RESPONSE OF A NONROTATING ROTOR BLADE TO LATERAL TURBULENCE .1. THEORY

Theoretical simulation of a rotor blade in forward flight by a nonrota ting rotor blade in a longitudinal sinusoidal pulsating now, and the n apping and torsional response of a flexible nonrotating rotor blade mo del 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 ha ve 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 f or both nap and torsional variance responses between the linear ONERA and classical aerodynamic models is reasonably good. The effects of ra ndom parametric excitation (when the longitudinal now includes a turbu lence 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.