Flame Spread Measurements on Single Ponderosa Pine Needles: Effect of Sample Orientation and Concurrent External Flow

Abstract

Measurement of the flame spread rate on single ponderosa pine needles as a function of angle of inclination and concurrent external flow speed arc reported. The ability to fit the orientation results with a single curve is of particular interest. Consideration of the results of previous experimenters concurs with this observation. Temperature measurements, visible observations and order of magnitude estimates are used to discuss the physical mechanisms for increasing flame spread rate with increasing angle from the downwards vertical, or with concurrent external flow speed. Volume expansion, species diffusion, finite rate gas phase kinetics, and buoyant convection are all thought to play a role