Numerical Simulation for sonic boom propagation through an Inhomogeneous atmosphere with winds

Abstract

Noise annoyance due to sonic boom is one of the serious problems for development of next-generation supersonic transport. To decrease this sonic boom noise, the design and analysis techniques are developed at Japan Aerospace eXploration Agency (JAXA). To predict the sonic boom on the ground accurately, we have developed a numerical code (Xnoise) using the augmented Burgers equation combined with the ray tracing. In this method, effects of nonlinearity, geometrical spreading, inhomogeneity of atmosphere, thermoviscous attenuation, molecular vibration relaxation and winds are taken into account. This method gives an estimation of the rise times of ground signatures without resorting to the weak shock theory and area balancing techniques. The nonlinear term is evaluated by the finite difference scheme in this method. In ray-path calculation, an explicit updating methodology is adopted. The augmented Burgers equation is numerically solved by using the operator split method entirely in the time domain. As for the effects of nonlinearity, geometrical spreading, and atmospheric inhomogeneity, the result obtained with the augmented Burgers equation agrees well with that obtained with the waveform parameter method (Thomas' method). For the effects of absorption and dispersion, the calculation based on the augmented Burgers equation is verified by comparing with a detailed one-dimensional CFD analysis. Moreover, we show calculations which account the effect of winds on the propagation of a sonic boom. The validation of model is a future work.