Prediction of BVI Noise Radiation Variation due to HHC Using Advanced Prescribed Wake Methodology

Abstract

DLR’s comprehensive isolated rotor code S4 is validated with a variety of wind tunnel experimental data from the HART II test of 2001 (Bo105 hingeless Mach-scaled model rotor) at low speed with and without higher harmonic control (HHC) using 3/rev control frequency in descending flight, known to generate strong BVI. To evaluate noise radiation, a coupled S4 and an analytic far field prediction method based on an integral Ffowcs-Williams and Hawkings approach are conducted. Overall, the quality of elasto-mechanical computations, aerodynamic section loads prediction, simulation of the wake geometry and the noise radiation is predicted to a good accuracy, validating the approach of reduced order modeling.