- Author
- Halli, Y. | Tien, J. S.
- Title
- Effect of Convective Velocity on Upward and Downward Burning Limits of PMMA Rods. Final Report. Volume 2.
- Coporate
- Case Western Reserve Univ., Cleveland, OH
- Sponsor
- National Bureau of Standards, Gaithersburg, MD
- Report
- NBS GCR 86-507, February 1986, 41 p.
- Distribution
- Available from National Technical Information Service
- Contract
- NBS-GRANT-60-NANB-D0013
- Keywords
- combustion physics | extinction | flame spread | flame velocity | oxygen index | polymethyl methacrylate
- Abstract
- Limiting oxygen mole fractions for 1.27 centimeter PMMA rods in upward and downward self-sustained burnings are measured as a function of the oxygen/nitrogen mixture flow velocity. For downward burning, the limiting oxygen mole fractions are found to be essentially independent on the flow velocity in the range between 5 to 40 cm/sec and increases when velocity is greater than 40 cm/sec. In the upward burning configuration, a stronger and non-monotonic velocity dependence is discovered. The limiting oxygen percentage reaches a minimum at a velocity of 12 cm/sec and increases in both directions as the mixture velocity increases or decreases. The minimum limiting oxygen mole fractions are, for the downward case, 0.184 and for the upward case, 0.15. Upward flame propagation limits in the presence of a small pilot flame have also been determined for PMMA rod. It is demonstrated that flames can propagate in an environment with an oxygen mole fraction lower than its critical extinction value for self-sustained flames.