Study of the Characteristics of Noise Radiation from Rectangular Nozzles and Its Influencing Parameters

Rectangular nozzles have gradually received attention in the design of military aircraft due to thrust vector control and stealth performance, and for civil aviation, they can also improve aircraft safety, based on this and for the current needs of integrated aircraft/engine design, this paper adopts a hybrid LES/PDS computational method for the rectangular nozzle with rectangular beveled nozzles of different bevel angles. The LES is used to obtain the turbulence structure in the nonconstant flow field of the jet, combined with the PDS technique based on the FW-H equation, to extract the noise source information of the rectangular nozzle jet, to obtain the spectral characteristics and directivity of the noise, and then to study the effect of different bevel angles on the jet noise. The results show that: the effect of bevel angles on the jet velocity of the small aspect ratio rectangular nozzle is small, compared with the benchmark rectangular nozzle, the length of the jet core of the rectangular bevel nozzle is slightly increased, and the distribution of the jet vortex structure and the root-meansquare (RMS) of the pressure pulsation value shows obvious asymmetry; in the XY plane, the OASPL of the jet noise of the rectangular bevel nozzle is mainly increased in the high-frequency range, and slightly decreased in the low-frequency range compared with that of the benchmark rectangular nozzle. Due to the bevel angle, the flow field is deflected, resulting in a certain asymmetry in the OASPL.