Numerical simulation of the noise from a subsonic jet in static and flight conditions

In this study, the noise from a subsonic cold jet with Mach number 0.9 in static and flight conditions is simulated with a high order spectral difference solver. The Mach number of the ambient air is set to be 0, 0.1 and 0.2 respectively to study the effect of forward flight on jet noise. The Large Eddy Simulation method is used to simulate the turbulence, and the Wall-Adapting Local Eddy-Viscosity (WALE) model is utilized to account for the unresolved dynamics on the solution. To maintain the ambient flow velocity to the fixed value, the Perfectly Matched Layer non-reflective boundary condition is applied to the left boundary region outside the nozzle. To speed up the simulation, the multi-time-step method based on Adam-Bashforth scheme is used for time marching. The mean flow results are presented and compared with the experimental data of static jet by other researchers. The effect of flight velocity on the mean flow velocity and Reynolds stresses is analyzed. The far field noise is obtained by the Ffowcs Williams-Hawkings integration method. The noise spectra with and without forward flight velocity at different observer angles are compared. It is found that the forward flight reduces the jet noise both in upstream and downstream directions, and the noise reduction increases with the forward flight velocity.