Simulation of Noise Generation in the Near-Nozzle Region of a Chevron Nozzle Jet

This paper reports on the simulation of the near-nozzle region of a moderate Reynolds number cold jet flow exhaustingfrom achevron nozzle.Thechevron nozzleconsideredinthis studyisthe SMC001nozzleexperimentally studied by researchers at the NASA John H. Glenn Research Center. This nozzle design contains six symmetric chevrons that have a 5-deg penetration angle. The flow inside the chevron nozzle and the free jet flow outside are computed simultaneously by a high-order accurate, multiblock, large-eddy simulation code with overset grid capability.Theresolutionofthesimulationisabout100milliongridpoints.Themainemphasisofthesimulationisto capture the enhanced shear-layer mixing due to the chevrons and the consequent noise generation that occurs in the mixing layers of the jet within the first few diameters downstream of the nozzle exit. Details of the computational methodology are presented together with an analysis of the simulation results. The simulation data are compared with available experimental measurements of the flowfield and the noise spectrum in the sideline direction. Overall, thesimulationresultsareveryencouraginganddemonstratethefeasibilityofchevronnozzlejetcomputationsusing our simulation methodology. Nomenclature c