Accession Number : AD0701927

Title :   ORIGIN AND PROPERTIES OF FIRE WHIRLS.

Descriptive Note : Final technical rept. Jul 67-Aug 69,

Corporate Author : IIT RESEARCH INST CHICAGO ILL

Personal Author(s) : Nielson,Hugo J.

Report Date : 15 AUG 1969

Pagination or Media Count : 64

Abstract : To determine the origin of fire whirls in fires, the origin of the vertical vorticity required to sustain them was investigated. It was found that the vertical vorticity developed by the bending upward of the horizontal vortex lines of the ambient wind boundary layer is greater than that produced by other mechanisms. The intensity and distribution pattern of the vorticity is also in agreement with the circulatory flow found to exist in experimental fire wind data. A method for estimating the intensity of fire whirls in urban fires is given which is based on the way the vorticity production scales with fire size and on existing analyses of the properties of convective vortices. (Author)

Descriptors :   (*FIRES, CONVECTION(ATMOSPHERIC)), (*VORTICES, FIRES), FOREST FIRES, MOMENTUM, WIND, ROTATION, CONVECTION(HEAT TRANSFER), TEST METHODS

Subject Categories : Forestry
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE