JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II AUTOMOTIVE ENGINES Previous Question Paper (December - 2018 - R13)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
List out the advantages of four stroke engines.
Answer
Four-stroke engines offer higher thermal efficiency, better fuel economy, and more complete combustion compared to two-stroke engines. They also provide smoother operation due to the power stroke occurring once every two revolutions and exhibit lower exhaust emissions.
What is meant by valve timing diagram? Draw the actual valve timing diagram for the high speed four stroke diesel engine.
Answer
A valve timing diagram is a graphical representation of the exact timing of valve opening and closing events in relation to the piston position (crank angle). For a high-speed diesel engine, the intake valve opens before Top Dead Centre (TDC) (valve lead) and closes after Bottom Dead Centre (BDC) (valve lag). Similarly, the exhaust valve opens before BDC and closes after TDC to ensure efficient scavenging and volumetric efficiency.
List out the functions of the piston rings.
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Explain how the connecting rod is manufactured. What are the different processes involved in the manufacturing processes of connecting rod?
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What are the advantages of petrol injection system?
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List out the functions of injection pumps.
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What is meant by crankcase ventilation?
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Give the detailed classification of lubricating oils.
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What is meant by specific fuel consumption and brake thermal efficiency of the engine?
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Explain the working of the catalytic convertor.
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Part B
What are the objectives of supercharging? How supercharging of two stroke engine is done?
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Explain the working of sterling engine with the neat sketch.
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Explain the working of variable compression engine with the neat sketch.
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Describe about the working principle of W-engine with the neat sketch.
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Describe with suitable sketches Main metering system and Idling systems of the carburetor.
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Explain the working of the fuel feed pump with the neat sketch.
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Explain the working of Zenith carburetor with the neat sketch.
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Explain any one of the petrol injection system with the neat sketch.
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Explain the differences of working of cylinder port and manifold injection systems.
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What are the different types of injection pumps? Explain the working of any one of the injection pump with the neat sketch.
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How the pressure waves produced in the fuel lines? What are the effects of the pressure waves in the fuel lines?
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Explain the working of the multipoint injection system with the neat sketch.
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Explain the working of wet sump lubrication system with the neat sketch.
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Explain the working of Unit injector with the neat sketch.
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Explain about the forced water cooling system with the neat sketches.
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What is the need of oil filter? Explain the working of oil filter.
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Explain the working of three-way catalytic convertor with the neat sketch.
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What is the importance of characteristic graphs of engines? Draw the various characteristic graphs of SI engine.
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A six cylinder, gasoline engine operates on the four stroke cycle. The bore of each cylinder is 80 mm and the stroke 100 mm. The clearance volume per cylinder is 70 cc. At a speed of 4000 rpm the fuel consumption is 20 kg/hr and the torque developed is 150 Nm. Calculate:
the brake power
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the brake mean effective pressure
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brake thermal efficiency if the calorific value of the fuel is 43000 kJ/kg
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the relative efficiency on a brake power basis assuming the engine works on the constant volume cycle. Υ =1.4 for air.
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