Effects of ventilation state of vertical shaft on fire tilt direction and smoke migration behaviours in a multi

Ventilation is an important method to control fire development in the building. However, most of the previous studies focused mainly on single building structure (shaft or corridor, respectively) and seldom considered composite structure. In this study, a scaled multi-composite building was studied to investigate the effects of ventilation state on building fire. Under positive pressurized air supply and negative pressure air exhaust conditions, the performance of flame direction and tilt angle was evaluated to analyse the interactive effect between air supply ventilation, stack effect and building structure. By analysing fire-related parameters (smoke field, fluid velocity and direction and temperature distribution), six typical migration paths were identified and validated by their corresponding experimental cases. Considering the impact factors of air supply pressure, stack effect and the pressure induced by the horizontal corridor smoke, a non-dimensional number, η , has been presented in this paper to identify the flame tilt direction for composite building, which had so far not been studied before