Category: Steam and Gas Turbines Objective Questions

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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Steam and Gas Turbines online test on “Film Coefficient, Pressure Losses and Regenerator Effectiveness”.

1. Film coefficient is also known as heat transfer coefficient.
a) True
b) False
Answer: a
Clarification: Film coefficient is also known as heat transfer coefficient.

2. Film coefficient is the proportionality coefficient between heat flux and ___________
a) opposing force
b) driving force
c) opposing & driving force
d) none of the mentioned
Answer: b
Clarification: Film coefficient is the proportionality coefficient between heat flux and driving force.

3. Film coefficient is represented by _______
a) t
b) g
c) h
d) f
Answer: c
Clarification: Heat transfer coefficient is represented by h.

4. ___________ is used in phase transition process.
a) Film coefficient
b) Pressure coefficient
c) Mean temperature
d) None of the mentioned
Answer: a
Clarification: Film coefficient is used in phase transition process.

5. Film coefficient is _________ of thermal insulance.
a) directly proportional
b) inverse
c) equal
d) none of the mentioned
Answer: b
Clarification: Film coefficient is inverse of thermal insulance. Film coefficient is the inverse of the resistance offered by the material towards heat.

6. Ratio of thermal conductivity to the length scale is known as __________
a) Film coefficient
b) Heat transfer coefficient
c) Film & Heat transfer coefficient
d) None of the mentioned
Answer: c
Clarification: Ratio of thermal conductivity to length is known as film coefficient.

7. Nusselt number has ________
a) no dimension
b) dimension
c) no units
d) none of the mentioned
Answer: a
Clarification: Nusselts number is a dimensionless number. Nusselt’s number is used in calculating heat transfer.

8. Overall heat transfer coefficient is represented by _______
a) K
b) A
c) U
d) I
Answer: c
Clarification: Overall heat transfer coefficient is represented by U.

9. Nusselts number applies to _______
a) Laminar flow
b) Turbulent flow
c) Laminar & Turbulent flow
d) None of the mentioned
Answer: c
Clarification: Nusselts number is applicable to both laminar and turbulent flow.

10. Mass flux is denoted by ______
a) J
b) G
c) U
d) None of the mentioned
Answer: a
Clarification: Mass flux is represented by j.

Steam and Gas Turbines for online test,

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Steam and Gas Turbines Multiple Choice Questions on “Turbine Casting and Exhaust Frames”.

1. Exhaust frame and exhaust diffuser are connected ____________
a) one after other
b) together
c) not connected
d) none of the mentioned
Answer: b
Clarification: Exhaust frame and exhaust diffuser are connected together. Gases coming out of exhaust frames has high pressure and when connected to diffuser pressure energy is converted into velocity.

2. Exhaust frame is connected to the _________
a) aft flange
b) diffuser
c) aft flange & diffuser
d) none of the mentioned
Answer:c
Clarification: Exhaust frame is connected to the aft flange and also diffuser. Exhaust frame is connected to diffuser using aft flange.

3. Aft flange is present on the turbine shell.
a) True
b) False
Answer: a
Clarification: Aft flange is present on the turbine shell.

4. _____________ are further divided in outer cylinder and inner cylinder.
a) Aft flange & Exhaust frame
b) Aft flange
c) Exhaust frame
d) None of the mentioned
Answer: c
Clarification: Exhaust frames are further divided in outer cylinder and inner cylinder. Inner cylinder of exhaust frame has parts used to connect to diffuser.

5. In exhaust frames inner and outer cylinder are connected using __________
a) structs
b) aft flange
c) structs & aft flange
d) none of the mentioned
Answer: a
Clarification: Structs are used to connect both inner and outer cylinder in exhaust frame. Where as aft flange is connected to outer casing of the exhaust frame.

6. Exhaust diffuser is located at extreme _________
a) aft flange
b) aft end
c) exhaust frame
d) none of the mentioned
Answer: b
Clarification: Exhaust diffuser is located at extreme aft end. Where one end of aft flange is connected to exhaust frame.

7. Exhaust diffuser is supported by exhaust frame.
a) True
b) False
Answer: a
Clarification: Exhaust diffuser is supported by exhaust frame.

8. __________ are present at the end of exhaust diffuser.
a) Guide vanes
b) Stationary vanes
c) Guide & Stationary vanes
d) None of the mentioned
Answer: c
Clarification: Guide vanes are present at the end of exhaust diffuser. Stationary vanes are used to guide the working fluid in the required direction and hence they are also called as guide vanes.

9. Struts supporting inner and outer cylinder are to be maintaned at _______ temperature.
a) increasing
b) variable
c) constant
d) none of the mentioned
Answer: c
Clarification: When temperature is not constant thermal stresses developed and center position may vary.

10. Cooling air is made to flow through the gaps in between struts.
a) True
b) False
Answer: a
Clarification: Cooling air is made to flow so that the temperature remains constant.

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Steam Turbine Interview Questions and Answers on “Heat and Steam Rate”.

1. Heat rate defines how much energy is to be expanded for obtaining a unit of useful work.
a) True
b) False

Answer: a
Clarification: Heat rate means the amount of energy that must be expanded for obtaining an unit of useful work.

2. What is heat rate in turbine?
a) Heat required for unit of power generated in specific conditions and specific fuel burning
b) Amount of heat required to expand turbine blades
c) Amount of heat required to increase pressure of steam
d) None of the mentioned

Answer: a
Clarification: Heat rate in turbines is defined as heat required to generate unit power in turbine at specific fuel being burned at specific conditions.

3. For calculating heat rate in steam turbines enthalpy is calculated.
a) False
b) True

Answer: b
Clarification: Heat rate can be calculated by using enthalpy method.

4. Steam turbine governing can be defined as __________
a) increasing the steam speed
b) adjusting the governors for particular speeds
c) controlling the flow rate of steam
d) none of the mentioned

Answer: c
Clarification: Governors are used to control the fuel needed to the load and they are no way related to the steam turbine governing. Steam turbine governing is controlling the flow rate of steam.

5. Why is steam turbine governing used?
a) To increase the steam speed
b) To maintain steam speed constant
c) To decrease the steam speed
d) None of the mentioned

Answer: b
Clarification: Flow rate if steam is controlled to maintain the constant speed.

6. In nozzle governing the flow rate is controlled by ____________
a) opening and closing the valves at nozzle
b) adding more number of nozzles
c) increasing nozzle efficiency
d) none of the mentioned

Answer: a
Clarification: Opening and closing of valves at nozzle is called nozzle governing.

7. During overload of turbines __________ are used.
a) throttle governing
b) nozzle valves
c) bypass governing
d) none of the mentioned

Answer: c
Clarification: During overload conditions fresh steam is added into later stages called as bypass governing.

8. When is emergency governing used?
a) Speed of shaft increased above 110%
b) When turbine is shut down due to overload
c) When Low steam is entering
d) None of the mentioned

Answer: a
Clarification: When speed of shaft is increased to 110% then emergency governing is used to control the speed.

9. When balancing of the turbine is disturbed ___________ is used.
a) Potter governor
b) Centrifugal governor
c) Emergency governor
d) None of the mentioned

Answer: c
Clarification: Emergency governor is also used when balancing of the turbine is disturbed.

10. When lubrication is failed _____________ is used.
a) Centrifugal governor
b) Emergency governor
c) Potter governor
d) None of the mentioned

Answer: b
Clarification: Emergency governor is used in all emergency situations like when the lubrication system is failed, when speed is increased when balancing is disturbed etc.

Steam Turbines for Interviews,

Steam and Gas Turbines Multiple Choice Questions on “Relationship between Velocity Ratios”.

1. Velocity ratio is represented by ___________
a) Alpha
b) Beta
c) Sigma
d) None of the mentioned
Answer: c
Clarification: Velocity ratio is represented by sigma.

2. For single stage impulse turbine optimum sigma value lies between ____________
a) 0.4 and 0.6
b) 0.2 and 0.4
c) 0.1 and 0.3
d) none of the mentioned
Answer: a
Clarification: 0.4 and 0.6 are the boundary values for sigma in single stage impulse turbine which can be found from graph plotted between sigma and efficiency.

3. For two stage impulse turbine optimum sigma value lies between __________
a) 0.3 and 0.5
b) 0.2 and 0.4
c) 0.1 and 0.5
d) none of the mentioned
Answer: b
Clarification: For two stage impulse turbine sigma value lies in between 0.2 and 0.4 which can be found out from graph plotted between sigma value and efficiency.

4. For reaction turbines the optimum sigma value lies between _____________
a) 0.8 and 1.0
b) 0.6 and 1.0
c) 0.4 and 0.8
d) none of the mentioned
Answer: a
Clarification: For reaction turbines sigma value lies between 0.8 and 1.0 which can be found out from graph plotted between sigma and efficiency.

5. Speed of the blade to speed of the gas ratio can be denoted by ___________
a) Alpha
b) Sigma
c) Gamma
d) None of the mentioned
Answer: b
Clarification: Blade to gas speed ratio is known as velocity ratio and it can be represented by sigma.

6. Best velocity ratio for four row impulse turbine is ________
a) one seventh
b) one sixth
c) half
d) none of the mentioned
Answer: a
Clarification: The best velocity ratio for four row impulse turbine is one seventh.

6. Efficiency of the four row impulse turbine with a velocity ratio of one seventh is ______
a) 55%
b) 44%
c) 34%
d) 77%
Answer: b
Clarification: Efficiency of four row impulse turbine with a velocity of one seventh is 44% which was found from graph plotted against efficiency and velocity ratio.

7. Velocity ratio is the integral of ________ of the velocity in each row.
a) fourth power
b) cube
c) square
d) none of the mentioned
Answer: c
Clarification: Velocity ratio is the integral of square of velocity in each row.

8. Velocity ratio is directly proportional to square of velocity.
a) True
b) False
Answer: b
Clarification: Velocity ratio is directly proportional to integral of square of velocity in each row.

9. When velocity in each row increases its velocity ratio __________
a) decreases
b) remains constant
c) increases
d) none
Answer: c
Clarification: When velocity in each row increases its velocity ratio also increases.

10. Velocity ratio is directly proportional to velocity in each row.
a) True
b) False
Answer: b
Clarification: Velocity in each row is inversely proportional to velocity ratio.

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

1. Radial vibration measurement measures ____________
a) unbalanced masses
b) cracked shafts
c) oil whirl
d) all of the mentioned
Answer: d
Clarification: Radial vibration measurement measures all the unbalanced masses, cracked shafts and also oil whirls.

2. Vibration measurements in steam turbines can be made in _______ planes.
a) 1
b) 2
c) 1 or 2
d) 4
Answer: c
Clarification: Vibration measurements in steam turbines can be measured in single plane or two planes.

3. Absolute shaft measurement is done when __________
a) weight of the rotating assemble is five times more than casing
b) weight of rotating assembly is two time more than the casing
c) weight of the rotating assembly is thrice the casing weight
d) none of the mentioned
Answer: a
Clarification: Absolute shaft measurement measures the shaft motion with respect to the free space. It is done when weight of the shaft assembly is five times more than the weight of casing.

4. Phase measurement is required for accurate balancing of the rotor.
a) True
b) False
Answer: a
Clarification: Phase measurement is required for accurate balancing of any rotor. Because phase is defined as angle between reference mark and heavy spot on the rotor.

5. Eccentricity measurement is used to indicate ______
a) bent shafts
b) when the rotor can be bought to the high speeds
c) bent shafts and when the rotor can be bought to the high speeds
d) none of the mentioned
Answer: c
Clarification: Eccentricity measurement makes us to know about the sag or bow in a rotor which helps us to get knowledge about whether to increase the speed or not.

6. DE measurement is used to get the knowledge about distance between case and rotor.
a) True
b) False
Answer: a
Clarification: As turbine casing has more weight than the rotor, when turbine is under operation it should be taken care that there should not be any contact between turbine and casing due to thermal expansion as turbine has more expansion when compared to the casing.

7. Rotor thrust measurement is done in order to _______
a) monitor thrust
b) monitor bearing wear
c) monitor thrust & bearing wear
d) none of the mentioned
Answer: c
Clarification: Rotor thrust measurement is done in order to monitor thrust and also bears wear.

8. Thrust position measurements are taken within _____ inches of thrust bearing.
a) 10
b) 12
c) 20
d) 24
Answer: b
Clarification: Thrust position measurement is done within 12 inches of thrust bearing.

9. Thrust measurement taken out of 12 inches are effected by ______
a) thrust forces
b) thrust forces & thermal expansions
c) thermal expansions
d) none of the mentioned
Answer: c
Clarification: Measurements taken out of q2 inches are generally effected by thermal expansions.

10. Valve position measurement is used to measure how much valve is used.
a) True
b) False
Answer: a
Clarification: Valve position measurement is used to measure how much the valve is opened, mainly throttle valve which gives us information about how much percentage the load can be increased.