The maximum efficiency of a reaction turbine is
2 sin²α/(1 + sin²α)
2 cos²α/(1 + cos²α)
(1 + sin²α)/2 sin²α
(1 + cos²α)/2 cos²α
Correct Answer :
B. 2 cos²α/(1 + cos²α)
Related Questions
An economiser in a boiler
Increases steam pressure
Increases steam flow
Decreases fuel consumption
Decreases steam pressure
Water boils when its vapour pressure
Equals that of the surroundings
Equals 760 mm of mercury
Equals to atmospheric pressure
Equals the pressure of water in the container
A supercritical boiler is one that operates above the pressure and temperature of following values
100 kg/cm² and 540°C
1 kg/cm² and 100°C
218 kg/cm² abs and 373°C
218 kg/cm² abs and 540°C
In an ideal impulse turbine, the
Absolute velocity at the inlet of moving blade is equal to that at the outlet
Relative velocity at the inlet of the moving blade is equal to that at the outlet
Axial velocity at inlet is equal to that at the outlet
Whirl velocity at inlet is equal to that at the outlet
Pick up the correct statement as regards Cornish boiler and Lancashire boiler
Cornish is fire tube and Lancashire is water tube
Cornish is water tube and Lancashire is fire tube
Cornish has two fire tubes and Lancashire has one
Lancashire has two fire tubes and Cornish has one
The basic job of feed water treatment in boilers is to overcome the problem of
Corrosion
Scale
Carryover
All of the above
The compounding of turbines is done in order to
Reduce speed of rotor
Improve efficiency
Reduce exit losses
All of these
Locomotive type' boiler is
Horizontal multi-tubular water tube boiler
Water wall enclosed furnace type
Vertical tubular fire tube type
Horizontal multi-tubular fire tube type
The diagram factor is the ratio of the
Area of the actual indicator diagram to the area of theoretical indicator diagram
Actual workdone per stroke to the theoretical workdone per stroke
Actual mean effective pressure to the theoretical mean effective pressure
Any one of the above
Natural water circulation, by convection in water tube boilers, with increase in pressure of boiler
Increases
Decreases
Remain unaffected
First increases and then decreases
For combustion of a fuel, following is essential
Correct fuel air ratio
Proper ignition temperature
O₂ to support combustion
All the three above
Curtis turbine is a
Simple reaction turbine
Velocity compounded turbine
Pressure compounded turbine
Pressure-velocity compounded turbine
One kg of steam sample contains 0.8 kg dry steam; Its dryness fraction is
0.2
0.8
1.0
0.6
The mechanical draught _________ with the amount of smoke.
Increases
Decreases
Does not effect
None of these
The critical pressure ratio is given by (where p₁ = Initial pressure of steam, and p₂ = Pressure of steam at throat or critical pressure)
p₁. p₂
p₁/p₂
p₂/p₁
p₁ + p₂
Duplex feed pumps are used in small steam boilers. These operate on the principle of
Centrifugal pump
Axial flow pump
Gear pump
Reciprocating pump
In case of non-condensing steam engines, the pressure of steam in the cylinder during exhaust stroke is _________ the condenser pressure.
Equal to
Lower than
Higher than
None of these
The steam leaves the nozzle at a
High pressure and a low velocity
High pressure and a high velocity
Low pressure and a low velocity
Low pressure and a high velocity
Besides mean effective pressure, the data required to determine the indicated power of an engine include
Piston diameter, length of stroke and calorific value of fuel
Piston diameter, specific fuel consumption and Calorific value of fuel
Piston diameter, length of stroke and speed of rotation
Specific fuel consumption, speed of rotation and torque
Alkaline pyrogallate is used in Orsat's apparatus for absorption of
CO₂
CO
O₂
N₂
The ratio of brake power to the indicated power is known as
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Brake thermal efficiency
The clearance in the engine cylinder
Increases the mean effective pressure
Increases the workdone
Decreases the efficiency of the engine
All of these
In accelerated circulation type boiler
Heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum
Water is supplied in drum and through down comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam
Feed pump is employed to supplement natural circulation in water wall type furnace
Water is converted into steam in one pass without any recirculation
Which of the following statement is correct?
A horizontal steam engine requires less floor area than a vertical steam engine
The steam pressure in the cylinder is not allowed to fall below the atmospheric pressure
The compound steam engines are generally non-condensing steam engines
All of the above
The ratio of the isentropic heat drop to the heat supplied, is called
Reheat factor
Stage efficiency
Internal efficiency
Rankine efficiency
A device used in a boiler to control the flow of steam from the boiler to the main pipe and to shut off the steam completely when required, is known as
Blow off cock
Fusible plug
Superheater
Stop valve
An impulse turbine as compared to a reaction turbine, for a given power has _________ row of blades.
Equal
Less
More
None of these
Which of the following is not a boiler mounting?
Blow off cock
Feed check valve
Economiser
Fusible plug
The change in internal energy in steam engines equals to
Work done during the Rankine cycle
Work done during compression
Work done during adiabatic expansion
Change in enthalpy
The value of diagram factor depends upon
Initial conditions of steam
Back pressure
Initial pressure of steam
All of these