Accession Number:

ADA172540

Title:

Swirl Induced by Large Area Fires.

Descriptive Note:

Technical rept. 15 Nov 84-1 Oct 85,

Corporate Author:

PACIFIC-SIERRA RESEARCH CORP LOS ANGELES CA

Personal Author(s):

• Weihs,D.
• Small,R. D.

Report Date:

1985-10-01

Pagination or Media Count:

23.0

Abstract:

Swirl has been suggested as the mechanism responsible for high fire-wind velocities and exceptional plume rises from large area fires. The potential sources of vorticity that could result in a swirling central column are examined. Coriolis forces produce only a small tangential velocity component for the time and length scales appropriate to a city size fire. Similarly, asymmetries in fuel load or burning distribution cannot generate sufficient swirl velocities to influence the plume motion or fire-wind velocities. Neither eddies or rotational systems of scale much larger or smaller than the fire radius can produce swirl. Wind systems with wavelength similar in scale to the fire diameter produce only a negligible tangential velocity component. As a consequence, plumes produced by large area fires are not likely to swirl. Keywords Firestorms Vorticity Circulation Plumes. Author

Descriptors:

• *NUCLEAR EXPLOSION SIMULATION
• *FIRES
• *PLUMES
• *NUCLEAR EXPLOSION DAMAGE
• VELOCITY
• SOURCES
• DISTRIBUTION
• WIND
• MOTION
• VORTICES
• COMBUSTION
• FUELS
• ASYMMETRY
• SCALE
• LENGTH
• TANGENTS
• ROTATION
• CIRCULATION
• BUOYANCY
• CORIOLIS EFFECT
• FIRE STORMS

Subject Categories:

• Safety Engineering
• Combustion and Ignition

Distribution Statement:

APPROVED FOR PUBLIC RELEASE