Probability Distribution of Plume Merging Induced by Two Unequal Turbulent Diffusion Flames of Propane

Buoyant diffusion flame is one of the main forms of undesirable source release. Hazardous fires in industrial accidents that cause heavy casualties and environmental damages are often accompanied by burning of multiple diffusion flames. To avoid and minimize damage and control energy release, efforts are being done to evaluate the fire hazard of multiple fires. This paper presents an experimental study on criteria of flame merging and interaction of two unequal propane gas fires. The dimensions of two square burners were different and fixed at 10 and 15 cm. The heat release rate of each burner varied from 10.8 to 64.8 kW and the burner spacing changed from 0 cm to 60 cm. The results showed that as the spacing increases, the interaction of two unequal flames presents fully merging, intermittent merging and non-merging states. The flame heights and tilt angles of two flames are different due to asymmetric air entrainment. The flame merging probability based on the statistical flame shape is proposed to determine the flame merging extent. Based on dimensional analysis method, a model for flame merging probability is proposed, which shows that spacing has the greatest influence on flame merging, followed by the heat release rates of burners. According to the proposed model, the safety distance between two discrete combustibles can be estimated, which helps to plan the layout and spacing of discrete fuels.