Numerical simulation of jet noise from different jet nozzle geometries

Abstract

This paper describes the numerical simulation of flow-induced noise from jets with different nozzle geometries. The nozzles considered include axisymmetric and nonaxisymmetric nozzles, such as circular and rectangular. Also the study is extended to examine the differences between noise radiated from nozzles with planar exists and those with nonplanar exist, such as beveled nozzles. The detached-eddy simulation (DES) approach is used to simulate both the jet nozzle internal and external flows as well as the jet plume. This methodology allows the turbulence model to transition from an unsteady Reynolds averaged Navier-Stokes (URANS) method for attached boundary layers to a large-eddy simulation (LES) in separated regions. Thus, it is ideally suited to jet flow simulations when the nozzle is included. Both cylindrical polar and Cartesian coordinate systems are used as the basis for grid generation. The one equation Spalart-Allmaras turbulence model is used to describe the evo! lution of the turbulent eddy viscosity. Dispersion relation preserving algorithms are used for spatial discretization and an explicit 4th order Runge-Kutta scheme is used for time marching. The far-field sound is evaluated using the Ffowcs Williams-Hawkings permeable surface acoustic analogy. This permits the noise to be predicted at large distances from the jet based on fluctuations in the jet’s near field. This provides a good compromise between numerical accuracy and computational cost. The results are compared with experimental data for both unheated and heated jet cases.