Definition check — stage efficiency in steam turbines:\nStage efficiency is defined as the ratio of the energy transferred to (and thus available for work in) the rotor blades per kilogram of steam to the total ideal energy supplied across the entire stage per kilogram of steam. State whether this statement is correct.

Introduction / Context:
Several efficiency definitions exist in turbomachinery: nozzle efficiency, blade (or rotor/diagram) efficiency, stage efficiency, and overall (isentropic) efficiency. Being precise about stage efficiency helps engineers compare real stages against their ideal energy conversion potential.

Given Data / Assumptions:

• One complete stage comprises a fixed (stator/nozzle) row and a moving (rotor) row.
• Ideal reference is the isentropic energy drop across the whole stage.
• Losses occur in stator and rotor; measured output is the work actually transferred to the rotor.

Concept / Approach:
Stage efficiency (sometimes called isentropic efficiency of the stage) is defined as: η_stage = (actual work output per kg across the stage) / (ideal isentropic enthalpy drop per kg across the stage). Since the actual work output equals the energy effectively supplied to and extracted by the rotor blades, the verbal statement aligns with the formal definition. This measure includes losses in both fixed and moving rows within that stage.

Step-by-Step Solution:

Verification / Alternative check:
On T–s diagrams, the ideal vertical (isentropic) drop represents the denominator, while the actual expansion curve enclosing a smaller area corresponds to the numerator (after accounting for exit kinetic energy and losses). The ratio gives η_stage.

Why Other Options Are Wrong:

• False: Conflicts with standard turbomachinery definitions.
• Only true for impulse/reaction stages: The definition applies to both; the isentropic reference and measured work are stage-level quantities regardless of degree of reaction.

Common Pitfalls:
Mixing stage efficiency with diagram (rotor) efficiency, which uses kinetic energy at rotor inlet as the reference rather than the stage isentropic drop.

Final Answer:
True