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Mechanical Engineering :: Compressors, Gas Turbines and Jet Engines

  1. For maximum work, the reheating should be done to an intermediate pressure of (Where p₁ = Maximum pressure, and p₂ = Minimum pressure)

  2. A.

     (p₁ - p₂)/2

    B.

     (p₁ + p₂)/2

    C.

     p₁/p₂

    D.

     p₁ p₂


  3. Inter-cooling in multistage compressors is done

  4. A.

     To cool the air during compression

    B.

     To cool the air at delivery

    C.

     To enable compression in two stages

    D.

     To minimize the work of compression


  5. The efficiency and work ratio of a gas turbine plant can be increased by

  6. A.

     Adding heat exchanger

    B.

     Injecting water in/around combustion chamber

    C.

     Reheating the air after partial expansion in the turbine

    D.

     All of the above


  7. The thrust of a jet propulsion power unit can be increased by

  8. A.

     Injecting water into the compressor

    B.

     Burning fuel after gas turbine

    C.

     Injecting ammonia into the combustion chamber

    D.

     All of the above


  9. Euler's equation can be used for

  10. A.

     Radial flow compressors

    B.

     Axial flow compressors

    C.

     Pumps

    D.

     All of these


  11. Adiabatic compression is one in which

  12. A.

     Temperature during compression remains constant

    B.

     No heat leaves or enters the compressor cylinder during compression

    C.

     Temperature rise follows a linear relationship

    D.

     Work done is maximum


  13. Ratio of compression is the ratio of

  14. A.

     Gauge discharge pressure to the gauge intake pressure

    B.

     Absolute discharge pressure to the absolute intake pressure

    C.

     Pressures at discharge and suction corresponding to same temperature

    D.

     Stroke volume and clearance volume


  15. The work done per unit mass of air in compression will be least when 'n' is equal to

  16. A.

     1

    B.

     1.2

    C.

     1.3

    D.

     1.4


  17. The efficiency of roots blower ________ with the increase in pressure ratio.

  18. A.

     Decreases

    B.

     Increases

    C.

     Does not change

    D.

     None of these


  19. During peak load periods, the best method of controlling compressors is

  20. A.

     Start-stop motor

    B.

     Constant speed unloader

    C.

     Relief valve

    D.

     Variable speed