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Reg. No. : .................................... Name : .........................................
Third Semester B.Tech. Degree Examination, June 2009
(03 Scheme) 03.305 : FLUID MECHANICS AND HYDRAULIC MACHINES (PU) Time : 3 Hours
Max. Marks : 100
Instructions :1) Answer all questions from Part–A. 2) Answer one question from each Module of Part– B. PART – A 1. Distinguish between a micro manometer and a differential manometer. 2. Explain about hydraulic gradient line for fluid flow through a piping system. 3) What are the advantages of triangular notch over a rectangular notch ? 4) What is the difference between the forces of a jet, when it strikes a stationary blade and a series of moving blades ? 5) Distinguish between a Kaplan and a Propeller turbine. 6) Explain the phenomenon of cavitation in a hydraulic turbine. 7) Explain the term manometric efficiency of a centrifugal pump. 8) What is a plunger pump ? Where is it used ? 9) What is meant by priming in centrifugal pumps ? 10) Explain the significant features of a vane pump ?
(10×4=40 Marks) P.T.O.
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PART – B MODULE – I 11. a) What is the application of a Pitot tube ? With the help of a neat sketch explain the working of a Prandtl Pitot tube ?
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b) What is the critical velocity of flow in a circular pipe ? What are the upper and lower critical velocity values ?
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c) Derive from first principles, Chezy’s formula for loss of head due to friction in a pipe.
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12. a) State and derive Bernoulli’s theorem, mentioning clearly the assumptions underlying it. b) A 30 cm diameter horizontal pipe terminates in a nozzle with the exit diameter of 7.5 cm. If the water flows through the pipe at the rate of 0.15m3/s. What force will be exerted by the fluid on the nozzle ?
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MODULE – II 13. a) Why a Pelton Wheel is suitable for high heads only ? b) How does power output and torque on the shaft of a Pelton Wheel vary with bucket speer ? c) A Pelton Wheel is required to develop 6 MW when working under a head of 300 m. It rotates with a speed of 550 rpm. Assuming jet ratio as 10 and overall efficiency as 85%, find
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i) Diameter of wheel ii) Quantity of water required and iii) Number of jets. Assume suitable values for the velocity coefficient and the speed ratio.
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14. a) Explain the purpose of providing scroll casing and guide vanes for a reaction turbine.
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b) A radially inward flow turbine under a head of 10 m and running at 250 rpm develops 185 kW at the turbine shaft. At inlet tip of the runner vane, the peripheral velocity of the wheel is 0.3 2gH
0.9 2gH
and the radial velocity of flow is
. H being the effective head on the turbine. If overall efficiency of the
turbine is 78% and the hydraulic losses amount to 12% of total head. Find i) Diameter of the runner and its width at inlet ii) Guide blade angle at which water is directed to runner and iii) Inlet angle of the runner vane. Assume that the turbine is a reaction one with radial discharge at outlet.
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MODULE – III 15. a) Define specific speed of a centrifugal pump ? Derive the formula.
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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 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. Find i) Vane angle at inlet ii) Work done by impeller on water/second and iii) Manometric efficiency. 12 16. Write short notes about following : a) Hydraulic Ram b) Selection of pumps c) Deep well pumps d) Gear Pumps.
(4×5=20 Marks) (3×20=60 Marks)
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