列车突人隧道时，会产生一系列气动效应。引起车厢内部压力变化，降低列车乘坐的舒适度。同时，还会在隧道出口形成噪声污染，在隧道口修筑缓冲结构是解决这一问题的有效措施。本文通过实验，对瞬变压力以及压力变化率与列车车速之间的关系进行了研究，并对缓冲结构的长度与降低瞬变压力的效果进行了分析比较，确定了相对最优的缓冲结构长度。

When high-speed train going through tunncl,a series of aerodynamics effect was created, including pressure variation in carriage and noises at tunnel exit, which are harm to passengers and environment. Building tunnel hood is efficient method #or solving these problems. In this paper, with model experiment, the function between impulsive wave and pressure grads and train speed were analyzed, the length effect of tunnel hood is compared, the relatively optimum tunnel hood length was ford.