CEAS-ASC highlights 2006 (edited by Stephane Caro): 5.1. Analysis of tail rotor noise reduction benefits using HeliNOVI aeroacoustic main/tail rotor test and post-test prediction results

Abstract

The EU HeliNOVI project was designed to improve the understanding of tail rotor (TR) noise reduction and vibration reduction technology by means of a comprehensive investigation of main rotor (MR)/TR interaction noise and rotor induced vibrations through both theory and experiment. Several TR noise reduction techniques were investigated both through wind tunnel testing and through simulations. The analysis of the TR noise reduction benefits from test and simulation results show that besides a reduction of rotor tip speed, the most efficient tail rotor noise reduction concept consists in changing the tail rotor sense of rotation from ‘advancing side down—ASD’ to ‘advancing side up—ASU’. The reduction of the overall noise in ASU TR mode is the consequence of reducing the TR loading noise which in turn is beneficial for the avoidance of BVI on the advancing side. In addition, the noise reduction for the tested change in TR position is mainly due to increasing the advancing blade distance to the observers rather than changing TR aerodynamic behavior.