Numerical Investigation of 3-D Supersonic Jet Flows Using Large-Eddy Simulation

Abstract

The farfield noise generated by supersonic jets is investigated by a computational aeroacoustics methodology that couples 3-D large-eddy simulation (LES) near field data with the Ffowcs Williams-Hawkings method for farfield noise prediction. In order to accurately simulate jets at off-design supersonic conditions, we employ LES with characteristic filters for shock-capturing. This approach limits the dissipation of noise-producing turbulent fluctuations, and is suitable for incorporation into existing solvers. To further limit dissipation, a shock detector is used to determine shock locations and characteristic filters are applied locally. In this study, both perfectly-expanded and under-expanded unheated jets are investigated, with and without using characteristic filters. Comparisons with similar numerical and experimental data show reasonable agreement of the jet mean flow, turbulent statistics, and acoustics results. Preliminary grid-refinement shows improvement in these results.

Equilibrium Wall Model for Large Eddy Simulations of Jets for Aeroacoustics

“…21 Furthermore, specialized treatments have been incorporated into the code to reduce CFL timestep restrictions that are caused by the fine grid spacing near the centerline of cylindrical grids, 22,46 and shock capturing capabilities have been added for simulating supersonic jets at off-design conditions. 7 Lastly, a variety of boundary conditions are also available in the LES application. Those utilized here are a non-reflecting outflow boundary condition from Tam and Dong 47, 48 and a stress-free symmetry boundary condition.…”

“…In the past, many LES have been performed without simulating the nozzle geometry [4][5][6][7] or by using a RANS-based solver for the nozzle flow. [8][9][10][11] Reasonable results have been obtained, but greater accuracy is desired.…”

Petascale large eddy simulation of jet engine noise based on the truncated SPIKE algorithm

“…Although beyond the scope of this paper, this methodology has been extended to handle shock waves through the use of characteristic filters [11,45]. See [21] for a description of these methods used with the legacy transposition-based version of the LES application. Our SPIKE-based solver has similarly been extended to allow simulations of supersonic jets, and research on this topic is ongoing.…”

Analysis of Converging-Diverging Beveled Nozzle Jets Using Large Eddy Simulation with a Wall Model

“…High-fidelity large eddy simulation (LES), as part of a computational aeroacoustics (CAA) methodology, is a promising tool for studying the fundamental mechanisms of jet noise and for analyzing the impact of nozzle modifications on the farfield noise. 2 In the past, many LES have been performed without simulating the nozzle geometry [3][4][5][6] or by using a Reynolds-averaged Navier-Stokes (RANS)-based solver to determine the flow at the nozzle exit. 7-10 Reasonable results have been obtained but greater accuracy is desired for farfield acoustics predictions.…”

“…39,40 A shock-capturing method based on local application of a weighted essentially non-oscillatory (WENO) characteristic filter 41 has also been included for supersonic flows. 6,38 For jet aeroacoustics, cylindrical grids are used with an artificial coarsening treatment in the azimuthal direction to avoid CFL timestep restrictions from the fine spacing near the pole. 35,38,42 Furthermore, an approximate inflow turbulent boundary condition [43][44][45] provides turbulent boundary layers on the interior nozzle walls.…”