Compressors, Gas Turbines and Jet Engines MCQs – Latest Competitive Mechanical Engineering MCQs

Compressors, Gas Turbines and Jet Engines MCQs – Latest Competitive Mechanical Engineering MCQs

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Latest Mechanical Engineering MCQs

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Latest Compressors, Gas Turbines and Jet Engines Mcqs

The most occurred mcqs of Compressors, Gas Turbines and Jet Engines in past papers. Past papers of Compressors, Gas Turbines and Jet Engines Mcqs. Past papers of Compressors, Gas Turbines and Jet Engines Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Compressors, Gas Turbines and Jet Engines Mcqs. The Important series of Compressors, Gas Turbines and Jet Engines Mcqs are given below:

Adiabatic compression is one in which___________________?

A. work done is maximum
B. no heat leaves or enters the compressor cylinder during compression
C. temperature rise follows a linear relationship
D. temperature during compression remains constant
E. entropy decreases

The most efficient method of compressing air is to compress it_________________?

A. isothermally
B. isentropically
C. adiabatically
D. isochronically
E. as per law pV

Isothermal compression effeicency can be attained by running the compressor__________________?

A. at average speed
B. at very slow speed
C. at very high speed
D. at zero speed
E. isothermally

Isothermal compression efficiency, even when running at high speed, can be approached by using __?


A. cold water spray
B. multi-stage compression
C. both A. and B. above
D. fully insulating the cylinder
E. high stroke

The overall isothermal eiffciency of compressor is defined as the ratio of_______________?

A. isothermal h.p. to the BHP of motor
B. power to drive compressor to isothermal h.p.
C. isothermal h.p. to adiabatic h.p.
D. work to compress air isothermally to work for actual compression
E. isothermal work to ideal work

1 m of air at atmospheric condition weighs approximately__________________?

A. 1.0 kg
B. 0.5 kg
C. 1.3 kg
D. 2.2 kg
E. 3.2 kg

Free air is the air at________________?

A. atmospheric conditions at any specific location
B. 15°C and 1 kg/cm2
C. 0°C and standard atmospheric conditions
D. 20°C and 1 kg/cm2 and relative humidity of 36%
E. 25°C, 1 kg/cm2 and relative humidity of 50%.

The capacity of a compressor is 5 m /mih. 5 m /min refers to_______________?

A. compressed air
B. free air
C. standard air
D. compressed air at delivery pressure
E. air sucked

Maximum work is done in compressing air when the compression is_________________?

A. polytropic
B. adiabatic
C. isothermal
D. any one of the above
E. none of the above

Standard air is the air at_____________________?

A. 15°C and 1 kg/cm2
B. 20°C and 1 kg/cm2 and relative humidity 36%
C. 0°C and standard atmospheric conditions
D. atmospheric conditions at any specific location
E. 25°C, 1 kg/cm2 and RH of 60%.

The compressor capacity with decrease in suction temperature_________________?

A. increases
B. remains unaffected
C. decreases
D. may increase or decrease depending on compressor capacity
E. increases upto certain limit and then decreases

Inter cooling in compressors__________________?

A. is the standard practice for big compressors
B. results in saving of power in compressing a given volume to given pressure
C. cools the delivered air
D. enables compression in two stages
E. prevents compressor jacket running very hot

Isothermal compression though most efficient, but is not -practicable because_________________?

A. ityrequires very big cylinder
B. it is impossible in practice
C. it does not increase pressure much
D. compressor has to run at very slow speed to achieve it
E. it requires cylinder to be placed in water

What will be the volume of air at 327°C if its volume at 27°C is 1.5 m3/mt ?

A. 3 m3/mt
B. 18 m3/mt
C. 1.5 m3/mt
D. 6 m3/mt
E. 0.75 m3/mt

An ideal air compressor cycle without clearance on p-v diagram can be represented by following processes________________?

A. one adiabatic, two isobaric, and one constant volume
B. two adiabatic, one isobaric and one constant volume
C. two adiabatic and two isobaric
D. one adiabatic, one isobaric and two constant volume
E. two isobaric, two adiabatic and one constant volume

The work done per unit mass of air in compression will’be least when n is equal to______________?

A. 1
B. 1.3
C. 1.2
D. 1.4
E. 1.5

An ideal air compressor cycle with clearance on p-v diagram can be represented by following processes_______________?

A. two adiabatic, one isobaric and one constant volume
B. two adiabatic and two isobaric
C. one adiabatic, two isobaric, and one constant volume
D. one adiabatic, one isobaric and two constant volume
E. two isobaric, two adiabatic and one constant volume

Compression efficiency is compared against_____________________?

A. adiabatic compression
B. ideal compression
C. botii isothermal and adiabatic compression
D. isentropic compression
E. isothermal compression

Aeroplanes employ following type of compressor_______________?

A. centrifugal
B. axial flow
C. radial flow
D. combination of above
E. none of the above

Ratio of indicated H.P. and brake H.P. is known as_________________?

A. mechanical efficiency
B. isothermal efficiency
C. volumetric efficiency
D. adiabatic efficiency
E. relative efficiency

Cylinder clearance in a compressor should be _________________?

A. about 50% of swept volume
B. as small as possible
C. as large as possible
D. about 100% of swept volume
E. none of the above

Volumetric efficiency of air compressors is of the order of________________?

A. 40-50%
B. 20-30%
C. 60-70%
D. 70-90%
E. 90-100%

Volumetric efficiency of a compressor without clearance volume________________?

A. decreases with increase in compression ratio
B. increases with increase in compression ratio
C. is not dependent upon compressin ratio
D. may increase/decrease depending on compressor capacity
E. unpredictable

Production Technology Mcqs

Volumetric efficiency is_____________________?

A. reciprocal of compression ratio
B. the ratio of the air actually delivered to the amount of piston displacement
C. the ratio of stroke volume to clearance volume
D. index of compressor performance
E. proportional to compression ratio

Ratio of compression is the ratio of__________________?

A. stroke volume and clearance volume
B. absolute discharge pressure to the ab-solute intake pressure
C. pressures at discharge and suction cor-responding to same temperature
D. gauge discharge pressure to the gauge intake pressure
E. none of the above

The ratio of work done per cycle to the swept volume in case of compressor is called ______________?

A. compression ratio
B. compression index
C. compressor efficiency
D. mean effective pressure
E. compressor effectiveness

The net work input required for compressor with increase in clearance volume_____________________?

A. decreases
B. increases
C. remains same
D. increases/decreases depending on com-pressor capacity
E. unpredictable

Clearance volume in actual reciprocating compressors is essential __________________?

A. to provide cushioning effect
B. to accommodate Valves in the cylinder head
C. to attain high volumetric efficiency
D. to avoid mechanical bang of piston with cylinder head
E. to provide cushioning effect and also to avoid mechanical bang of piston with cylinder head

Volumetric efficiency of a compressor with clearance volume ________________?

A. in not dependent upon compression ratio
B. decreases with increase in compression ratio
C. increases with increase in compression ratio
D. may increase/decrease depending on compressor capacity
E. unpredictable

Out of the following, from where you will prefer to take intake for air compressor_________________?

A. from an air conditioned room maintained at 20°C
B. from coal yard side
C. from outside atmosphere at 1°C
D. from a side where cooling tower is located nearby
E. from any one of the above locations

Which is false statement about multistage compression ?

A. Outlet temperature is reduced
B. Volumetric efficiency is high
C. It is best suited for compression ratios around 7:1
D. The moisture in air is condensed in the intercooler
E. Power consumption per unit of air delivered is low

Euler’s equation is applicable for__________________?

A. axial compressor
B. centrifugal compressor
C. pumps
D. all of the above
E. none of the above

Ratio of indicated h.p. to shaft h.p. in known as__________________?

A. isothermal efficiency
B. compressor efficiency
C. volumetric efficiency
D. mechanical efficiency
E. adiabatic efficiency

The clearance volume of the air compressor is kept minimum because____________________?

A. it results in minimum work
B. it greatly affects volumetric efficiency
C. it allows maximum compression to be achieved
D. it permits isothermal compression
E. none of the above

Which is false statement about air receivers ___________________?

A. These act as reservoir to- take care of sudden demands
B. These are used to dampen pulsations ,
C. These increase compressor efficiency
D. These knock out some oil and moisture
E. These reduce frequent on/off operation of compressors

Rotary compressor is best suited for_____________________?

A. small quantity of air at low pressure
B. small quantity of air at high pressure
C. large quantity of air at high pressure
D. large quantity of air at low pressure
E. any one of the above

After-cooler is used to__________________?

A. reduce volume
B. decrease the delivery temperature for ease in handling
C. cause moisture and oil vapour to drop out
D. cool the air
E. increase pressure

Reciprocating air compressor is best suited for___________________?

A. large quantity of air at high pressure
B. small quantity of air at low pressure
C. small quantity of air at high pressure
D. large quantity of air at low pressure
E. any one of the above

The capacity of compressor will be highest when its intake temperature is___________________?

A. highest
B. lowest
C. anything.
D. atmospheric
E. none of the above

In multistage compressor, the isothermal compression is achieved by_________________?

A. by constantly cooling the cylinder
B. employing intercooler
C. by running compressor at very slow speed
D. by insulating the cylinder
E. none of the above

Refrigeration And Air Conditioning Mcqs

Mining industry usually employs following motive power___________________?

A. petrol engine
B. compressed air
C. A.C. electric motor
D. diesel engine
E. D.C. electric motor

Separators in compressor installations are located_____________________?

A. after intercooler
B. before intercooler
C. after receiver
D. between after-cooler and air receiver
E. before suction

An air compressor may be controlled by____________________?

A. clearance control
B. throttle control
C. blow-off control
D. any one of the above
E. none of the above

During peak load periods, the best method of controlling compressors is___________________?

A. relief valve
B. constant speed unloader
C. start-stop motor
D. variable speed
E. none of the above

The compressor performance at higher altitude compared to sea level will be _______________?

A. higher
B. same
C. lower
D. dependent on other factors
E. none of the above

A centrifugal compressor works on the principle of__________________?

A. conversion of pressure energy into kinetic energy
B. conversion of kinetic energy into pres¬sure energy
C. generating pressure directly
D. centripetal action
E. combination of A. and D.

A compressor at high altitude will draw________________?

A. same power
B. less power
C. more power
D. more/less power depending on other factors
E. none of the above

The thrust on the rotor in a centrifugal compressor is produced by________________?

A. tangential component
B. axial component
C. radial component
D. resultant component

The area of actual indicator diagram on an air compressor as compared to area of ideal indicator diagram is_____________________?

A. same
B. more
C. less
D. more/less depending on compressor capacity
E. unpredictable

To aviod moisture troubles, the compressed air main line should __________________?

A. be laid vertically
B. drop gradually towards the point of use
C. rise gradually towards the point of use
D. be laid exactly horizontally
E. none of the above

To avoid moisture troubles, the branch connections from compressed air lines should be taken from_________________?

A. top side of main
B. left side of main
C. bottom side of main
D. right side of main
E. any location

For a compressor, least work will be done if the compression is________________ ?

A. polytropic
B. isothermal
C. isentropic
D. somewhere in between isentropic and isothermal
E. none of the above

The compressor efficiecny is the__________________?

A. isothermal H.P/indicated H.R
B. total output/air input
C. isothermal H.P./shaft H.R
D. compression work/motor input
E. none Of the above

For slow-speed large capacity compressor, following type of valve will be best suited________________?

A. mechanical valve of the corliss, sleeve, rotary or semirotary type
B. poppet valve
C. disc or feather type
D. any of the above
E. none of the above

The volumetirc efficiency of a compressor is calculated on the basis of __________________?

A. volume at 0°C and 1 kg/cm2
B. volume of air inhaled at N.T.P. conditions
C. volume of air inhaled at working conditions
D. volume at 20°C and 1 kg/cm2
E. none of the above

During base load operation, the best method of controlling compressor is ___________________?

A. start-stop motor
B. relief valve
C. constant speed unloader
D. variable speed
E. none of the above

The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation___________________?

A. 0.5%
B. 0.1%
C. 1.0%
D. 5%
E. 10%.

In a compressor, free air delivered is the actual volume delivered at the stated pressure reduced to ____________________?

A. 0°C and 1 kg/cm2
B. intake temperature and pressure conditions
C. N.T.P. conditions
D. 20°C and 1 kg/cm2
E. none of the above

The advantage of multistage compression over single stage compression is ________________?

A. lower power consumption per unit of air delivered
B. decreased discharge temperature
C. higher volumetric efficiency
D. moisture free air
E. all of the above

As the value of index ‘«’ is decreased, the volumetric efficiency will___________________?

A. remain unaffected
B. decrease
C. increase
D. may increase/decrease depending on compressor clearance
E. none of the above

The indicated work per unit mass of air delivered is___________________?

A. greatly affected by clearance volume
B. directly proportional to clearance volume
C. not affected by clearance volume
D. inversely proportional to clearance volume

The ratio of isentropic work to Euler work is known as_____________________?

A. pressure coefficient
B. polytropic reaction
C. work coefficient
D. slip factor
E. compressor efficiency

Phenomenon of choking in compressor means __________________?

A. increased inclination of chord with air steam
B. fixed mass flow rate regardless of pressure ratio
C. reducing mass flow rate with increase in pressure ratio
D. no flow of air
E. does not occur

Diffuser in a compressor is used to _____________________?

A. make the flow stream-line
B. increase velocity
C. convert pressure energy into kinetic energy
D. convert kinetic energy into pressure energy
E. increase degree of reaction

For supplying intermittent small quantity of air at high pressure, following compressor is best suited__________________?

A. axial
B. reciprocating
C. centrifugal
D. screw
E. turbo jet

Which is false statement about advantages of multistage compressor in comparison to single stage compressor_________________?

A. better mechanical balance
B. less power requirement
C. less loss of air due to leakage past the cylinder
D. more effective lubrication
E. lower volumetric efficiency

For minimum work in multistage compression, assuming same index of compression in all stages_________________?

A. work done in subsequent stages should increase
B. work done in first stage should be more
C. work done in subsequent stages should decrease
D. work done in all stages should be equal
E. work done in any stage is no criterion for minimum work but depends on other factors

The volumetric efficiency of a compressor falls roughly as follows for every 5°C increase in atmospheric temperature__________________?

A. 0.5%
B. 0.1%
C. 1%
D. 5%
E. 10%

The criterion of the thermodynamic efficiency for rotary compressor is_________________?

A. isentropic compression
B. polytropic compression
C. isothermal compression
D. any one of the above
E. none of the above

The indicated work per unit mass of air delivered is___________________?

A. greatly affected by clearance volume
B. directly proportional to clearance volume
C. not affected by clearance volume
D. inversely proportional to clearance volume

The ratio of isentropic work to Euler work is known as_____________________?

A. pressure coefficient
B. polytropic reaction
C. work coefficient
D. slip factor
E. compressor efficiency

Phenomenon of choking in compressor means __________________?

A. increased inclination of chord with air steam
B. fixed mass flow rate regardless of pressure ratio
C. reducing mass flow rate with increase in pressure ratio
D. no flow of air
E. does not occur

Diffuser in a compressor is used to _____________________?

A. make the flow stream-line
B. increase velocity
C. convert pressure energy into kinetic energy
D. convert kinetic energy into pressure energy
E. increase degree of reaction

For supplying intermittent small quantity of air at high pressure, following compressor is best suited__________________?

A. axial
B. reciprocating
C. centrifugal
D. screw
E. turbo jet

Which is false statement about advantages of multistage compressor in comparison to single stage compressor_________________?

A. better mechanical balance
B. less power requirement
C. less loss of air due to leakage past the cylinder
D. more effective lubrication
E. lower volumetric efficiency

Machine Design Mcqs

For minimum work in multistage compression, assuming same index of compression in all stages_________________?

A. work done in subsequent stages should increase
B. work done in first stage should be more
C. work done in subsequent stages should decrease
D. work done in all stages should be equal
E. work done in any stage is no criterion for minimum work but depends on other factors

The volumetric efficiency of a compressor falls roughly as follows for every 5°C increase in atmospheric temperature__________________?

A. 0.5%
B. 0.1%
C. 1%
D. 5%
E. 10%

The criterion of the thermodynamic efficiency for rotary compressor is_________________?

A. isentropic compression
B. polytropic compression
C. isothermal compression
D. any one of the above
E. none of the above

For a two stage compressor* if index of compression for higher stage is greater than index of compression for lower stage, then the optimum pressure as compared to ideal case will___________________?

A. increase
B. remain unaffected
C. decrease
D. other factors control it
E. unpredictable

Losses in a centrifugal compressor are due to__________________?

A. impeller channel losses
B. inlet losses
C. diffuser losses
D. all of the above
E. none of the above

Pick up the wrong statement about advantages of multistage compression____________________?

A. mechanical balance is better
B. more loss of air due to leakage past the cylinder
C. better lubrication is possible advantages of multistage
D. air can be cooled perfectly in between
E. more uniform torque, light cylinder and saving in work

More than one stage will be preferred for reciprocating compressor if the delivery pressure is more than____________________?

A. 2 kg/cm2
B. 10 kg/cm2
C. 6 kg/cm2
D. 14.7 kg/cm2
E. none of the above

The ratio of outlet whirl velocity to blade velocity in case of centrifugal compressor is called__________________?

A. slip factor
B. velocity coefficient
C. velocity factor
D. blade effectiveness

The ratio of isentropic work to euler’s work is known as _____________________?

A. isentropic efficiency
B. compressor efficiency
C. Euler’s efficiency
D. pressure coefficient
E. pressure ratio

The maximum compression ratio in an actual single stage axial flow comperssor is of the order of________________?

A. 1 : 1.2
B. 1 : 5
C. 1 : 2
D. 1 : 10
E. 1 : 1

Surging is the phenomenon of___________________?

A. motion of air at sonic velocity
B. air stream blocking the passage
C. unsteady, periodic and reversed flow
D. air stream not able to follow the blade contour
E. production of no air pressure

The thermodynamic efficiency of rotary compressor is based on_______________?

A. isentropic compression
B. adiabatic compression
C. isothermal compression
D. polytropic compression
E. none of the above

Maximum delivery pressure is a rotary air compressor is of the order of__________________?

A. 16 kg/cm2
B. 10 kg/cm2
C. 6 kg/cm2
D. 25 kg/cm2
E. 40 kg/cm2

Axial flow compressor has the following advantage over centrifugal compressor__________________?

A. larger air handling ability per unit frontal area
B. aerofoil blades are used
C. higher pressure ratio per stage
D. higher average velocities
E. none of the above

Atmospheric pressure is 1.03 kg/cm and vapour pressure is 0.03 kg/cm . The air pressure will be_____________________ ?

A. 1.06 kg/cm2
B. 1.03 kg/cm2
C. 1.00 kg/cm2
D. 0.53 kg/cm2
E. 0.5 kg/cm2

Axial flow compressor resembles____________________ ?

A. reciprocating pump
B. centrifugal pump
C. turbine
D. sliding vane compressor
E. none of the above

The vloumetric efficiency of compressor with increase in compression ratio will ___________________?

A. remain same
B. decrease
C. increase
D. may increase/decrease depending on clearance volume
E. none of the above

The work ratio of simple gas turbine cycle depends on_________________?

A. maximum cycle temperature
B. pressure ratio
C. minimum cycle temperature
D. all of the above
E. none of die above

Open cycle gas turbine works on___________________?

A. Brayton or Atkinson cycle
B. Carnot cycle
C. Rankine cycle
D. Erricsson cycle
E. Joule cycle

Gas turbines for power generaion are normally used___________________?

A. in emergency
B. to supply peak load requirements
C. to enable start thermal power plant
D. to supply base load requirements
E. when other sources of power fail

Surging phenomenon in centrifugal com-pressor depends on ___________________?

Pick up wrong statement ?
A. pressure ratio
B. mass flow rate
C. change in load
D. stagnation pressure at the outlet
E. all of the above

The ratio of the increase in pressure in rotor blades to total increase in pressure in the stage is called__________________?

A. pressure coefficient
B. pressure ratio
C. degree of reaction
D. slip factor
E. stage factor

Actual compression curve is___________________?

A. same as adiabatic
B. same as isothermal
C. better than isothermal and adiabatic
D. in between isothermal and adiabatic
E. none of the above

The pressure ratio of an ideal vaned compressor with increase in mass flow rate_________________?

A. decreases
B. increases
C. remains constant
D. first decreases and then increases
E. unpredictable

Compressors, Gas Turbines and Jet Engines MCQs – Latest Competitive Mechanical Engineering MCQs

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