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Mechanical Engineering :: Compressors,Gas Dynamics and Gas Turbines

  1. An aftercooler is used to

  2. A.
    remove impurities from air
    B.
    reduce volume of air
    C.
    cause moisture and oil vapour to drop out
    D.
    cool the air

  3. High air-fuel ratio in gas turbines

  4. A.
    increases power output
    B.
    improves thermal efficiency
    C.
    reduces exhaust temperature
    D.
    do not damage turbine blades

  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. If p1, is the pressure of air entering the L.P. cylinder and p2 is the pressure of air leaving the L.P. cylinder (or intercooler pressure), then the ratio of cylinder diameters for a single acting, two stage reciprocating air compressor with complete intercooling is given by (where D1 = Dia. of L.P. cylinder, and D2 = Dia. of H.P. cylinder)

  8. A.
    D1/D2 = p1p2
    B.
    D1/D2 = p1/p2
    C.
    D1/D2 = p2/p1
    D.
    none of these

  9. The ratio of the indicated power to the shaft power or brake power of the motor or engine required to drive the compressor, is called

  10. A.
    compressor efficiency
    B.
    volumetric efficiency
    C.
    isothermal efficiency
    D.
    mechanical efficiency

  11. The increase in pressure in a roots blower is entirely due to back flow of air.

  12. A.
    Agree
    B.
    Disagree

  13. The type of rotary compressor used in aeroplanes, is of

  14. A.
    centrifugal type
    B.
    axial flow type
    C.
    radial flow type
    D.
    none of these

  15. An axial compressor gives optimum performance at high speeds and large volume flows.

  16. A.
    Agree
    B.
    Disagree

  17. In a reciprocating air compressor, the compression work per kg of air

  18. A.
    increases as clearance volume increases
    B.
    decreases as clearance volume increases
    C.
    is independent of clearance volume
    D.
    increases as clearance volume decreases

  19. The degree of reaction in an axial flow compressor is defined as the ratio of static enthalpy rise in the

  20. A.
    rotor to static enthalpy rise in the stator
    B.
    stator to static enthalpy rise in the rotor
    C.
    rotor to static enthalpy rise in the stage
    D.
    stator to static enthalpy rise in the stage