Compressors, Gas Turbines and Jet Engines - Set 07

Practice Test: Question Set - 07

1. Rotary compressor is best suited for
    (A) Large quantity of air at high pressure
    (B) Small quantity of air at high pressure
    (C) Small quantity of air at low pressure
    (D) Large quantity of air at low pressure

2. The inter-cooler pressure, for minimum work required, for a two stage reciprocating air compressor, is given by (where p₁ = Intake pressure of air, p₂ = Inter-cooler pressure, and p₃ = Delivery pressure of air)
    (A) p₂ = p₁ × p₃
    (B) p₂ = p₁/p₃
    (C) p₂ = p₁ × p₂
    (D) p₂ = p₃/p₁

3. The compressor efficiency is the
    (A) Isothermal H.P/indicated H.R
    (B) Isothermal H.P./shaft H.R
    (C) Total output/air input
    (D) Compression work/motor input

4. The ratio of the net work obtained from the gas turbine plant to the turbine work is known as
    (A) Compression ratio
    (B) Work ratio
    (C) Pressure ratio
    (D) None of these

5. The thrust on the rotor in a centrifugal compressor is produced by
    (A) Radial component
    (B) Axial component
    (C) Tangential component
    (D) None of the above

6. In a centrifugal compressor, the highest Mach number leading to shock wave in the fluid flow occurs at
    (A) Diffuser inlet radius
    (B) Diffuser outlet radius
    (C) Impeller inlet radius
    (D) Impeller outlet radius

7. A compressor at high altitude will draw
    (A) More power
    (B) Less power
    (C) Same power
    (D) More/less power depending on other factors

8. In a single acting reciprocating air compressor, without clearance, the compression of air may be
    (A) Isothermal
    (B) Polytropic
    (C) Isentropic
    (D) Any one of these

9. During peak load periods, the best method of controlling compressors is
    (A) Start-stop motor
    (B) Constant speed unloader
    (C) Relief valve
    (D) Variable speed

10. The temperature of air at the beginning of the compression stroke is ________ the atmospheric temperature.
    (A) Equal to
    (B) Less than
    (C) More than
    (D) None of these

11. A centrifugal compressor works on the principle of
    (A) Conversion of pressure energy into kinetic energy
    (B) Conversion of kinetic energy into pressure energy
    (C) Centripetal action
    (D) Generating pressure directly

12. The air is delivered ________ in one revolution in case of a three lobbed rotor.
    (A) Two times
    (B) Three times
    (C) Four times
    (D) Six times

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

14. The blades of gas turbine are made of
    (A) High nickel alloy
    (B) Stainless steel
    (C) Carbon steel
    (D) High alloy steel

15. The maximum delivery pressure in a rotary air compressor is
    (A) 10 bar
    (B) 20 bar
    (C) 30 bar
    (D) 50 bar

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Item Reviewed: Compressors, Gas Turbines and Jet Engines - Set 07 Rating: 5 Reviewed By: Pranab Debnath
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