Linear stability analyses and large eddy simulations for acoustic wave generation mechanism of a transitional supersonic jet

Abstract

The flow fluctuation and acoustic waves generated in a transitional supersonic jet are investigated by a linear stability analysis (LSA) and a large-eddy simulation (LES). Using the LSA code developed here and the LES results reported previously, the development of an instability wave and the transition behavior are discussed. As predicted by the LSA code, helical modes are more unstable than axisymmetric modes in LES results. The LES results show that the fluctuation of the helical mode leads to the transition, but sound generation from the transition is much weaker than that from a subsonic transitional jet investigated in the previous studies.