Which sequence correctly describes the Brayton cycle as applied in a gas turbine engine?

• A. The Brayton cycle consists of intake/compression, combustion, expansion in the turbine, and exhaust; air is compressed, fuel is burned, hot gas expands to produce work, then exhaust.
• B. Inlet, compression, expansion, exhaust.
• C. Intake, combustion, compression, expansion, exhaust.
• D. Exhaust, intake, compression, combustion.

Answer: (A)

Understanding how the Brayton cycle works in a gas turbine means following the flow of air and fuel and how energy is added and then converted to work. The air is first compressed to raise its pressure and temperature. Next, fuel is injected and burned in the combustor, adding energy to the gas while keeping pressure high. The hot, high-energy gas then expands through the turbine, doing work to turn the shaft (and also to drive the compressor). Finally, the spent gas is exhausted to the atmosphere.

This order—intake/compression, combustion, expansion in the turbine, exhaust—best describes how a Brayton cycle operates. If you omit the combustion step, there’s no energy addition to the gas. If combustion occurred before compression, or if the sequence rearranged the stages, it wouldn’t reflect the actual flow and energy exchange in a gas turbine.