Correct option is D
A diaphragm is a partition or disc-like structure mounted between successive rotor stages in a turbine casing.
It is typically made of cast steel or iron and is split horizontally (for assembly and maintenance).
It contains fixed nozzles (guide blades) that direct steam onto the next rotor stage.
Functions:
Pressure Separation: It acts as a barrier between high-pressure and low-pressure sections of the turbine, maintaining the pressure gradient.
Nozzle Holding: The diaphragm holds the stationary nozzles that accelerate steam to high velocity, converting pressure energy to kinetic energy.
Steam Direction: The nozzles guide steam at the optimal angle onto the rotor blades, ensuring efficient energy transfer.
Sealing: It often includes labyrinth seals around the rotor shaft to prevent steam leakage between stages, improving efficiency.
