Practice Test: Question Set - 15
1. The ratio of the brake power to the indicated power is called
- (A) Mechanical
efficiency
- (B) Overall
efficiency
- (C) Indicated
thermal efficiency
- (D) Volumetric
efficiency
2. The cetane (C₁₆H₃₄) which is a straight chain paraffin, is assigned a cetane number of
- (A) 0
- (B) 50
- (C) 100
- (D) 120
3. The thermodynamic cycle on which the petrol engine works, is
- (A) Otto cycle
- (B) Joule cycle
- (C) Rankine
cycle
- (D) Stirling
cycle
4. The correct mixture strength (by weight) for petrol is about
- (A) 14.6 : 1
- (B) 18.5 : 1
- (C) 20.4 : 1
- (D) 22.6 : 1
5. The scavenging efficiency of a four stroke cycle diesel engine is
- (A) Below 50%
- (B) Between
50 and 85%
- (C) Between 85
and 95%
- (D) Between 95
and 100%
6. If the speed of the engine is increased, the indicated power will
- (A) Increase
- (B) Decrease
- (C) Remain same
- (D) None of
these
7. The specific fuel consumption per B.P. hour for a petrol engine is about
- (A) 0.2 kg
- (B) 0.25 kg
- (C) 0.3 kg
- (D) 0.35 kg
8. The injector nozzle of a compression ignition engine is required to inject fuel at a sufficiently high pressure in order to
- (A) Inject
fuel in a chamber of high pressure at the end of compression stroke
- (B) Inject
fuel at a high velocity to facilitate atomization
- (C) Ensure
that penetration is not high
- (D) All
of the above
9. A fuel of cetane number 40 has the same ignition quality as a mixture of
- (A) 40%
cetane and 60% alpha methyl naphthalene
- (B) 40%
alpha methyl naphthalene and 60% cetane
- (C) 40%
petrol and 60% diesel
- (D) 40%
diesel and 60% petrol
10. The two reference fuels used for cetane rating are
- (A) Cetane
and iso-octane
- (B) Cetane
and alpha-methyl naphthalene
- (C) Cetane
and normal heptane
- (D) Cetane
and tetra ethyl lead
11. In petrol engines, the delay period is of the order of
- (A) 0.001 second
- (B) 0.002 second
- (C) 0.003 second
- (D) 0.004 second
12. A diesel engine is _________ as compared to petrol engine, both running at rated load.
- (A) Equally
efficient
- (B) Less
efficient
- (C) More
efficient
- (D) None
of these
13. The pressure at the end of compression, in petrol engines, is approximately
- (A) 10 bar
- (B) 20 bar
- (C) 25 bar
- (D) 35 bar
14. The turbine of the turboprop engine is __________ that of the turbojet engine.
- (A) Same as
- (B) Smaller than
- (C) Bigger than
- (D) None
of these
15. A higher compression ratio causes
- (A) Pre-ignition
- (B) Increase
in detonation
- (C) Acceleration
in the rate of combustion
- (D) Any
one of these
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