In a reaction turbine, when steam flows through the fixed blades,

pressure and velocity both decreases

pressure increases while velocity decreases

pressure decreases while velocity increases

pressure and velocity both decreases

pressure and velocity both increases

Steam turbines are used for

direct drive of fans, compressors, pumps

The Parsons' reaction turbine has

fixed and moving blades of different shape

identical fixed and moving blades

fixed and moving blades of different shape

The reheat factor is the ratio of the

isentropic heat drop to the heat supplied

cumulative heat drop to the isentropic heat drop

isentropic heat drop to the heat supplied

total useful heat drop to the total isentropic heat drop

47 + Mcqs in Steam Nozzles and Turbines in Automobile Engineering Page 1 McqOptions

1.	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
Answer» B. False

Discussion

2.	The efficiency ratio is the ratio of total useful heat drop to the total isentropic heat drop.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

3.	The Rankine efficiency depends upon total useful heat drop and total isentropic heat drop.
A.	Correct
B.	Incorrect
Answer» C.

Discussion

4.	The ratio of the cumulative heat drop to the isentropic heat drop is called reheat factor.
A.	Yes
B.	No
Answer» B. No

Discussion

5.	The pressure velocity compounded impulse turbine allows a bigger pressure drop and hence __________ number of stages are required.
A.	more
B.	less
Answer» C.

Discussion

6.	In velocity compounding of an impulse turbine, the expansion of steam takes place in a nozzle or a set of nozzles from the boiler pressure to condenser pressure.
A.	True
B.	False
Answer» B. False

Discussion

7.	In pressure compounding of an impulse turbine, the total pressure drop of the steam does not take place in the first nozzle ring, but is divided equally among all the nozzle rings.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

8.	The efficiency of reaction turbine is maximum when (where α = Angle made by the absolute velocity (V) at inlet)
A.	Vb = 0.5 V cos α
B.	Vb = V cos α
C.	Vb = 0.5 V2 cos α
D.	Vb = V2 cos α
Answer» C. Vb = 0.5 V2 cos α

Discussion

9.	For maximum efficiency of an impulse turbine, the steam should leave the blades at right angles to their motion.
A.	Correct
B.	Incorrect
Answer» B. Incorrect

Discussion

10.	The stage efficiency is the ratio of energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam.
A.	True
B.	False
Answer» C.

Discussion

11.	The ratio of the energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam is called mechanical efficiency.
A.	Yes
B.	No
Answer» C.

Discussion

12.	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

13.	The pressure of steam, in reaction turbines, is reduced in the fixed blades as well as in moving blades.
A.	Correct
B.	Incorrect
Answer» B. Incorrect

Discussion

14.	The velocity of steam, in reaction turbines, is increased in the fixed blades as well as in moving blades.
A.	True
B.	False
Answer» B. False

Discussion

15.	An impulse turbine as compared to a reaction turbine, for a given power has __________ row of blades.
A.	equal
B.	less
C.	more
Answer» D.

Discussion

16.	In a single stage impulse turbine, the velocity of steam approaching nozzles is negligible.
A.	True
B.	False
Answer» B. False

Discussion

17.	A single stage turbine is not used because it requires large reduction gearing due to very high rotational speed.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

18.	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
Answer» B. less than

Discussion

19.	In a De-Laval impulse turbine, the nozzle is kept very close to the blades.
A.	Yes
B.	No
Answer» B. No

Discussion

20.	The discharge through a nozzle is maximum for a certain value of exit pressure. This pressure is known as critical pressure.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

21.	In a nozzle, the effect of supersaturation is to increase the dryness fraction of steam.
A.	Yes
B.	No
Answer» B. No

Discussion

22.	In a De-Laval nozzle expanding superheated steam from 10 bar to 0.1 bar, the pressure at the minimum cross-section (i. e. pressure at throat, p2) will be
A.	3.3 bar
B.	5.46 bar
C.	8.2 bar
D.	9.9 bar
Answer» C. 8.2 bar

Discussion

23.	The critical pressure ratio (p2/p1) is given by
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» C. [C].

Discussion

24.	The critical pressure ratio is given by (where p1 = Initial pressure of steam, and p2 = Pressure of steam at throat or critical pressure)
A.	p1 p2
B.	p1/p2
C.	p2/p1
D.	p1 + p2
Answer» D. p1 + p2

Discussion

25.	The pressure of steam at throat of a steam nozzle is called critical pressure.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

26.	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
Answer» B. No

Discussion

27.	A nozzle is said to be a convergent-divergent nozzle, when the cross-section of a nozzle first decreases from its entrance to throat and then increases from its throat to exit.
A.	True
B.	False
Answer» B. False

Discussion

28.	During flow through a nozzle, no heat is supplied or rejected by the steam.
A.	Agree
B.	Disagree
Answer» B. Disagree

Discussion

29.	In a reaction turbine, when steam flows through the fixed blades,
A.	pressure increases while velocity decreases
B.	pressure decreases while velocity increases
C.	pressure and velocity both decreases
D.	pressure and velocity both increases
Answer» C. pressure and velocity both decreases

Discussion

30.	The turbine blades are
A.	straight
B.	circular
C.	curved
D.	-
Answer» D. -

Discussion

31.	The ratio of the useful heat drop to the isentropic heat drop is called
A.	condenser efficiency
B.	nozzle efficiency
C.	boiler efficiency
D.	vacuum efficiency
Answer» C. boiler efficiency

Discussion

32.	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

33.	Steam turbines are used for
A.	large marine propulsion
B.	electric power generation
C.	direct drive of fans, compressors, pumps
D.	all of these
Answer» E.

Discussion

34.	In a convergent divergent nozzle, the discharge depends upon the initial conditions of steam and the area of nozzle at throat.
A.	Correct
B.	Incorrect
C.	-
D.	-
Answer» B. Incorrect

Discussion

35.	The critical pressure ratio for initially dry saturated steam is more as compared to initially wet steam.
A.	Yes
B.	No
C.	-
D.	-
Answer» C. -

Discussion

36.	In a De-Laval nozzle expanding superheated steam from 10 bar to 0.1 bar, the pressure at the minimum cross-section (i. e. pressure at throat, p 2 ) will be
A.	3.3 bar
B.	5.46 bar
C.	8.2 bar
D.	9.9 bar
Answer» C. 8.2 bar

Discussion

37.	The blade velocity coefficient is ratio of relative velocity of steam at outlet tip of the blade to the relative velocity of steam at inlet tip of the blade.
A.	True
B.	False
C.	-
D.	-
Answer» B. False

Discussion

38.	The Parsons' reaction turbine has
A.	only moving blades
B.	only fixed blades
C.	identical fixed and moving blades
D.	fixed and moving blades of different shape
Answer» D. fixed and moving blades of different shape

Discussion

39.	The reheat factor is the ratio of the
A.	cumulative heat drop to the isentropic heat drop
B.	isentropic heat drop to the heat supplied
C.	total useful heat drop to the total isentropic heat drop
D.	none of the above
Answer» B. isentropic heat drop to the heat supplied

Discussion

40.	The ratio of the workdone on the blades to the energy supplied to the blades, is called
A.	blading efficiency
B.	nozzle efficiency
C.	gross or stage efficiency
D.	mechanical efficiency
Answer» B. nozzle efficiency

Discussion

41.	Thermal equilibrium means that the flow of steam is
A.	isothermal
B.	isentropic
C.	hyperbolic
D.	polytropic
Answer» C. hyperbolic

Discussion

42.	The turbine blades do not change the direction of steam issuing from the nozzle.
A.	True
B.	False
C.	-
D.	-
Answer» C. -

Discussion

43.	The critical pressure gives the velocity of steam at the throat equal to the velocity of sound.
A.	Agree
B.	Disagree
C.	-
D.	-
Answer» B. Disagree

Discussion

44.	The turbine, in which the general direction of the steam flow is parallel to the turbine axis, is called axial flow turbines
A.	True
B.	False
C.	-
D.	-
Answer» B. False

Discussion

45.	The pressure at which the steam leaves the nozzle is known as back pressure.
A.	Correct
B.	Incorrect
C.	-
D.	-
Answer» B. Incorrect

Discussion

46.	The flow through a nozzle is regarded as
A.	constant volume flow
B.	constant pressure flow
C.	isothermal flow
D.	isentropic flow
Answer» E.

Discussion

47.	A turbine is said to have an axial discharge when the steam leaves the blade tip at __________ to the direction of the blade motion.
A.	60Â°
B.	90Â°
C.	180Â°
D.	270Â°
Answer» C. 180Â°

Discussion

Explore topic-wise MCQs in Automobile Engineering.

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

The efficiency ratio is the ratio of total useful heat drop to the total isentropic heat drop.

The Rankine efficiency depends upon total useful heat drop and total isentropic heat drop.

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

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

In velocity compounding of an impulse turbine, the expansion of steam takes place in a nozzle or a set of nozzles from the boiler pressure to condenser pressure.

In pressure compounding of an impulse turbine, the total pressure drop of the steam does not take place in the first nozzle ring, but is divided equally among all the nozzle rings.

The efficiency of reaction turbine is maximum when (where α = Angle made by the absolute velocity (V) at inlet)

For maximum efficiency of an impulse turbine, the steam should leave the blades at right angles to their motion.

The stage efficiency is the ratio of energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam.

The ratio of the energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam is called mechanical efficiency.

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

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

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

An impulse turbine as compared to a reaction turbine, for a given power has __________ row of blades.

In a single stage impulse turbine, the velocity of steam approaching nozzles is negligible.

A single stage turbine is not used because it requires large reduction gearing due to very high rotational speed.

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.

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

The discharge through a nozzle is maximum for a certain value of exit pressure. This pressure is known as critical pressure.

In a nozzle, the effect of supersaturation is to increase the dryness fraction of steam.

In a De-Laval nozzle expanding superheated steam from 10 bar to 0.1 bar, the pressure at the minimum cross-section (i. e. pressure at throat, p2) will be

The critical pressure ratio (p2/p1) is given by

The critical pressure ratio is given by (where p1 = Initial pressure of steam, and p2 = Pressure of steam at throat or critical pressure)

The pressure of steam at throat of a steam nozzle is called critical pressure.

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 nozzle is said to be a convergent-divergent nozzle, when the cross-section of a nozzle first decreases from its entrance to throat and then increases from its throat to exit.

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

In a reaction turbine, when steam flows through the fixed blades,

The turbine blades are

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

Parson's turbine is a

Steam turbines are used for

In a convergent divergent nozzle, the discharge depends upon the initial conditions of steam and the area of nozzle at throat.

The critical pressure ratio for initially dry saturated steam is more as compared to initially wet steam.

In a De-Laval nozzle expanding superheated steam from 10 bar to 0.1 bar, the pressure at the minimum cross-section (i. e. pressure at throat, p 2 ) will be

The blade velocity coefficient is ratio of relative velocity of steam at outlet tip of the blade to the relative velocity of steam at inlet tip of the blade.

The Parsons' reaction turbine has

The reheat factor is the ratio of the

The ratio of the workdone on the blades to the energy supplied to the blades, is called

Thermal equilibrium means that the flow of steam is

The turbine blades do not change the direction of steam issuing from the nozzle.

The critical pressure gives the velocity of steam at the throat equal to the velocity of sound.

The turbine, in which the general direction of the steam flow is parallel to the turbine axis, is called axial flow turbines

The pressure at which the steam leaves the nozzle is known as back pressure.

The flow through a nozzle is regarded as

A turbine is said to have an axial discharge when the steam leaves the blade tip at __________ to the direction of the blade motion.