Which term describes turbine blades that are attached to the shaft and convert the thermal energy in steam into mechanical energy?

• A. Fixed blading
• B. Rotor blades
• C. Moving blading or buckets
• D. Guide vanes

Answer: (C)

The concept being tested is which blades actually drive the shaft by taking energy from the steam. Blades that are attached to the shaft are the moving blades, also called buckets. As steam expands and flows through these blades, it exerts a force that has a tangential component, producing torque on the rotor. This energy transfer converts the steam’s thermal energy into mechanical energy in the shaft.

Fixed blades, or guide vanes, stay stationary and mainly direct the steam flow to control its direction and speed; they do not rotate the shaft or extract energy from the steam. So the blades that perform the energy extraction and rotate the rotor are the moving blades.