Predicting broadband rotor noise under turbulence ingestions

An efficient model is developed to predict the turbulence-ingesting rotor noise. The rotor aerodynamic variables are modeled by the blade element momentum theory, and the blade surface is discretized into various strips to compute the broadband noise generation, for which the Amiet's model of turbulence-flat plate interaction is implemented. The Doppler correction is applied by considering the effect of the relative movement between the blade and background flow. The axial freestream condition is considered. To verify the prediction accuracy, we compare the prediction results with the anechoic wind tunnel measurements. The grid-generated isotropic turbulence is employed as input, and the broadband noise at various observers is compared. Good agreements are obtained. A parametric study is then conducted to investigate the effects of rotation rate, freestream velocity, and turbulence properties on broadband noise caused by turbulence ingestion. The dependence of these influential parameters on noise level is analyzed.