Mathematical modeling and sensitive analysis of the train-induced unsteady airflow in subway tunnel

With the flourishing development of the subway construction, more and more attentions are paid to the subway tunnel ventilation. The piston wind caused by the running trains can not only improve the tunnel environment, but also strengthen the power of the tunnel ventilation. The majority of the current researches are based on similar experiments or CFD simulations, yet most of which lack universality. It takes long time to finish the research cycles and it is difficult to generalize the conclusions based on these researches. This paper is aimed to put forward a universal prediction formula to estimate the ventilation effect of piston wind. In this paper, a uniformly accelerated Bernoulli theoretical model is established firstly, which is validated by the experimental data and numerical simulations. Secondly, a passing through model is built with the verified theoretical method and the influence of the key parameters on the ventilation rate are analyzed. Thirdly, the grey correlation analysis is conducted to study each influencing factors, meanwhile, a general prediction formula on the ventilation rate is proposed, which is applicable to the most subway tunnels in China. Finally, the effects of the trailing distance between multi-trains on the tunnel ventilation is discussed.