Nozzles And Turbines MCQ

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

  sin²α

  খ

  cos²α

  গ

  tan²α

  ঘ

  cot²α
• The efficiency of an impulse turbine is maximum when (where V_b = Blade speed, V = Absolute velocity of steam entering the blade and α = Nozzle angle)
  ক

  V_b = 0.5 V cosα

  খ

  V_b = V cosα

  গ

  V_b = 0.5 V²cosα

  ঘ

  V_b = V²cosα
• The variation of steam pressure in the nozzle depends upon
  ক

  Velocity of steam

  খ

  Specific volume of steam

  গ

  Dryness fraction of steam

  ঘ

  All of these
• The maximum discharge of steam through a convergent-divergent nozzle depends upon
  ক

  Area of nozzle at throat

  খ

  Initial pressure and volume of steam

  গ

  Final pressure of steam leaving the nozzle

  ঘ

  Both (A) and (B)
• When the nozzle operates with the maximum mass flow, the nozzle is said to be
  ক

  Choked

  খ

  Under-damping

  গ

  Over-damping

  ঘ

  None of these
• When the back pressure of a nozzle is below the designed value of pressure at exit of nozzle, the nozzle is said to be
  ক

  Choked

  খ

  Under-damping

  গ

  Over-damping

  ঘ

  None of these
• Hard coke is produced by carburization of coal at
  ক

  Atmospheric temperature

  খ

  500-600°C

  গ

  700-850°C

  ঘ

  950-1100°C
• One kg of steam sample contains 0.8 kg dry steam? Its dryness fraction is
  ক

  0.2

  খ

  0.8

  গ

  1.0

  ঘ

  0.6
• In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 mts. and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is
  ক

  40%

  খ

  25%

  গ

  50%

  ঘ

  80%
• The actual power generated in the engine cylinder is called
  ক

  Indicated power

  খ

  Brake power

  গ

  Frictional power

  ঘ

  None of these
• Efficiency of a thermal cycle increases by
  ক

  Regeneration

  খ

  Reheating of steam

  গ

  Both (A) and (B)

  ঘ

  Cooling of steam
• The specific heat of superheated steam in kcal/kg is generally of the order of
  ক

  0.1

  খ

  0.3

  গ

  0.5

  ঘ

  0.8
• The nozzle efficiency is the ratio of
  ক

  Workdone on the blades to the energy supplied to the blades

  খ

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

  গ

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

  ঘ

  None of the above
• The diagram efficiency is the ratio of
  ক

  Workdone on the blades to the energy supplied to the blades

  খ

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

  গ

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

  ঘ

  None of the above
• For combustion of a fuel, following is essential
  ক

  Correct fuel air ratio

  খ

  Proper ignition temperature

  গ

  O₂ to support combustion

  ঘ

  All the three above
• The water tubes in a Babcock and Wilcox boiler are
  ক

  Horizontal

  খ

  Vertical

  গ

  Inclined

  ঘ

  Horizontal and inclined
• The pressure at which latent heat of vaporization of water is zero, is
  ক

  Below atmospheric pressure

  খ

  1 kg/cm²

  গ

  100 kg/cm²

  ঘ

  225.6 kg/cm²
• Which device is used in thermal power plants to reduce level of pollution?
  ক

  Induced draft fan

  খ

  Smoke meter

  গ

  Chimney

  ঘ

  Precipitator
• The high steam and low water safety valve is not used in
  ক

  Cochran boiler

  খ

  Cornish boiler

  গ

  Lancashire boiler

  ঘ

  Locomotive boiler
• Bomb calorimeter is used to determine
  ক

  Higher calorific value at constant volume

  খ

  Lower calorific value at constant volume

  গ

  Higher calorific value at constant pressure

  ঘ

  Lower calorific value at constant pressure
• In locomotive boiler, maximum steam pressure is limited to
  ক

  1 kg/cm²

  খ

  5 kg/cm²

  গ

  10 kg/cm²

  ঘ

  18 kg/cm²
• The turbine blades are
  ক

  Straight

  খ

  Circular

  গ

  Curved

  ঘ

  None of these
• Willian’s line follows the law (where b = A constant representing the shape of the Willian’s line, a = Another constant i.e. no load consumption per hour, I.P. = Indicated Power and m = Steam consumption per hour)
  ক

  I.P. = a × m + b

  খ

  m = a + b × I.P.

  গ

  I.P. = b × m + a

  ঘ

  $${\text{m}} = \frac{{\text{b}}}{{{\text{I}}{\text{.P}}.}} - {\text{a}}$$
• In an ideal impulse turbine, the
  ক

  Absolute velocity at the inlet of moving blade is equal to that at the outlet

  খ

  Relative velocity at the inlet of the moving blade is equal to that at the outlet

  গ

  Axial velocity at inlet is equal to that at the outlet

  ঘ

  Whirl velocity at inlet is equal to that at the outlet
• Which of the following boiler works on a forced circulation of water?
  ক

  Lamont boiler

  খ

  Benson boiler

  গ

  Loeffler boiler

  ঘ

  All of these
• The ratio of the energy required to produce the artificial draught (expressed in meters head or J/kg of flue gas) to the mechanical equivalent of extra heat carried away per kg of flue gases due to natural draught, is known as
  ক

  Efficiency of the boiler

  খ

  Efficiency of the chimney

  গ

  Efficiency of the fan

  ঘ

  Power of the boiler
• A boiler in India should conform to safety regulations of
  ক

  DIN

  খ

  BS

  গ

  ASTM

  ঘ

  IBR
• Cut-off governing as compared to throttle governing is
  ক

  Less efficient and less economical

  খ

  Less efficient and more economical

  গ

  More efficient and less economical

  ঘ

  More efficient and more economical
• Water boils when its vapor pressure
  ক

  Equals that of the surroundings

  খ

  Equals 760 mm of mercury

  গ

  Equals to atmospheric pressure

  ঘ

  Equals the pressure of water in the container
• The missing quantity per stroke is equal to
  ক

  Cylinder feed indicated mass of steam

  খ

  Cylinder feed + indicated mass of steam

  গ

  Mass of cushion steam + indicated mass of steam

  ঘ

  Mass of cushion steam + cylinder feed