The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced.
Remains same
Decreases
Increases
None of these
Correct Answer :
C. Increases
Related Questions
In turbines, the fluid undergoes a continuous steady flow process and the speed of flow is
Low
Very low
High
Very high
A wet vapour can be completely specified by
Pressure only
Temperature only
Dryness fraction only
Pressure and dryness fraction
The draught produced by a steam jet issuing from a nozzle placed in the ash-pit under the fire grate of the furnace is called
Induced steam jet draught
Chimney draught
Forced steam jet draught
None of these
If partial pressure of air and steam be pa and ps respectively in a condenser, then according to Dalton's law, the pressure in condenser is equal to
ps - pa
pa - ps
pa + ps
None of these
In forced circulation steam boilers, the force is applied
To draw water
To circulate water
To drain off the water
All of these
The length of Cornish boiler is of the order of
24 m
35 m
57.5 m
79 m
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
A fusible plug is fitted in small boilers in order to
Avoid excessive build up of pressure
Avoid explosion
Extinguish fire if water level in the boiler falls below alarming limit
Control steam dome
The critical pressure ratio (p₂/p₁) is given by
(p₂/p₁) = [2/(n - 1)] n/(n + 1)
(p₂/p₁) = [2/(n + 1)] n/(n-1)
(p₂/p₁) = [(n - 1)/2] n + (1/n)
(p₂/p₁) = [(n + 1)/2] n - (1/n)
A turbine is said to have an axial discharge when the steam leaves the blade tip at _________ to the direction of the blade motion.
60°
90°
180°
270°
The ratio of brake power to the indicated power is known as
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Brake thermal efficiency
One kg of steam sample contains 0.8 kg dry steam; Its dryness fraction is
0.2
0.8
1.0
0.6
Sublimation region is the region where
Solid and vapour phases are in equilibrium
Solid and liquid phases are in equilibrium
Liquid and vapour phases are in equilibrium
Solid, liquid and vapour phases are in equilibrium
A device used to increase the temperature of saturated steam without raising its pressure, is called
Blow off cock
Fusible plug
Superheater
Stop valve
The ratio of the actual vacuum to the ideal vacuum in a condenser is called
Condenser efficiency
Vacuum efficiency
Nozzle efficiency
Boiler efficiency
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.
Equal to
Less than
Greater than
None of these
In a nozzle, whole frictional loss is assumed to occur between
Inlet and throat
Inlet and outlet
Throat and exit
All of these
The maximum steam pressure in a Locomotive boiler is limited to
0.18 MN/m²
1.8 MN/m²
18 MN/m²
180 MN/m²
The ratio of the energy required to produce the artificial draught (expressed in metres 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
Efficiency of the boiler
Efficiency of the chimney
Efficiency of the fan
Power of the boiler
Steam engine operates on
Carnot cycle
Joule cycle
Stirling cycle
Brayton cycle
Fire tube boilers are limited to a maximum design working pressure of
1 kg/cm
6 kg/cm
17 kg/cm²
100 kg/cm²
The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is
Less
More
Equal
May be less or more depending on temperature
The ratio of total useful heat drop to the total isentropic heat drop, is called
Stage efficiency
Internal efficiency
Rankine efficiency
None of these
An impulse turbine as compared to a reaction turbine, for a given power has _________ row of blades.
Equal
Less
More
None of these
Lancashire boiler is used where working pressure and power required are
Low
Moderate
High
None of these
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
The three Ts for good combustion are
Temperature, time, and turbulence
Total air, true fuel, and turbulence
Thorough mixing, total air and temperature
Total air, time, and temperature
Which of the following statement indicates the difference between Cornish boiler and Lancashire boiler?
Cornish boiler is a water tube boiler whereas Lancashire boiler is a fire tube boiler
Cornish boiler is a fire tube boiler whereas Lancashire boiler is a water tube boiler
Cornish boiler has one flue tube whereas Lancashire boiler has two flue tubes
Cornish boiler has two flue tubes whereas Lancashire boiler has one flue tube
In order to obtain superheated steam, a superheater is added in an existing boiler. As as result, furnace vacuum will
Remain unaffected
Improve
Worsen
May improve/worsen depending on size
The equivalent evaporation is defined as
The ratio of heat actually used in producing the steam to the heat liberated in the furnace
The amount of water evaporated or steam produced in kg per kg of fuel burnt
The amount of water evaporated from and at 100°C into dry and saturated steam
The evaporation of 15.653 kg of water per hour from and at 100°C