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4

The term scavenging is generally associated with

A. 2-stroke cycle engines

B. 4-stroke cycle engines

C. Aeroplane engines

D. High efficiency engines

Correct Answer :

D. High efficiency engines


Related Questions

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4

The ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time is called

A. Mechanical efficiency

B. Overall efficiency

C. Indicated thermal efficiency

D. Volumetric efficiency

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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

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 power actually developed by the engine cylinder of an I.C. engine is known as

A. Theoretical power

B. Actual power

C. Indicated power

D. None of these

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4

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

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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 self ignition temperature of petrol is ________ as compared to diesel oil.

A. Same

B. Lower

C. Higher

D. None of these

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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

The inlet value of a four stroke cycle I.C engine remains open for nearly

A. 180°

B. 125°

C. 235°

D. 200°

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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

In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.

A. Equal to

B. Below

C. Above

D. None of these

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4

By higher octane number of spark ignition fuel, it is meant that the fuel has

A. Higher heating value

B. Higher flash point

C. Lower volatility

D. Longer ignition delay

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4

A supercharged engine as compared to an ordinary engine

A. Requires smaller foundation

B. Is lighter

C. Consumes less lubricating oil

D. All of these

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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

In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the

A. Beginning of suction stroke

B. End of suction stroke

C. Beginning of exhaust stroke

D. End of exhaust stroke

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4

Scavenging air in diesel engine means

A. Air used for combustion sent under pressure

B. Forced air for cooling cylinder

C. Burnt air containing products of combustion

D. Air used for forcing burnt gases out of engine's cylinder during the exhaust period

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4

Which of the following fuel has little tendency towards detonation?

A. Benzene

B. Iso-octane

C. Normal heptane

D. Alcohol

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4

Which of the following statement is wrong?

A. A four stroke cycle engine develops twice the power as that of a two stroke cycle engine

B. For the same power developed, a four stroke cycle engine is lighter, less bulky and occupies less floor area

C. The petrol engines are costly than diesel engines

D. All of the above

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4

The colour of exhaust from diesel engine is generally

A. White

B. Bluish

C. Black

D. Violet

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4

The cetane number of diesel oil, generally available, is

A. 20 to 25

B. 25 to 30

C. 30 to 40

D. 40 to 55

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4

The operation of forcing additional air under pressure in the engine cylinder is known as

A. Scavenging

B. Turbulence

C. Supercharging

D. Pre-ignition

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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

Pick up the wrong statement about supercharging

A. Supercharging reduces knocking in diesel engines

B. There can be limited supercharging in petrol engines because of detonation

C. Supercharging at high altitudes is essential

D. Supercharging results in fuel economy

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4

The maximum propulsive efficiency of a turbojet engine is at a speed of

A. 1000 km/h

B. 2000 km/h

C. 2400 km/h

D. 3000 km/h

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4

The theoretically correct air fuel ratio for petrol engine is of the order of

A. 6 : 1

B. 9 : 1

C. 12 : 1

D. 15 : 1

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4

Solid fuel fabricated into various small shapes, which are assembled to form fuel elements, is in the form of

A. Plates

B. Pallets

C. Pins

D. All of these

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4

The cam shaft of a four stroke I.C. engine running at 1500 rpm will run at

A. 1500 rpm

B. 750 rpm

C. 3000 rpm

D. Any value independent of engine speed

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4

In a four stroke cycle diesel engine, the compression

A. Starts at 40° after bottom dead centre and ends at 10° before top dead centre

B. Starts at 40° before top dead centre and ends at 40° after top dead centre

C. Starts at top dead centre and ends at 40° before bottom dead centre

D. May start and end anywhere

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4

The mean effective pressure obtained from engine indicator indicates the

A. Maximum pressure developed

B. Minimum pressure

C. Instantaneous pressure at any instant

D. Average pressure

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4

The thermal efficiency of diesel engines on weak mixtures is

A. Unaffected

B. Lower

C. Higher

D. Dependent on other factors