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Mechanical Engineering :: Compressors, Gas Turbines and Jet Engines

  1. In open cycle turbojet engines used in military aircraft, reheating the exhaust gas from the turbine by burning, more fuel is used to increase the

  2. A.

     Thrust and range of aircraft

    B.

     Efficiency of the engine

    C.

     Both (A) and (B)

    D.

     None of these

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  3. The efficiency of the vane blower is (where W₁ = Workdone due to compression, and W₂ = Workdone due to back flow)

  4. A.

     W₁/(W₁ + W₂)

    B.

     W₂/(W₁ + W₂)

    C.

     (W₁ + W₂)/W₁

    D.

     (W₁ + W₂)/W₂

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  5. A compressor at high altitudes will require ________ power.

  6. A.

     Same

    B.

     Less

    C.

     More

    D.

     None of these

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  7. In a jet propulsion unit, the products of combustion after passing through the gas turbine are discharged into

  8. A.

     Atmosphere

    B.

     Vacuum

    C.

     Discharge nozzle

    D.

     Back to the compressor

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  9. In jet engines the products of combustion after passing through the gas turbine are discharged into

  10. A.

     Atmosphere

    B.

     Back to the compressor

    C.

     Discharge nozzle

    D.

     Vacuum

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  11. Pick up the false statement

  12. A.

     Gas turbine is a self starting unit

    B.

     Gas turbine does not require huge quantity of water like steam plant

    C.

     Exhaust losses in gas turbine are high due to large mass flow rate

    D.

     Overall efficiency of gas turbine plant is lower than that of a reciprocating engine

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  13. The closed cycle in gas turbines

  14. A.

     Provides greater flexibility

    B.

     Provides lesser flexibility

    C.

     In never used

    D.

     Is used when gas is to be burnt

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  15. Efficiency of gas turbine is increased by

  16. A.

     Reheating

    B.

     Inter cooling

    C.

     Adding a regenerator

    D.

     All of the above

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  17. The pressure ratio for an open cycle gas turbine compared to closed cycle gas turbine of same h.p. is

  18. A.

     Low

    B.

     High

    C.

     Same

    D.

     Low/high depending on make and type

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  19. Air-fuel ratio in a jet engine will be of the order of

  20. A.

     10: 1

    B.

     15: 1

    C.

     20: 1

    D.

     60: 1

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