Lateral cutoff analysis of sonic boom using full-field simulation
Lateral cutoff analysis of sonic boom using full-field simulation
复制标题
使用全场模拟进行音爆横向截止分析
DOI：
10.1016/j.ast.2019.03.020
复制
发表时间：
2019
影响因子：
5.6
通讯作者：
Kojiro Suzuki
中科院分区：
文献类型：
--
作者：
Rei;Kojiro Suzuki
本文描述了世界上第一次成功模拟了由于大气温度随高度变化而引起的远离飞行路径的音爆横向切断现象。本文采用带重力项的三维欧拉方程的全场模拟方法，对轴对称抛物面周围的流场进行了分析。在整个区域内，包括超音速体周围的近场和到达地面的远场，构建了一个适应解决方案的结构化网格，使网格线与前后激波表面对齐。假设飞行速度为1.2马赫，高度为10公里，计算域范围为距对称轴30公里。计算结果表明，在横向截止点以外的阴影区，倏逝波呈指数衰减，变为渐进式舍入波形。波形转换特性与飞行试验中观察到的结果吻合良好。因此，在包括侧向截止波和消失波在内的全音爆噪声范围内，全场模拟被认为是研究音爆强度的一种很有前途的方法。此外，计算结果表明，除地面附近外，音爆聚焦发生在地面以上，并且从三维激波面探测到的横向截止曲线上的聚焦强度随高度增加而增加。射线追迹分析的结果与模拟结果的合理性相吻合，向下凸的散度与横向截止曲线吻合较好。在阴影区，指数衰减幅度随海拔高度的增加而增大，压力上升迅速下降的侧向距离随海拔高度的增加而缩短。
This paper describes the world's first successful simulation for lateral cutoff phenomena of sonic boom far from the flight path due to variation in atmospheric temperature with altitude. A flow field around an axi-symmetric paraboloid has been analyzed by the full-field simulation method that solves the three-dimensional Euler equations with a gravity term to create a horizontally stratified atmosphere. A solution-adapted structured grid is constructed to align the grid lines with the front and rear shock-wave surfaces in the entire domain, including the near field around a supersonic body and far field reaching the ground beyond lateral cutoff. The flight is assumed to have a speed of Mach 1.2 at an altitude of 10 km, and the computational domain ranges over a distance of 30 km from the axis of symmetry. The computational results show that the evanescent wave in the shadow zone beyond lateral cutoff decays exponentially and changes into a progressive rounding waveform. The characteristics of the waveform transition are in good agreement with those observed in the flight tests. Therefore, the full-field simulation is recognized as a promising approach for investigating sonic boom strength in the full extent of sonic boom noise, including lateral cutoff and evanescent waves. Moreover, the computational results clarify that sonic boom focusing occurs above the ground, except for the vicinity of the ground, and the focusing strength along the lateral cutoff curve detected from the three-dimensional shock-wave surface increases with altitude. The results of ray tracing analysis collaborate the reasonability of the simulation results, and the caustic of downward convex agrees well with the lateral cutoff curve. In the shadow zone, the magnitude of exponential decay increases with altitude, and the lateral distance where the pressure rise decreases rapidly shortens with altitude.