Aerospace Engineering
GATE AE Turbomachinery PYQs
Build your understanding with focused practice from past exam papers.
Questions 11–20 of 20. Imported answers require independent review unless marked reviewed.
Question 65
Open questionAENAT2 marksNeeds review
A multistage axial compressor takes in air at 1 atm, 300 K and compresses it to a minimum of 5 atm.
The mean blade speed is 245 m/s and work coefficient,
is 0.55 for each stage. For air, use
J/(kg-K),
J/(kg-K) and
.If the compression is isentropic, the number of stages required is __________ (rounded off to the next higher integer).
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At the design conditions, the velocity triangle at the mean radius of a single stage axial compressor is such that the blade angle at the rotor exit is equal to 30°. The absolute velocities at the rotor inlet and exit are equal to 140 m/s and 240 m/s, respectively. The flow velocities relative to the rotor at inlet and exit of the rotor are equal to 240 m/s and 140 m/s, respectively.
The blade speed (
) at the mean radius of the rotor is __________ m/s (round off to two decimal places).Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 23
Open questionAENAT1 markNeeds review
Air enters the rotor of an axial compressor stage with no pre-whirl (
) and exits the rotor with whirl velocity,
m/s. The velocity of rotor vanes,
is 200 m/s. Assuming
J/(kg K), the stagnation temperature rise across the rotor is ______ K (round off to one decimal place).Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 33
Open questionAEMCQ2 marksNeeds review
An axial compressor is designed to operate at a rotor speed of 1500 rpm and an inlet station temperature of 300 K. During compressor testing, the inlet station temperature of the compressor measured was 280 K. What should be the rotor speed for the compressor to develop the same performance characteristics during this test as in the design condition?
Your answerChoose one option.
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 12
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For a single stage subsonic compressor, which of the following statements about the highest possible compressor pressure ratio (CPR) is correct?
Your answerChoose one option.
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 48
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The figure shows the velocity triangles for an axial compressor stage. The specific work input to the compressor stage is ______ kJ/kg (round off to 2 decimal places).
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 34
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An axial compressor that generates a station pressure ratio of 4.0, operates with inlet and exit station temperatures of 300 K and 480 K, respectively. If the ratio of specific heats (
) is 1.4, the isentropic efficiency of the compressor isYour answerChoose one option.
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 53
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An axial compressor rotor with 50 % degree of reaction, operates with an axial velocity of 200 m/s. The absolute flow angle at the inlet of the rotor is 22° with reference to the axial direction. If the axial velocity is assumed to remain constant through the rotor, the magnitude of the relative velocity (in m/s) at the rotor exit is __________ (accurate to one decimal place).
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 17
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The maximum gas flow rate that can be handled by a multistage axial compressor at a given rotational speed is dictated by
Your answerChoose one option.
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 46
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The given diagram represents the velocity triangles at the leading edge (1) and trailing edge (2) at the mean radius of a single stage axial compressor rotor. The stage efficiency of the compressor is 0.8. The stagnation temperature of air entering the stage is 298 K and the specific heat at constant pressure for air is 1.005 kJ/kgK. The ratio of specific heats for air is 1.4. Considering actual work in the rotor is equal to the ideal work, the pressure ratio for the stage is equal to ________ (in two decimal points).
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