Researchers accurately simulate noise created by supersonic jets

While numerous models have been developed for predicting the noise generated by supersonic jets, few adequately address jets at Mach 3 or greater since these involve nonlinear acoustic propagation and complex configurations. In the new paper, the authors investigate three components of noise production in such jets: turbulent mixing, shock-associated and the Mach wave radiation.

Through a collaboration between the French aerospace laboratory ONERA and École Centrale de Lyon, Langenais et al. simulated a hot supersonic jet at Mach 3.1 using a turbulence tripping method along with a two-way coupling of unstructured flow and acoustic solvers. This approach uses the Navier-Stokes equations for flow computation, as well as the full Euler equations for calculating nonlinear acoustic propagation.

Their simulated aerodynamic near field and acoustic far field results agree well with the available experimental data. Their model successfully reproduced the shear layer with the appropriate spread rate, velocity fluctuations and turbulence spectra, and their calculated far field acoustic levels are within one-decibel of the experimental data for most observation angles.

The results from this study support the current models, which describe noise created by supersonic jets as primarily generated by two mechanisms—Mach wave radiation downstream and broadband shock-associated noise upstream. According to Langenais, this work provides numerical tools that can be used for the design of future space launchers and launch pads.

“We are now able to finely reproduce a wide range of physical phenomena over a large domain, within a single global simulation,” said Langenais. “The proposed numerical methodology is quite mature, and I hope it could be applied to real-scale problems in the next few years.”

Source: “Accurate simulation of the noise generated by a hot supersonic jet including turbulence tripping and nonlinear acoustic propagation,” by Adrien Langenais, François Vuillot, Julien Troyes, and Christophe Bailly, Physics of Fluids (2019). The article can be accessed at https://doi.org/10.1063/1.5050905 .