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Reg. No. : .................................... Name : .........................................
Third Semester B.Tech. Degree Examination, June 2009 (2003 Scheme) 03-306 : FLUID MECHANICS AND MACHINES (N) Time : 3 Hours
Max. Marks : 100
Instructions :1) Answer all questions in Part – A and one full question from each Module in Part – B. 2) Draw neat sketches wherever necessary. 3) Required data may be suitably assumed. PART – A
1. State and explain Newton’s viscosity law. 2. How is local velocity of fluid flow measured using a Pitot tube ? 3. Explain the concept of boundary layer. 4. Schematically show the flow through pipes in parallel and write down the expressions for total discharge and total head loss in terms of individual discharge and head loss. 5. State and explain Buckingham’s π theorem. 6. A jet water, 2.5cm diameter and moving at 15 m/s strikes upon the centre of a symmetrical vane. After impingement, the jet gets deflected through 160° by the vane. Calculate the thrust exerted by jet on the vane, assuming the vane to be smooth. 7. Write down any four differences between impulse and reaction turbines. 8. Explain cavitation in pumps. 9. Draw the performance characteristics of a centrifugal pump. 10. Describe the working of a vane pump. P.T.O.
PART – B
*3104* (3×20=60 Marks)
MODULE – 1 11. a) Discuss the different types of manometers used in pressure measurement.
b) A horizontal conical pipe has end diameters 150 mm and 80 mm. If the rate of water flow through the pipe is 50 lit/s, find the velocity at end sections. Also calculate the intensity of pressure at smaller and if the pressure at larger end is 15 bar. Neglect frictional losses. 10 OR 12. a) Derive the Hagen-Poiseuille equation for laminar flow through a circular pipe.
b) The pressure at the inlet of a pipe is 7 N/mm 2 and the pressure drop is 0.7 N/mm 2. The pipe line is 15 km. If 75 kW is to be transmitted through this line, find the pipe diameter and the efficiency of transmission. Take friction factor f = 0.006. 10 MODULE – 2 13. a) Explain the important dimensionless numbers in fluid mechanics and their practical significance . 10 b) Tests are made in a water tunnel in 1:10 model of a two dimensional cylinder place to ensure similar flow pattern the prototype would experience under 400 km/hr wind velocity at 0 °C. The size of the model piece diameter is 30 mm. Calculate what should be the velocity of water at 40°C in the tunnel ? 10 OR 14. a) Explain the construction and operation of a Francis turbine with the help of a schematic diagram.
b) A double jet pelton wheel operates under a 40 m head and develops 750 kW at 450 rpm. Calculate the flow rate and the diameter of the nozzle jet. Assume overall efficiency as 85% and coefficient of velocity as 0.98. 10
MODULE â€“ 3 15. a) Explain with the help of a schematic diagram the working of a double acting reciprocating pump.
b) A three throw pump has cylinders of 25 cm diameter and stroke of 50 cm each. The pump is required to deliver 100 litres per second of water at a head of 100 m. Friction losses are estimated to be 1 m in suction pipe and 19 m in delivery pipe. Velocity of water in the delivery pipe is 1 m/s, overall pump efficiency is 85% and the slip is 3%. Determine the speed of pump and the power required to run it. 10 OR 16. a) Prove that in an open cylinder the depression of vortex below the original level of still water is proportional to the square of angular velocity of rotation. 10 b) Explain with sketches the working of a single-stage centrifugal pump. ___________________