The shrouding on the blades of a steam turbine primarily serves to

• A. Confine the steam to the blades
• B. Cool the blade tips
• C. Expand the steam like a nozzle
• D. Change the steam direction

Answer: (A)

Shrouding creates a continuous ring at the blade tips, which seals the gap between the tips and the casing. This confinement keeps the steam inside the blade passages instead of leaking around the tips, so more of the steam’s energy is extracted through the blade, improving efficiency and reducing tip-related vibrations and flutter at high speeds. It isn’t mainly for cooling blade tips, nor does it function as a nozzle to expand the steam or primarily steer the flow—the blade geometry and stator vanes handle expansion and direction changes.