Rateau staging identification:\nThe Rateau turbine is best described as which type of impulse staging?

Introduction / Context:
Impulse turbines can be compounded either by velocity (Curtis), by pressure (Rateau), or by combined pressure-velocity methods. Recognizing these distinctions is important for predicting stage count, efficiency, and blade loading in design and analysis.

Given Data / Assumptions:

• Impulse staging: pressure drops primarily in fixed nozzles.
• Compounding approach defines how the total pressure drop is shared among stages.
• Rateau is a historical and widely taught scheme.

Concept / Approach:
In Rateau (pressure-compounded) turbines, the overall boiler-to-condenser pressure drop is divided across multiple nozzle–rotor pairs. Each stage has its own nozzle where a portion of the pressure drop occurs to produce a moderate velocity, followed by an impulse rotor that extracts work. This limits extreme velocities and losses while maintaining impulse characteristics in each stage.

Step-by-Step Solution:

Verification / Alternative check:
Rateau’s scheme is contrasted with Curtis (velocity compounding) where a single nozzle gives a large velocity drop followed by multiple moving rows to share velocity changes within one stage.

Why Other Options Are Wrong:

• Simple reaction turbine: Reaction involves pressure drop in moving blades, not impulse.
• Velocity compounded: That is Curtis staging, not Rateau.
• Pressure-velocity compounded: A hybrid method, not the classic Rateau approach.

Common Pitfalls:
Confusing the locus of pressure drop (nozzles vs blades) when distinguishing impulse from reaction forms.

Final Answer:
pressure compounded turbine