Experimental Study on Radiative Ignition of Filter Paper with Near Infrared Radiation Under Microgravity

Experiments with radiative ignition were performed in microgravity to elucidate the events arising during the ignition process in a quiescent field. Filter paper was irradiated by Diode laser light (800.1 nm), which is little absorbed in the gas phase, at various oxygen concentrations (0 - 50%). The ignition delay was measured for various experimental conditions. The density changes of the gas phase before ignition was observed in detail by a Mach-Zehnder interferometer. The results showed that heat conduction from the sample surface induced a weak chemical reaction in the vicinity of the sample surface, and this propagated outward to achieve combustion. The ignition delay decreased with increases in O 2 concentration because the mixture near the sample surface contained more oxygen causing an immediate transition from the weak chemical reactions to the strong reactions of the combustion.

[1]  A. Fernandez-Pello,et al.  Convection Effects on the Endothermic Gasification and Piloted Ignition of a Radiatively Heated Combustible Solid , 2000 .

[2]  Chiun-Hsun Chen,et al.  Numerical Analyses for Radiative Autoignition and Transition to Flame Spread over a Vertically Oriented Solid Fuel in a Gravitational Field , 2000 .

[3]  Hiroshi Yamashita,et al.  Effects of gravity and ambient oxygen on a gas-phase ignition over a heated solid fuel , 2000 .

[4]  S. Olson,et al.  Effects of ignition and wind on the transition to flame spread in a microgravity environment , 1996 .

[5]  J. E. Brown,et al.  Gas phase oxygen effect on chain scission and monomer content in bulk poly(methyl methacrylate) degraded by external thermal radiation , 1996 .

[6]  R. Flagan,et al.  Laser Ignition of Levitated Char Particles , 1995 .

[7]  Kevin B. McGrattan,et al.  Ignition and transition to flame spread over a thermally thin cellulosic sheet in a microgravity environment , 1994 .

[8]  John-Chang Chen,et al.  Laser Ignition of Pulverized Coals , 1994 .

[9]  J. Ekmann,et al.  High-energy Nd-Yag laser ignition of coals : experimental observations , 1993 .

[10]  C. Blasi,et al.  Heat and Mass Transport from Thermally Degrading Thin Cellulosic Materials in a Microgravity Environment , 1992 .

[11]  Takashi Kashiwagi,et al.  Global kinetic constants for thermal oxidative degradation of a cellulosic paper , 1992 .

[12]  Gennaro Russo,et al.  Numerical model of ignition processes of polymeric materials including gas-phase absorption of radiation , 1991 .

[13]  Takashi Kashiwagi,et al.  Effects of sample orientation on radiative ignition , 1982 .

[14]  Takashi Kashiwagi,et al.  Experimental observation of radiative ignition mechanisms , 1979 .

[15]  F. Williams,et al.  Gas-Phase Ignition of a Solid with In-Depth Absorption of Radiation , 1977 .

[16]  A. D. Cross,et al.  An Introduction to Practical Infra-red Spectroscopy , 1969 .