- Author
-
Ray, S. R.
- Title
- Flame Spread Over Solid Fuels.
- Coporate
- Princeton Univ., NJ
- Sponsor
- National Bureau of Standards, Gaithersburg, MD
- Report
-
NBS GCR 82-388,
April 1982,
224 p.
- Distribution
- Available from National Technical Information Service
- Contract
- GRANT-7-9004
- Keywords
-
Damkohler number
|
vapor phases
|
heat transfer
|
laminar flames
|
laser doppler velocimeter
|
solid fuels
|
oxygen concentration
|
radiometers
- Abstract
- An experimental investigation of the flame spread process over solid fuels using a Laser Doppler Veclocimeter (LDV) to provide two dimensional velocity measurements near the flame and the fuel surface; and thermocouple probes and radiometers were used to develop a more complete picture of the interactions of the fluid flow, heat transfer species transport near a spreading flame. Flames spread against low opposed flows and/or high oxygen concentrations are controlled by heat transfer effects. At higher opposed flows and/or lower oxygen concentrations, gas phase chemistry effects begin to dominate. It is believed that the fuel is vaporized behind the flame front, followed by diffusion upstream within the quench layer next to the fuel surface. The process results in a decrease in flame spread rate with opposed flow velocity and leads eventually to extinction. A correlation of a wide range of flame spread results is presented based on two dimensionless parameters: a Damkohler number which addressed the gas phase phenomena and a dimensionless spread rate which incorporated the heat transfer effects. The correlation was successful for both thermally thick and thin fuels.