Deflection characteristic of flame with the airflow induced by stack effect

Abstract

A set of experiments was conducted in a small scale high-rise building model with 12 floors to study the deflection characteristic of flame with the airflow induced by the stack effect. The results show that the position of the open window influences the location of the neutral plane, which determines the airflow velocity induced by the stack effect, and a correlation is proposed for their relationship. The airflow has a significant impact on the burning rate. The stack effect would cause a separation of flame base from the pan at the windward side, resulting in the exposure of part of the fuel surface to the cold air. The dimensionless flame height (Hf/D) and length (Lf/D) of leaned heptane flame are proportional to 1/4 power of the dimensionless heat release rate (Q*). The temperature rise (ΔT) at the continuous flame zone is lower under the stack effect than that of a free burning case at open space due to the cooling of airflow. The flame of pool fire is stretched and the lengths of continuous and intermittent flame zones are much greater than those obtained at the open space. The ratio of L/Q2/5 in the intermittent flame zone ranges from 0.12 to 0.25 in the current research whereas it ranges from 0.08 to 0.2 at the open space.