Practice Test: Question Set - 10
1. With the decrease in compression ratio, the volumetric efficiency
- (A) Does
not change
- (B) Increases
- (C) Decreases
- (D) First
decrease and then increase
2. Pick up wrong statement. Surging phenomenon in centrifugal compressor depends on
- (A) Mass flow rate
- (B) Pressure ratio
- (C) Change in load
- (D) Stagnation pressure
at the outlet
3. In air compressors, free air delivery means the
- (A) Actual
volume of the air delivered by the compressor when reduced to normal temperature
and pressure conditions
- (B) Volume of
air delivered by the compressor
- (C) Volume
of air sucked by the compressor during its suction stroke
- (D) None
of the above
4. The ratio of the increase in pressure in rotor blades to total increase in pressure in the stage is called
- (A) Pressure ratio
- (B) Pressure coefficient
- (C) Degree of reaction
- (D) Slip factor
5. A turboprop is preferred to turbojet because
- (A) It
has high propulsive efficiency at high speeds
- (B) It can fly
at supersonic speeds
- (C) It can fly
at high elevations
- (D) It has high
power for take off
6. Axial flow compressor resembles
- (A) Centrifugal pump
- (B) Reciprocating pump
- (C) Turbine
- (D) Sliding vane compressor
7. The efficiency of roots blower ________ with the increase in pressure ratio.
- (A) Decreases
- (B) Increases
- (C) Does
not change
- (D) None of
these
8. Axial flow compressor has the following advantage over centrifugal compressor
- (A) Larger air handling
ability per unit frontal area
- (B) Higher pressure ratio
per stage
- (C) Aerofoil blades are used
- (D) Higher average
velocities
9. The maximum temperature in a gas turbine is
- (A) 200°C
- (B) 500°C
- (C) 700°C
- (D) 1000°C
10. Actual compression curve is
- (A) Same as isothermal
- (B) Same as adiabatic
- (C) Better than
isothermal and adiabatic
- (D) In between isothermal and adiabatic
11. In a centrifugal compressor, an increase in speed at a given pressure ratio causes
- (A) Increase
in flow
- (B) Decrease
in flow
- (C) Increase
in efficiency
- (D) Increase
in flow and decrease in efficiency
12. Atmospheric pressure is 1.03 kg/cm and vapour pressure is 0.03 kg/cm. The air pressure will be
- (A) 1.03 kg/cm²
- (B) 1.06 kg/cm²
- (C) 1.00 kg/cm²
- (D) 0.53 kg/cm²
13. For maximum work, the reheating should be done to an intermediate pressure of
(Where p₁
= Maximum pressure, and p₂ = Minimum pressure)
- (A) (p₁ - p₂)/2
- (B) (p₁ + p₂)/2
- (C) p₁/p₂
- (D) p₁ p₂
14. The pressure ratio of an ideal vaned compressor with increase in mass flow rate
- (A) Increases
- (B) Decreases
- (C) Remain constant
- (D) First decreases and then increases
15. If the flow of air through the compressor is parallel to its axis, then the compressor is
- (A) Reciprocating
compressor
- (B) Centrifugal
compressor
- (C) Axial flow
compressor
- (D) Turbo
compressor
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