Test: Fuels, Supercharging & Jet Propulsion - 2 - Mechanical Engineering MCQ

Assertion (A): Iso-octane has been chosen as the reference for S.I. engine fuels and hasbeen assigned a value of octane number 100.

Reason (R): Among the fuels, iso-octane ensures the highest compression ratio atwhich an S.I. engine can be operated without knocking.

The Cetane number of automotive diesel fuel used in India is in which one of the following ranges? 

Consider the following statements regarding n-Cetane: 
1. It is a standard fuel used for knock rating of diesel engines.
2. Its chemical name is n-hexadecane
3. It is a saturated hydrocarbon of paraffin series.
4. It has long carbon chain structure.
Of the above correct statements are

Consider the following statements:
1. Supercharging increases the power output and increases the volumetricefficiency.
2. Supercharging is more suitable for S.I. engines than C.I. engines. 
3. The limit of supercharging for an S.I. engine is set by knock while that for a C.I. engine is set by thermal loading.
Which of the statements given above are correct?

Which one of the following types of compressors is mostly used for super charging of I.C. engines?  

Consider the following statements with reference to supercharging of I.C. engines:
1. Reciprocating compressors are invariably used for high degree of supercharging
2. Rotary compressors like roots blowers are quite suitable for low degree of supercharging 
3. Axial flow compressors are most commonly employed for super charging diesel engines used in heavy duty transport vehicles
4. Centrifugal compressors are used for turbo -charging
Which of the statements given above are correct?

What is the purpose of employing super charging for an engine?  

Which one of the following is correct?The turbine of the turbo-prop engine as compared to that of the turbojetengine is

In a turbojet engine, subsequent to heat addition to compressed air, to get the power output, the working substance is expanded in  

Propulsion efficiency of a jet engine is given by (where u is flight velocity andV is jet velocity relative to aircraft). 

Consider the following statements:
In a turbojet engine, thrust may be increased by 
1. Increasing the jet velocity
2. Increasing the mass flow a rate of air
3. After burning of the fuel.
Of these statements

The theoretical mechanical efficiency of a jet engine (neglecting frictional and thermal losses), when driving a vehicle, has its maximum 

The efficiency of jet engine is  

Assertion (A): A bypass jet engine gives a better propulsive efficiency and better fuele conomy than a straight jet engine.  
Reason (R): A bypass jet engine gives lower velocity of jet efflux than a straight jet engine.

In turbo prop, the expansion of gases takes place approximately  

Assertion (A): The use of turboprop engine is limited to medium speed applications.

Reason (R): The efficiency of a turboprop engine decreases at higher speed. 

A turbo prop is preferred to turbo-jet because  

Consider the following statements relating to rocket engines: 
1. The combustion chamber in a rocket engine is directly analogous to the reservoir of a supersonic wind tunnel.
2. Stagnation conditions exist at the combustion chamber.
3. The exit velocities of exhaust gases are much higher than those in jet engines.
4. Efficiency of rocket engines is higher than that of jet engines.
Of these correct statements are

Which one of the following is the correct sequence of the position of the givencomponents in a turboprop?  

Assertion (A): Turbojet engine is superior to turboprop engine at all operating conditions.  
Reason (R): Efficiency of the propeller is low at high altitude and at high speeds.

Consider the following statements about a rocket engine: 
1. It is very simple in construction and operation.
2. It can attain very high vehicle velocity.
3. It can operate for very long duration.
Of these statements

Only rocket engines can be propelled to 'SPACE' because  

Assertion (A): Liquid oxygen-liquid hydrogen propellant system has a higher specificimpulse relative to the liquid oxygen-hydrocarbon system.  Reason (R): Hydrogen has a higher burning velocity than hydrocarbons.

In solid propellants rockets, ammonium picrate is usually added as:

Consider the following statements indicating a comparison between rocket and jet propulsion systems:
1. Both rocket and jet engines carry the fuel and oxidant. 
2. Rockets do not employ compressor or propeller.
3. Rockets can operate in vacuum also.
4. Rockets can use solid fuels and oxidants.
Which of the statements given above are correct?

Assertion (A): A rocket engine can operate even in vacuum and in any fluid medium.

Reason (R): Rocket engine is a pure reaction engine, wherein a propulsive thrust is obtained as a reaction of momentum of ejected matter. 

Consider the following statements:
The thrust of a rocket engine depends upon  
1. Effective jet velocity
2. Weight of the rocket
3. Rate of propellant consumption
Of these statements