JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III AEROSPACE PROPULSION- I Previous Question Paper (November/December - 2017 - 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
Answer all questions (25 Marks)
What are the different types of air-breathing engine?
Answer
Air-breathing engines are categorized into two main types: non-rotating engines, which include Ramjets and Scramjets, and rotating engines, which include Turbojets, Turbofans, Turboprops, and Turboshafts.
Draw the schematic diagram of Ramjet engine? Explain about its parts.
Answer
A Ramjet consists of a diffuser, a combustion chamber, and a nozzle. The diffuser slows down incoming supersonic air to subsonic speeds, increasing pressure. Fuel is injected and burned in the combustion chamber, and the high-pressure gas is expanded through the nozzle to produce thrust. It has no moving parts and relies on forward speed for compression.
What do you understand by polytropic process? Draw P-V diagram of it.
Answer
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Explain in brief about the figure of merit? Draw t-s diagram for turbojet engine with reheat.
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With the help of neat sketches explain the characteristics of supersonic inlets?
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What do you mean by surging? What is its impact on performance of engine?
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What do you understand by the term rotating stall? Explain with diagram.
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Why turbine blade cooling is required? Explain types of turbine blade cooling.
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Explain the features of turbine inlet vane.
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Explain the effect of nozzle area on the performance of the aircraft.
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Part B
Answer any one full question from each unit (50 Marks)
Derive an expression of thrust produced by the jet engine. Consider all the necessary assumptions.
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A turbojet operates at 5486 m and moves at Mach 0.80. The area of the exit is 81 m2. The exit pressure is 154.4 × 103 N/m2, and the exit velocity is 590 m/s. The developed thrust is 51892 N and the fuel flow rate is 4.04 kg/s. Find the air mass flow rate. Do this problem for two conditions: First consider the fuel flow to be negligible, then, include the effect of finite fuel flow.
Answer
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What are the assumptions involved parametric cycle analysis of ideal cycle? Explain the steps involved for the turbofan engine.
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An ideal turbofan with an exhausted fan flies at sea level at a Mach number of 0.75. The primary flow is 74.83 kg/s, and the bypass ratio is 1.20. The compressor pressure ratio is 15, whereas that of the fan is 3. The fuel has a heating value of 41,400 kJ/g, and the burner exit total temperature is 1389K. Find the developed thrust and the TSFC if γ = 1.4.
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Discuss with neat sketch i) Thrust vectoring mechanism ii) Thrust reversing mechanism.
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Discuss the cooling methods employed for combustion chamber.
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What do you mean by recirculation–flame stabilization and mixing process? Explain the criteria for engine selection.
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Explain in brief about the Euler’s turbo-machinery equation and flow analysis.
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With the help of sketch describe about the cascade-blade geometry. What are the types of flow losses? Explain.
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Why the requirement is there for the component matching? How it plays an important role in engine performance.
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What do you mean by multi-spooled turbines? Explain the effect of turbine inlet temperature on performance analysis.
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