JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III Year AIRCRAFT PROPULSION Previous Question Paper (March - 2024 - R18)
Note: Part A is compulsory (25 Marks). In Part B, answer any one question from each unit (10 Marks each).
Part A
Answer all questions:
List different types of airbreathing engines.
Answer
Airbreathing engines are classified based on their method of compression and cycle operation:
- Ramjet
- Scramjet
- Turbojet
- Turbofan
- Turboprop
- Turboshaft
- Pulsejet
Explain the principle of operation of gas turbine engine.
Answer
The gas turbine engine operates on the Brayton cycle, which consists of four continuous processes:
- Compression: Atmospheric air is drawn in and compressed by the compressor, increasing its pressure and temperature.
- Combustion: Fuel is injected into the compressed air and ignited in the combustion chamber, leading to a constant-pressure heat addition process.
- Expansion: The high-energy, high-temperature gas expands through the turbine, which extracts work to drive the compressor.
- Exhaust: The remaining energy in the gas is converted into kinetic energy through a nozzle to produce thrust.
Classify combustion chambers based on their design and operating principles.
Answer
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Explain the concept of shock swallowing in the context of area variation in supersonic inlets.
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What are the conditions at the throat of a nozzle?
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Define nozzle efficiency and its significance.
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List different types of aerofoil profiles used for axial compressor blades shapes.
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Explain on the significance of solidity and aspect ratio of compressor blade.
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What are the flame stability problems in ramjet combustors?
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Show possible different types of velocity diagrams.
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Part B
Explain the basic principles of operation for ramjet engines. Discuss their advantages and limitations in specific flight regimes.
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A turbojet engine operates at 20000 ft altitude moving at a speed of 260 m/s. It ingests 80 kg/s of air and has negligible fuel flow. Exit diameter of nozzle is 750 mm. Gas has exit velocity 800 m/s and pressure 0.5 bar. Find thrust developed.
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Explore the relationship between minimum area ratio and external deceleration ratio in inlets. Discuss their influence on the efficiency of the inlet.
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Define combustion chamber performance and discuss the key parameters used to evaluate its efficiency. Explore the significance of combustion chamber performance in overall propulsion system efficiency.
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Explore the characteristics of over-expanded and under-expanded nozzles, including their effects on thrust and efficiency. Discuss the conditions under which these phenomena occur.
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Discuss the role of variable area nozzles in propulsion systems. Explore how they are utilized to optimize performance under varying operating conditions.
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Flow enters axial compressor at an angle of 20 degrees with a velocity 120 m/s. Rotor mean speed is 280 m/s. If hub tip radius ratio is 0.5, draw velocity triangles at mean, hub, and tip locations, assuming 50 % degree of reaction.
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Illustrate the working of axial flow compressor. (Make use of equations, diagrams, and charts).
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Compare and contrast free vortex and constant angle designs of axial flow turbines, discussing their respective characteristics and applications.
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Hot products of burner enter axial flow turbine that has blade height 0.13 m, and blade hub diameter 0.59 m. Stagnation temperature and pressure of hot gases are 1310 K and 3.7 bar. The speed of turbine rotor is 1150 rpm. Stage has DOR 50%, blade loading factor 2.7 and flow coefficient 0.65 at mean radius. Draw stage blade profiles and velocity polygons.
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