Home
Current Affairs January 2024

What is the correct answer?

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

Correct Answer :

A. Short delay period


Related Questions

What is the correct answer?

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

What is the correct answer?

4

The basic requirement of a good combustion chamber is

A. Minimum turbulence

B. Low compression ratio

C. High thermal efficiency and power output

D. Low volumetric efficiency

What is the correct answer?

4

The octane number of petrol, generally available, is

A. 20 to 40

B. 40 to 60

C. 60 to 80

D. 80 to 100

What is the correct answer?

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

What is the correct answer?

4

The ignition quality of diesel oil is expressed by

A. Cetane number

B. Octane number

C. Calorific value

D. None of these

What is the correct answer?

4

The object of providing masked inlet valve in the air passage of compression ignition engines is to

A. Enhance flow rate

B. Control air flow

C. Induce primary swirl

D. Induce secondary turbulence

What is the correct answer?

4

The _________ engines can work on very lean mixture of fuel.

A. Spark ignition

B. Compression ignition

C. Both (A) and (B)

D. None of these

What is the correct answer?

4

The brake power of a diesel engine, keeping other parameters constant, can be increased by

A. Decreasing the density of intake air

B. Increasing the temperature of intake air

C. Increasing the pressure of intake air

D. Decreasing the pressure of intake air

What is the correct answer?

4

The reference fuels for knock rating of spark ignition engines would include

A. Iso-octane and alpha-methyl naphthalene

B. Normal octane and aniline

C. Isooctane and normal hexane

D. Normal heptane and isooctane

What is the correct answer?

4

The increase of efficiency of a compression ignition engine, as the load decreases, is due to

A. Higher maximum temperature

B. Qualitative governing

C. Quantitative governing

D. Hit and miss governing

What is the correct answer?

4

The frictional power (F.P.) is given by

A. F.P. = B.P. - I.P.

B. F.P. = I.P. - B.P.

C. F.P. = B.P./I.P.

D. F.P. = I.P./B.P.

What is the correct answer?

4

Volatility of diesel fuel oil is

A. 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

B. Temperature at which it solidifies or congeals

C. It catches fire without external aid

D. Indicated by 90% distillation temperature, i.e., when 90% of sample oil has distilled off

What is the correct answer?

4

The combustion in compression ignition engines is

A. Homogeneous

B. Heterogeneous

C. Both (A) and (B)

D. None of these

What is the correct answer?

4

In a four stroke cycle petrol engine, the charge is ignited at

A. 30° before top dead centre

B. 30° after top dead centre

C. 30° before bottom dead centre

D. 30° after bottom dead centre

What is the correct answer?

4

Air fuel ratio for idling speed of a petrol engine is approximately

A. 1 : 1

B. 5 : 1

C. 10 : 1

D. 15 : 1

What is the correct answer?

4

Compression ratio of I.C. Engines is

A. The ratio of volumes of air in cylinder before compression stroke and after compression stroke

B. Volume displaced by piston per stroke and clearance volume in cylinder

C. Ratio of pressure after compression and before compression

D. Swept volume/cylinder volume

What is the correct answer?

4

In a typical medium speed, 4-stroke cycle diesel engine

A. Fuel injection starts at 10° before to dead center and ends at 20° after tor dead center

B. Fuel injection starts at top dead center and ends at 20° after top dead center

C. Fuel injection starts at just before top dead center and ends just after top dead center

D. May start and end anywhere

What is the correct answer?

4

The thermal efficiency of diesel engines is about

A. 15 %

B. 30 %

C. 50 %

D. 70 %

What is the correct answer?

4

The expansion of fuel in a four stroke cycle diesel engine

A. Starts at 15° before top dead centre and ends at 30° after top dead centre

B. Starts at top dead centre and ends at 30° after top dead centre

C. Starts at 15° after top dead centre and ends at 30° before bottom dead centre

D. May start and end anywhere

What is the correct answer?

4

In a four stroke cycle diesel engine, the inlet valve

A. Opens at 20° before top dead centre and closes at 40° after bottom dead centre

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

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

D. May open and close anywhere

What is the correct answer?

4

The object of supercharging the engine is

A. To reduce mass of the engine per brake power

B. To reduce space occupied by the engine

C. To increase the power output of an engine when greater power is required

D. All of the above

What is the correct answer?

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)

What is the correct answer?

4

In case of gas turbines, the gaseous fuel consumption guarantees are based on

A. High heat value

B. Low heat value

C. Net calorific value

D. Calorific value

What is the correct answer?

4

In a diesel engine, the duration between the time of injection and ignition, is known as

A. Pre-ignition period

B. Delay period

C. Period of ignition

D. Burning period

What is the correct answer?

4

The normal heptane (C7H16) is given a rating of ________ octane number.

A. 0

B. 50

C. 100

D. 120

What is the correct answer?

4

The calorific value of gaseous fuels is expressed in terms of

A. kcal

B. kcal/kg

C. kcal/m²

D. kcal/m3

What is the correct answer?

4

A petrol engine has compression ratio from

A. 6 to 10

B. 10 to 15

C. 15 to 25

D. 25 to 40

What is the correct answer?

4

In a four stroke cycle petrol engine, the inlet valve

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

B. Opens at 20° before top dead centre and closes at 40° after bottom dead centre

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

D. May open or close anywhere

What is the correct answer?

4

Which one of the following engines will have heavier flywheel than the remaining ones?

A. 30 kW four-stroke petrol engine running at 1500 r.p.m.

B. 30 kW two-stroke petrol engine running at 1500 r.p.m.

C. 30 kW two-stroke diesel engine running at 750 r.p.m.

D. 30 kW four-stroke diesel engine running at 750 r.p.m.

What is the correct answer?

4

The delay period in compression ignition engines depends upon

A. Temperature and pressure in the cylinder at the time of injection

B. Nature of the fuel mixture strength

C. Relative velocity between the fuel injection and air turbulence pressure of residual gases

D. All of the above