The diagram efficiency is the ratio of

workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam

workdone on the blades to the energy supplied to the blades

workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam

energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam

In an impulse turbine

the steam is expanded both in fixed and moving blades continuously

the steam is expanded in nozzles only and there is a pressure drop and heat drop

the steam is expanded both in fixed and moving blades continuously

the steam is expanded in moving blades only

the pressure and temperature of steam remains constant

pressure-velocity compounded turbine

When the inlet pressure of steam is equal to the exit pressure, then

there is a pressure drop in the nozzle

pressure drops and fluid flows through the nozzle

there is no pressure drop and fluid does not flow through the nozzle

Reheating of steam in a turbine

increases the workdone through the turbine

increases the efficiency of the turbine

A nozzle is said to be a divergent nozzle

when the cross-section of the nozzle decreases continuously from entrance to exit

when the cross-section of the nozzle increases continuously from entrance to exit

when the cross-section of the nozzle decreases continuously from entrance to exit

when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit

The effect of supersaturation is that the

mass of the steam discharged increases

entropy and specific volume of the steam increases

In an impulse turbine, steam expands

partly in the nozzle and partly in blades

A steam nozzle converts

kinetic energy into heat energy of steam

heat energy of steam into kinetic energy

kinetic energy into heat energy of steam

heat energy of steam into potential energy

potential energy into heat energy of steam

In a reaction turbine

the steam is expanded from a high pressure to a condenser pressure in one or more nozzles

the steam is allowed to expand in the nozzle, where it gives a high velocity before it enters the moving blades

the expansion of steam takes place partly in the fixed blades and partly in the moving blades

the steam is expanded from a high pressure to a condenser pressure in one or more nozzles

the pressure and temperature of steam remains constant

A nozzle is said to be a convergent nozzle

when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit

when the cross-section of the nozzle increases continuously from entrance to exit

when the cross-section of the nozzle decreases continuously from entrance to exit

when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit

In a reaction turbine when the degree of reaction is zero, then there is

maximum heat drop in moving blades

maximum heat drop in fixed blades

De-Laval turbines are mostly used

for small power purposes and low speeds

for small power purposes and high speeds

Which of the following statement is correct for steam turbines as compared to reciprocating steam engines?

A steam turbine develops higher speeds

The efficiency of steam turbine is higher

146 + Mcqs in Steam Turbines in Power Systems Page 1 McqOptions

1.	Read the statements below. I. The built up rotor is cheaper and easier to manufacture. II. The high pressure and intermediate pressure rotors are always of integral type.
A.	Only statement I is correct
B.	Only statement II is correct
C.	I and II are correct
D.	I and II are wrong
Answer» D. I and II are wrong

Discussion

2.	The diagram efficiency is the ratio of
A.	workdone on the blades to the energy supplied to the blades
B.	workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
C.	energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
D.	none of the above
Answer» B. workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam

Discussion

3.	The critical pressure ratio for initially superheated steam is __________ as compared to initially dry saturated steam.
A.	more
B.	less
C.	Can't say
D.	None of these
Answer» C. Can't say

Discussion

4.	In an impulse turbine
A.	the steam is expanded in nozzles only and there is a pressure drop and heat drop
B.	the steam is expanded both in fixed and moving blades continuously
C.	the steam is expanded in moving blades only
D.	the pressure and temperature of steam remains constant
Answer» B. the steam is expanded both in fixed and moving blades continuously

Discussion

5.	The maximum efficiency of a De-Laval turbine is (where α = Nozzle angle)
A.	sin2 α
B.	cos² α
C.	tan2 α
D.	cot2 α
Answer» C. tan2 α

Discussion

6.	The pressure of steam, in reaction turbines, is reduced in the fixed blades as well as in moving blades.
A.	Correct
B.	Incorrect
C.	Can't say
D.	None of these
Answer» B. Incorrect

Discussion

7.	The compounding of turbines is done in order to
A.	reduce speed of rotor
B.	improve efficiency
C.	reduce exit losses
D.	all of these
Answer» E.

Discussion

8.	When the cross-section of a nozzle __________ continuously from entrance to exit, it is called a convergent nozzle.
A.	increases
B.	decreases
C.	Can't say
D.	None of these
Answer» C. Can't say

Discussion

9.	If the critical pressure ratio for steam is 0.546, then the steam is initially
A.	wet steam
B.	dry saturated steam
C.	superheated steam
D.	none of these
Answer» D. none of these

Discussion

10.	Rateau turbine is
A.	simple reaction turbine
B.	velocity compounded turbine
C.	pressure compounded turbine
D.	pressure-velocity compounded turbine
Answer» D. pressure-velocity compounded turbine

Discussion

11.	In a Parson's turbine stage, blade velocity is 320 m/s at the mean radius and rotor blade exit angle is 30°. For minimum kinetic energy of the steam leaving the stage, the steam velocity at the exit of the rotor will be
A.	160/3 m/s
B.	320/3 m/s
C.	640/3 m/s
D.	640 m/s
Answer» D. 640 m/s

Discussion

12.	The critical pressure ratio for gases is
A.	0.528
B.	0.546
C.	0.577
D.	0.582
Answer» B. 0.546

Discussion

13.	In impulse turbines, when friction is neglected, the relative velocity of steam at outlet tip of the blade is __________ the relative velocity of steam at inlet tip of the blade.
A.	equal to
B.	less than
C.	greater than
D.	None of these
Answer» B. less than

Discussion

14.	The ratio of the cumulative heat drop to the isentropic heat drop is called reheat factor.
A.	Yes
B.	No
C.	Can't say
D.	None of these
Answer» B. No

Discussion

15.	When the inlet pressure of steam is equal to the exit pressure, then
A.	there is a pressure drop in the nozzle
B.	fluid flows through the nozzle
C.	pressure drops and fluid flows through the nozzle
D.	there is no pressure drop and fluid does not flow through the nozzle
Answer» E.

Discussion

16.	When the nozzle operates with the maximum mass flow, the nozzle is said to be
A.	choked
B.	underdamping
C.	overdamping
D.	none of these
Answer» B. underdamping

Discussion

17.	Reheating of steam in a turbine
A.	increases the workdone through the turbine
B.	increases the efficiency of the turbine
C.	reduces wear on the blades
D.	all of these
Answer» E.

Discussion

18.	A stage, in reaction turbine, is represented by
A.	number of casing
B.	number of entries of steam
C.	number of exits of steam
D.	each row of blades
Answer» E.

Discussion

19.	A nozzle is said to be a divergent nozzle
A.	when the cross-section of the nozzle increases continuously from entrance to exit
B.	when the cross-section of the nozzle decreases continuously from entrance to exit
C.	when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit
D.	none of the above
Answer» B. when the cross-section of the nozzle decreases continuously from entrance to exit

Discussion

20.	The effect of supersaturation is that the
A.	mass of the steam discharged increases
B.	entropy and specific volume of the steam increases
C.	exit velocity of steam reduces
D.	all of these
Answer» E.

Discussion

21.	The pressure of steam __________ while flowing through a nozzle.
A.	increases
B.	decreases
C.	remains constant
D.	None of these
Answer» C. remains constant

Discussion

22.	The friction present between the steam and the nozzle surfaces reduces the heat drop by
A.	10 to 15 percent
B.	15 to 25 percent
C.	25 to 40 percent
D.	40 to 60 percent
Answer» B. 15 to 25 percent

Discussion

23.	When the cross-section of a nozzle first increases from its entrance to throat, and then decreases from its throat to exit, it is not a convergent-divergent nozzle.
A.	Yes
B.	No
C.	Can't say
D.	None of these
Answer» B. No

Discussion

24.	For a Parson's reaction turbine, if α1 and α2 are fixed blade angles at inlet and exit respectively and β1 and β2 are the moving blade angles at entrance and exit respectively, then
A.	α1 = α2 and β1 = β2
B.	α1 = β1 and α2 = β2
C.	α1 < β1 and α2 > β2
D.	α1 = β2 and β1 = α2
Answer» E.

Discussion

25.	In an impulse turbine, steam expands
A.	wholly in blades
B.	wholly in nozzle
C.	partly in the nozzle and partly in blades
D.	none of these
Answer» C. partly in the nozzle and partly in blades

Discussion

26.	The process of maintaining the speed of the turbine constant for various load conditions, is known as
A.	bleeding
B.	reheating
C.	governing
D.	none of these
Answer» D. none of these

Discussion

27.	The density of supersaturated steam is about __________ that of the ordinary saturated vapour at the corresponding pressure.
A.	same as
B.	2 times
C.	4 times
D.	8 times
Answer» E.

Discussion

28.	A steam nozzle converts
A.	heat energy of steam into kinetic energy
B.	kinetic energy into heat energy of steam
C.	heat energy of steam into potential energy
D.	potential energy into heat energy of steam
Answer» B. kinetic energy into heat energy of steam

Discussion

29.	In a reaction turbine
A.	the steam is allowed to expand in the nozzle, where it gives a high velocity before it enters the moving blades
B.	the expansion of steam takes place partly in the fixed blades and partly in the moving blades
C.	the steam is expanded from a high pressure to a condenser pressure in one or more nozzles
D.	the pressure and temperature of steam remains constant
Answer» C. the steam is expanded from a high pressure to a condenser pressure in one or more nozzles

Discussion

30.	The ratio of the isentropic heat drop to the heat supplied, is called
A.	reheat factor
B.	stage efficiency
C.	internal efficiency
D.	Rankine efficiency
Answer» E.

Discussion

31.	During flow through a nozzle, no heat is supplied or rejected by the steam.
A.	Agree
B.	Disagree
C.	Can't say
D.	None of these
Answer» B. Disagree

Discussion

32.	The friction in the nozzle __________ exit velocity of steam.
A.	has no effect on
B.	decreases
C.	increases
D.	None of these
Answer» C. increases

Discussion

33.	The velocity of steam, in reaction turbines, is increased in the fixed blades as well as in moving blades.
A.	True
B.	False
C.	Can't say
D.	None of these
Answer» B. False

Discussion

34.	In a De-Laval impulse turbine, the nozzle is kept very close to the blades.
A.	Yes
B.	No
C.	Can't say
D.	None of these
Answer» B. No

Discussion

35.	Blading efficiency is also known as
A.	stage efficiency
B.	diagram efficiency
C.	nozzle efficiency
D.	none of these
Answer» C. nozzle efficiency

Discussion

36.	The blade friction in the impulse turbine reduces the velocity of steam by __________ while it passes over the blades.
A.	10 to 15%
B.	15 to 20%
C.	20 to 30%
D.	30 to 40%
Answer» B. 15 to 20%

Discussion

37.	In a nozzle, whole frictional loss is assumed to occur between
A.	inlet and thoroat
B.	inlet and outlet
C.	throat and exit
D.	all of these
Answer» D. all of these

Discussion

38.	The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced.
A.	remains same
B.	decreases
C.	increases
D.	None of these
Answer» D. None of these

Discussion

39.	The discharge of steam in a convergent-divergent nozzle __________ after the throat (i.e. in the divergent portion of the nozzle)
A.	remains constant
B.	decreases
C.	increases
D.	None of these
Answer» B. decreases

Discussion

40.	A nozzle is said to be a convergent nozzle
A.	when the cross-section of the nozzle increases continuously from entrance to exit
B.	when the cross-section of the nozzle decreases continuously from entrance to exit
C.	when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit
D.	none of the above
Answer» C. when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit

Discussion

41.	In order to reduce the rotor speed of an impulse turbine, the method employed is
A.	velocity compounding
B.	pressure compounding
C.	pressure-velocity compounding
D.	all of these
Answer» E.

Discussion

42.	In a reaction turbine when the degree of reaction is zero, then there is
A.	no heat drop in moving blades
B.	no heat drop in fixed blades
C.	maximum heat drop in moving blades
D.	maximum heat drop in fixed blades
Answer» B. no heat drop in fixed blades

Discussion

43.	The efficiency of a pressure-velocity compounded impulse turbine is __________ as compared to pressure compounded impulse turbine.
A.	same
B.	less
C.	more
D.	None of these
Answer» C. more

Discussion

44.	De-Laval turbines are mostly used
A.	where low speeds are required
B.	for small power purposes and low speeds
C.	for large power purposes
D.	for small power purposes and high speeds
Answer» E.

Discussion

45.	Which of the following statement is correct for steam turbines as compared to reciprocating steam engines?
A.	A steam turbine develops higher speeds
B.	The efficiency of steam turbine is higher
C.	The steam consumption is less
D.	all of these
Answer» E.

Discussion

46.	The ratio of total useful heat drop to the total isentropic heat drop, is called
A.	stage efficiency
B.	internal efficiency
C.	Rankine efficiency
D.	none of these
Answer» C. Rankine efficiency

Discussion

47.	The pressure velocity compounded impulse turbine allows a bigger pressure drop and hence __________ number of stages are required.
A.	more
B.	less
C.	Can't say
D.	None of these
Answer» C. Can't say

Discussion

48.	The expansion of steam, as it flows over the blades in reaction turbine, represents
A.	isothermal process
B.	isentropic process
C.	throttling process
D.	free-expansion process
Answer» C. throttling process

Discussion

49.	Parson's turbine is a
A.	simple impulse turbine
B.	simple reaction turbine
C.	impulse-reaction turbine
D.	none of these
Answer» C. impulse-reaction turbine

Discussion

50.	The ratio of the work delivered at the turbine shaft to the heat supplied is called overall thermal efficiency of turbine.
A.	True
B.	False
C.	Can't say
D.	None of these
Answer» B. False

Discussion

Explore topic-wise MCQs in Power Systems.

Read the statements below. I. The built up rotor is cheaper and easier to manufacture. II. The high pressure and intermediate pressure rotors are always of integral type.

The diagram efficiency is the ratio of

The critical pressure ratio for initially superheated steam is __________ as compared to initially dry saturated steam.

In an impulse turbine

The maximum efficiency of a De-Laval turbine is (where α = Nozzle angle)

The pressure of steam, in reaction turbines, is reduced in the fixed blades as well as in moving blades.

The compounding of turbines is done in order to

When the cross-section of a nozzle __________ continuously from entrance to exit, it is called a convergent nozzle.

If the critical pressure ratio for steam is 0.546, then the steam is initially

Rateau turbine is

In a Parson's turbine stage, blade velocity is 320 m/s at the mean radius and rotor blade exit angle is 30°. For minimum kinetic energy of the steam leaving the stage, the steam velocity at the exit of the rotor will be

The critical pressure ratio for gases is

In impulse turbines, when friction is neglected, the relative velocity of steam at outlet tip of the blade is __________ the relative velocity of steam at inlet tip of the blade.

The ratio of the cumulative heat drop to the isentropic heat drop is called reheat factor.

When the inlet pressure of steam is equal to the exit pressure, then

When the nozzle operates with the maximum mass flow, the nozzle is said to be

Reheating of steam in a turbine

A stage, in reaction turbine, is represented by

A nozzle is said to be a divergent nozzle

The effect of supersaturation is that the

The pressure of steam __________ while flowing through a nozzle.

The friction present between the steam and the nozzle surfaces reduces the heat drop by

When the cross-section of a nozzle first increases from its entrance to throat, and then decreases from its throat to exit, it is not a convergent-divergent nozzle.

For a Parson's reaction turbine, if α1 and α2 are fixed blade angles at inlet and exit respectively and β1 and β2 are the moving blade angles at entrance and exit respectively, then

In an impulse turbine, steam expands

The process of maintaining the speed of the turbine constant for various load conditions, is known as

The density of supersaturated steam is about __________ that of the ordinary saturated vapour at the corresponding pressure.

A steam nozzle converts

In a reaction turbine

The ratio of the isentropic heat drop to the heat supplied, is called

During flow through a nozzle, no heat is supplied or rejected by the steam.

The friction in the nozzle __________ exit velocity of steam.

The velocity of steam, in reaction turbines, is increased in the fixed blades as well as in moving blades.

In a De-Laval impulse turbine, the nozzle is kept very close to the blades.

Blading efficiency is also known as

The blade friction in the impulse turbine reduces the velocity of steam by __________ while it passes over the blades.

In a nozzle, whole frictional loss is assumed to occur between

The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced.

The discharge of steam in a convergent-divergent nozzle __________ after the throat (i.e. in the divergent portion of the nozzle)

A nozzle is said to be a convergent nozzle

In order to reduce the rotor speed of an impulse turbine, the method employed is

In a reaction turbine when the degree of reaction is zero, then there is

The efficiency of a pressure-velocity compounded impulse turbine is __________ as compared to pressure compounded impulse turbine.

De-Laval turbines are mostly used

Which of the following statement is correct for steam turbines as compared to reciprocating steam engines?

The ratio of total useful heat drop to the total isentropic heat drop, is called

The pressure velocity compounded impulse turbine allows a bigger pressure drop and hence __________ number of stages are required.

The expansion of steam, as it flows over the blades in reaction turbine, represents

Parson's turbine is a

The ratio of the work delivered at the turbine shaft to the heat supplied is called overall thermal efficiency of turbine.