MCQOPTIONS
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MCQOPTIONS
This section includes 146 Mcqs, each offering curated multiple-choice questions to sharpen your Power Systems knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
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. | |
| 52. |
The steam enters the nozzle at a |
| A. | high pressure and a low velocity |
| B. | high pressure and a high velocity |
| C. | low pressure and a low velocity |
| D. | low pressure and a high velocity |
| Answer» B. high pressure and a high velocity | |
| 53. |
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 | |
| 54. |
The efficiency of steam turbines may be improved by |
| A. | reheating of steam |
| B. | regenerative feed heating |
| C. | binary vapour plant |
| D. | any one of these |
| Answer» E. | |
| 55. |
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. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 56. |
The action of steam in a steam turbine is |
| A. | static |
| B. | dynamic |
| C. | static and dynamic |
| D. | neither static nor dynamic |
| Answer» C. static and dynamic | |
| 57. |
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 | |
| 58. |
The critical pressure gives the velocity of steam at the throat |
| A. | equal to the velocity of sound |
| B. | less than the velocity of sound |
| C. | more than the velocity of sound |
| D. | none of these |
| Answer» B. less than the velocity of sound | |
| 59. |
The impulse reaction turbine has its driving force |
| A. | as an impulsive force |
| B. | as a reaction force |
| C. | partly as an impulsive force and partly as a reaction force |
| D. | none of the above |
| Answer» D. none of the above | |
| 60. |
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 |
| Answer» B. 0.56 | |
| 61. |
The steam leaves the nozzle at a |
| A. | high pressure and a low velocity |
| B. | high pressure and a high velocity |
| C. | low pressure and a low velocity |
| D. | low pressure and a high velocity |
| Answer» E. | |
| 62. |
The supersaturated flow of steam through a nozzle as compared to a stable flow, the available heat drop |
| A. | remains the same |
| B. | increases |
| C. | decreases |
| D. | is unpredictable |
| Answer» D. is unpredictable | |
| 63. |
The discharge is __________ at critical pressure. |
| A. | zero |
| B. | minimum |
| C. | maximum |
| D. | None of these |
| Answer» D. None of these | |
| 64. |
The expansion of steam in a nozzle follows |
| A. | Carnot cycle |
| B. | Rankine cycle |
| C. | Joule cycle |
| D. | Stirling cycle |
| Answer» C. Joule cycle | |
| 65. |
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't say |
| D. | None of these |
| Answer» B. Disagree | |
| 66. |
The critical pressure ratio for initially dry saturated steam is |
| A. | 0.546 |
| B. | 0.577 |
| C. | 0.582 |
| D. | 0.601 |
| Answer» C. 0.582 | |
| 67. |
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 |
| Answer» D. none of the above | |
| 68. |
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 | |
| 69. |
In a single stage impulse turbine, the velocity of steam approaching nozzles is negligible. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 70. |
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 |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 71. |
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't say |
| D. | None of these |
| Answer» B. Disagree | |
| 72. |
An impulse turbine as compared to a reaction turbine, for a given power has __________ row of blades. |
| A. | equal |
| B. | less |
| C. | more |
| D. | None of these |
| Answer» D. None of these | |
| 73. |
A regenerative steam cycle renders |
| A. | increased work output per unit mass of steam |
| B. | decreased work output per unit mass of steam |
| C. | increased thermal efficiency |
| D. | decreased work output per unit mass of steam as well as increased thermal efficiency |
| Answer» E. | |
| 74. |
The effect of bleeding is that |
| A. | it increases the thermodynamic efficiency of the turbine |
| B. | boiler is supplied with hot water |
| C. | it decreases the power developed by the turbine |
| D. | all of the above |
| Answer» E. | |
| 75. |
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 | |
| 76. |
The velocity of whirl at outlet for an axial discharge turbine is |
| A. | minimum |
| B. | maximum |
| C. | zero |
| D. | None of these |
| Answer» D. None of these | |
| 77. |
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 | |
| 78. |
A binary vapour plant consists of |
| A. | steam turbine |
| B. | steam condenser |
| C. | mercury boiler |
| D. | all of these |
| Answer» E. | |
| 79. |
In reaction turbines, the axial thrust is due to |
| A. | pressure drop across the rotor |
| B. | change in axial velocity |
| C. | both (a) and (b) |
| D. | none of these |
| Answer» D. none of these | |
| 80. |
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't say |
| D. | None of these |
| Answer» B. Disagree | |
| 81. |
The effect of friction in the nozzle __________ dryness fraction of steam. |
| A. | has no effect on |
| B. | decreases |
| C. | increases |
| D. | None of these |
| Answer» D. None of these | |
| 82. |
Curtis turbine is a |
| A. | simple reaction turbine |
| B. | velocity compounded turbine |
| C. | pressure compounded turbine |
| D. | pressure-velocity compounded turbine |
| Answer» E. | |
| 83. |
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't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 84. |
In an ideal impulse turbine, the |
| A. | absolute velocity at the inlet of moving blade 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. | axial velocity at inlet is equal to that at the outlet |
| D. | whirl velocity at inlet is equalto that at the outlet |
| Answer» C. axial velocity at inlet is equal to that at the outlet | |
| 85. |
De-Laval turbine is a |
| A. | single rotor impulse turbine |
| B. | multi-rotor impulse turbine |
| C. | impulse reaction turbine |
| D. | none of these |
| Answer» B. multi-rotor impulse turbine | |
| 86. |
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. | regenerative heating |
| B. | reheating of steam |
| C. | bleeding |
| D. | none of these |
| Answer» D. none of these | |
| 87. |
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 |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 88. |
In an impulse reaction turbine, the pressure drops gradually and continuously over |
| A. | fixed blades |
| B. | moving blades |
| C. | both fixed and moving blades |
| D. | none of these |
| Answer» D. none of these | |
| 89. |
The efficiency ratio is the ratio of total useful heat drop to the total isentropic heat drop. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 90. |
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 |
| Answer» B. 1.08 to 1.l0 | |
| 91. |
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. | blading efficiency |
| B. | nozzle efficiency |
| C. | stage efficiency |
| D. | mechanical efficiency |
| Answer» D. mechanical efficiency | |
| 92. |
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 velocity coefficient is unity |
| C. | blades are equiangular and frictionless |
| D. | blade solidity is 0.65 |
| Answer» D. blade solidity is 0.65 | |
| 93. |
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 these |
| Answer» B. less than | |
| 94. |
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 |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 95. |
Stage efficiency is also known as |
| A. | diagram efficiency |
| B. | nozzle efficiency |
| C. | gross efficiency |
| D. | none of these |
| Answer» D. none of these | |
| 96. |
The pressure compounded impulse turbine as compared to velocity compounded turbine require __________ number of stages. |
| A. | same |
| B. | less |
| C. | more |
| D. | None of these |
| Answer» D. None of these | |
| 97. |
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 |
| Answer» D. increase the exit temperature without any effect on mass flow rate | |
| 98. |
The pressure at which the steam leaves the nozzle is known as back pressure. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 99. |
The flow through a nozzle is regarded as |
| A. | constant volume flow |
| B. | constant pressure flow |
| C. | isothermal flow |
| D. | isentropic flow |
| Answer» E. | |
| 100. |
The flow of steam is super-sonic |
| A. | at the entrance to the nozzle |
| B. | at the throat of the nozzle |
| C. | in the convergent portion of the nozzle |
| D. | in the divergent portion of the nozzle |
| Answer» E. | |