Test: Fuels, Supercharging & Jet Propulsion - 1 - Mechanical Engineering MCQ

Consider the following statements regarding knock rating of SI engine fuels:
1. Iso-octane is assigned a rating of zero octane number. 
2. Normal heptane is assigned a rating of hundred octane number
3. Iso-octane is assigned a rating of hundred octane number
4. Normal heptane is assigned a rating of zero octane number
Which of the above statements are correct?

Reference fuels for knock rating of SI engine fuels would include 

The two reference fuels used for cetane rating are  

Consider the following statements  
1. Motor gasoline is a mixture of various hydrocarbons with a major proportion being aromatic hydrocarbons.
2. Compressed natural gas is mainly composed of methane.
3. Producer gas has a predominant component of hydrogen with lesser proportion of carbon monoxide.
4. Cetane number of fuel used in diesel engines in India is in the range of 80 to 90.
Which of these statements are correct?

What is the main objective of supercharging of the engine?  

Consider the following statements: 
1. Supercharging increases the power output of an engine.
2. Supercharging increases the brake thermal efficiency considerably.
3. Supercharging helps scavenging of cylinders.
Which of the statements given above are correct?

Surging basically implies  

Assertion (A): The CI engine is basically more suitable for supe rcharging than the SI engine. 
Reason (R): In the CI engine super charging tends to prevent diesel knocking.

Consider the following statements: 

In open cycle turbo-jet engines used in military aircraft, reheating theexhaust gas from the turbine by burning more fuel is used to increase.

1. Thrust
2. The efficiency of engine
3. The range of aircraft.

correct statements are

Assertion (A): Compared to a turbo-jet engine, a turbo-prop engine has a higher power for take-off and higher propulsive efficiency at low speeds. 
Reason (R): By mounting the propeller on the turbine shaft, the propeller can be runat a very high speed to obtain higher efficiency.

Assertion (A): In the subsonic range the propulsive efficiency of a rocket is less thanthat of a turbojet.  
Reason (R): The jet velocity of rocket is independent of forward motion.

For a jet propulsion unit, ideally the ratio of compressor work and turbinework is 

Assertion (A): After burning increases the thrust of a jet engine.

Reason (R): The air fuel ratio of jet engine is high. 

Consider the following statements regarding performance of turbojet engines:
1. The thrust decreases at higher altitude due to reduced density of air and consequently lower mass flow of air.
2 At subsonic speeds, the effect of increased velocity is to increase the air flow and the thrust increases.
3. The relative velocity of jet with respect to the medium decreases at higher speeds which tends to reduce the thrust.
4 For turbojet engine the thrust of jet at subsonic speeds remains relatively constants.
Which of the statements given above are correct?

Assertion (A): Propulsion efficiency of propeller driven aircraft is low at very highspeeds.

Reason (R): At high speeds, shock waves are formed over propeller blades. 

The thrust of a jet propulsion power unit can be increased by 

Consider the following statements: 
As compared to a turboprop, a turbojet
1. Can operate at higher altitudes
2. Can operate at higher flight velocities
3. Is more fuel efficient at lower speeds
Of these statements