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

 
The ratio of the work delivered at the turbine shaft to the heat supplied is called overall thermal efficiency of turbine.

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

The pressure of steam at throat of a steam nozzle is called critical pressure.

De-Laval turbine is a

For maximum efficiency of an impulse turbine, the steam should leave the blades at right angles to their motion.

The flow of steam is super-sonic

In a De-Laval impulse turbine, the nozzle is kept very close to the blades.

In a reaction turbine, when steam flows through the fixed blades,

 
The efficiency of steam turbines may be improved by