Train-Induced Unsteady Airflow (TIUA) Characteristics in Subway Ventilation Network

Nowadays, subway is rapidly developing globally; meanwhile, it costs huge energy. Train-induced unsteady airflow (TIUA) takes a crucial influence on the environment and energy consumption of subway. In the present study, 1D simulation was conducted using IDA tunnel software to analyze the TIUA characteristics of various components in subway ventilation network, such as platform, piston vent shaft, and bypass duct. The results demonstrate that the platform had the diverging and converging effect on the TIUA, and the converging effect was more outstanding with the piston vent shafts and bypass ducts closed condition. Moreover, bypass ducts at the upstream tunnel of subway stations mainly exerted a diverging effect on the TIUA, whose time-average diverging coefficients were approximately 0.16. In addition, piston vent shafts and bypass ducts at the downstream tunnel primarily took a converging effect on the TIUA; the time-average converging coefficients of the piston vent shaft were approximately 0.18 with the bypass ducts open and approximately 0.29 with the bypass ducts closed, respectively; and the time-average converging coefficients of the bypass duct were approximately 0.40. In addition, this study will provide meaningful design guidance for designer and enormous energy-conservation potential for subways.