Simulation and analysis for sonic boom on several benchmark cases

Accurate prediction and simulation of sonic boom are of significant importance to the design of supersonic aircraft. The mainstream research approach for sonic boom prediction consists of two steps. First, the distribution of over-pressure in near field is calculated with wind tunnels or CFD, then the over-pressure is propagated to the ground by the modified linear wave equations or nonlinear Burger's equations. Using several benchmark cases, the accuracy of typical near field sonic boom prediction method is verified. For nearfield over-pressure prediction, the influence of semi-sphere radius, spatial discretization schemes and viscosity are investigated. For far-field sonic boom prediction, based on the nearfield over-pressure of LM1021 configuration, the influence of different discretization and with/without viscosity in nearfield simulation to the far-field signature prediction have been investigated. The results show that it is necessary to use semi-sphere to deal with the sharp tip in supersonic model. Using semi-sphere with reasonable radius will help guarantee the accuracy of nearfield prediction. The scale of modification will influence the shape of shock wave and the peak values of shock wave and expansion waves. For nearfield sonic boom prediction, the entropy consistent scheme performs better than the Roe and Central schemes. However, the discretization scheme has little influence on the key indicators of the far-field propagated signatures (mainly peak value of over-pressure and raise time). The effect of viscosity in the nearfield prediction is small, however, the slight difference caused by the viscosity in the nearfield domain would cause obvious difference in the far-field domain.