Comparing burner fire whirls to pool fire whirls

The fire whirl literature largely focuses on studies of whirls generated using pool fires instead of burn-ers. Pool fire whirls probably more closely represent in situ fire whirls as both have a burning rate that depends on the horizontal area of the fuel source. However, in a laboratory setting, working with burn-ers allow for control of all parameters involved in whirl formation, including the independent effects of source diameter and fuel rate. A comparison of the structure and scaling relationships of burner and pool fire whirls is presented here, so that the impact of using a burner or pool fire whirl in an experiment can be understood. It is shown that, in addition to being similarly tall and thin, the whirls have similar precession diameters, similarly structured air entrainment regions, and have azimuthal velocity profiles that are well-described by a Burgers vortex both inside and outside the whirl core. However, the depths of the air entrainment regions relative to whirl height are different, where the pool whirls have a region of slow axial flow above the air entrainment region that the burner whirls do not, and the whirls' cir-culation and height follow different scaling relationships. The primary source of these differences is the fuel source itself, where, in contrast to the pool fire, the burner whirl heat release rate is independent of the size of the fuel source.(c) 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.