Abstract: This definition takes the direction of the vorticity into account and can accelerate the transition from Reynolds-averaged Navier-Stokes (RANS) region to large-eddy-simulation(LES) region. An isolated jet with Mach number of 0.9 and Reynolds number of 1.1 million based on the nozzle diameter is simulated. The flow quantities and noise from two meshes are compared. The two meshes both provide reasonable results, but the results from the fine mesh are closer to the measurements. Beside noise from five integral surfaces of dense mesh are compared. It is proved that the numerical methods are competent to predict jet-noise. When the freestream Mach number increases to 0.2, the length of potential core increases and the turbulent kinetic energy (TKE) and the far-field noise decrease. The changes of far-field noise due to flight velocity by our simulations are similar to the measurements. This method can be extended to predict flight velocity effects on jet noise.