What is considered a stage on an impulse turbine?

In an impulse turbine, a stage consists of both the nozzles that convert the pressure energy of steam into velocity, and the blades that extract energy from this high-velocity steam. The correct answer identifies that a stage includes one set of nozzles followed by a row of moving blades. The nozzles accelerate the steam, which then impinges on the moving blades, causing them to rotate and generate work.

This design allows for the efficient transfer of energy from the steam to the turbine, as the nozzles direct the steam flow in a way that maximizes the impact on the moving blades. Furthermore, including the fixed blades in the stage does not accurately represent the function of an impulse turbine because these blades typically perform in subsequent stages to guide the flow or recover pressure.

The other response options present elements that do not constitute a full stage in an impulse turbine. For example, a stage cannot consist of only one set of moving blades or solely multiple sets of nozzles, as this configuration would not provide the necessary conversion of steam energy into mechanical energy. Understanding the structure and operation of impulse turbines is critical for properly identifying how the stages work in generating power.