Modeling shock formation and propagation in high-performance jet aircraft noise

Abstract

Nonlinear propagation can play an important role in both time and frequency-domain features of far-field supersonic jet noise. Many aspects of nonlinear propagation, such as waveform steepening and greater-than-expected high-frequency spectral levels, have been previously predicted for select angles and engine conditions. This paper builds on previous successes and presents a comparison of nonlinear and linear predictions for the F-35B aircraft. Results are shown over a wide spatial and angular range and over varying engine power conditions, including showing evidence of nonlinear propagation in the forward direction at the highest engine conditions. In addition, specific features, such as individual shocks, are compared between numerically propagated and measured waveforms, highlighting the successes and deficiencies of current propagation models. Weather and multi-path interference effects are also addressed and corrected using an empirical model. [Work supported by USAFRL through ORISE. Distribution A: Approved for public release; distribution unlimited; Cleared 07/10/2017; JSF17-714.]