Simulation of Noise Generation in 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 How exhausting from a chevron nozzle. The chevron nozzle considered in this study is the SMC001 nozzle experimentally studied by researchers at the NASA John H. Glenn Research Center. This nozzle design contains six symmetric chevrons that haw a 5-deg penetration angled The How 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. The resolution of the simulation is about 100 million grid points. The main emphasis of the simulation is to 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, the simulation results are very encouraging and demonstrate the feasibility of chevron nozzle jet computations using our simulation methodology.