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Mechanical Engineering : Steam Nozzles and Turbines - Quiz(MCQ)
1 .
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 the above

Correct Answer :   internal efficiency

2 .
A nozzle is said to be a convergent nozzle
A)
when the cross-section of the nozzle decreases continuously from entrance to exit
B)
when the cross-section of the nozzle increases 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

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

3 .
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)
60°
B)
90°
C)
180°
D)
270°

Correct Answer :   90°

4 .
The flow through a nozzle is regarded as
A)
isothermal flow
B)
constant volume flow
C)
isentropic flow
D)
constant pressure flow

Correct Answer :   isentropic flow

5 .
When the nozzle operates with the maximum mass flow, the nozzle is said to be
A)
overdamping
B)
underdamping
C)
choked
D)
None of the above

Correct Answer :   choked

6 .
The maximum discharge of steam through a convergent-divergent nozzle depends upon
A)
area of nozzle at throat
B)
initial pressure and volume of steam
C)
final pressure ofsteam leaving the nozzle
D)
Both (A) and (B)

Correct Answer :   Both (A) and (B)

7 .
A steam nozzle converts
A)
heat energy of steam into kinetic energy
B)
kinetic energy into heat energy of steam
C)
potential energy into heat energy of steam
D)
heat energy of steam into potential energy

Correct Answer :   heat energy of steam into kinetic energy

8 .
In a velocity compounded impulse turbine, when steam flows through the second row of moving blades,
A)
velocity increases
B)
velocity decreases
C)
velocity remains constant
D)
pressure remains constant

Correct Answer :   velocity decreases

9 .
Steam turbines may be classified according to
A)
number of stages
B)
direction of steam flow
C)
mode of steam action
D)
All of the above

Correct Answer :   All of the above

10 .
The process of draining steam from the turbine, at certain points during its expansion and using this steam for heating the feed water in feed water heaters and then supplying it to the boiler is known as
A)
bleeding
B)
reheating of steam
C)
regenerative heating
D)
None of the above

Correct Answer :   bleeding

11 .
In an impulse turbine, steam expands
A)
wholly in blades
B)
partly in the nozzle and partly in blades
C)
wholly in nozzle
D)
None of the above

Correct Answer :   wholly in nozzle

12 .
In a 50% reaction turbine stage, tangential component of absolute velocity at rotor inlet is 537 m/s and the blade velocity is 454 m/s. The power output in kW of steam will be
A)
260 kW
B)
282 kW
C)
296 kW
D)
302 kW

Correct Answer :   282 kW

13 .
The discharge of steam in a convergent-divergent nozzle __________ after the throat (i.e. in the divergent portion of the nozzle)
A)
increases
B)
decreases
C)
remains constant
D)
None of the above

Correct Answer :   increases

14 .
The critical pressure ratio for initially wet steam is
A)
0.546
B)
0.562
C)
0.577
D)
0.582

Correct Answer :   0.582

15 .
In a nozzle, whole frictional loss is assumed to occur between
A)
inlet and outlet
B)
inlet and thoroat
C)
throat and exit
D)
All of the above

Correct Answer :   throat and exit

16 .
The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced.
A)
decreases
B)
increases
C)
remains same
D)
None of the above

Correct Answer :   increases

17 .
The velocity of steam leaving the nozzle (V) is given by (where K = Nozzle coefficient or nozzle efficiency, and hd = Enthalpy or heat drop during expansion of steam in a nozzle)
A)
V = 44.72 K hd
B)
V = 44.72 hd√K
C)
V = 44.72 K√hd
D)
V = 44.72 √K hd

Correct Answer :   V = 44.72 √K hd

18 .
The isentropic enthalpy drop in moving blade is two-third of the isentropic enthalpy drop in fixed blades of a turbine. The degree of reaction will be
A)
0.4
B)
0.56
C)
0.67
D)
1.67

Correct Answer :   0.4

19 .
De-Laval turbine is a
A)
impulse reaction turbine
B)
multi-rotor impulse turbine
C)
single rotor impulse turbine
D)
None of the above

Correct Answer :   single rotor impulse turbine

20 .
The efficiency of reaction turbine is maximum when (where α = Angle made by the absolute velocity (V) at inlet)
A)
Vb = V2 cos α
B)
Vb = V cos α
C)
Vb = 0.5 V cos α
D)
Vb = 0.5 V2 cos α

Correct Answer :   Vb = V cos α

21 .
A regenerative steam cycle renders
A)
increased thermal efficiency
B)
increased work output per unit mass of steam
C)
decreased work output per unit mass of steam
D)
decreased work output per unit mass of steam as well as increased thermal efficiency

Correct Answer :   decreased work output per unit mass of steam as well as increased thermal efficiency

22 .
The impulse reaction turbine has its driving force
A)
as a reaction force
B)
as an impulsive force
C)
partly as an impulsive force and partly as a reaction force
D)
None of the above

Correct Answer :   partly as an impulsive force and partly as a reaction force

23 .
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 the above

Correct Answer :   All of the above

24 .
A stage, in reaction turbine, is represented by
A)
number of casing
B)
each row of blades
C)
number of exits of steam
D)
number of entries of steam

Correct Answer :   each row of blades

25 .
The nozzle 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

Correct Answer :   energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam

26 .
The friction in the nozzle __________ exit velocity of steam.
A)
decreases
B)
increases
C)
has no effect on
D)
None of the above

Correct Answer :   decreases

27 .
In a reaction turbine
A)
the expansion of steam takes place partly in the fixed blades and partly in the moving blades
B)
the pressure and temperature of steam remains constant
C)
the steam is expanded from a high pressure to a condenser pressure in one or more nozzles
D)
the steam is allowed to expand in the nozzle, where it gives a high velocity before it enters the moving blades

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

28 .
The ratio of the workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam is called
A)
nozzle efficiency
B)
stage efficiency
C)
blading efficiency
D)
mechanical efficiency

Correct Answer :   stage efficiency

29 .
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 Not Say
D)
None of the above

Correct Answer :   Correct

30 .
The diagram efficiency is the ratio of
A)
workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
B)
energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
C)
Both (A) and (B)
D)
workdone on the blades to the energy supplied to the blades

Correct Answer :   workdone on the blades to the energy supplied to the blades

31 .
Blading efficiency is also known as
A)
stage efficiency
B)
nozzle efficiency
C)
diagram efficiency
D)
None of the above

Correct Answer :   diagram efficiency

32 .
In a nozzle, the effect of supersaturation is to
A)
increase the heat drop
B)
increase the entropy
C)
decrease dryness fraction of steam
D)
decrease specific volume of steam

Correct Answer :   increase the entropy

33 .
Which of the following statement is wrong?
A)
The flowin the convergent portion of the nozzle is sub-sonic.
B)
The flow in the divergent portion of the nozzle is super-sonic.
C)
The critical pressure gives the velocity of steam at the throat equal to the velocity of sound.
D)
To increase the velocity of steam above sonic velocity (super-sonic) by expanding steam below the critical pressure, the divergent portion for the nozzle is not necessary.

Correct Answer :   To increase the velocity of steam above sonic velocity (super-sonic) by expanding steam below the critical pressure, the divergent portion for the nozzle is not necessary.

34 .
Which of the following statement is correct?
A)
A flywheel is a must for steam turbine.
B)
The efficiency of steam turbines is greater than steam engines.
C)
The turbine blades do not change the direction of steam issuing from the nozzle
D)
The pressure of steam, in reaction turbines, is increased in fixed blades as well as in moving blades

Correct Answer :   The efficiency of steam turbines is greater than steam engines.

35 .
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 the above

Correct Answer :   superheated steam

36 .
The maximum efficiency of a De-Laval turbine is (where α = Nozzle angle)
A)
cos² α
B)
sin² α
C)
cot² α
D)
tan² α

Correct Answer :   cos² α

37 .
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

Correct Answer :   640/3 √m/s

38 .
The pressure compounded impulse turbine as compared to velocity compounded turbine require __________ number of stages.
A)
less
B)
more
C)
same
D)
None of the above

Correct Answer :   more

39 .
In a reaction turbine when the degree of reaction is zero, then there is
A)
no heat drop in fixed blades
B)
maximum heat drop in fixed blades
C)
maximum heat drop in moving blades
D)
no heat drop in moving blades

Correct Answer :   no heat drop in moving blades

40 .
The effect of friction in the nozzle __________ dryness fraction of steam.
A)
increases
B)
decreases
C)
has no effect on
D)
None of the above

Correct Answer :   increases

41 .
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)
Can Not Say
D)
None of the above

Correct Answer :   True

42 .
Thermal equilibrium means that the flow of steam is
A)
polytropic
B)
hyperbolic
C)
isentropic
D)
isothermal

Correct Answer :   isentropic

43 .
The critical pressure gives the velocity of steam at the throat equal to the velocity of sound.
A)
Agree
B)
Disagree
C)
Can Not Say
D)
None of the above

Correct Answer :   Agree

44 .
The reheat factor is the ratio of the
A)
isentropic heat drop to the heat supplied
B)
cumulative heat drop to the isentropic heat drop
C)
total useful heat drop to the total isentropic heat drop
D)
None of the above

Correct Answer :   cumulative heat drop to the isentropic heat drop

45 .
The steam leaves the nozzle at a
A)
low pressure and a low velocity
B)
low pressure and a high velocity
C)
high pressure and a low velocity
D)
high pressure and a high velocity

Correct Answer :   low pressure and a high velocity

46 .
The supersaturated flow of steam through a nozzle as compared to a stable flow, the available heat drop
A)
increases
B)
remains the same
C)
is unpredictable
D)
decreases

Correct Answer :   decreases

47 .
When the back pressure of a nozzle is below the designed value of pressure at exit of nozzle, the nozzle is said to be
A)
choked
B)
overdamping
C)
underdamping
D)
None of the above

Correct Answer :   underdamping

48 .
The ratio of the workdone on the blades to the energy supplied to the blades, is called
A)
blading efficiency
B)
nozzle efficiency
C)
mechanical efficiency
D)
gross or stage efficiency

Correct Answer :   blading efficiency

49 .
The discharge is __________ at critical pressure.
A)
zero
B)
minimum
C)
maximum
D)
None of the above

Correct Answer :   maximum

50 .
The pressure of steam __________ while flowing through a nozzle.
A)
increases
B)
decreases
C)
remains constant
D)
None of the above

Correct Answer :   decreases

51 .
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

Correct Answer :   8 times

52 .
The process of maintaining the speed of the turbine constant for various load conditions, is known as
A)
bleeding
B)
governing
C)
reheating
D)
None of the above

Correct Answer :   governing

53 .
Which of the following statement is correct for steam turbines as compared to reciprocating steam engines?
A)
The steam consumption is less
B)
A steam turbine develops higher speeds
C)
The efficiency of steam turbine is higher
D)
All of the above

Correct Answer :   All of the above

54 .
Reheating of steam in a turbine
A)
reduces wear on the blades
B)
increases the efficiency of the turbine
C)
increases the workdone through the turbine
D)
All of the above

Correct Answer :   All of the above

55 .
The compounding of turbines is done in order to
A)
improve efficiency
B)
reduce exit losses
C)
reduce speed of rotor
D)
All of the above

Correct Answer :   All of the above

56 .
In an impulse turbine
A)
the steam is expanded in moving blades only
B)
the pressure and temperature of steam remains constant
C)
the steam is expanded in nozzles only and there is a pressure drop and heat drop
D)
the steam is expanded both in fixed and moving blades continuously

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

57 .
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

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

58 .
The reheat factor depends upon
A)
exit pressure
B)
turbine stage efficiency
C)
initial pressure and superheat
D)
All of the above

Correct Answer :   All of the above

59 .
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
C)
Can Not Say
D)
None of the above

Correct Answer :   Agree

60 .
In a reaction turbine, when steam flows through the moving blades,
A)
pressure and velocity both increases
B)
pressure and velocity both decreases
C)
pressure increases while velocity decreases
D)
pressure decreases while velocity increases

Correct Answer :   pressure and velocity both decreases

61 .
In an ideal impulse turbine, the
A)
axial velocity at inlet is equal to that at the outlet
B)
relative velocity at the inlet of the moving blade is equal to that at the outlet
C)
whirl velocity at inlet is equalto that at the outlet
D)
absolute velocity at the inlet of moving blade is equal to that at the outlet

Correct Answer :   relative velocity at the inlet of the moving blade is equal to that at the outlet

62 .
During flow through a nozzle, no heat is supplied or rejected by the steam.
A)
Agree
B)
Disagree
C)
Can Not Say
D)
None of the above

Correct Answer :   Agree

63 .
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

Correct Answer :   p2 / p1

64 .
Stage efficiency is also known as
A)
gross efficiency
B)
nozzle efficiency
C)
diagram efficiency
D)
None of the above

Correct Answer :   gross efficiency

65 .
A steam turbine, in which a part of the steam after partial expansion, is used for process heating and the remaining steam is further expanded for power generation, is known as
A)
impulse turbine
B)
pass out turbine
C)
low pressure turbine
D)
back pressure turbine

Correct Answer :   pass out turbine

66 .
A single stage turbine is not used because it requires large reduction gearing due to very high rotational speed.
A)
Agree
B)
Disagree
C)
Can Not Say
D)
None of the above

Correct Answer :   Agree

67 .
When the inlet pressure of steam is equal to the exit pressure, then
A)
fluid flows through the nozzle
B)
there is a pressure drop in 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

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

68 .
In turbines, the fluid undergoes a continuous steady flow process and the speed of flow is
A)
low
B)
very low
C)
high
D)
very high

Correct Answer :   very high

69 .
In an impulse reaction turbine, the pressure drops gradually and continuously over
A)
fixed blades
B)
moving blades
C)
Both (A) and (B)
D)
None of the above

Correct Answer :   Both (A) and (B)

70 .
The critical pressure gives the velocity of steam at the throat
A)
less than the velocity of sound
B)
equal to the velocity of sound
C)
more than the velocity of sound
D)
None of the above

Correct Answer :   equal to the velocity of sound

71 .
The Parsons' reaction turbine has
A)
identical fixed and moving blades
B)
only fixed blades
C)
only moving blades
D)
fixed and moving blades of different shape

Correct Answer :   identical fixed and moving blades

72 .
The action of steam in a steam turbine is
A)
static
B)
dynamic
C)
static and dynamic
D)
neither static nor dynamic

Correct Answer :   dynamic

73 .
Multi-stage steam turbines are of the
A)
reaction type
B)
velocity compounded type
C)
pressure compounded type
D)
All of the above

Correct Answer :   All of the above

74 .
In reaction turbines, the axial thrust is due to
A)
change in axial velocity
B)
pressure drop across the rotor
C)
Both (A) and (B)
D)
None of the above

Correct Answer :   Both (A) and (B)

75 .
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

Correct Answer :   5.46 bar

76 .
Which of the following statement is correct?
A)
The expansion of steam in a nozzle follows Rankine cycle.
B)
The pressure of steam at throat is called critical pressure.
C)
The friction in the nozzle increases the dryness fraction of steam.
D)
All of the above

Correct Answer :   All of the above

77 .
A binary vapour plant consists of
A)
steam turbine
B)
mercury boiler
C)
steam condenser
D)
All of the above

Correct Answer :   All of the above

78 .
The stage efficiency (ηS) is given by (where ηB = Blading efficiency, and ηN = Nozzle efficiency)
A)
ηS = ηB x ηN
B)
ηS = ηB/ηN
C)
ηS = ηN/ηB
D)
None of the above

Correct Answer :   ηS = ηB x ηN

79 .
The turbine blades are
A)
curved
B)
circular
C)
straight
D)
None of the above

Correct Answer :   curved

80 .
Parson's reaction turbine is a __________ reaction turbine.
A)
70 percent
B)
60 percent
C)
50 percent
D)
40 percent

Correct Answer :   50 percent

81 .
The ratio of the isentropic heat drop to the heat supplied, is called
A)
Rankine efficiency
B)
reheat factor
C)
stage efficiency
D)
internal efficiency

Correct Answer :   Rankine efficiency

82 .
The efficiency ratio is the ratio of total useful heat drop to the total isentropic heat drop.
A)
Agree
B)
Disagree
C)
Can Not Say
D)
None of the above

Correct Answer :   Agree

83 .
De-Laval turbines are mostly used
A)
for large power purposes
B)
for small power purposes and high speeds
C)
where low speeds are required
D)
for small power purposes and low speeds

Correct Answer :   for small power purposes and high speeds

84 .
The purpose of governing in steam turbines is to
A)
reduce the effective heat drop
B)
completely balance against end thrust
C)
reheat the steam and improve its quality
D)
maintain the speed of the turbine

Correct Answer :   maintain the speed of the turbine

85 .
The critical pressure ratio for gases is
A)
0.582
B)
0.577
C)
0.528
D)
None of the above

Correct Answer :   0.528

86 .
The efficiency of a pressure-velocity compounded impulse turbine is __________ as compared to pressure compounded impulse turbine.
A)
less
B)
same
C)
more
D)
None of the above

Correct Answer :   less

87 .
The effect of friction on the flow of steam through a nozzle is to
A)
decrease the mass flow rate and to increase the wetness of steam
B)
increase the mass flow rate and to increase the exit temperature
C)
decrease the mass flow rate and to decrease the wetness of steam
D)
increase the exit temperature without any effect on mass flow rate

Correct Answer :   decrease the mass flow rate and to decrease the wetness of steam

88 .
The effect of supersaturation is that the
A)
exit velocity of steam reduces
B)
mass of the steam discharged increases
C)
entropy and specific volume of the steam increases
D)
All of the above

Correct Answer :   All of the above

89 .
The blade friction in the impulse turbine reduces the velocity of steam by __________ while it passes over the blades.
A)
15 to 20%
B)
10 to 15%
C)
30 to 40%
D)
20 to 30%

Correct Answer :   10 to 15%

90 .
For a Parson's reaction turbine, if α₁ and αâ‚‚ are fixed blade angles at inlet and exit respectively and β₁ and βâ‚‚ are the moving blade angles at entrance and exit respectively, then
A)
α1 = αâ‚‚ and β₁ = βâ‚‚
B)
α1 = β₁ and αâ‚‚ = βâ‚‚
C)
α1 < β₁ and αâ‚‚ > βâ‚‚
D)
α1 = βâ‚‚ and β₁ = αâ‚‚

Correct Answer :   α1 = βâ‚‚ and β₁ = αâ‚‚

91 .
The effect of bleeding is that
A)
boiler is supplied with hot water
B)
it decreases the power developed by the turbine
C)
it increases the thermodynamic efficiency of the turbine
D)
All of the above

Correct Answer :   All of the above

92 .
The expansion of steam, as it flows over the blades in reaction turbine, represents
A)
isentropic process
B)
throttling process
C)
isothermal process
D)
free-expansion process

Correct Answer :   isentropic process

93 .
An impulse turbine as compared to a reaction turbine, for a given power has __________ row of blades.
A)
less
B)
equal
C)
more
D)
None of the above

Correct Answer :   more

94 .
The friction present between the steam and the nozzle surfaces reduces the heat drop by
A)
10 to 15%
B)
15 to 25%
C)
25 to 40%
D)
40 to 60%

Correct Answer :   10 to 15%

95 .
The velocity of whirl at outlet for an axial discharge turbine is
A)
minimum
B)
zero
C)
maximum
D)
None of the above

Correct Answer :   zero

96 .
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 the above

Correct Answer :   equal to

97 .
The efficiency of an impulse turbine is maximum when (where Vb = Blade speed, V = Absolute velocity of steam entering the blade, and α = Nozzle angle)
A)
Vb = V cos α
B)
Vb = V2 cosα
C)
Vb = 0.5 V cos α
D)
Vb = 0.5 V2 cos α

Correct Answer :   Vb = 0.5 V cos α

98 .
The steam enters the nozzle at a
A)
low pressure and a low velocity
B)
low pressure and a high velocity
C)
high pressure and a high velocity
D)
high pressure and a low velocity

Correct Answer :   high pressure and a low velocity

99 .
The variation of steam pressure in the nozzle depends upon
A)
velocity of steam
B)
specific volume of steam
C)
dryness fraction of steam
D)
All of the above

Correct Answer :   All of the above

100 .
Steam turbines are used for
A)
large marine propulsion
B)
electric power generation
C)
direct drive of fans, compressors, pumps
D)
All of the above

Correct Answer :   All of the above

101 .
The value of the reheat factor varies from
A)
1.02 to 1.06
B)
1.08 to 1.l0
C)
1.2 to 1.6
D)
1.6 to 2.02

Correct Answer :   1.02 to 1.06

102 .
In a reaction turbine, when steam flows through the fixed blades,
A)
pressure and velocity both decreases
B)
pressure decreases while velocity increases
C)
pressure and velocity both increases
D)
pressure increases while velocity decreases

Correct Answer :   pressure decreases while velocity increases

103 .
The difference of supersaturated temperature and saturation temperature at that pressure is called
A)
degree of superheat
B)
degree of supersaturation
C)
degree of undercooling
D)
None of the above

Correct Answer :   degree of undercooling

104 .
The ratio of the useful heat drop to the isentropic heat drop is called
A)
boiler efficiency
B)
vacuum efficiency
C)
nozzle efficiency
D)
condenser efficiency

Correct Answer :   nozzle efficiency

105 .
The efficiency of steam turbines may be improved by
A)
reheating of steam
B)
binary vapour plant
C)
regenerative feed heating
D)
Any one of the above

Correct Answer :   Any one of the above

106 .
The expansion of steam in a nozzle follows
A)
Rankine cycle
B)
Joule cycle
C)
Stirling cycle
D)
Carnot cycle

Correct Answer :   Rankine cycle

107 .
Degree of reaction is defined as the ratio of
A)
heat drop in moving blades to the heat drop in fixed blades
B)
heat drop in moving blades to the heat drop in fixed blades plus heat drop in moving blades
C)
heat drop in fixed blades to the heat drop in moving blades
D)
heat drop in fixed blades plus heat drop in moving blades to the heat drop in moving blades

Correct Answer :   heat drop in moving blades to the heat drop in fixed blades plus heat drop in moving blades

108 .
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
C)
Can Not Say
D)
None of the above

Correct Answer :   Agree

109 .
Curtis turbine is a
A)
simple reaction turbine
B)
velocity compounded turbine
C)
essure compounded turbine
D)
pressure-velocity compounded turbine

Correct Answer :   pressure-velocity compounded turbine

110 .
The critical pressure ratio for initially dry saturated steam is
A)
0.521
B)
0.546
C)
0.577
D)
0.582

Correct Answer :   0.577

111 .
The velocity of steam at throat of the nozzle is __________ the velocity of sound.
A)
equal to
B)
less than
C)
more than
D)
None of the above

Correct Answer :   equal to

112 .
A single stage impulse turbine with a diameter of 1.2 m runs at 3000 r.p.m. If the blade speed ratio is 0.42, then the inlet velocity of steam will be
A)
79 m/s
B)
188 m/s
C)
450 m/s
D)
900 m/s

Correct Answer :   450 m/s

113 .
For maximum efficiency of an impulse turbine, the steam should leave the blades at right angles to their motion.
A)
Correct
B)
Incorrect
C)
Can Not Say
D)
None of the above

Correct Answer :   Correct

114 .
The flow of steam is super-sonic
A)
at the throat of the nozzle
B)
in the divergent portion of the nozzle
C)
at the entrance to the nozzle
D)
in the convergent portion of the nozzle

Correct Answer :   in the divergent portion of the nozzle

115 .
Rateau turbine is
A)
velocity compounded turbine
B)
simple reaction turbine
C)
pressure-velocity compounded turbine
D)
pressure compounded turbine

Correct Answer :   pressure compounded turbine

116 .
The impulse turbine rotor efficiency will have a maximum value of 0.5 cos2 α, where α is the nozzle exit flow angle, if the
A)
blades are equiangular
B)
blade solidity is 0.65
C)
blade velocity coefficient is unity
D)
blades are equiangular and frictionless

Correct Answer :   blades are equiangular and frictionless