A NEW AERODYNAMICACOUSTIC COMPUTATION CHAIN FOR BVI NOISE PREDICTION IN UNSTEADY FLIGHT CONDITIONS

摘要

Although the problem of rotorcraft noise in unsteady flight conditions has recently been addressed, most of the corresponding studies focused on thickness and non impulsive loading noise. Because of the difficulties to predict the rotor wake and aerodynamics in maneuvers, the prediction of Blade Vortex Interaction noise for non stationary flight conditions has remained untackled until 2004. A new unsteady Blade Vortex Interaction aerodynamic & acoustic prediction chain has been developed to examine this issue. The paper describes this new computational tool. Applications to a low noise flight procedure and a transient maneuver demonstrates its capabilities. For each application a thorough analysis of the noise directivity and levels is conducted. The wake evolution is also considered in order to get a better understanding of the unsteady phenomena at stake.