JNTU
JNTU B.Tech III Year AEROSPACE PROPULSION- II Previous Question Paper (May - 2019 - R15)
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.
Part A
Differentiate between a rocket and a missile
Answer
A rocket is a vehicle or device propelled by the reaction of ejected exhaust gases, typically carrying its own oxidizer. A missile is a guided weapon system that uses rocket propulsion (or jet propulsion) to deliver a payload to a specific target.
Explain the importance of specific thrust.
Answer
Specific thrust is defined as the thrust produced per unit mass flow rate of air. It is a critical performance parameter because it indicates the efficiency of the engine in converting the kinetic energy of the incoming air and the energy released by fuel combustion into useful propulsive force. Higher specific thrust allows for smaller, lighter engines for a given mission requirement.
What are the limitations of ramjet engines?
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Draw the line diagram of air turbo-rocket (ATR)?
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Mention the typical values of specific impulse for different chemical rockets
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How do you assure guaranteed minimum performance of chemical rocket engines?
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What do you understand by ‘buzzing’ combustion instability
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Mention the principal components solid propellant rocket motors.
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What are the advantages of magneto plasma dynamic (MPD) over pulsed plasma (PPT) thrusters?
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Classify the types of electric propulsion systems.
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Part B
Describe various types of rocket engines and the concept of staging of rockets.
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Define specific thrust, specific impulse, internal efficiency, propulsive efficiency of a rocket propulsion system. Write the expressions for them.
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What are the advantages and disadvantages of Integral Ram-rocket over a simple ramjet engine? What are the applications of an Integral ram-rocket?
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A ramjet is to propel an aircraft at Mach 3 at high altitude where the ambient pressure is 8.5 kPa and the ambient temperature Ta is 220 K. The turbine inlet temperature T is 2540 K. If all components are ideal, i.e. frictionless determine the following:
a) The thermal efficiency
b) The propulsion efficiency
c) The overall efficiency
Let the specific heat ratio be 1.4 and fuel-to-air ratio, f = 0.03.
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Define the following quantities; explain the significance of each quantity. Write down their formulas and units:
a) Specific impulse
b) Total impulse
c) Average impulse
d) Impulse to weight ratio
e) Specific propellant consumption.
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What are the engine parameters that can affect the performance of chemical rocket?
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The following data relates to composite solid propellant: Specific impulse = 240 sec at sea level and 1000 psi, Burning rate = 1.0 in/sec at 1000 psi and 600 F, Specific weight = 0.066 lb/in3, Specific heat ratio = 1.25, Chamber pressure = 1000 psi, Desired average thrust = 20000 lb, Maximum vehicle diameter = 16 in, Desired duration = 5.0 sec, Ambient pressure = 3 psi (at altitude), Vehicle payload = 5010 lb, Thrust coefficient = 1.73. Make a preliminary determination of:
a) Propellant weight & volume
b) Web thickness
c) Wall thickness
d) Grain configuration
e) Nozzle design.
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Explain the process of combustion in a liquid propellant rocket motor. Explain the various factors affecting the combustion process.
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Describe the principles of electro static thrusters and the ionization schemes used there in.
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How plasma propulsion differs from ion propulsion? Explain a typical plasma propulsion system with the help of a suitable diagram.
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