Coupling of Large Fire Phenomenon with Object Geometry and Object Thermal Response

Abstract

The effect of an object in or near a large fire on the physical pro cesses which result in the heat flux from the fire is defined by the object geometry and temperature, and therefore the fire phenomena and the object physical states can be coupled. Two primary modes of coupling, radiative and convective, and their relative influence on heat flux, are investigated using observations from ex perimental data and numerical simulations. Radiative coupling occurs when a comparatively cold object reduces the incident heat flux (by up to 65%) due to radiative cooling of nearby media. Convective coupling includes: (1) changes in the geometry of the flame zone, and (2) object-induced turbulence which alters and often enhances the flow, mixing, and, hence, combustion processes within the fire. Increases in the heat flux approaching a factor of three have been observed due to these phenomena.