How many Curtis stages are contained in the...

How many Curtis stages are contained in the turbine shown in the illustration? Illustration SE-0003

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🔍 Key Concepts

• Curtis stage in an impulse turbine is defined by a single large pressure drop across a set of nozzles, followed by one or more rows of moving blades with constant pressure through those blade rows. • On the diagram, the steam absolute pressure curve shows where pressure actually drops, while the steam absolute velocity curve shows how the velocity is divided among the blade rows. • The illustration also labels nozzles, fixed blades, and moving blades; how these are grouped tells you how many Curtis stages are present.

💭 Think About

• Look at the steam absolute pressure graph at the top: how many distinct pressure drops do you see between the inlet and outlet of the turbine shown? • Each Curtis stage begins with a nozzle set where pressure falls sharply; after that, pressure should be nearly constant while steam passes through multiple moving and fixed blade rows. How many such nozzle-and-pressure-drop groups are in this cutaway? • Ask yourself: is a Curtis stage counted by the number of moving-blade rows, or by the number of times the steam has a major pressure drop across nozzles? How does that affect your choice among the options?

✅ Before You Answer

• Before choosing, count the separate nozzle groups actually shown in the lower turbine section, not just the number of blade rows. • Verify on the pressure diagram how many major pressure drops occur that line up with those nozzle groups. • Confirm that a Curtis (velocity-compounded) stage is identified by one pressure drop in nozzles with velocity compounding in subsequent blades, not by the total number of rows of moving blades alone.

🔍 Key Concepts

💭 Think About

✅ Before You Answer