GATE AE Engine Performance PYQs & Answers

Questions 1–10 of 20. Imported answers require independent review unless marked reviewed.

For a given air-standard power, the propulsive efficiency of a turbofan engine is more than that of a turbojet engine. Which of the following is/are the reason(s) for this?

Your answerSelect all correct options. You can choose more than one.

The mass flow rate is more for a turbofan engine

The exit velocity is lower for a turbofan engine

A turbofan engine operates at a lower altitude

The fan of a turbofan engine consumes lesser power

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In an ideal turbofan engine shown in the figure below, the compressor is driven by the high pressure turbine, and the fan is driven by the low pressure turbine. The stations 0, 2, 3, 4, 4.5 and 5 refer to free-stream, compressor inlet, compressor outlet, combustor exit, high pressure turbine exit, and low pressure turbine exit, respectively, and the subscript ‘t’ refers to the total condition. Also,

and

. The total temperature ratio of the high pressure turbine (

) is given by ______.

Diagram for Aerospace Engineering question 38

Your answerChoose one option.

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Which of the following process(es) is/are involved in the compression of air in an ideal ramjet engine?

Your answerSelect all correct options. You can choose more than one.

oblique shock

mechanical compression

normal shock

subsonic diffusion

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An ideal ramjet with an optimally expanded exhaust is travelling at Mach 3. The ambient temperature and pressure are 260 K and 60 kPa, respectively. The inlet air mass flow rate is 50 kg/s. Exit temperature of the exhaust gases is 700 K. Fuel mass flow rate is negligible compared to air mass flow rate. Gas constant is R= 287 J/kg/K, and specific heat ratio is

. The thrust generated by the engine is ____ kN (rounded off to one decimal place).

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An aircraft with a turbojet engine is flying with 250 m/s speed at an altitude, where the density of air is 1 kg/m

. The inlet area of the engine is 1 m

. The average velocity of the exhaust gases at the exit of the nozzle, with respect to aircraft, is 550 m/s. Assume the engine exit pressure is equal to the ambient pressure and the fuel-air ratio is negligible. The uninstalled thrust produced by the engine at these conditions is ________ N (rounded off to the nearest integer).

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From the options given, select all that are true for turbofan engines with afterburners.

Your answerSelect all correct options. You can choose more than one.

Turning afterburner ON increases specific fuel consumption.

Turbofan engines with afterburners have variable area nozzles.

Turning afterburner ON decreases specific fuel consumption.

Turning afterburner ON increases stagnation pressure across the engine.

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A supersonic vehicle powered by a ramjet engine is cruising at a speed of 100 m/s. The ramjet engine burns hydrogen in a subsonic combustor to produce thrust. The heat of combustion for hydrogen is 120 MJ/kg. The overall efficiency of the engine

, defined as the ratio of propulsive power to the total heat release in the combustor, is 40%. Taking acceleration due to gravity

m/s

, the specific impulse of the engine is ____________ seconds. (round off to the nearest integer).

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In a static test, a turbofan engine with bypass ratio of 9 has core hot exhaust speed 1.5 times that of fan exhaust speed. The engine is operated at a fuel to air ratio of

. Both the fan and the core streams have no pressure thrust. The ratio of fan thrust to thrust from the core engine is _____ (round off to one decimal place).

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An ideal ramjet is to operate with exhaust gases optimally expanded to ambient pressure at an altitude where temperature is 220 K. The exhaust speed at the nozzle exit is 1200 m/s at a temperature of 110 K.

Given:

at 220 K;

J/(kg-K) for air

at 110 K;

J/(kg-K) for exhaust gases.

The cruise speed of this ramjet is ________ m/s (rounded off to nearest integer).

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How does the specific thrust of a turbojet engine change for a given flight speed with increase in flight altitude?

Your answerChoose one option.

Increases monotonically

Decreases monotonically

Remains constant

First increases and then decreases

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GATE AE Engine Performance PYQs

How to practice Engine Performance

Question 24

Question 38

Question 44

Question 64

Question 34

Question 28

Question 35

Question 34

Question 64

Question 6