亚声速热射流声源模型的应用

Abstract

The noise generation mechanisms associated with instability waves in the heated subsonic transitional jet are studied, which are compared with its cold counterpart. The spatial evolution of instability waves is obtained by solving linear parabolized stability equations (LPSE) based on the time-averaged flow field of the large eddy simulation (LES). Then, the linear and nonlinear models for jet noise are built based on the LPSE solutions, coupled with the acoustic analogy. The LPSE results show that heating increases the spatial-growth rate and leads to earlier saturation. For high-frequency components, the sound pressure levels (SPL) are raised by heating as shown in the linear model. In general, compared with that for the cold jet, the gap of SPL between the linear model and the LES is reduced for the heated jet, which indicates that the linear mechanism plays a more important role in the hot jet. For a cold subsonic jet, previous studies have shown that the nonlinear model is able to raise acoustic efficiency. Here, it is found that the gap of SPL between the nonlinear model and the LES could be further decreased in the hot jet, and the thermodynamic sound source terms play a bigger role.