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Mechanical Engineering :: Compressors, Gas Turbines and Jet Engines

  1. In a compressor, free air delivered is the actual volume delivered at the stated pressure reduced to

  2. A.

     N.T.P. conditions

    B.

     Intake temperature and pressure conditions

    C.

     0°C and 1 kg/cm²

    D.

     20°C and 1 kg/cm²


  3. When the temperature of air leaving the inter-cooler, in a two stage compression with inter-cooler, is ________ the original atmospheric air temperature, then the intercooling is known as perfect or complete intercooling.

  4. A.

     Equal to

    B.

     Less than

    C.

     More than

    D.

     None of these


  5. The mass of gas turbine per kW developed is about ________ as that of an I.C. engine.

  6. A.

     Same

    B.

     One-half

    C.

     One fourth

    D.

     One sixth


  7. A jet engine works on the principle of conservation of

  8. A.

     Mass

    B.

     Energy

    C.

     Flow

    D.

     Linear momentum


  9. A compressor mostly used for supercharging of I.C. engines is

  10. A.

     Radial flow compressor

    B.

     Axial flow compressor

    C.

     Roots blower

    D.

     Reciprocating compressor


  11. Propulsive efficiency is defined as ratio of

  12. A.

     Thrust power and fuel energy

    B.

     Engine output and propulsive power

    C.

     Propulsive power and fuel input

    D.

     Thrust power and propulsive power


  13. The degree of reaction is usually kept ________ for all types of axial flow compressors.

  14. A.

     0.2

    B.

     0.3

    C.

     0.4

    D.

     0.5


  15. The material commonly used for air craft gas turbine is

  16. A.

     Stainless steel

    B.

     High alloy steel

    C.

     Duralumin

    D.

     Timken, Haste alloys


  17. Which one of the following is the effect of blade shape on performance of a centrifugal compressor?

  18. A.

     Backward curved blades has poor efficiency

    B.

     Backward curved blades lead to stable performance

    C.

     Forward curved blades has higher efficiency

    D.

     Forward curved blades produce lower pressure ratio


  19. Intercooling in gas turbines

  20. A.

     Decreases net output but increases thermal efficiency

    B.

     Increases net output but decreases thermal efficiency

    C.

     Decreases net output and thermal efficiency both

    D.

     Increases net output and thermal efficiency both