Practice Test: Question Set - 13
1. A jet engine has
- (A) No propeller
- (B) Propeller in
front
- (C) Propeller at
back
- (D) Propeller on
the top
2. The material commonly used for air craft gas turbine is
- (A) Stainless steel
- (B) High alloy steel
- (C) Duralumin
- (D) Timken, Haste alloys
3. In open cycle turbojet engines used in military aircraft, reheating the exhaust gas from the turbine by burning, more fuel is used to increase the
- (A) Thrust
and range of aircraft
- (B) Efficiency
of the engine
- (C) Both (A) and
(B)
- (D) None of
these
4. It is not possible to use closed gas turbine cycle in aeronautical engines because
- (A) It is inefficient
- (B) It is bulky
- (C) It requires cooling
water for its operation
- (D) None of the above
5. The combustion efficiency of a gas turbine using perfect combustion chamber is of the order of
- (A) 75%
- (B) 85%
- (C) 90%
- (D) 99%
6. For an irreversible gas turbine cycle, the efficiency and work ratio both depend on
- (A) Pressure ratio alone
- (B) Maximum cycle
temperature alone
- (C) Minimum cycle
temperature alone
- (D) Both pressure ratio
and maximum cycle temperature
7. Separators are generally used in air compressor installations
- (A) Before the
inter-cooler
- (B) After the
inter-cooler
- (C) Between
the after-cooler and receiver
- (D) Before first
stage suction
8. Producer gas is produced by
- (A) Carbonisation of coal
- (B) Passing steam over
incandescent coke
- (C) Passing air and a
large amount of steam over waste coal at about 65°C
- (D) Partial combustion of
coal, coke, anthracite coal or charcoal in a mixed air steam blast
9. Water gas is produced by
- (A) Carbonisation of coal
- (B) Passing steam over
incandescent coke
- (C) Passing air and a large amount of steam
over waste coal at about 65°C
- (D) Partial combustion of
coal, eke, anthracite coal or charcoal in a mixed air steam blast
10. In a single stage, single acting reciprocating air compressor without clearance volume, the work-done is maximum during
- (A) Isothermal
compression
- (B) Isentropic
compression
- (C) Polytropic
compression
- (D) None
of these
11. Water is injected in gas turbine cycle to
- (A) Control temperature
- (B) Control output of
turbine
- (C) Control fire hazards
- (D) Increase efficiency
12. A gas turbine used in air craft should have
- (A) High h.p. and low
weight
- (B) Low weight and small frontal area
- (C) Small frontal area and high h.p.
- (D) High speed and high h.p.
13. The volumetric efficiency for reciprocating air compressors is about
- (A) 10 to 40%
- (B) 40 to 60%
- (C) 60 to 70%
- (D) 70 to 90%
14. In the axial flow gas turbine, the work ratio is the ratio of
- (A) Compressor work and turbine work
- (B) Output and input
- (C) Actual total head
temperature drop to the isentropic total head drop from total head inlet to
static head outlet
- (D) Actual compressor work and theoretical
compressor work
15. The degree of reaction of an axial flow turbine is the ratio of isentropic temperature drop in a blade row to the
- (A) Adiabatic temperature
drop in the stage
- (B) Total temperature
drop
- (C) Total temperature
drop in the stage
- (D) Total adiabatic
temperature drop
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