基于气动声学理论的喇叭型隧道缓冲结构优化

为了有效缓解隧道空气动力学效应导致的声爆现象，基于气动声学理论，对带喇叭型缓冲结构的隧道入口参数进行了优化。采用Green函数求解气动声学FW-H方程，得到了隧道内初始压缩波波前的压力和压力梯度，并根据喇叭型缓冲结构的特点，对缓冲结构的横断面积函数、入口断面积和长度进行优化设计。优化结果显示:隧道内压力梯度峰值随缓冲结构长度的增大而逐渐减小；考虑经济性因素，喇叭型缓冲结构的优化长度为10倍的隧道半径，优化缓冲结构的横断面积函数、入口断面积后，可使压力曲线成线性变化，压力梯度峰值降低63.9%，可避免入口处压力突变，缓解了声爆等微压波现象。 

Optimizing Flared Hood of Tunnel Based on Aeroacoustics

In order to alleviate the sonic boom caused by aerodynamic effect in a tunnel, design parameters of the tunnel entrance with a flared hood were optimized. By solving the FW-H equation with Green's function, the pressure and pressure gradient of the initial compression wavefront in the tunnel were obtained. Then, the cross-sectional area function, the entrance cross-section area and the length of the flared hood were optimized according to the characteristics of the flared hood. The optimization results show that the peak pressure gradient decreases with an increase in the length of the tunnel hood. Considering economic factors, the optimal length of the flared hood is 10 times the tunnel diameter. With the optimized cross sectional area function and entrance area of the tunnel hood, the curves of pressure present a linear growth, and the peak pressure gradient is reduced by 63.9%. Consequently, the abrupt change of pressure at the tunnel entrance is avoided, and the phenomenon of the micro pressure wave such as sonic boom can be relieved effectively.