Moving model test on the aerodynamic pressure of bilateral inverted-L-shaped noise barriers caused by high-speed trains

Abstract

With the increasing speed of high-speed trains, the aerodynamic impact of trains on high-speed railway noise barriers has gradually become a focus of attention. Compared with traditional vertical noise barriers, the bilateral inverted-L-shaped noise barrier (BILSNB) has better noise insulation performance, but its aerodynamic impact may be more prominent. In this research, a moving train-BILSNB test system with a scale ratio of 1:16.8 is established, and the influence of train speed and the opening width on the aerodynamic pressure is analysed and discussed. The large eddy simulation is applied to investigate the influence mechanism of flow field on the aerodynamic performance of the BILSNB. The main conclusions are as follows. (1) The pressure amplitude caused by the passing of the train head is 36.67% greater than that generated by the passing of the train tail on average. (2) The maximum pressure of the BILSNB appears at the bottom area. When the height of the measuring point increases from 0.5H to 1.6H, the pressure coefficient of peak positive pressure, peak negative pressure and pressure amplitude decrease by 29.0%, 17.0% and 15.5%, respectively. (3) The aerodynamic pressure in the BILSNB has a longitudinal end effect: the pressure coefficient of positive peak pressure and pressure amplitude at the inlet section are 27.6% and 17.5% higher than the corresponding average value of all middle sections, respectively. (4) The pressure amplitude of the BILSNB is approximately proportional to 2.15 power of the train speed. The pressure coefficient of the BILSNB is approximately a power function of the opening width, and the value range of the index is about (−0.26, −0.30). (5) The mechanism of the longitudinal end effect is as follows: When the train arrives at the inlet section, the high-speed airflow in front of the train head cannot flow around in time resulting in the impact effect of the airflow on the inlet section becomes greater than that on the middle section. The influence mechanism of the opening width is as follows: The narrower the opening width is, the more intense the airflow inside the BILSNB is compressed, and the impact effect of the airflow on the noise barrier is more significant.