Engine Noise Source Placement for Shielding Calculation

Abstract

Shielding the fan sound is a key element to further reduce aircraft noise immission of future aircraft designs. In recent studies the engine is represented as a single point source within scientific aircraft noise prediction tools, which can be a good approximation. In most low noise concept studies the engine is mounted above the wing or above the fuselage. The attenuation depends on the engine chordwise position due to the fact that either the fan forward noise or the fan aft noise is significantly shielded by the wing. The investigated simulation approach models the engine noise shielding more realistic by splitting the engine noise source into two noise sources. Herein one noise source is placed at the engine inlet position and radiates the fan forward noise, while the second one is placed at the nozzle exit position and radiates the fan aft noise. Depending on the relative position of the noise source to the aircraft surface, the results of attenuation due to shielding can be improved. This study investigates the differences in the results of splitting approach compared to a single point source approach.