The operation of forcing additional air under pressure in the engine cylinder is known as
Scavenging
Turbulence
Supercharging
Pre-ignition
Correct Answer :
C. Supercharging
Related Questions
The two reference fuels used for cetane rating are
Cetane and iso-octane
Cetane and alpha-methyl naphthalene
Cetane and normal heptane
Cetane and tetra ethyl lead
In a petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a
Fuel pump
Fuel injector
Spark plug
None of these
Engine pistons are usually made of aluminium alloy because it
Is lighter
Wear is less
Absorbs shocks
Is stronger
The correct mixture strength (by weight) for petrol is about
14.6 : 1
18.5 : 1
20.4 : 1
22.6 : 1
In a four stroke cycle diesel engine, the exhaust valve
Opens at 30° before bottom dead centre and closes at 10° after top dead centre
Opens at 30° after bottom dead centre and closes at 10° before top dead centre
Opens at bottom dead centre and closes at top dead centre
May open and close anywhere
For the same power developed in I.C. engines, the cheaper system is
Naturally aspirated
Supercharged
Centrifugal pump
Turbo charger
A petrol engine, during suction stroke draws
Air only
Petrol only
A mixture of petrol and air
None of these
Which of the following medium is compressed in a Diesel engine cylinder?
Air alone
Air and fuel
Air and lub oil
Fuel alone
Scavenging is usually done to increase
Thermal efficiency
Speed
Power output
Fuel consumption
In a four stroke cycle petrol engine, the charge is ignited at
30° before top dead centre
30° after top dead centre
30° before bottom dead centre
30° after bottom dead centre
In a naturally aspirated diesel engine, the air is supplied by
A supercharger
A centrifugal blower
A vacuum chamber
An injection tube
Pick up the false statement
Thermal efficiency of diesel engine is about 34%
Theoretically correct mixture of air and petrol is approximately 15:1
High speed compression engines operate on dual combustion cycle
S.I. engines are quality governed engines
The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
Net efficiency
Efficiency ratio
Relative efficiency
Overall efficiency
The effective inhibitor of pre-ignition is
Alcohol
Water
Lead
None of these
During idling, a petrol engine requires _________ mixture.
Lean
Rich
Chemically correct
None of these
Pick up the wrong statement about supercharging
Supercharging reduces knocking in diesel engines
There can be limited supercharging in petrol engines because of detonation
Supercharging at high altitudes is essential
Supercharging results in fuel economy
The sensing element in the control system of nuclear reactors measures the _________ of the neutron flux in the reactor.
Temperature
Volume
Density
None of these
In petrol engines, the delay period is of the order of
0.001 second
0.002 second
0.003 second
0.004 second
Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to
Cylinder walls being too hot
Overheated spark plug points
Red hot carbon deposits on cylinder walls
Any one of these
The theoretically correct mixture of air and petrol is
10 : 1
15 : 1
20 : 1
25 : 1
The mean effective pressure obtained from engine indicator indicates the
Maximum pressure developed
Minimum pressure
Instantaneous pressure at any instant
Average pressure
Volatility of diesel fuel oil is
Minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame
Temperature at which it solidifies or congeals
It catches fire without external aid
Indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off
A gas engine has a swept volume of 300 cm3 and clearance volume of 25 cm3. Its volumetric efficiency is 0.88 and mechanical efficiency is 0.90. The volume of the mixture taken in per stroke is
248 cm3
252 cm3
264 cm3
286 cm3
In order to eliminate knocking in compression ignition engines, there should be
Short delay period
Late auto-ignition
Low compression ratio
High self ignition temperature of fuel
If V₁ is the jet velocity and V₀ is the vehicle velocity, then the propulsive efficiency of a rocket is given by
[2(V₀/V₁)]/ [1 + (V₀/V₁)²]
(V₀/V₁)/ [1 + (V₀/V₁)²]
V₀/(V₀ + V₁)
V₁/(V₀ + V₁)
The fuels in order of decreasing knock tendency for spark ignition engines are
Paraffin, aromatic, napthene
Paraffin, napthene, aromatic
Napthene, aromatics, paraffin
Napthene, paraffin, aromatic
In a four stroke cycle engine, the sequence of operations is
Suction, compression, expansion and exhaust
Suction, expansion, compression and exhaust
Expansion, compression, suction and exhaust
Compression, expansion, suction and exhaust
The function of a distributor in a coil ignition system of I.C. engines is
To distribute spark
To distribute power
To distribute current
To time the spark
Diesel as compared to petrol is
Highly ignitable
More difficult to ignite
Less difficult to ignite
None of these
For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of
9 : 1
12 : 1
15 : 1
18 : 1