V/STOL Dynamics and Aeroelastic Rotor-Airframe Technology. Volume I. State-of-the-Art Review of V/STOL Rotor Technology

摘要

The aeroelastic phenomena associated with prop/rotor systems are discussed and classified. It is concluded that an acceptable technology exists in several areas, including wing/rotor divergence, whirl flutter, aeromechanical instability, and air and ground resonance. The technology is less successful in those areas where the flow through the rotor is significantly nonaxial, e.g., tilt-rotor transition regime and high-speed helicopter flight; also when forms of intermodal blade coupling exist due to finite deflections of the blades. It is believed that, in addition to collective deflections, finite cyclical deflections of the blades produce destabilizing coupling effects in some cases. Significantly large edgewise flow in combination with nonzero blade steady-state deflections is also seen to be destabilizing. A minimum-complexity methodology which may be expected to correlate with currently identified phenomena is defined. (Author)