A simple-source model of military jet aircraft noise.

Several inverse methods exist to analyze and characterize the turbulence‐induced aeroacoustic sources from military jet aircraft. The current study’s purpose is to explore an alternative approach, using a semiempirical equivalent simple source model. The model originated as a single point source located above a hard plane such that the locations of destructive interference from its mirror image matched the measured interference nulls. This appears to provide useful information about the location of the dominant noise source region from the jet. The model has developed into a superposition of Rayleigh‐distributed line arrays of uncorrelated and correlated monopoles. The model is tested on an extensive set of acoustic data taken on an F‐22 Raptor. Although the model’s line source characteristics are developed using data from only one measurement plane, it is able to accurately reproduce the radiation at other measurement planes. This equivalent line source matches the current prevailing theory that the sideline radiation is largely due to uncorrelated noise whereas the correlated sources dominate downstream. In addition, the semiempirical, simple‐source model results corroborate the theory that the peak source location moves upstream with increasing frequency and lower engine conditions.

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