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Reg. No. : .................................... Name : .........................................
Third Semester B.Tech. Degree Examination, November 2009 (2008 Scheme) Branch : Electrical and Electronics 08.303 : HYDRAULIC MACHINES AND HEAT ENGINES (E) Time : 3 Hours
Max. Marks : 100
Instructions: Answer all questions from Part – A and any one question from each of the Module of Part – B. Include neat sketches wherever necessary. PART – A 1. What are the advantages of an orificemeter over a venturimeter ? 2. Distinguish between Laminar and Turbulent flows. 3. Derive Darcy-Weisbac equation for frictional head loss in a pipe. 4. Why is priming necessary for a centrifugal pump ? 5. Give the comparison between impulse and reaction turbines. 6. What is meant by specific speed of a pump ? Derive an expression for the same. 7. What are the methods used for determining the frictional horse power in IC engines ? 8. What are the main advantages of multi stage compressor ? 9. What is the advantage of regeneration in gas turbines ? 10. Define the volumetric efficiency of an IC engine. How is it measured ? (4×10=40 Marks) P.T.O .
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PART – B MODULE – I 11. a) Prove that the pressure is same in all directions at a point in a static fluid. b) A 1m2, 10 kg flat plate slides down a 30° inclined plane over a 0.1 cm uniform layer of oil, μ = 0.05 Ns/m2. Determine the steady state velocity. 12. a) Obtain Bernoulli’s equation for one dimensional steady flow. State the assumptions. b) A U-tube differential manometer is attached to two sections A and B in a horizontal pipe in which oil of specific gravity 0.8 is flowing. The difference in mercury level is 60 cm, the level nearer to A being the lower one. Calculate the pressure difference (in Pascals) between sections A and B. MODULE – II 13. a) Explain the working of a Francis turbine with the aid of a neat sketch. b) What is meant by acceleration head of a reciprocating pump ? Establish an expression for the acceleration head, discuss its effects on the indicator diagram. 14. a) Derive an expression for the hydraulic efficiency of a Pelton wheel. b) Determine the overall efficiency of a Kaplan turbine developing 2850 kW under a head of 5.2 m. It is provided with a draft tube with its inlet (diameter 3 m) set 1.8 m above the tail race level. A vacuum gauge connected to the draft tube indicates a reading of 5.2 m of water. Assume draft tube efficiency as 75%.
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MODULE – III 15. a) Explain various methods of governing of steam turbines, give merits and demerits of each method. b) The following results were obtained in a trial of a single cylinder four stroke compression ignition engine 11.4 cm bore by 14 cm stroke when running at 1000 RPM. Brake load 60 N at 0.6 m radius, fuel consumption per minute 0.0232 kg of calorific value 42880 kJ/kg. Calculate the thermal efficiency, the brake mean effective pressure, the specific fuel consumption in kilogram per BP kWh when running under the given conditions. 16. a) Explain with a schematic diagram, the working of a closed cycle gas turbine with intercooling and reheating. What is the condition for perfect inter cooling ? b) Air enters the compressor of a gas turbine plant operating on Brayton cycle at 101.325 kPa, 27°C. The pressure ratio in the cycle is 6. Calculate the maximum temperature in the cycle and cycle efficiency. Assume WT = 2.5 Wc where W and W are the turbine and compressor work respectively. Take γ = 1.4. T
c
(20×3=60 Marks) _____________