| description abstract | A mitigation system is significant in that it blocks the flow of toxic gas and prevents the growth of hazardous areas, thereby securing sufficient evacuation time. A new air curtain mitigation system was developed to prevent the dispersion of toxic gas by breaking the momentum of flow and reducing the extent of the affected region. To investigate the effect of key factors, computational fluid dynamics (CFD) simulations were performed for various values of air curtain angle and velocity. The air curtain velocity was adjusted at 0, 30, 40, and 50 m/s, whereas the air curtain angle was varied at 0°, 10°, 20°, and 30°. In this study, the mechanism of the air curtain by which the linear motion of the released toxic cloud is converted into rotational motion was clarified. The transformed rotational motion was evaluated by vorticity, and its value increased as the air curtain velocity increased. Increasing the air curtain velocity improved the mitigation effect at a fixed air curtain angle. Increasing the air curtain angle contributed to a dilution of toxic gas concentration by enhancing the mixing with air and breaking the momentum of flow. Based on the simulation results, the toxic gas mitigation effect of the air curtain system is confirmed, and air curtain design guidelines are presented. | |
