Rotor Dynamic Inflow Derivatives and Time Constants from Various Inflow Models

摘要

A linear, unsteady theory is developed that related transient rotor loads (thrust, roll moment, and pitch moment) to the overall transient response of the rotor induced-inflow field. The relationships are derived from an unsteady, actuator-disc theory; and some are obtained in closed form. The theory is used to determine the effects of lift distribution and shaft angle-of-attack on the said relationships. Also, two different assumptions are used in the unsteady calculations, finally, a prescribed wake analysis is used to validate the actuator-disc theory for normal flight conditions. The results reveal both the strengths and weaknesses of previous formulations and reveal areas in which further study is needed. The most significant result is an analytic, three-degree-of-freedom inflow model that is shown to be accurate for use in the dynamic analysis of rotors. (Author)