Ignition of a Liquid Fuel under High Intensity Radiation.
Final progress rept. 1 May 78-30 Sep 79,
NATIONAL BUREAU OF STANDARDS WASHINGTON DC CENTER FOR FIRE RESEARCH
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This report summarizes progress in the study of ignition of a liquid fuel under high intensity radiation. It describes an experimental study of the key processes during ignition and a theoretical modeling study of part of the phenomena during the ignition period. The experiments were conducted using a CW CO2 laser with incident fluxes from 1000 to 5000 Wsq cm and n-decane as the flammable liquid. High speed photographs of ignition events showed a periodic depression in the decane surface, probably caused by the thrust of the strong decane vapor flux radial outward motion of the liquid, probably caused by a surface tension, gradient was also observed. The first appearance flame was in the gas phase well above the surface. The proposed autoignition mechanism of decane by the CO2 laser is the absorption of the incident laser beam by the vapor plume. The effect on ignition of the incident angle of the laser beam with respect to the decane surface was studied from 90 to 30 degrees. On reducing the incident angle, the ignition delay time becomes longer and the minimum incident flux for ignition increases significantly. A theoretical model describing the flow motion in the gas phase caused by a heated surface was calculated numerically and solved analytically. Author
- Lasers and Masers
- Combustion and Ignition