Aerodynamic Effect Associated with Tunnel Length

Aerodynamic pressure is one of the important elements impacting the degradation of service performance of high-speed railways. Aerodynamic characteristics produced by high-speed train associated with tunnel length are studied using numerical method. The input parameters, which are adopted in simulation, are verified with the on-site monitoring obtained by other researchers. The characteristics of aerodynamic pressure and micro pressure wave associated with tunnel length are systematically explored. It can be found that, when tunnel length is increases from 200 to 1,000 m, the maximum peaks related to positive and negative pressure are respectively shifted from the position nearby tunnel exit and entrance to that of tunnel middle section. Before train tail leaves tunnel exit, the maximum peak-to-peak values increase and then decrease with the increase of tunnel length. After train tail leaves, the maximum peak-to-peak values decrease and then increase. The characteristics of the maximum positive peak of initial micro pressure wave at identical location associated with different tunnel lengths are negligible. And the relationships between maximum positive peak and the distance away from tunnel exit are similar for different tunnel lengths, which can be fitted by a power function.