Application of Large-Eddy Simulations and Kirchhoff Method to Jet Noise Prediction

Abstract

The prediction of aerodynamic sound sources and transmission has been the object of new developments. Recent interest in jet acoustics has led to the implementation of highly accurate codes with appropriate inflow and outflow boundary conditions. Nonreflective boundary conditions, based on Thompson's (Thompson, K. W., Time Dependent Boundary Conditions for Hyperbolic Systems I, Journal of Computational Physics, Vol. 68, 1987, pp. 1-24) and Giles' (Giles, M., Non-Reflecting Boundary Conditions for Euler Equation Calculations,' AIAA Journal, Vol. 28, No. 12, 1990, pp. 2050-2058) approaches, are coupled with a 2-4 MacCormack interior scheme. The full time-dependent Navier-Stokes equations are solved in the two- or three-dimensional case. Subgrid scale modeling is provided by the second-order velocity structure-function model of Metais and Lesieur (Metais, O., and Lesieur, M., Spectral Large-Eddy Simulation of Isotropic and Stably Stratified Turbulence,' Journal of Fluid Mechanics, Vol. 239, 1992, pp. 157-194). Large-eddy simulations of the near field of jet flows can then be used to estimate the sound sources. After the sound sources have been predicted, a linear convective wave equation is used in the outside flow to address the sound transmission. An integral method based on a Kirchhoff surface integral is used to calculate the linear propagation of pressure waves in the far field. It is then possible to obtain the far-field pressure at observation positions at large distances. Results based on axisymmetric and fully three-dimensional near-field calculations of a supersonic jet are presented.