Numerical Investigations of Parallel BVI Noise with Split Tip Vortices

To reduce the helicopter blade-vortex interaction(BVI) noise, various efforts have been pursued for 20 years or so. One of the passive methods is using a split tip vortex. There are several studies on such a kind of concept using the vortex wake model. In this study, two dimensional CFD model is used to investigate the detailed flow dynamics for parallel interaction of a blade and split vortices. High-order compact scheme with optimized coefficients is employed for the simulation since it exhibit little numerical dissipation and dispersion error for vorticity and acoustic waves. From the simulation results importance of miss-distances between blade and vortices is emphasized. It is also shown that the BVI with split-vortices can be decomposed into individual interactions of each vortex with the miss-distance modified by co-rotation of the vortices.