Latest Competitive Mechanical Engineering MCQs – Compressors, Gas Turbines and Jet Engines 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:
Gas turbine works on_______________?
A. Brayton or Atkinson cycle
B. Rankine cycle
C. Carnot cycle
D. Erricsson cycle
E. Joule cycle
Gas turbine works on______________?
A. Brayton or Atkinson cycle
B. Rankine cycle
C. Carnot cycle
D. Erricsson cycle
E. Joule cycle
Rotary compressors are suitable for ____________________?
A. low discharge at high pressure
B. large discharge at high pressure
C. large discharge at low pressure
D. low discharge at low pressure
E. there is no such limitation
The work ratio of a gas turbine plant is defined as the ratio of__________________?
A. actual heat drop and isentropic heat drop
C. net work output and heat supplied (6) net work output and work done by tur¬bine
D. net work output and isentropic heat drop
E. isentropic increase/drop in tempera¬ture and actual increase/ drop in temperature
The pressure ratio for an open cycle gas turbine compared to closed cycle gas turbine of same h.p. is_______________?
A. low
B. same
C. high
D. low/high depending on make and type
E. unpredictable
The fuel consumption in gas turbines is accounted for by___________________?
A. low.er heating value
B. heating value
C. higher heating value
D. higher calorific value
E. highest calorific value
Mechanical efficiency of gas turbines as compared to I.C engines is____________________?
A. higher
B. same
C. lower
D. depends on on odier considerations
E. unpredictable
The air-fuel ratio in gas turbines is of the order of ______________________?
A. 15 : 1
B. 7 : 1
C. 30 : 1
D. 40 : 1
E. 50: 1
Gas turbine blades are given a rake___________________?
A. depending on the velocity
B. in the direction of motion of blades
C. opposite to the direction of motion of blades
D. equal to zero
E. none of the above
The thermal efficiency of a gas turbine as compared to a diesel plant is__________________?
A. more
B. same
C. less
D. depends on other factors
E. unpredictably
The ratio of specific weighf/h.p. of gas turbine and I.C engines may be typically of the order of_______________________?
A. 2 : 1
B. 1 : 1
C. 4 : 1
D. 1:2
E. 1 : 6
The pressure ratio in gas turbines is of the order of__________________?
A. 4:1
b. 2:l
C. 61: 1
D. 9 : 1
E. 12:1.
Temperature of gases at end of compression as compared to exhaust gases in a gas turbine is_________________?
A. equal
B. lower
C. higher
D. can’t be compared
E. unpredictable
The hottest point in a gas turbine is______________________?
A. at the tip
B. at the base
C. in the center
D. between ~ to i of the blade height
E. uniformly heated
Efficiency of gas turbine is increased by________________ ?
A. inter cooling
B. reheating
C. adding a regenerator
D. all of the above
E. none of the above
The following is true for an open cycle gas turbine having exhaust heat exchanger. Atmospheric air before entering the compressor is____________________?
A. exhaust gases drive the compressor
B. compressed air before entering the combustion chamber is heated
C. bled gas from turbine is heated and readmitted for complete expansion
D. heated
E. part of exhaust gases are heated and mixed up with atmospheric air to utilise exhaust heat
The thermal efficiency of a simple gas turbine for a given turbine inlet temperature with increase in pressure ratio_____________________?
A. increases
B. first increases and then decreases
C. decreases
D. first decreases and then increases
E. remains same
Water gas is produced by ___________________ ?
A. same way as the natural gas
B. passing steam over incandescent coke
C. passing air and a large amount of steam over waste coal at about 65°C
D. partial combustion of caol, eke, anthractie coal or charcoal in a mixed air steam blast
E. carbonisation of coal
The combustion efficiency of a gas turbine using perfect combustion chamber is of the order of________________?
A. 75%
B. 50%
C. 85%
D. 90%
E. 99%
There is a certain pressure ratio (optimum) for a gas turbine at which its thermal efficiency is maximum. With increase in turbine temperature, the value of pressure ratio for the peak efficiency would__________________?
A. decrease
B. remain same
C. increase
D. unpredictable
E. none of the above
The ideal efficiency of simple gas turbine cycle depends on________________?
A. pressure ratio
B. minimum cycle temperature
C. maximum cycle temperature
D. all of the above
E. none of the above
The material commonly used for air craft gas turbine is__________________?
A. high alloy’ steel
B. stainless steel
C. duralumin
D. Timken, Haste and Inconel allpys
E. titanium
The jnaximum combustion pressure in gas turbine as compared to I.C. engine is_________________?
A. same
B. less
C. more
D. depends on other factors
E. unpredictable
As the turbine inlet temperature increases, the thermal efficiency of gas turbine for the optimum pressure ratio_____________________?
A. increases
B. remains same
C. decreases
D. first increases and then decreases
E. first decreases and then increases
It is not possible to use closed gas turbine cycle in aeronautical engines because_________________ ?
A. it is bulky
B. it is inefficient
C. it requires cooling water for its operation
D. non of theses
For an irreversible gas turbine cycle, the efficiency and work ratio both depend on___________________?
A. maximum cycle temperature alone
B. pressure ratio alone
C. minimum cycle temperature alone
D. both pressure ratio and maximum cycle temperature
E. none of the above
Producer gas is produced by_____________________?
A. passing steam over incandescent coke
B. carbonisation of coal
C. passing air and a large amount of steam over waste coal at about 65°C
D. partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast
E. same way as the natural gas
Fluid Mechanics Mcqs
A gas turbine used in air craft should have______________________?
A. high speed and high h.p.
B. low weight and small frontal area
C. small frontal area and high h.p.
D. high h.p. and low weight
E. all of the above
The degree of reaction of an axial flow turbine is the ratio of isentropic temperature drop in a blade row to the_____________________?
A. adiabatic temperature drop in the stage
B. total adiabaitc temperature drop
C. total temperature drop in the stage
D. total temperature drop
E. difference of maximum and minimum temperature in the cycle
The closed cycle in gas turbines_________________?
A. provides greater flexibility
B. in never used
C. provides lesser flexibility
D. is used when gas is to be burnt
E. none of the above
Water is injected in gas turbine cycle to___________________?
A. control fire hazards
B. control output of turbine
C. control temperature
D. increase efficiency
E. it is never done
In the axial flow gas turbine, the work ratio is the ratio of____________________?
A. output and input
B. compressor work and turbine work
C. actual total head tempeature drop to the isentrpic total head drop from total head inlet to static head outlet
D. actual compressor work and theoretical comprssor work
E. none of the above
A closed gas turbine in which fuel is burnt directly in the air is not possible because of__________________?
A. high specific volume
B. increasing gas temperature
C. high pressure ratio
D. high friction losses
E. paucity of 02
In gas turbines^ high thermal efficiency is obtained in_________________?
A. closed cycle
B. both of the above
C. open cycle
D. closed/open depending on other con-siderations
E. unpredictable
In jet engines, for the efficient production of large power, fuel is burnt in an atmosphere of__________________?
A. atmospheric air
B. vacuum
C. compressed air
D. oxygen alone
E. liquid hydrogen
Turbo propeller has the following additional feature over the turbojet __________________?
A. peopeller
B. intercooler
C. diffuser
D. turbine and combustion chamber
E. starting engine
In jet engines, paraffin is usually used as the fuel because of its _________________?
A. low freezing point
B. ease of atomisation
C. high calorific value
D. A. and C. above
E. none of the above
If infinite number of heaters be used in a gas turbine, then expansion process in turbine approaches _________________?
A. isothermal
B. adiabatic
C. isentropic
D. isochoric
E. isobaric
Intercooling in gas turbine results in ____________________ ?
A. increase in net output but decrease in thermal efficiency
B. increase in both thermal efficiency and net output
C. increase in thermal efficiency but decrease in net output
D. decrease in both thermal efficiency and net output
E. none of the above
The power available for take off and climb in case of turbojet engine as compared to reciprocating engine is ___________________?
A. less
B. same
C. more
D. may be less or more depending on ambient conditons
E. unpredictable
Ram compression in turbojet involves____________________?
A. reduction of speed of incoming air and conversion of part of it into pressure energy
B. lost work
C. increasing speed of incoming air
D. compression of inlet air
E. leakage losses
A jet engine works on the principle of conservation of____________________?
A. energy
B. mass
C. flow
D. linear momentum
E. angular momentum
Which of the following fuels can be used in turbojet engines _____________________?
A. high speed diesel oil
B. liquid hydrogne
C. kerosene
D. demethylated spirit
E. methyl alcohol
A rocket engine for the combustion of its fuel_____________________?
A. carries its own oxygen
B. uses compressed atmospheric air
C. uses surrounding air
D. does not require oxygen
E. depends on electrical energy supplied by solar cells
Propulsive efficiency is defined as ratio of___________________?
A. engine output and propulsive power
B. thrust power and fuel energy
C. propulsive power and fuel input
D. thrust power and propulsive power
E. none of the above
In the cross compounding of the gas turbine plant__________________?
A. both the arrangements can be employed
B. h.p. compressor is connected to l.p. turbine and l.p. compressor is con-nected to h.p. turbine
C. h.p. compressor L connected to h.p. turbine and l.p. compressor ot l.p. tur-bine
D. all are connected in series
E. none of the above
A rocket works with maximum overall efficiency when air craft velocity is equal to the_________________?
A. twice the jet velocity
B. jet velocity
C. half the jet velocity
D. average of the jet velocity
E. no such co-relationship with jet velocity exists
The maximum propulsion efficiency of a turbojet is attained at around following speed __________________?
A. 1050km/hr
B. 550 km/hr
C. 1700 km/hr
D. 2400km /hr
E. 4000 km/hr
Propulsion efficiency of the following order-is obtained in practice _______________?
A. 50%
B. 34%
C. 60%
D. 72%
E. 85%.
The air entry velocity m a rocket as compared to aircraft is_________________?
A. more
B. same
C. less
D. zero
E. dependent on power and speed
In jet propulsion power unit, the inlet duct of diverging shape is used in order to _______________ ?
A. provide robust structure
B. convert kinetic energy of air into pres-sure energy
C. collect more air
D. beautify the shape
E. none of the above
The weight per horse power ratio for gas. turbine as compared to I.C. engine and steam turbine is________________?
A. higher
B. same
C. lower
D. uncomparable
E. unpredictable
The blades of gas turbine are made of_________________?
A. stainless steel
B. mild steel
C. carbon steel
D. high alloy seel
E. high nicket alloy (neimonic)
Fighter bombers use following type of engine __________________?
A. turbo-jet
B. rocket
C. turbo-propeller
D. ram-jet
E. pulsojet
The following property is most important for material used for gas turbine blade___________________?
A. fatigue
B. toughness
C. creep
D. corrosion resistance
E. bulk modulus
The specific output per kg mass flow rate of a gas turbine (having fixed efficiencies of compressor and turine and fixed higher and lower temperature) with increase in pressure ratio will___________________?
A. increase first at fast rate and then slow
B. decrease continuously
C. increase first at slow rate and then fast
D. first increase, reach maximum and then decrease
E. none of the above
The effective power of gas turbines is increased by adding the following in compressor__________________?
A. ammonia and water vapour
B. nitrogen
C. carbon dioxide
D. hydrogen
E. none of the above
Air-fuel ratio in a jet engine will be of the order of__________________?
A. 15: 1
B. 10: 1
C. 20: 1
D. 60: 1
E. 100: 1
In jet engines the compression ratio__________________?
A. Varies linearly to the speed
B. varies as square root of the speed
C. varies as square of the speed
D. varies as cube of the speed
E. is constant irrespective of variation in speed
Fluid Mechanics Mcqs – Mechanical Engineering Mcqs
High air-fuel ratio is used in gas turbines______________________?
A. to save fuel
B. to increase the efficiency
C. to increase the output
D. to reduce the exit temperature
E. none of the above
In which case the air-fuel ratio is likely to be maximum _________________?
A. 4-stroke petrol engine
B. 2-stroke engine
C. 4-stroke diesel engine
D. multi-cylinder engine
E. gas turbine
Reheating in gas turbine results in___________________?
A. decrease of thermal efficiency
B. decrease of work ratio
C. decrease of work ratio
D. both A. and B. above
E. both B. and C. above
Work ratio of a gas turbine may be improved by f____________________?
A. increasing the turbine work
B. increasing the compression work
C. decreasing the compression work
D. decreasing the turbine work
E. A. and C. above
In the aircraft propellers __________________?
A. the propulsive matter is caused to flow around the propelled body
B. its functioning does not depend on presence of air
C. propulsive matter is ejected from within the propelled body
D. all of the above
E. none of the above
Work ratio of a gas turbine plant is ratio of______________________?
A. net work output and work done by turbine
B. work done by turbine and heat supplied
C. net work output and heat supplied
D. work done by turbine and net work output
E. actual/heat drop and isentropic heat drop
The main purpose of reheating in gas turbine is to__________________?
A. reduce turbine size
B. increase temperature
C. increase power output
D. increase speed
E. increase pressure ratio
Gas turbine cycle with Regenerator __________________?
A. increases thermal efficiency
B. decreases heat loss is exhaust
C. allows high compression ratio
D. allows operation at very high altitudes
E. permits high moisture content fuel to be used
Reheating in multistage expansion gas turbine results in____________________?
A. reduction in compressor work
B. high thermal efficiency
C. decrease of heat loss in exhaust
D. maximum work output
E. none of the above
Maximum temprature in a gas turbine is of the order of COMPRESSORS, GAS TURBINES AND JET ENGINES______________________?
A. 2000°C
B. 2500°C
C. 1500°C
D. 1000°C
E. 700°C
In air breathing jet engine, the jet is formed by expanding__________________?
A. solids
B. gases
C. liquid
D. plasma
E. highly heated atmospheric air
The efficiency of jet engine is__________________?
A. same at all altitudes
B. higher at high altitudes
C. higher at ground
D. higher at high speed
E. lower at low speed
For speed above 3000 km/hour, it is more advantageous to use____________________?
A. propellers
B. ram-jet engine
C. turbo-jet engine
D. rockets
E. hydraulic jet propulsion
The compression ratio in a jet engine varies proportional to ____________________?
A. altitude
B. speed
C. speed
D. Vspeed
E. does not Vary
The efficiency and work ratio of a gas turbine plant can be increased by _____________________?
A. using mulit-stage compressor with mfercooler
B. injecting water in/around combustion chamber
C. adding heat exchanger
D. reheating the air after partial expansion in the turbine
E. all of the above
Turbofan engine employs ____________________ ?
A. no air stream
B. two or more air streams
C. one air stream
D. solid fuel firing
E. rocket principle for its operation
Which of the following plants is smallest and lightest for genrating a given amount of power__________________?
A. petrol engine
B. steam power plant
C. diesel engine’
D. solar plant
E. gas turbine plant
Pressure ratio in gas turbines is the ratio of ____________________?
A. pressures across the turbine
B. highest pressure to exhaust pressure
C. inlet pressure to exhaust pressure
D. compressor pressure ratio
E. none of the above
In turbo fan engine, the jet velocity as compared to turbo-jet engine is_________________?
A. less
B. same
C. more
D. may be less or more depening upon speed
E. none of the above
A simple turbo-jet engine is basically_________________?
A. chemical rocket engine
B. gas-turbine engine equipped with a propulsive nozzle and diffuse*
C. a propeller system
D. ram-jet engine
E. none of the above
Ram-jet engine__________________?
A. requires no air for its operation
B. is not self-operating at zero^flight speed
C. is self-operating at zero flight speed
D. produces a jet consisting of plasma
E. none of the above
The compression ratio in a gas turbine is of the roder of____________________?
A. 5 : 1
B. 3 : 1
C. 8 : 1
D. 12 : 1
E. 20 : 1
The working fluid in ai turbine is___________________?
A. in three phases
B. in two phases
C. in a single phase
D. in the form of air and water mixture
E. gas and no air
If V, U and Vr represent the absolute velocity of fluid, velocity of blade, and relative velocity of fluid, and suffix i and o stand for entry and exit conditions, then in a rotary machine whose degree of reaction is unity______________?
A. Vi=V0B
B. U,<V0
C. Vt>V0
D. V,= U0
E. Vri=Vm
In jet engines the products of combustion after passing through the gas lurbine are discharged into_______________?
A. back to the compressor
B. atmosphere
C. discharge nozzle
D. vacuum
E. none of the above
Pick up the false statement ?
A. gas turbine is a self-starting unit
B. gas turbine does not require huge quantity of water like steam plant
C. overall efficiency of gas turbine plant is lower than that of a reciprocating engine
D. exhaust losses in gas turbine are high due to large mass flow rate
E. gas turbine can be easily started and stopped and thus is best suited for peaking demands
Pick up the correct statement?
A. air-fuel ratio in a gas turbine is 100 : 1
B. gas turbine uses same working fluid over and over again
C. closed cycle gas turbine is an I.C engine
D. ideal efficiency of closed cycle gas turbine plant is more than carnot cycle efficiency
E. thrust in turbo-jet is produced by nozzle exit gases
Pick up the wrong statement ?
A. pulsojet requires no ambient air for propulsion
B. turbine drives compressor in a burbojet
C. ramjet-engine has no turbine
D. bypass turbo-jet engine increases the thrust without adversely affecting, the propulsive efficiency and fuel economy
E. propeller is an indirect reaction device
Pick up the correct statement ?
A. gas turbines use both air and liquid cooling
B. gas turbines have their blades similar to steam turbine
C. gas .turbine’s blade will appear as impulse section at the hub and as a reaction section at tip
D. large gas turbines use radial inflow turbines
E. all of the above are correct.
Choose the correct statement ________________?
A. gas turbines have flat efficiency at part loads
B. gas turbine is capable of rapid start up and loading
C. gas turbine requires lot of cooling water
D. gas turbines have high standby losses and require lot of maintenance
E. gas turbines can be used to generate power only
Pick up the wrong statement ?
A. axial flow compressors have high capacity and efficiency
B. axial flow compressors are more stable than centrifugal type compressors but not as efficient
C. large gas turbines employ axial flow compressors
D. axial flow compressors have instability region of operation
E. centrifugal compressors are used mainly on low flow pressure ratio gas turbines
Pick up the correct statement ?
A. gas turbine uses low air-fuel ratio to develop the high thrust required
B. gas turhine uses high air-fuel ratio to reduce outgoing temperature
C. gas turbine uses low air-fuel ratio to economize on fuel
D. all of the above
E. none of the above
Pick up the wrong statement ?
A. centrifugal compressors deliver prac-tically constant pressure over a considerable range of capacities
B. centrifugal compressors have a wider stable operating range than axial flow compressors
C. Axial flow compressors have a sub-stantially constant delivery at variable pressures
D. axial flow compressors are bigger in diameter compared to centrifugal type
E. axial flow compressors apt to be longer as compared to centrifugal type