How is the gas path through a gas turbine described?

• A. Air bypasses the compressor and goes directly to the combustor.
• B. Air enters the combustor before the compressor.
• C. Exhaust gases cool the inlet air.
• D. Air enters the compressor, passes to the combustor, expands through the turbines to produce shaft power, then exits via the exhaust.

Answer: (D)

The gas path is the sequence of stages the working fluid follows inside a gas turbine: air is drawn in, compressed, combusted with fuel, the hot gases expand through turbines to drive the shaft, and then exit as exhaust. This flow exactly describes how the turbine produces shaft power: air enters the compressor to be pressurized, moves on to the combustor where fuel is burned, the high-energy gases then expand through the turbines to produce mechanical power, and finally leave through the exhaust. The other descriptions don’t fit this typical sequence: bypassing the compressor skips the essential compression step; combusting before compression would not allow proper pressure for efficient burning and turbine work; exhaust cooling of inlet air isn’t how the standard gas-path flow is defined.