Compressors, Gas Turbines and Jet Engines - Set 04 - ObjectiveBooks

Compressors, Gas Turbines and Jet Engines - Set 04

Practice Test: Question Set - 04

1. A rotary compressor is driven by an
    (A) Electric motor
    (B) Engine
    (C) Either (A) or (B)
    (D) None of these

2. Isothermal compression though most efficient, but is not practicable because
    (A) It requires very big cylinder
    (B) It does not increase pressure much
    (C) It is impossible in practice
    (D) Compressor has to run at very slow speed to achieve it

3. Gas turbine as compared to steam turbine
    (A) Requires less space for installation
    (B) Has compressor and combustion chamber
    (C) Has less efficiency
    (D) All of these

4. The following property is most important for material used for gas turbine blade
    (A) Toughness
    (B) Fatigue
    (C) Creep
    (D) Corrosion resistance

5. The ratio of work done per cycle to the swept volume in case of compressor is called
    (A) Compression index
    (B) Compression ratio
    (C) Compressor efficiency
    (D) Mean effective pressure

6. Intercooling in gas turbines
    (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

7. The efficiency of jet engine is
    (A) Lower at low speed 
    (B) Higher at high altitudes
    (C) Same at all altitudes
    (D) Higher at high speed

8. Compression efficiency is compared against
    (A) Ideal compression
    (B) Adiabatic compression
    (C) Isentropic compression
    (D) Isothermal compression

9. High air-fuel ratio in gas turbines
    (A) Increases power output
    (B) Improves thermal efficiency
    (C) Reduces exhaust temperature
    (D) Do not damage turbine blades

10. An ideal air compressor cycle with clearance on P-V diagram can be represented by following processes
    (A) One adiabatic, two isobaric, and one constant volume
    (B) Two adiabatic and two isobaric
    (C) Two adiabatic, one isobaric and one constant volume
    (D) One adiabatic, one isobaric and two constant volumes

11. If p₁ is the pressure of air entering the L.P, cylinder and p₃ is the pressure of air leaving the H.P. cylinder, then the ratio of cylinder diameters for a single acting, two stage reciprocating compressor with complete intercooling is given by
    (A) D₁/D₂ = (p₁ p₃)1/2
    (B) D₁/D₂ = (p₁/p₃)1/4
    (C) D₁/D₂ = (p₁ p₃)1/4
    (D) D₁/D₂ = (p₃/p₁)1/4

12. In gas turbines, high thermal efficiency is obtained in
    (A) Closed cycle
    (B) Open cycle
    (C) Both of the above
    (D) Closed/open depending on other considerations

13. Ratio of indicated H.P. and brake H.P. is known as
    (A) Mechanical efficiency
    (B) Volumetric efficiency
    (C) Isothermal efficiency
    (D) Adiabatic efficiency

14. The ratio of the volume of free air delivery per stroke to the swept volume of the piston, is known as
    (A) Compressor efficiency
    (B) Volumetric efficiency
    (C) Isothermal efficiency
    (D) Mechanical efficiency

15. Clearance volume in actual reciprocating compressors is essential
    (A) To accommodate Valves in the cylinder head
    (B) To provide cushioning effect
    (C) To attain high volumetric efficiency
    (D) To provide cushioning effect and also to avoid mechanical bang of piston with cylinder head

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