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Mechanical Engineering :: Compressors,Gas Dynamics and Gas Turbines

  1. The axial flow compressor is preferred in air-craft gas turbines because of

  2. A.
    low frontal area
    B.
    higher thrust
    C.
    high pressure rise
    D.
    none of these

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  3. Which of the following statement is correct as regard to centrifugal compressors?

  4. A.
    The flow of air is parallel to the axis of the compressor.
    B.
    The static pressure of air in the impeller increases in order to provide centripetal force on the air.
    C.
    The impeller rotates at high speeds.
    D.
    The maximum efficiency is higher than multi-stage axial flow compressors.

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  5. The ratio of the net work obtained from the gas turbine plant to the turbine work is known as

  6. A.
    compression ratio
    B.
    work ratio
    C.
    pressure ratio
    D.
    none of these

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  7. The process, which causes the air to enter the impeller blades of a centrifugal compressor at __________ velocity (without effecting the mass of air to flow and velocity of flow) is known as prewhirl.

  8. A.
    reduced
    B.
    increased

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  9. In jet propulsion power unit, the inlet duct of diverging shape is used for converting kinetic energy of air into pressure energy.

  10. A.
    True
    B.
    False

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  11. The temperature of air at the beginning of the compression stroke is __________ the atmospheric temperature.

  12. A.
    equal to
    B.
    less than
    C.
    more than

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  13. The compressor efficiency is defined as the ratio of volume of free air delivery per stroke to the swept volume of the piston.

  14. A.
    Correct
    B.
    Incorrect

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  15. In a gas turbine, air is obtained from the atmosphere and compressed in an air compressor.

  16. A.
    True
    B.
    False

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  17. In open cycle turbo-jet engines used in military aircraft, reheating the exhaust gas from the turbine by burning, more fuel is used to increase the

  18. A.
    thrust and range of aircraft
    B.
    efficiency of the engine
    C.
    both (a) and (b)
    D.
    none of these

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  19. Gas turbine as compared to internal combustion engine

  20. A.
    can be driven at a very high speed
    B.
    produces uniform torque
    C.
    has more efficiency
    D.
    all of these

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