🔍 Key Concepts

• Single-shaft vs. split-shaft (free turbine) gas turbines and how power turbine speed is controlled • Mechanical connection between compressor, turbine, and output shaft in a single-shaft arrangement • Role of reduction gears in changing speed vs. changing the relationship (direct vs. inverse)

💭 Think About

• In a single-shaft gas turbine, ask yourself: are the compressor and power output on the same shaft or on separate shafts? What does that imply about how their speeds relate? • Think about what reduction gears actually do: do they reverse the relationship (make it inverse), or simply change the ratio while keeping the direction of the relationship the same? • Compare this with a free turbine (split-shaft) design: in which design can the power output speed vary independently of compressor speed?

✅ Before You Answer

• Verify how a single-shaft, cold-end drive gas turbine is constructed: is there one continuous shaft from compressor to power output? • Confirm whether independent speed variation between compressor and power output requires a separate (free) turbine on its own shaft. • Check your understanding of direct vs. inverse mechanical relationships through gears: does a reduction gear normally keep speeds linked (though different), or make one go up when the other goes down?