Practice Test: Question Set - 18
1. Which is false statement about advantages of multistage compressor in comparison to single stage compressor?
- (A) Less power requirement
- (B) Better mechanical
balance
- (C) Less loss of air due
to leakage past the cylinder
- (D) Lower volumetric
efficiency
2. In a jet propulsion
- (A) The
propulsive matter is ejected from within the propelled body
- (B) The
propulsive matter is caused to flow around the propelled body
- (C) Its
functioning does not depend upon presence of air
- (D) None
of the above
3. The ratio of isentropic work to Euler work is known as
- (A) Pressure coefficient
- (B) Work coefficient
- (C) Polytropic reaction
- (D) Slip factor
4. If the clearance ratio for a reciprocating air compressor is 'K', then its volumetric efficiency is given by
- (A) 1 - k + k (p₁/p₂)1/n
- (B) 1 + k - k (p₂/p₁)1/n
- (C) 1 - k + k (p₁/p₂) n- 1/n
- (D) 1 + k - k (p₂/p₁) n-1/n
5. The criterion of the thermodynamic efficiency for rotary compressor is
- (A) Isentropic
compression
- (B) Isothermal
compression
- (C) Polytropic
compression
- (D) None of the above
6. The maximum compression ratio in an actual single stage axial flow compressor is of the order of
- (A) 1 : 1.2
- (B) 1 : 2
- (C) 1 : 5
- (D) 1 : 10
7. Volumetric efficiency of a compressor decreases with ________ in compression ratio.
- (A) Decrease
- (B) Increase
- (C) Remain same
- (D) Does
not change
8. Maximum delivery pressure is a rotary air compressor is of the order of
- (A) 6 kg/cm²
- (B) 10 kg/cm²
- (C) 16 kg/cm²
- (D) 25 kg/cm²
9. The efficiency of the vane blower is (where W₁ = Workdone due to compression, and W₂ = Workdone due to back flow)
- (A) W₁/(W₁ + W₂)
- (B) W₂/(W₁ + W₂)
- (C) (W₁ + W₂)/W₁
- (D) (W₁ + W₂)/W₂
10. Surging is the phenomenon of
- (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
11. Rotary compressors are suitable for
- (A) Large discharge at
high pressure
- (B) Low discharge at high
pressure
- (C) Large discharge at
low pressure
- (D) Low discharge at low
pressure
12. For perfect intercooling in a two stage compressor
- (A) p₂/p₁ = p₃/p₂
- (B) p₁/p₃ = p₂/p₁
- (C) p₁ = p3
- (D) p₁ = p₂
p3
13. The volumetric efficiency of compressor with increase in compression ratio will
- (A) Increase
- (B) Decrease
- (C) Remain same
- (D) May increase or decrease depending on
clearance volume
14. The propulsive power of the rocket is (where v₁ = Jet velocity, and v₂ = Aircraft velocity)
- (A) (v₁² -v₂²)/2g
- (B) (v₁ - v₂)²/2g
- (C) (v₁² -v₂²)/g
- (D) (v₁ - v₂)²/g
15. Stalling of blades in axial flow compressor is the phenomenon of
- (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
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