Use of correlation technique for estimating in-flight noise radiated by wing-mounted jet engines on a fuselage

Abstract

Turbulent boundary layer pressure fluctuations and noise radiated by jet engines form two major sources of pressure fluctuations on the exterior of many commercial jet fuselages. The expressions for correlations and mean square pressures of two statistically independent noise sources are derived. A method of decomposing the two pressure fields is illustrated using flight test measurements. In flight, the jet engine noise contribution is separated from the turbulent boundary layer wall pressure fluctuations at Mach 0·78, aft fuselage location, and Mach 0·60 forward fueslage location. The flight test measurements indicated that the turbulent boundary layer pressure fluctuations and the noise radiated by jet engines are of the same order of magnitude at Mach 0·78, 25 000 ft (7620 m) altitude at the aft fuselage location.