Abstract
In a high-speed forward flight of a helicopter, HSI (High Speed Impulsive) noise is known to be generated from the advancing blade tip. The noise is related to the existence of shock waves at blade surfaces and the region out of the blade tip. In this paper, the noise prediction methods associated with a CFD (Computational Fluid Dynamics) code and acoustic code are presented. CFD is suitable tool to capture shock waves and give good resolution of pressure distribution around rotor blade. Two types of wave equations; Kirchhoff equation and FW-H (Ffowcs Williams and Hawkings) equation are used to calculate sound propagation. For aeroacoustic code validation, a wind tunnel test was conducted in NAL low speed wind tunnel and sound pressure histories were obtained with 2.4m diameter 2-bladed rotor. Comparison between the wind tunnel test results and the numerical results shows good agreement.
