Large scale model measurements of airframe noise using cross‐correlation techniques

Publisher Website
Google Scholar
Abstract
[Since jet aircraft are responsible for noise-pollution of the human environment], cross-correlation techniques were used to measure the sound radiated by wind/flap airfoil configurations in the NASA [National Aeronautics and Space Administration] Ames 40- by 80 ft wind tunnel using a 6.7-m semispan model with 3 deployed flaps. The sound from the flap side edges exceeds other airframe noise sources by > 10 dB, with the noise from the side edges of the leading flaps the strongest. The radiated sound is estimated using 2 formulas based on the standard aeroacoustic theory and 1 method using only the near and farfield cross correlation. The last method is essentially independent of such theory. The classic dipole angular distribution pattern is modified by wing diffraction effects to yield stronger radiation in the forward direction. The radiated intensity increases at slightly higher than the 5th power of the mean flow speed (Uo). The location of the flap track fairings has a substantial effect on the radiated intensity: placing the fairings at or near the lateral edges of the flaps substantially reduces the radiated noise.

This publication has 0 references indexed in Scilit: