Category: Steam and Gas Turbines Objective Questions

Steam and Gas Turbines Multiple Choice Questions on “Combustion System in Gas Turbines”.

1. After burners are used to ________ the thrust.
a) increase
b) decrease
c) afterburners are not related to thrust
d) none of the mentioned
Answer: a
Clarification: After burners are used to increase the thrust. After burners collect the exhaust gases from exhaust frame and reheat them and uses the remaining kinetic energy of the gases and increases the thrust produced.

2. Extra fuel is injected to afterburners to _________ the thrust.
a) decrease
b) increase
c) extra fuel is not injected
d) none of the mentioned
Answer: b
Clarification: Extra fuel is injected to afterburners to increase the thrust. All the exhaust gases from exhaust frame is brought into afterburners and burned again with the help of extra fuel added into afterburner.

3. Afterburners consume _______ fuel amounts.
a) medium
b) low
c) high
d) none of the mentioned
Answer: c
Clarification: Afterburners consume high fuel amounts. For exhaust gases left after combustion from combustion chamber extra amount of fuel is added to the afterburner to burn again so that the remaining traces of fuel in exhaust gases get burned.

4. By using afterburners efficiency is _________
a) increased
b) decreased
c) not effected
d) none of the mentioned
Answer: b
Clarification: By using afterburners efficiency is decreased. As more amount of fuel is required in after burners.

5. When jet engines use afterburners engines are ________
a) wet
b) dry
c) semi dry
d) none of the mentioned
Answer: a
Clarification: When jet engines use afterburners engines are wet. For working of afterburners a continuous supply of fuel need to be given and hence they are wet.

6. When afterburners are not used in jet engines they are ________
a) wet
b) dry
c) semi dry
d) none of the mentioned
Answer: b
Clarification: When afterburners are not used in jet engines they are dry. Exhaust gases are dry which makes jet engine dry.

7. Afterburners are not equipped with case and liners.
a) True
b) False
Answer: b
Clarification: After burners are equipped with both case and liners.

8. Afterburners have _______ rise in temperature than combustors.
a) low
b) equal
c) high
d) none of the mentioned
Answer: c
Clarification: Afterburners have high rise in temperature when compared to combustors. As already the exhaust gases are present in high temperatures and when again burned by adding some fuel the exhaust gases that are released from afterburners that have high temperatures.

9. Mixing of fuel takes place efficiently in afterburners.
a) True
b) False
Answer: b
Clarification: Mixing of fuel is not that efficient in afterburners.

10. Afterburners require _________
a) flame holder
b) nozzle
c) casing
d) none of the mentioned
Answer: a
Clarification: Flame holders are used to maintain a constant velocity of flame. If the flame in afterburners are produced with different velocities combustion of the flame may not be constant.

Automobile Engineering Multiple Choice Questions on “Conventional Fuels”.

1. How are hydrocarbons decomposed into smaller hydrocarbons?
a) By reforming
b) By refining
c) By cracking
d) By polymerization
Answer: c
Clarification: Hydrocarbons are decomposed into smaller hydrocarbons by cracking. Cracking consists of breaking down large complex hydrocarbon molecules into simpler compounds.

2. For SI engines which fuels are preferred?
a) Aromatics
b) Paraffin
c) Olefins
d) Napthenes
Answer: a
Clarification: For SI engines aromatic fuels are preferred. Aromatic compounds are ring structured. They have a benzene molecule as their central structure and also a general chemical formula is C_nH_2n-6.

3. For CI engines which fuels are preferred?
a) Napthenes
b) Paraffin
c) Olefins
d) Aromatics
Answer: b
Clarification: For CI engines paraffin fuels are preferred. The paraffin family consists of an open-chain structure with an attached branch. They are usually termed branched-chain paraffin.

4. Which molecular structure does the paraffin possess?
a) Chain saturated
b) Chain unsaturated
c) Ring saturated
d) Ring unsaturated
Answer: a
Clarification: The paraffin possesses a chain structure and is saturated in nature. In these hydrocarbons, the valency of all four carbon atoms is fully utilized by single bonds with hydrogen atoms.

5. Which of the following is the advantage of the gaseous fuel?
a) It can be stored easily
b) It can mix easily with air
c) It can displace more air from the engine
d) It can be stored, get mixed with air and can displace more air from the engine.
Answer: b
Clarification: The advantage of the gaseous fuel is that it can mix easily with air. Gaseous fuels are ideal fuels. They pose very few problems in using them in IC engines.

6. What is octane number of iso-octane?
a) 0
b) 30
c) 60
d) 100
Answer: d
Clarification: Iso-octane has octane number 100. The octane number fuel is defined as the percentage of iso-octane in a mixture of iso-octane and normal heptane by volume.

7. By which quantity is ignition quality of diesel fuel indicated?
a) Fire point
b) Flashpoint
c) Cetane point
d) Octane point
Answer: c
Clarification: Ignition quality of diesel fuel indicated by cetane point. Cetane number of a fuel is defined as the percentage of normal cetane in a mixture of normal cetane and α-methyl naphthalene by volume.

8. How is paraffin represented by?
a) C_nH_n
b) C_nH_2n
c) C_nH_2n+2
d) C_nH_2n-6
Answer: c
Clarification: The paraffin is represented by C_nH_2n+2. The normal paraffin hydrocarbons are of straight-chain molecular structure. Iso-butane has the same general chemical formula and molecular weight as butane.

9. What are the characteristics of good CI engine fuel?
a) High octane number
b) Very high cetane number
c) Short ignition lag
d) Short ignition lag, high cetane number, and high octane number
Answer: c
Clarification: Short ignition lags are the characteristics of good CI engine fuel. The CI engine fuel should be volatile in the operating range of temperature to produce good mixing and combustion.

10. How is the molecular structure of the straight-run gasoline changed?
a) By cracking
b) By reforming
c) By refining
d) By boiling
Answer: b
Clarification: The molecular structure of the straight-run gasoline is changed by reforming. Reforming is a cracking process which is used to convert the low antiknock quality gasoline into gasoline of higher octane rating.

Steam and Gas Turbines Multiple Choice Questions on “Heat and Steam Rate – 1”.

1. Heat rate is used to define the efficiency of steam power plant.
a) True
b) False
Answer: a
Clarification: Heat rate = (Input energy)/(output power).

2. Inverse of efficiency is called as ____________
a) steam rate
b) heat rate
c) heat utilized
d) none of the mentioned
Answer: b
Clarification: From the formula, we can identify heat rate is the inverse of steam rate.

3. To increase plant efficiency heat rate is to be _________
a) increased
b) decreased
c) no relation with the heat rate
d) none of the mentioned
Answer: b
Clarification: As heat rate is inverse of plant efficiency, to increase plant efficiency heat rate is to be decreased.

4. What are the units of heat rate?
a) Kw/hr
b) No units
c) BTU/KWh
d) None of the mentioned
Answer: c
Clarification: Chemical energy input units are BTU and electrical energy output units are KWh. So units of heat rate are BTU/KWh.

5. Chemical energy of the fuel can be calculated by _________
a) Chemical energy of fuel = (Total fuel used) * (Higher heating value)
b) Chemical energy of fuel = (Calorific value) * (Fuel required for 1 Kcal of energy)
c) Cannot be determined theoretically
d) None of the mentioned
Answer: a
Clarification: Chemical energy of fuel = (Total fuel used) * (Higher heating value).

6. Heat rate losses that can be directly effected by actions of operators is called ______
a) uncontrollable losses
b) controllable losses
c) non-Value added losses
d) none of the mentioned
Answer: b
Clarification: Heat rate losses than be directly effected by actions of operator are called controllable losses.

7. Heat rate deviation can be defined as _______
a) difference between actual and target heat rate
b) difference between heat rates at maximum and minimum temperatures
c) difference between calorific value of ideal fuel and actual fuel used
d) none of the mentioned
Answer: a
Clarification: Heat rate deviation can be defined as the difference between the actual and target heat rates.

8. Steam flow rate can be calculated by _______
a) 3600/p
b) 3600 He/p
c) 3600 P/He
d) None of the mentioned
Answer: c
Clarification: Steam flow rate can be calculated by Ms = 3600 p/He.

9. The rate at which boiler in steam turbine produces steam is called __________
a) Steam rate
b) Steaming rate
c) Heat rate
d) None of the mentioned
Answer: b
Clarification: The rate at which the boiler produces steam is called steaming rate.

10. Heat rate can be used to find annual fuel costs.
a) True
b) False
Answer: a
Clarification: Annual Fuel cost = Heat rate deviation * Fuel capacity * Capacity factor * (Gross capacity * Auxiliary loads) * Time.

Steam and Gas Turbines Multiple Choice Questions on “Cascade Principle”.

1. Arrangement of blades in an order to represent the blade ring in Turbo machinery is called as cascade.
a) True
b) False
Answer: a
Clarification: Cascade is an array of blades to represent the blade ring in turbo machinery.

2. Cascades __________ the efficiency.
a) decreases
b) increases
c) does not effect
d) none
Answer: b
Clarification: Cascades are introduced to improve the efficiency.

3. When steam is passed through the cascade the direction of air __________
a) reverse
b) remains the same
c) turned
d) cascade is nowhere related to direction
Answer: c
Clarification: When steam is passed through cascade its direction is reversed.

4. Across the turbine cascade static pressure _________
a) drops
b) increases
c) remains same
d) none of the mentioned
Answer: a
Clarification: Across the turbine cascade the static pressure drops.

5. Due to the formation of boundary layers on blades friction losses _________
a) remains the same
b) decreases
c) increases
d) none of the mentioned
Answer: c
Clarification: Due to the formation of boundary layers frictional losses increase due to viscous forces.

6. In compressor cascade when internal pressure is lost ____________
a) axial force is gained
b) axial force is reduced
c) efficiency reduces
d) none of the mentioned
Answer: a
Clarification: In compressor cascade when internal pressure is lost axial force is developed.

7. Drag force is parallel to lift force.
a) True
b) False
Answer: b
Clarification: Drag force is always perpendicular to lift force.

8. Due to viscosity lift force is __________
a) increased
b) decreased
c) remains constant
d) none
Answer: b
Clarification: Due to viscosity lift force is decreased.

9. Due to turbine cascade the drag ________ the lift.
a) increases
b) decreases
c) does not change
d) none of the mentioned
Answer: a
Clarification: Due to turbine cascade drag contributes some useful work which increases the lift.

10. Due to compressor cascade, the static pressure is __________
a) reduced
b) does not change
c) increased
d) none of the mentioned
Answer: c
Clarification: Due to compressor cascade viscous force decreased and hence static pressure is also decreased.

Steam and Gas Turbines Multiple Choice Questions on “Control and Perfomance”.

1. Gas turbine controls are classified into ____ types.
a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: Gas turbine drives are classified into two types.

2. DSC interface is used in __________
a) compressor drive
b) turbine drive
c) compressor & turbine drive
d) none of the mentioned
Answer: c
Clarification: Both DSC interface and Graphic interface is used in both compressor drive and turbine drive.

3. In gas turbines Load control is available in _______
a) compressor drives
b) generator drives
c) compressor & generator drive
d) none of the mentioned
Answer: b
Clarification: Load control is available in generator drives as load can be applied or decreased only on the generator not on the compressor.

4. Communication interfaces are ___________ in steam drives.
a) available
b) not available
c) depends on the usage
d) none
Answer: a
Clarification: Communication interface is available in steam drives.

5. Steam turbine performance is expressed in _______
a) heat rate
b) steam rate
c) heat & steam rate
d) none of the mentioned
Answer: b
Clarification: Steam turbine performance is expressed in steam rate.

6. Gas turbine performance is expressed in terms of _______
a) heat & steam rate
b) steam rate
c) heat rate
d) none of the mentioned
Answer: c
Clarification: Gas turbine performance is expressed in terms of heat rate while steam turbine is expressed in terms of steam rate.

7. Gas turbine performance is directly proportional to the ______
a) inlet air density
b) inlet air temperature
c) inlet air density & inlet air temperature
d) none of the mentioned
Answer: a
Clarification: Gas turbine performance is directly proportional to inlet air density as inlet air density increases its inlet air mass which increases the performance of gas turbine.

8. In a gas turbine power produced is _________ to inlet air density.
a) indirectly proportional
b) directly proportional
c) not proportional
d) one
Answer: b
Clarification: As inlet air density is directly related to the performance of gas turbine, When inlet air density is increased its performance increased which means the power produced by gas turbine is increased.

9. In a gas turbine when firing temperature is __________ engine efficiency changes.
a) increased
b) decreased
c) remained constant
d) none of the mentioned
Answer: a
Clarification: When firing temperature is increased its environmental air conditions are altered so that its engine efficiency changes.

10. In steam turbines vapor and vapor conditions change with time.
a) True
b) False
Answer: a
Clarification: In steam turbine both vapor and vapor conditions are constant and that’s what makes calculating the steam turbine performance easy where as in gas turbines both vapor and vapor conditions are not constant and that makes it difficult for calculating performance.

Steam Turbines Aptitude Test on “Adiabatic Efficiency “.

1. Adiabatic efficiency is the ___________ of actual work required by condenser to bring to certain temperature and actual work input.
a) product
b) ratio
c) sum
d) none of the mentioned
Answer: b
Clarification: Adiabatic efficiency is the ratio of work required to raise to a certain temperature to actual work input.

2. While calculating adiabatic efficiency of a nozzle exit conditions for iso-entropic nozzle are ___________
a) Exit temperature are equal
b) Exit pressure’s are equal
c) Inlet states are same
d) All of the mentioned
Answer: d
Clarification: While calculating adiabatic efficiency of nozzle exit temperature, pressure and inlet states of iso-entropic nozzle are treated the same as normal one.

3. For calculating adiabatic efficiency they are ________ iso-entropic efficiency.
a) not compared with
b) compared with
c) multiplied with
d) none of the mentioned
Answer: b
Clarification: Adiabatic efficiency is always calculated by comparing with isoentropic efficiency.

4. It is assumed that all the processes internally are _________
a) reversible
b) irreversible
c) reversible but not in all conditions
d) none of the mentioned
Answer: a
Clarification: It is assumed that all the processes internally are reversible.

5. In air standard assumption combustion is replaced by ___________
a) heat rejection
b) heat addition
c) compression
d) none of the mentioned
Answer: b
Clarification: In air standard assumption combustion is replaced by heat addition.

6. In air standard assumptions heat exhaust process is replaced by _________
a) heat addition
b) compressio
c) heat rejection
d) none of the mentioned
Answer: c
Clarification: In air standard assumptions exhaust process is replaced by heat rejection process.

7. In air standard process working fluid air is assumed as an ____________
a) ideal gas
b) inert gas
c) high pressure gas
d) none of the mentioned
Answer: a
Clarification: In air standard assumptions working fluid air is assumed as ideal gas and assumed to rotate in closed loop.

8. In Air standard cycle air standard assumptions are ________
a) not applicable
b) applicable
c) depends on the situation
d) none of the mentioned
Answer: b
Clarification: Air standard cycle is a cycle where air standard assumptions are applicable.

9. Maximum work output that can be obtained from a system is called as _______
a) Adiabatic efficiency
b) Isoentropic efficiency
c) Availability
d) None of the mentioned
Answer: c
Clarification: Availability is the maximum work output that can be obtained from a system.

10. Combination of _______ vapor cycles is called as binary vapor cycle.
a) two
b) one
c) multi
d) none of the mentioned
Answer: a
Clarification: Binary vapor cycle is a combination of two cycles one operated at high temperatures and others operated at low temperatures.

Steam Turbines for aptitude tests, here is complete set of 1000+ Multiple Choice Questions and Answers

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