Simulations and measurements of the flow and noise in hot supersonic jets

This paper describes a combined computational and experimental study of the noise of exhaust jets with operating conditions typical of high performance military aircraft engines. Baseline nozzles and nozzles with chevrons for noise reduction are simulated. The numerical simulations use a hybrid URANS/LES approach for the turbulence modeling. Structured multiblock grids are used to represent the complex nozzle geometries. The immersed boundary method is used to avoid the difficulty of creating body-conformal grids around the chev¬rons. Dual time-stepping is used to advance the solution in time and multigrid and implicit residual smoothing are used to accelerate the convergence of the sub-iterations. The acoustic field is determined by integration over an acoustic data surface based on solutions to the Ffowcs Williams-Hawkings equation. Both the near and far acoustic fields are determined. The companion experiments, whose measurements are used to assess the quality of the numerical simulations, are performed in an anechoic jet facility. The facility includes a forward flight stream and uses helium-air mixtures to simulate the effects of jet heating. Flow and noise measurements are described for both baseline and chevron nozzles. Comparisons are made between the numerical predictions and the Penn State measurements with additional measurements performed at NASA Glenn Research Center used to complement the Penn State data.