Flight effects on fan noise with static and wind-tunnel comparisons

Abstract

A flight test program utilizing a JT15D 1 turbofan engine has been conducted with the objective of studying flight effects on fan noise and evaluating the simulation effectiveness of both a wind tunnel and a static test configuration incorporating an inlet control device (ICD) In conjunction with synchronized laser radar tracking and meteorological profile information, data obtained from a linear array of ground microphones were narrowband analyzed and ensemble averaged to yield highly accurate far field flight acoustic results Utilizing appropriate corrections, flight, wind tunnel, and static acoustic data were normalized to a static equivalent, 100 ft radius, lossless reference condition Data comparisons showed that both the static test with ICD and wind tunnel were generally very effective in simulating flight blade passage frequency (BPF) noise levels However, differences were observed in broadband noise levels and in the details of the multiple pure tone harmonics. © 1984 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.