Laboratory-scale investigation of air entrainment in burn pits used for waste disposal

Open-air fires are a common method of waste disposal in low infrastructure areas and these fires are often placed in burn pits to provide physical safety measures. This paper seeks to understand how the distance between the fuel surface and the pit opening (ullage) affects fire behavior by using a gas burner. The gas used is methane with a varying fuel supply (2, 4, 6 g/min) to represent different types of waste loading. As the ullage is varied, distinct flame fluctuations are observed inside the pit and aspects of flame dynamics at different fuel flow rates are espoused. A semi-empirical correlation for the entrainment of the ambient air into the flame is developed.