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Mechanical Engineering :: Compressors, Gas Turbines and Jet Engines

  1. In an axial flow compressor, the ratio of pressure in the rotor blades to the pressure rise in the compressor in one stage is known as

  2. A.

     Work factor

    B.

     Slip factor

    C.

     Degree of reaction

    D.

     Pressure coefficient


  3. A rocket engine for the combustion of its fuel

  4. A.

     Carries its own oxygen

    B.

     Uses surrounding air

    C.

     Uses compressed atmospheric air

    D.

     Does not require oxygen


  5. The ratio of the volume of free air delivery per stroke to the swept volume of the piston, is known as

  6. A.

     Compressor efficiency

    B.

     Volumetric efficiency

    C.

     Isothermal efficiency

    D.

     Mechanical efficiency


  7. More than one stage will be preferred for reciprocating compressor if the delivery pressure is more than

  8. A.

     2 kg/cm²

    B.

     6 kg/cm²

    C.

     10 kg/cm²

    D.

     14.7 kg/cm²


  9. In a centrifugal compressor, an increase in speed at a given pressure ratio causes

  10. A.

     Increase in flow

    B.

     Decrease in flow

    C.

     Increase in efficiency

    D.

     Increase in flow and decrease in efficiency


  11. The clearance volume of the air compressor is kept minimum because

  12. A.

     It allows maximum compression to be achieved

    B.

     It greatly affects volumetric efficiency

    C.

     It results in minimum work

    D.

     It permits isothermal compression


  13. Which is false statement about multistage compression?

  14. A.

     Power consumption per unit of air delivered is low

    B.

     Volumetric efficiency is high

    C.

     It is best suited for compression ratios around 7:1

    D.

     The moisture in air is condensed in the inter-cooler


  15. The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is

  16. A.

     Heated

    B.

     Compressed air before entering the combustion chamber is heated

    C.

     Bled gas from turbine is heated and readmitted for complete expansion

    D.

     Exhaust gases drive the compressor


  17. If the flow of air through the compressor is parallel to its axis, then the compressor is

  18. A.

     Reciprocating compressor

    B.

     Centrifugal compressor

    C.

     Axial flow compressor

    D.

     Turbo compressor


  19. Surging is the phenomenon of

  20. A.

     Air stream blocking the passage

    B.

     Motion of air at sonic velocity

    C.

     Unsteady, periodic and reversed flow

    D.

     Air stream not able to follow the blade contour