Is power going into the turbine to oscillate the airfoils? If so, have you subtracted this power from the turbine output?

1. Achieving >59% efficiency refers to thermal efficiency, i.e., how much of the chemical energy in fuel is converted to useful work.

2. Modern combined-cycle gas turbines (Siemens SGT-800 or GE’s H-class) routinely exceed 60% efficiency in lab conditions. But this is still below 100%, meaning no violation of the first law of thermodynamics.

3. Betz’s Limit: Only for Wind Turbines in Steady Flows

Betz’s limit (59.3%) is a theoretical cap on the maximum efficiency of a wind turbine in extracting power from the kinetic energy of wind in steady, 1D, incompressible, inviscid flow.

• It does not apply to: Combustion-based turbines (gas, steam) Systems with unsteady, compressible, or turbulent flows Internal flows in machinery like jet engines or turbojets

Betz’s limit is irrelevant to combustion turbines or most unsteady flow regimes.