Numerical Analysis of BVI Noise Reduction by Active Tab

The effect of active tab on rotor thrust, tip vortex, and noise is numerically analyzed in hover and forward flight conditions of helicopters. The active tab is originally devised for the reduction of BVI (blade-vortex interaction) noise by JAXA (Japan Aerospace Exploration Agency) and Kawada Industries, Inc. A 3D unsteady Euler CFD code and an acoustic code based on the FW-H formulation are applied. The grid generation is conducted in every time step of unsteady CFD calculation in order to simulate the motion of active tab. As a result, it becomes clear that active tabs with tab angle have a great possibility of controlling miss-distance at the BVI event enough to reduce BVI noise by changing rotor thrust.