Brayton Cycle - Gas Turbine Efficiency
Ideal Brayton-cycle thermal efficiency given pressure ratio and specific-heat ratio - the air-standard LM2500/MGT baseline.
Ideal η
56.2%
Formula, assumptions, and limits
$$\eta_{Brayton} = 1 - \frac{1}{r_p^{(k-1)/k}}$$
Real gas turbines deliver 36–42 % thermal η due to component inefficiencies. Add intercooling and reheat for improved efficiency; combined with a bottoming Rankine for 55 %+ in combined cycle.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $r_p$ | Compressor pressure ratio | - | engine spec |
| $k$ | Specific-heat ratio | - | air ≈ 1.4 |
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