Toward a Unified Aerodynamic Model for Use in Rotor Blade Stability Analyses

This paper presents a modification of the ONERA dynamic-stall, lift model. This modification includes the pitch-plunge distinction, the unsteady free-stream, large angles of attack, and reversed flow. Numerical applications to a flapping rotor show that the new model is stable, in contrast to the original ONERA model which can become unstable. The new model is also more consistent than the old one in that it reduces to Greenberg theory for small angles of attack and further reduces to Theodorsen theory for steady free stream.