分 层 大 气 湍 流 场 对 远 场 声 爆 传 播 的 影 响

It is of significance to study the effect of atmospheric turbulence on sonic boom for the design of next-generation low-boom supersonic commercial aircraft. The atmosphere turbulence in the real world will distort the waveform and change the sound energy distribution on the spectrum domain，when the sonic boom is propagated from the cruising altitude to the ground. In this paper，a modified Heterogeneous One-Way Approximation for the Resolution of Diffraction （HOWARD） equation is developed to study the effects of the stratified atmosphere turbulence on sonic boom waveforms，taking the N-type wave of a Tu-144-like aircraft and the low-boom waveform designed based on the JSGD sonic boom minimization theory as examples. First，a method for simulating sonic boom propagation through the atmospheric boundary layer is introduced，which includes the modified HOWARD equation together with the numerical solving strategy and the modeling method for stratified atmospheric turbulence. The above method is validated by comparing the predictions with the flight test data of LBM and NWM in the JAXA D-SEND project. Comparisons of predictions by the above method and the KZK equation are also carried out. Second，the method proposed is applied to investigate the propagation of N-type and low-boom waves through an atmospheric turbulence. The statistics of noises and the peak overpressure for the observable waveforms on the ground show that the probability of increasing noises（ASEL and PLdB）due to atmosphere turbulence is lower，but peak overpressure is highly possible to increase due to atmosphere turbulence. Finally，the method is also applied to study the effect of intensity of atmosphere turbulence on sonic boom by changing three parameters for generating turbulence. The enhancement of atmosphere turbulence described by the wind fluctuation and the integral scale has great influence on the perceived level of the N-type and low-boom waves. With the increase of turbulence intensity，the average values of the decibel become lower，while the maximum values of the decibel become greater. Therefore，it is necessary to evaluate effects of atmosphere turbulence on sonic boom in the design of low-boom supersonic commercial aircraft.