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4

Most high speed compression engines operate on

A. Diesel cycle

B. Otto cycle

C. Dual combustion cycle

D. Special type of air cycle

Correct Answer :

C. Dual combustion cycle


Related Questions

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4

The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called

A. Mechanical efficiency

B. Overall efficiency

C. Volumetric efficiency

D. Relative efficiency

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4

The fuel valve in a four stroke cycle diesel engine

A. Opens at 15° after top dead centre and closes at 20° before bottom dead centre

B. Opens at 15° before top dead centre and closes at 20° after top dead centre

C. Opens at top dead centre and closes at bottom dead centre

D. May open and close anywhere

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4

Detonation is harmful due to

A. Increase in the rate of heat transfer, there is a reduction in the power output and efficiency of the engine

B. Excessive turbulence which removes most of the insulating gas boundary layer from the cylinder walls

C. High intensity of knock causes crankshaft vibration and the engine runs rough

D. None of the above

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4

The knocking in spark ignition engines can be reduced by

A. Retarding the spark

B. Increasing the engine speed

C. Both (A) and (B)

D. None of these

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4

When crude oil is heated, then which of the following hydrocarbon is given off first?

A. Kerosene

B. Gasoline

C. Paraffin

D. Natural gas

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4

The reason for supercharging in any engine is to

A. Increase efficiency

B. Increase power

C. Reduce weight and bulk for a given output

D. Effect fuel economy

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4

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

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4

In order to eliminate knocking in compression ignition engines, there should be

A. Short delay period

B. Late auto-ignition

C. Low compression ratio

D. High self ignition temperature of fuel

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4

If V₁ is the jet velocity and V₀ is the vehicle velocity, then propulsive efficiency of a turbojet engine is

A. V₁/(V₀ + V₁)

B. V₀/(V₀ + V₁)

C. 2V₀/(V₀ + V₁)

D. 2V₁/(V₀ + V₁)

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4

The rating of a diesel engine, with increase in air inlet temperature, will

A. Increase linearly

B. Decrease linearly

C. Increase parabolically

D. Decrease parabolically

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4

The pressure inside the cylinder is _________ the atmospheric pressure during the exhaust stroke.

A. Equal to

B. Below

C. Above

D. None of these

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4

Compression loss in I.C engines occurs due to

A. Leaking piston rings

B. Use of thick head gasket

C. Clogged air inlet slots

D. All of the above

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4

Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to

A. Cylinder walls being too hot

B. Overheated spark plug points

C. Red hot carbon deposits on cylinder walls

D. Any one of these

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4

The output of a diesel engine can be increased without increasing the engine revolution or size in following way

A. Feeding more fuel

B. Heating incoming air

C. Scavenging

D. Supercharging

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4

Which of the following statement is correct?

A. Compression ratio for petrol engines varies from 6 to 10

B. Higher compression ratio in diesel engines results in higher pressures

C. Petrol engines work on Otto cycle

D. All of the above

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4

If petrol is used in a diesel engine, then

A. Low power will be produced

B. Efficiency will be low

C. Higher knocking will occur

D. Black smoke will be produced

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4

High speed compression engines operate on

A. Otto cycle

B. Diesel cycle

C. Dual combustion cycle

D. All of these

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4

The pressure and temperature at the end of compression stroke in a petrol engine are of the order of

A. 4-6 kg/cm² and 200-250°C

B. 6-12 kg/cm² and 250-350°C

C. 12-20 kg/cm² and 350-450°C

D. 20-30 kg/cm² and 450-500°C

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4

Stoichiometric ratio is

A. Chemically correct air-fuel ratio by weight

B. Chemically correct air-fuel ratio by volume

C. Actual air-fuel ratio for maximum efficiency

D. None of the above

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4

The effective inhibitor of pre-ignition is

A. Alcohol

B. Water

C. Lead

D. None of these

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4

The firing order in an I.C. engine depends upon

A. Arrangement of the cylinders

B. Design of crankshaft

C. Number of cylinders

D. All of these

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4

The actual volume of fresh charge admitted in 4-stroke petrol engine is

A. Equal to stroke volume

B. Equal to stroke volume and clearance volume

C. Less than stroke volume

D. More than stroke volume

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4

The ignition quality of diesel oil is expressed by

A. Cetane number

B. Octane number

C. Calorific value

D. None of these

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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

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4

Supercharging is the process of supplying the intake air to the engine cylinder at a density _________ the density of the surrounding atmosphere.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

If V₁ is the jet velocity and V₀ is the vehicle velocity, then the propulsive efficiency of a rocket is given by

A. [2(V₀/V₁)]/ [1 + (V₀/V₁)²]

B. (V₀/V₁)/ [1 + (V₀/V₁)²]

C. V₀/(V₀ + V₁)

D. V₁/(V₀ + V₁)

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4

The volumetric efficiency of a well designed engine may be

A. 30 to 40 %

B. 40 to 60 %

C. 60 to 70 %

D. 75 to 90 %

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4

Thermal efficiency of a two stroke cycle engine is ________ a four stroke cycle engine.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

In order to mix air and petrol in the required proportion and to supply it to the engine during suction stroke, then _________ is employed.

A. Fuel pump

B. Injector

C. Carburettor

D. None of these

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4

The exhaust valve in a four stroke cycle petrol engine

A. Opens at 50° before bottom dead centre and closes at 15° after top dead centre

B. Opens at bottom dead centre and closes at top dead centre

C. Opens at 50° after bottom dead centre and closes at 15° before top dead centre

D. May open and close anywhere