Branch 08.303 FLUID MECHANICS AND MACHINES (MPU)_0