Max Butler; Caleb Harper, Brigham Young University
Understanding how flames spread is essential in understanding how to best predict, prepare for, and prevent fires, both in wildlands and in urban environments. Flame merging is a common phenomenon during fire spread, particularly in shrubs. Distances between fuel sources play an important role in determining merged flame behavior. Flame-merging research has been performed with multiple flames situated on a flat plane, involving either pool fires, fuel jets, or wood cribs. There is a need to study flame-merging behavior for fuels in three-dimensional arrangements, which applies to shrub or warehouse fires, where fuel sources are not always on a horizontal plane. The main purpose of this research is to better understand how both vertical and horizontal spacing between fuel sources affect flame propagation, or spreading. To accomplish this purpose, a series of flame-merging experiments have been designed, and performed. The experiments consisted of felt pads soaked in n-heptane mounted on ceramic rods, and spaced at specific distances from each other. The burning felt pads are roughly similar to adjacent leaves burning in a shrub. The heptane-soaked pads were lit simultaneously, and the behavior of the resulting flames was monitored via video recorder. Flame characteristics such as flame height, width, flame area, and flame merging were gathered. Additional characteristics were derived, such as heat release rate and dimensionless heat release, in order to compare with published theories. It was concluded that both horizontal and vertical spacing have a significant influence on merged flame behavior. A region of maximum combined flame size was determined. In the future, study of three fuel sources spaced three-dimensionally from each other will provide further insight into flame merging behavior. It is anticipated that a similar region of maximum flame size due to merging will appear in the three-dimensional analysis.