Prediction of Cavity Noise Based on IDDES and NLAS Methods

The prediction of cavity noise is one of the key technologies for the internal weapon bay of high-speed aircraft. Numerical simulations were conducted on open cavity with a length to depth ratio of 5 at different Mach numbers using the improved delayed detached-eddy simulation (IDDES) method and the non-linear acoustics solver (NLAS) method for solving the non-linear disturbance equations. The calculation results show that both methods can effectively predict the overall sound pressure level of wall under subsonic flow conditions; Under the condition of supersonic inflow, the sound pressure level of each mode obtained by the NLAS method is in good agreement with the experimental results, while the results obtained by the IDDES method are relatively small. The frequency of each mode obtained by the two methods is in good agreement with the experimental results. The reason for the difference is that when the IDDES method transitions from RANS to LES, the turbulent kinetic energy dissipation is relatively large, while the NLAS method can simulate the noise propagation process accurately due to its low dissipation. The comparison of the computing resources required by the two methods shows that the IDDES method requires fine mesh and a small time step, which requires more computing resources; The NLAS method uses the method of artificially synthesized turbulence to simulate small-scale fluctuations, which can select rough mesh and large time step to save computing resources.