GATE AE Turbomachinery PYQs & Answers

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

The figure below shows the blading of the rotors of two different axial turbomachines under their typical operating conditions, labelled as Configuration I and Configuration II. Which of the following statements is/are TRUE?

Diagram for Aerospace Engineering question 27

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Configuration I corresponds to the rotor of a compressor and Configuration II corresponds to the rotor of a turbine

Configuration I corresponds to the rotor of a turbine and Configuration II corresponds to the rotor of a compressor

The rotor blades of the turbomachine in Configuration I move along the

direction

The rotor blades of the turbomachine in Configuration II move along the

direction

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A multi-stage axial compressor can be operated at two points, A and B, both of which lie on the same speed line, as shown in the figure below. If

is the isentropic efficiency of the compressor, select the statements that are TRUE.

Diagram for Aerospace Engineering question 28

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In comparison to point B, point A is closer to the surge point

In comparison to point A, point B is closer to the choke point

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The figure below shows a compressor stage with station numbers 1, 2, and 3 as indicated. If

, and

refer to the average values of total pressure, total temperature, and absolute flow speed, respectively, at the

station, select the CORRECT option considering loss.

Diagram for Aerospace Engineering question 42

Your answerChoose one option.

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The figure below shows the velocity triangles at the inlet and outlet of the rotor of a low hub-to-tip ratio axial compressor at the mid-span of the blade. The absolute and relative velocities of the flow are denoted by C and W, respectively. The subscripts 1 and 2 refer to the locations before and after the rotor, respectively. The blade velocity is denoted by U. Select the CORRECT statement(s) for this device.

Diagram for Aerospace Engineering question 46

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The axial velocity is constant across the rotor

The flow coefficient is 0.6

The blade loading coefficient is 0.6

If the acoustic velocity at the rotor inlet is 350 m/s, then the inlet relative Mach number is 0.333

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A single-stage axial compressor, with a 50 % degree of reaction, runs at a mean blade speed of 250 m/s. The overall pressure ratio developed is 1.3. Inlet pressure and temperature are 1 bar and 300 K, respectively. Axial velocity is 200 m/s. Specific heat at constant pressure,

J/kg/K and specific heat ratio,

. The rotor blade angle at the outlet is ____ degrees (rounded off to two decimal places).

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A multistage axial compressor, with overall isentropic efficiency of 0.83, is used to compress air at a station temperature of 300 K through a pressure ratio of 10:1. Each stage of the compressor is similar, and the stagnation temperature rise across each compressor stage is 20 K. Assume

and

for air. How many stages are there in the compressor?

Your answerChoose one option.

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Which of the following statements is/are TRUE for a single stage axial compressor?

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

Starting from design condition and keeping the mass flow rate constant, if the blade RPM is increased, the compressor rotor may experience positive incidence flow separation (actual relative flow angle greater than the design blade angle)

Starting from design condition at the same blade RPM, if the mass flow rate is increased, the compressor rotor may experience positive incidence flow separation (actual relative flow angle greater than the design blade angle)

Keeping the mass flow rate constant, if the blade RPM is increased, the compressor may experience surge

At the same blade RPM, if the mass flow rate is increased, the compressor may experience surge

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In a single-spool aviation turbojet engine, which of the following is the correct relationship between the total work output

of a 2-stage axial turbine and the total work required

by a 6-stage axial compressor, neglecting losses?

Your answerChoose one option.

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For a stage of a 50% reaction ideal axial flow compressor (symmetrical blading), select the correct statement from the options given.

Your answerChoose one option.

The stagnation enthalpy rise across the rotor is 50% of the rise across the stage.

The static enthalpy rise across the rotor is 50% of the rise across the stage.

Axial velocity component of the flow at the rotor exit is 50% of that at the rotor entry.

The static pressure rise across the rotor is 50% of the rise across the stator.

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A high-pressure-ratio multistage axial compressor encounters an extreme loading mismatch during starting. Which of the following technique(s) can be used to alleviate this problem?

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

Blade cooling

Variable angle stator vanes

Blow-off valves

Multi-spool shaft

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GATE AE Turbomachinery PYQs

How to practice Turbomachinery

Question 27

Question 28

Question 42

Question 46

Question 65

Question 40

Question 50

Question 20

Question 21

Question 30