The air-fuel ratio in petrol engines is controlled by
Controlling valve opening/closing
Governing
Injection
Carburetion
Correct Answer :
D. Carburetion
Related Questions
The delay period in compression ignition engines depends upon
Temperature and pressure in the cylinder at the time of injection
Nature of the fuel mixture strength
Relative velocity between the fuel injection and air turbulence pressure of residual gases
All of the above
The object of providing masked inlet valve in the air passage of compression ignition engines is to
Enhance flow rate
Control air flow
Induce primary swirl
Induce secondary turbulence
Gaseous fuel guarantees are based on
Calorific value of oil
Low heat value of oil
High heat value of oil
Mean heat value of oil
In an internal combustion engine, the process of removing the burnt gases from the combustion chamber of the engine cylinder is known as
Scavenging
Detonation
Supercharging
Polymerisation
Supercharging is essential in
Diesel engines
Gas turbines
Petrol engines
Aircraft engines
Thermal efficiency of a two stroke cycle engine is ________ a four stroke cycle engine.
Equal to
Less than
Greater than
None of these
The ratio of the indicated thermal efficiency to the air standard efficiency is known as
Mechanical efficiency
Overall efficiency
Volumetric efficiency
Relative efficiency
Theoretically, a four stroke cycle engine should develop _________ power as that of a two stroke cycle engine.
Half
Same
Double
Four times
The air-fuel ratio of the petrol engine is controlled by
Fuel pump
Governor
Injector
Carburettor
Most high speed compression engines operate on
Diesel cycle
Otto cycle
Dual combustion cycle
Special type of air cycle
The theoretically correct air fuel ratio for petrol engine is of the order of
6 : 1
9 : 1
12 : 1
15 : 1
In a naturally aspirated diesel engine, the air is supplied by
A supercharger
A centrifugal blower
A vacuum chamber
An injection tube
A heat engine utilises the
Calorific value of oil
Low heat value of
High heat value of oil
Mean heat value of oil
The higher combustion chamber wall temperature in compression ignition engines will _________ knocking tendency.
Increase
Reduce
Not effect
None of these
Compression ratio of I.C. Engines is
The ratio of volumes of air in cylinder before compression stroke and after compression stroke
Volume displaced by piston per stroke and clearance volume in cylinder
Ratio of pressure after compression and before compression
Swept volume/cylinder volume
A stoichiometric air-fuel ratio is
Chemically correct mixture
Lean mixture
Rich mixture for idling
Rich mixture for over loads
The thermal efficiency of petrol and gas engines is about
15 %
30 %
50 %
70 %
In the crankcase method of scavenging, the air pressure is produced by
Supercharger
Centrifugal pump
Natural aspirator
Movement of engine piston
The turbine of the turboprop engine is __________ that of the turbojet engine.
Same as
Smaller than
Bigger than
None of these
The correct mixture strength (by weight) for petrol is about
14.6 : 1
18.5 : 1
20.4 : 1
22.6 : 1
Fuel consumption of diesel engines is not guaranteed at one quarter load because at such low loads
The friction is high
The friction is unpredictable
The small difference in cooling water temperature or in internal friction has a disproportionate effect
The engine is rarely operated
Which of the following statement is wrong?
In compression ignition engines, detonation occurs near the beginning of combustion.
Since the fuel, in compression ignition engines, is injected at the end of compression stroke, therefore, there will be no pre-ignition.
To eliminate knock in compression ignition engines, we want to achieve auto-ignition not early and desire a long delay period.
In compression ignition engines, because of heterogeneous mixture, the rate of pressure rise is comparatively lower.
The normal heptane (C7H16) is given a rating of ________ octane number.
0
50
100
120
Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged?
Yes
No
To some extent
Unpredictable
Which of the following fuel has little tendency towards detonation?
Benzene
Iso-octane
Normal heptane
Alcohol
The loud pulsating noise heard within the cylinder of an internal combustion engine is known as
Detonation
Turbulence
Pre-ignition
Supercharging
The combustion in compression ignition engines is
Homogeneous
Heterogeneous
Both (A) and (B)
None of these
The air requirement of a petrol engine during starting compared to theoretical air required for complete combustion is
More
Less
Same
May be more or less depending on engine capacity
The octane number of petrol, generally available, is
20 to 40
40 to 60
60 to 80
80 to 100
The probability of knocking in diesel engines is increased by
High self ignition temperature
Low volatility
Higher viscosity
All of these