Compressors, Gas Turbines And Jet Engines MCQs

Option A: centrifugal compressors deliver prac-tically constant pressure over a considerable range of capacities

Option B: Axial flow compressors have a sub-stantially constant delivery at variable pressures

Option C: centrifugal compressors have a wider stable operating range than axial flow compressors

Option D: axial flow compressors are bigger in diameter compared to centrifugal type

Correct Answer: axial flow compressors are bigger in diameter compared to centrifugal type ✔

Option A: gas turbine uses low air-fuel ratio to economise on fuel

Option B: gas turhine uses high air-fuel ratio to reduce outgoing temperature

Option C: gas turbine uses low air-fuel ratio to develop the high thrust required

Option D: all of the above

Correct Answer: gas turhine uses high air-fuel ratio to reduce outgoing temperature ✔

Option A: large gas turbines employ axial flow compressors

Option B: axial flow compressors are more stable than centrifugal type compressors but not as efficient

Option C: axial flow compressors have high capacity and efficiency

Option D: axial flow compressors have instability region of operation

Correct Answer: axial flow compressors are more stable than centrifugal type compressors but not as efficient ✔

Option A: gas turbine requires lot of cooling water

Option B: gas turbine is capable of rapid start up and loading

Option C: gas turbines have flat efficiency at part loads

Option D: gas turbines have high standby losses and require lot of maintenance

Correct Answer: gas turbine is capable of rapid start up and loading ✔

Option A: large gas turbines use radial inflow turbines

Option B: gas turbines have their blades similar to steam turbine

Option C: gas .turbine’s blade will appear as impulse section at the hub and as a reaction section at tip

Option D: gas turbines use both air and liquid cooling

Correct Answer: gas .turbine’s blade will appear as impulse section at the hub and as a reaction section at tip ✔

Option A: pulsojet requires no ambient air for propulsion

Option B: ramjet-engine has no turbine

Option C: turbine drives compressor in a burbojet

Option D: bypass turbo-jet engine increases the thrust without adversely affecting, the propulsive efficiency and fuel economy

Correct Answer: pulsojet requires no ambient air for propulsion ✔

Option A: closed cycle gas turbine is an I.C engine

Option B: gas turbine uses same working fluid over and over again

Option C: air-fuel ratio in a gas turbine is 100 : 1

Option D: ideal efficiency of closed cycle gas turbine plant is more than carnot cycle efficiency

Correct Answer: thrust in turbo-jet is produced by nozzle exit gases ✔

Option A: gas turbine is a self-starting unit

Option B: gas turbine does not require huge quantity of water like steam plant

Option C: exhaust losses in gas turbine are high due to large mass flow rate

Option D: overall efficiency of gas turbine plant is lower than that of a reciprocating engine

Correct Answer: gas turbine is a self-starting unit ✔

Option A: atmosphere

Option B: back to the compressor

Option C: discharge nozzle

Option D: vacuum

Correct Answer: discharge nozzle ✔

Option A: Vi=V0B

Option B: Vt>V0

Option C: U,<V0

Option D: V,= U0

Correct Answer: Vi=V0B ✔

Option A: in two phases

Option B: in three phases

Option C: in a single phase

Option D: in the form of air and water mixture

Correct Answer: in a single phase ✔

Option A: 3.5 : 1

Option B: 5 : 1

Option C: 8 : 1

Option D: 12 : 1

Correct Answer: 8 : 1 ✔

Option A: is self-operating at zero flight speed

Option B: is not self-operating at zero^flight speed

Option C: requires no air for its operation

Option D: produces a jet consisting of plasma

Correct Answer: is not self-operating at zero^flight speed ✔

Option A: a propeller system

Option B: gas-turbine engine equipped with a propulsive nozzle and diffuse*

Option C: chemical rocket regine

Option D: ram-jet enigne

Correct Answer: gas-turbine engine equipped with a propulsive nozzle and diffuse* ✔

Option A: less

Option B: more

Option C: same

Option D: may be less or more depening upon speed

Correct Answer: less ✔

Option A: compressor pressure ratio

Option B: highest pressure to exhaust pressure

Option C: inlet pressure to exhaust pressure

Option D: pressures across the turbine

Correct Answer: highest pressure to exhaust pressure ✔

Option A: steam power plant

Option B: petrol engine

Option C: diesel engine’

Option D: solar plant

Correct Answer: gas turbine plant ✔

Option A: one air stream

Option B: two or more air streams

Option C: no air stream

Option D: solid fuel firing

Correct Answer: two or more air streams ✔

Option A: using mulit-stage compressor with mfercooler

Option B: adding heat exchanger

Option C: injecting water in/around combustion chamber

Option D: reheating the air after partial expansion in the turbine

Correct Answer: all of the above ✔

Option A: speed

Option B: speed

Option C: altitude

Option D: Vspeed

Correct Answer: speed ✔

Option A: turbo-jet engine

Option B: ram-jet engine

Option C: propellers

Option D: rockets

Correct Answer: ram-jet engine ✔

Option A: higher at ground

Option B: higher at high altitudes

Option C: same at all altitudes

Option D: higher at high speed

Correct Answer: higher at high altitudes ✔

Option A: gases

Option B: solids

Option C: liquid

Option D: plasma

Correct Answer: highly heated atmospheric air ✔

Option A: 2500°C

Option B: 2000°C

Option C: 1500°C

Option D: 1000°C

Correct Answer: 700°C ✔

Option A: high thermal efficiency

Option B: reduction in compressor work

Option C: decrease of heat loss in exhaust

Option D: maximum work output

Correct Answer: maximum work output ✔

Option A: increases thermal efficiency

Option B: allows high compression ratio

Option C: decreases heat loss is exhaust

Option D: allows operation at very high altitudes

Correct Answer: increases thermal efficiency ✔

Option A: increase temperature

Option B: reduce turbine size

Option C: increase power output

Option D: increase speed

Correct Answer: increase power output ✔

Option A: net work output and work done by turbine

Option B: net work output and heat supplied

Option C: work done by turbine and heat supplied

Option D: work done by turbine and net work output

Correct Answer: net work output and work done by turbine ✔

Option A: the propulsive matter is caused to flow around the propelled body

Option B: propulsive matter is ejected from within the propelled body

Option C: its functioning does not depend on presence of air

Option D: all of the above

Correct Answer: all of the above ✔

Option A: decreasing the compression work

Option B: increasing the compression work

Option C: increasing the turbine work

Option D: decreasing the turbine work

Correct Answer: E. A. and C. above ✔

Option A: increase of work ratio

Option B: decrease of thermal efficiency

Option C: decrease of work ratio

Option D: both A. and B. above

Correct Answer: D. both A. and B. above ✔

Option A: 2-stroke engine

Option B: 4-stroke petrol engine

Option C: 4-stroke diesef engine

Option D: multi-cylinder engine

Correct Answer: gas turbine ✔

Option A: to increase the output

Option B: to increase the efficiency

Option C: to save fuel

Option D: to reduce the exit temperature

Correct Answer: to reduce the exit temperature ✔

Option A: varies as square root of the speed

Option B: Varies linearly to the speed

Option C: varies as square of the speed

Option D: varies as cube of the speed

Correct Answer: varies as square of the speed ✔

Option A: 10: 1

Option B: 15: 1

Option C: 20 : 1

Option D: 60 : 1

Correct Answer: 60 : 1 ✔

Option A: ammonia and water vapour

Option B: carbon dioxide

Option C: nitrogen

Option D: hydrogen

Correct Answer: ammonia and water vapour ✔

Option A: increase first at fast rate and then slow

Option B: increase first at slow rate and then fast

Option C: decrease continuously

Option D: first increase, reach maximum and then decrease

Correct Answer: first increase, reach maximum and then decrease ✔

Option A: toughness

Option B: fatigue

Option C: creep

Option D: corrosion resistance

Correct Answer: creep ✔

Option A: turbo-jet

Option B: turbo-propeller

Option C: rocket

Option D: ram-jet ,

Correct Answer: turbo-jet ✔

Option A: mild steel

Option B: stainless steel

Option C: carbon steel

Option D: high alloy seel

Correct Answer: high nicket alloy (neimonic) ✔

Option A: same

Option B: higher

Option C: lower

Option D: uncomparable

Correct Answer: lower ✔

Option A: collect more air

Option B: convert kinetic energy of air into pres-sure energy

Option C: provide robust structure

Option D: beautify the shape

Correct Answer: convert kinetic energy of air into pres-sure energy ✔

Option A: same

Option B: more

Option C: less

Option D: zero

Correct Answer: zero ✔

Option A: 34%

Option B: 50%

Option C: 60%

Option D: 72%

Correct Answer: 60% ✔

Option A: 550 km/hr

Option B: 1050km/hr

Option C: 1700 km/hr

Option D: 2400km /hr

Correct Answer: 2400km /hr ✔

Option A: jet velocity

Option B: twice the jet velocity

Option C: half the jet velocity

Option D: average of the jet velocity

Correct Answer: jet velocity ✔

Option A: h.p. compressor L connected to h.p. turbine and l.p. compressor ot l.p. tur-bine

Option B: h.p. compressor is connected to l.p. turbine and l.p. compressor is con-nected to h.p. turbine

Option C: both the arrangements can be employed

Option D: all are connected in series

Correct Answer: h.p. compressor is connected to l.p. turbine and l.p. compressor is con-nected to h.p. turbine ✔

Option A: thrust power and fuel energy

Option B: engine output and propulsive power

Option C: propulsive power and fuel input

Option D: thrust power and propulsive power

Correct Answer: thrust power and propulsive power ✔

Option A: carries its own oxygen

Option B: uses surrounding air

Option C: uses compressed atmospheric air

Option D: does not require oxygen

Correct Answer: carries its own oxygen ✔

Option A: liquid hydrogne

Option B: high speed diesel oil

Option C: kerosene

Option D: demethylated spirit

Correct Answer: kerosene ✔

Option A: mass

Option B: energy

Option C: flow

Option D: linear momentum

Correct Answer: linear momentum ✔

Option A: reduction of speed of incoming air and conversion of part of it into pressure energy

Option B: compression of inlet air

Option C: increasing speed of incoming air

Option D: lost work

Correct Answer: reduction of speed of incoming air and conversion of part of it into pressure energy ✔

Option A: less

Option B: more

Option C: same

Option D: may be less or more depending on ambient conditons

Correct Answer: less ✔

Option A: increase in net output but decrease in thermal efficiency

Option B: increase in thermal efficiency but decrease in net output

Option C: increase in both thermal efficiency and net output

Option D: decrease in both thermal efficiency and net output

Correct Answer: increase in net output but decrease in thermal efficiency ✔

Option A: isothermal

Option B: isentropic

Option C: adiabatic

Option D: isochoric

Correct Answer: isothermal ✔

Option A: high calorific value

Option B: ease of atomisation

Option C: low freezing point

Option D: A. and C. above

Correct Answer: D. A. and C. above ✔

Option A: peopeller

Option B: diffuser

Option C: intercooler

Option D: turbine and combustion chamber

Correct Answer: peopeller ✔

Option A: vacuum

Option B: atmospheric air

Option C: compressed air

Option D: oxygen alone

Correct Answer: compressed air ✔

Option A: closed cycle

Option B: open cycle

Option C: both of the above

Option D: closed/open depending on other con-siderations

Correct Answer: closed cycle ✔

Option A: high pressure ratio

Option B: increasing gas temperature

Option C: high specific volume

Option D: high friction losses

Correct Answer: paucity of 02 ✔

Option A: compressor work and turbine work

Option B: output and input

Option C: actual total head tempeature drop to the isentrpic total head drop from total head inlet to static head outlet

Option D: actual compressor work and theoretical comprssor work

Correct Answer: actual total head tempeature drop to the isentrpic total head drop from total head inlet to static head outlet ✔

Option A: control temperature

Option B: control output of turbine

Option C: control fire hazards

Option D: increase efficiency

Correct Answer: control output of turbine ✔

Option A: provides greater flexibility

Option B: provides lesser flexibility

Option C: in never used

Option D: is used when gas is to be burnt

Correct Answer: provides greater flexibility ✔

Option A: adiabatic temperature drop in the stage

Option B: total temperature drop

Option C: total temperature drop in the stage

Option D: total adiabaitc temperature drop

Correct Answer: total temperature drop ✔

Option A: high h.p. and low weight

Option B: low weight and small frontal area

Option C: small frontal area and high h.p.

Option D: high speed and high h.p.

Correct Answer: low weight and small frontal area ✔

Option A: carbonisation of coal

Option B: passing steam over incandescent coke

Option C: passing air and a large amount of steam over waste coal at about 65°C

Option D: partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast

Correct Answer: partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast ✔

Option A: pressure ratio alone

Option B: maximum cycle temperature alone

Option C: minimum cycle temperature alone

Option D: both pressure ratio and maximum cycle temperature

Correct Answer: both pressure ratio and maximum cycle temperature ✔

Option A: it is inefficient

Option B: it is bulky

Option C: it requires cooling water for its operation

Option D: non of theses

Correct Answer: it requires cooling water for its operation ✔

Option A: increases

Option B: decreases

Option C: remains same

Option D: first increases and then decreases

Correct Answer: increases ✔

Option A: more

Option B: less

Option C: same

Option D: depends on other factors

Correct Answer: less ✔

Option A: stainless steel

Option B: high alloy’ steel

Option C: duralumin

Option D: Timken, Haste and Inconel allpys

Correct Answer: Timken, Haste and Inconel allpys ✔

Option A: pressure ratio

Option B: maximum cycle temperature

Option C: minimum cycle temperature

Option D: all of the above

Correct Answer: pressure ratio ✔

Option A: remain same

Option B: decrease

Option C: increase

Option D: unpredictable

Correct Answer: increase ✔

Option A: 50%

Option B: 75%

Option C: 85%

Option D: 90%

Correct Answer: 99% ✔

Option A: carbonisation of coal

Option B: passing steam over incandescent coke

Option C: passing air and a large amount of steam over waste coal at about 65°C

Option D: partial combustion of caol, eke, anthractie coal or charcoal in a mixed air steam blast

Correct Answer: passing steam over incandescent coke ✔

Option A: increases

Option B: decreases

Option C: first increases and then decreases

Option D: first decreases and then increases

Correct Answer: increases ✔

Option A: heated

Option B: compressed air before entering the combustion chamber is heated

Option C: bled gas from turbine is heated and readmitted for complete expansion

Option D: exhaust gases drive the compressor

Correct Answer: heated ✔

Option A: reheating

Option B: inter cooling

Option C: adding a regenerator

Option D: all of the above

Correct Answer: adding a regenerator ✔

Option A: at the base

Option B: at the tip

Option C: in the center

Option D: between ~ to i of the blade height

Correct Answer: between ~ to i of the blade height ✔

Option A: higher

Option B: lower

Option C: equal

Option D: can’t be compared

Correct Answer: lower ✔

Option A: 2:l

Option B: 61: 1

Option C: 9 : 1

Option D: 12:1.

Correct Answer: 61: 1 ✔

Option A: 1 : 1

Option B: 2 : 1

Option C: 4 : 1

Option D: 1:2

Correct Answer: 1 : 6 ✔

Option A: same

Option B: more

Option C: less

Option D: depends on other factors

Correct Answer: less ✔

Option A: equal to zero

Option B: in the direction of motion of blades

Option C: opposite to the direction of motion of blades

Option D: depending on the velocity

Correct Answer: in the direction of motion of blades ✔

Option A: 7 : 1

Option B: 15 : 1

Option C: 30 : 1

Option D: 40 : 1

Correct Answer: 50: 1 ✔

Option A: higher

Option B: lower

Option C: same

Option D: depends on on odier considerations

Correct Answer: higher ✔

Option A: low.er heating value

Option B: higher heating value

Option C: heating value

Option D: higher calorific value

Correct Answer: low.er heating value ✔

Option A: low

Option B: high

Option C: same

Option D: low/high depending on make and type

Correct Answer: low ✔

Option A: net work output and heat supplied (6) net work output and work done by tur¬bine

Option B: actual heat drop and isentropic heat drop

Option C: net work output and isentropic heat drop

Option D: isentropic increase/drop in tempera¬ture and actual increase/ drop in temperature

Correct Answer: net work output and isentropic heat drop ✔

Option A: large discharge at high pressure

Option B: low discharge at high pressure

Option C: large discharge at low pressure

Option D: low discharge at low pressure

Correct Answer: large discharge at low pressure ✔

Option A: Brayton or Atkinson cycle

Option B: Carnot cycle

Option C: Rankine cycle

Option D: Erricsson cycle

Correct Answer: Brayton or Atkinson cycle ✔

Option A: Brayton or Atkinson cycle

Option B: Carnot cycle

Option C: Rankine cycle

Option D: Erricsson cycle

Correct Answer: Brayton or Atkinson cycle ✔

Option A: increases

Option B: decreases

Option C: remains constant

Option D: first decreases and then increases

Correct Answer: remains constant ✔

Option A: same as isothermal

Option B: same as adiabatic

Option C: better than isothermal and adiabatic

Option D: in between isothermal and adiabatic

Correct Answer: in between isothermal and adiabatic ✔

Option A: pressure ratio

Option B: pressure coefficient

Option C: degree of reaction

Option D: slip factor

Correct Answer: degree of reaction ✔

Option A: mass flow rate

Option B: pressure ratio

Option C: change in load

Option D: stagnation pressure at the outlet

Correct Answer: stagnation pressure at the outlet ✔

Option A: to supply base load requirements

Option B: to supply peak load requirements

Option C: to enable start thermal power plant

Option D: in emergency

Correct Answer: to supply peak load requirements ✔

Option A: Brayton or Atkinson cycle

Option B: Carnot cycle

Option C: Erricsson cycle

Option D: Joule cycle

Correct Answer: Brayton or Atkinson cycle ✔

Option A: pressure ratio

Option B: maximum cycle temperature

Option C: minimum cycle temperature

Option D: all of the above

Correct Answer: all of the above ✔

Option A: increase

Option B: decrease

Option C: remain same

Option D: may increase/decrease depending on clearance volume

Correct Answer: decrease ✔