Results from a computational investigation into the noise reduction capabilities of chevron nozzles in hot jet flows are presented. The computational data is compared against experimental data captured from tests performed on the Small Hot Jet Acoustic Rig (SHJAR) at the NASA Glenn Research Center. The nozzles, part of the Short Metal Chevron (SMC) series, were comprised of two chevron versions (SMC003 and SMC010) as well as one reference, non-chevron, version (SMC000). The Lattice Boltzmann solver PowerFLOW® was used to capture time-accurate flow data with sound propagation to the far field accomplished using a Ffowcs-Williams and Hawkings (FW-H) acoustic analogy approach. Aerodynamically, the increase in core energy as well as the greater mixing of the shear layer was well-captured through simulation. Acoustically, a decrease in noise levels was realized as a result of the chevron tips across the range of Strouhal numbers analyzed. The simulation results were also able to discern the relatively small differences in noise from each nozzle configuration, identifying the unique spectral trends represented by each model. Close agreement with the experimental dataset was found. Further insight into the noise reduction mechanisms was achieved through a wavelet decomposition applied to the turbulent flow to separate the coherent flow motion, usually attributed to the hydrodynamic fluctuations, and the chaotic perturbations, which have a more dominant acoustic character.
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