Response of a Nonrotating Rotor Blade to Lateral Turbulence Part I: Theory

Abstract

Theoretical simulation of a rotor blade in forward flight by a nonrotating rotor blade in a longitudinal sinusoidal pulsating flow, and the flapping and torsional response of a flexible nonrotating rotor blade model to lateral turbulence have been investigated. A direct time domain computational method using a modified linear ONERA aerodynamic model and a time-frequency approach using the classical aerodynamic model have been proposed. A theoretical lift comparison between the classical aerodynamic theory and the modified ONERA model is made. The numerical calculations indicate that the statistically quantitative agreement for both flap and torsional variance responses between the linear ONERA and classical aerodynamic models is reasonably good. The effects of random parametric excitation (when the longitudinal flow includes a turbulence component) and parameter variations are discussed. The numerical results are used to confirm the validity of a new experimental method presented as a companion paper, Part II. a.c b, b C, Cm dFM, dMv dM0 E e