During subway train operation in tunnels, piston wind is generated, which significantly affects the tunnel flow field. Understanding piston wind characteristics is crucial for its effective utilization. It is of great significance to study the characteristics of piston wind for rational utilization of piston wind. Based on Bernoulli equation of unsteady flow, a lumped parameter theoretical model of piston wind in subway tunnel is established, and the characteristics of unsteady piston wind are analyzed. In order to verify the accuracy of the theoretical model, a reduced size model test bench of 1:16 was established, and the piston wind speed was tested experimentally. The comparison between the model value and the measured value shows that the Pearson correlation coefficient is higher than 0.98, and the average error is lower than 13%, which verifies the correlation and accuracy of the theoretical model. By using the lumped parameter theory model, the influence of different factors on the piston wind in subway tunnel is explored, and the grey correlation degree is analyzed. The results show that the congestion ratio is the biggest factor affecting the ventilation effect of the tunnel piston, followed by the train length and train speed, and the tunnel length is the least. Based on this, a fitting formula for the ventilation effect of the piston in common subway tunnels in China is proposed.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |