Sound Emission from the Helical Mode of Supersonic Jet

Abstract

A numerical simulation of sound emission from the helical mode of an under-expanded supersonic jet has been implemented. This simulation is still a challenging problem, since aeroacoustic noise from a supersonic jet is closely associated with the three-dimensional, complicated flow structure including various scale vortices, shock cell structure, and a turbulent mixing layer, which is very sensitive to the accuracy of computation. In the present study, an accurate numerical code is used; that is, the fourth order WENO scheme in spatial discretization to reduce numerical dissipation, and the third order Runge-Kutta method in time integration. The computed sound frequency of screech tone and the instability mode agree with the experimental data measured at our laboratory. The mechanism of sound generation along with the flow field is explained in this paper.