Q.1

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

  • True
  • False
Q.2

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

  • blading efficiency
  • nozzle efficiency
  • stage efficiency
  • mechanical efficiency
Q.3

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

  • True
  • False
Q.4

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

  • reheat factor
  • stage efficiency
  • internal efficiency
  • Rankine efficiency
Q.5

The pressure of steam __________ while flowing through a nozzle.

  • increases
  • decreases
  • remains constant
Q.6

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

  • choked
  • underdamping
  • overdamping
  • none of these
Q.7

De-Laval turbine is a

  • simple impulse turbine
  • simple reaction turbine
  • impulse-reaction turbine
  • none of these
Q.8

Curtis turbine is a

  • simple reaction turbine
  • velocity compounded turbine
  • pressure compounded turbine
  • pressure-velocity compounded turbine
Q.9

The diagram efficiency is the ratio of

  • 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
  • none of the above
Q.10

The critical pressure ratio for gases is

  • 0.528
  • 0.546
  • 0.577
  • 0.582
Q.11

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.

  • Yes
  • No
Q.12

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

  • bleeding
  • reheating
  • governing
  • none of these
Q.13

In a velocity compounded impulse turbine, when steam flows through the second row of moving blades,

  • velocity increases
  • velocity decreases
  • velocity remains constant
  • pressure remains constant
Q.14

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

  • blades are equiangular
  • blade velocity coefficient is unity
  • blades are equiangular and frictionless
  • blade solidity is 0.65
Q.15

The reheat factor depends upon

  • initial pressure and superheat
  • exit pressure
  • turbine stage efficiency
  • all of these
Q.16

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

  • velocity compounding
  • pressure compounding
  • pressure-velocity compounding
  • all of these
Q.17

The velocity of steam at throat of the nozzle is __________ the velocity of sound.

  • equal to
  • less than
  • more than
Q.18

The critical pressure ratio for initially dry saturated steam is

  • 0.546
  • 0.577
  • 0.582
  • 0.601
Q.19

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

  • Correct
  • Incorrect
Q.20

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

  • same
  • less
  • more
Q.21

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

  • Agree
  • Disagree
Q.22

Reheating of steam in a turbine

  • increases the workdone through the turbine
  • increases the efficiency of the turbine
  • reduces wear on the blades
  • all of these
Q.23

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.

  • Yes
  • No
Q.24

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

  • divergent nozzle
  • convergent nozzle
  • convergent-divergent nozzle
  • none of these
Q.25

In an impulse turbine

  • 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
Q.26

The nozzle efficiency is the ratio of

  • 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
  • none of the above
Q.27

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

  • Agree
  • Disagree
Q.28

Blading efficiency is also known as

  • stage efficiency
  • diagram efficiency
  • nozzle efficiency
  • none of these
Q.29

The effect of supersaturation is that the

  • mass of the steam discharged increases
  • entropy and specific volume of the steam increases
  • exit velocity of steam reduces
  • all of these
Q.30

The purpose of governing in steam turbines is to

  • maintain the speed of the turbine
  • reduce the effective heat drop
  • reheat the steam and improve its quality
  • completely balance against end thrust
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