Flame lengths under ceilings

The evaluation of hazards from developing room fires often requires a knowledge of flame lengths developed by burning objects. Procedures for estimating flame lengths have been available only for vertical plume fires, where there is no flame impingement on the room ceiling. Calculational procedures are developed for approximate calculation of flame lengths when part of the flame flow is along the ceiling. Four common geometries are treated: unbounded ceiling, plume near corner, plume in corner and one‐directional corridor spread. Ceiling flame lengths are calculated by use of the assumption that the total air entrained up to the flame tip is the same for ceiling flow as for the free fire. Comparison with limited experimental data suggests potential for prediction in full‐scale room fires.