Pressure compounding (Rateau staging) in impulse turbines In pressure compounding of an impulse turbine, is the total pressure drop divided among multiple nozzle rings rather than occurring entirely in the first nozzle ring?

Introduction / Context:
Impulse turbines can be compounded to manage speed and efficiency. Understanding the difference between velocity compounding (Curtis) and pressure compounding (Rateau) helps in matching turbine design to pressure ratio and power requirements.

Given Data / Assumptions:

• Impulse turbine architecture (no pressure drop ideally in moving blades).
• Multiple stages of stationary nozzles and rotors.
• Goal: reduce jet velocity per stage and achieve practical rotor speed.

Concept / Approach:

In pressure compounding (Rateau), the total pressure drop from boiler to exhaust is split across several nozzle–rotor stages. Each nozzle ring takes only a portion of the pressure drop, creating a moderate jet velocity for its rotor, thereby reducing the required blade speed. This contrasts with Curtis (velocity) compounding, where most pressure drop occurs in a single nozzle set and multiple moving rows extract kinetic energy.

Step-by-Step Solution:

Verification / Alternative check:

Stage-by-stage enthalpy–pressure diagrams and measured velocities show reduced jet speeds compared to a single-stage impulse design, validating the principle.

Why Other Options Are Wrong:

Curtis stages are velocity-compounded, not pressure-compounded.Impulse rotors ideally have negligible pressure drop; saying pressure drops only in moving blades is incorrect.

Common Pitfalls:

Confusing “compounding” types. Remember: Rateau = pressure compounding (many nozzle rings); Curtis = velocity compounding (many moving rows after one big nozzle drop).

Final Answer:

Agree