Abstract
Flame spread and extinction phenomena over a thick PMMA in purely opposed and concurrent flows are investigated by conducting systematical experiments in a narrow channel apparatus. The present tests focus on low-velocity flow regime and hence complement experimental data previously reported for high and moderate velocity regimes. In the flow velocity range tested, the opposed flame is found to spread much faster than the concurrent flame at a given flow velocity. The measured spread rates for opposed and concurrent flames can be correlated by corresponding theoretical models of flame spread, indicating that existing models capture the main mechanisms controlling the flame spread. In low-velocity gas flows, however, the experimental results are observed to deviate from theoretical predictions. This may be attributed to the neglect of radiative heat loss in the theoretical models, whereas radiation becomes important for low-intensity flame spread. Flammability limits using oxygen concentration and flow velocity as coordinates are presented for both opposed and concurrent flame spread configurations. It is found that concurrent spread has a wider flammable range than opposed case. Beyond the flammability boundary of opposed spread, there is an additional flammable area for concurrent spread, where the spreading flame is sustainable in concurrent mode only. The lowest oxygen concentration allowing concurrent flame spread in forced flow is estimated to be approximately 14 % O2, substantially below that for opposed spread (18.5 % O2).
Similar content being viewed by others
References
Altenkirch, R.A., Eichhorn, R., Shang, P.C.: Buoyancy effects on flames spreading down thermally thin fuels. Combust. Flame 37, 71–83 (1980)
Altenkirch, R.A., Tang, L., Sacksteder, K., Bhattacharjee, S., Delichatsios, M.A.: Inherently unsteady flame spread to extinction over thick fuels in microgravity. Proc. Combust. Inst. 27, 2515–2524 (1998)
Bhattacharjee, S., Altenkirch, R.A.: Radiation-controlled, opposed flow flame spread in a microgravity environment. Proc. Combust. Inst. 23, 1627–1633 (1990)
Bhattacharjee, S., West, J., Altenkirch, R.A.: Determination of the spread rate in opposed-flow flame spread over thick solid fuels in the thermal regime. Proc. Combust. Inst. 26, 1477–1485 (1996)
de Ris, J.N.: Spread of a laminar diffusion flame. Proc. Combust. Inst. 12, 241–252 (1969)
Fernandez-Pello, A.C.: Flame spread in a forward forced flow. Combust. Flame 36, 63–78 (1979)
Fernandez-Pello, A.C., Ray, S.R., Glassman, I.: Flame spread in an opposed forced flow: The effect of ambient oxygen concentration. Proc. Combust. Inst. 18, 579–589 (1981)
Fernandez-Pello, A.C.: Flame spread modeling. Combust. Sci. Tech. 39, 119–134 (1984)
Hu, W.R., Zhao, J.F., Long, M., Zhang, X.W., Liu, Q.S., Hou, M.Y., Kang, Q., Wang, Y.R., Xu, S.H., Kong, W.J., Zhang, H., Wang, S.F., Sun, Y.Q., Hang, H.Y., Huang, Y.P., Cai, W.M., Zhao, Y., Dai, J.W., Zheng, H.Q., Duan, E.K., Wang, J.F.: Space program SJ-10 of microgravity research. Microgravity Sci. Technol. 26, 159–169 (2014)
Ivanov, A.V., Balashov, Ye.V., Andreeva, T.V., Melikhov, A.S.: Experimental verification of material flammability in space. National Aeronautics and Space Administration, NASA CR-1999-209405 (1999)
Kashiwagi, T., McGrattan, K.B., Olson, S.L., Fujita, O., Kikuchi, M., Ito, K.: Effects of slow wind on localized radiative ignition and transition to flame spread in microgravity. Proc. Combust. Inst. 26, 1345–1352 (1996)
Kumar, A., Shih, H.Y., T’ien, J.S.: A comparison of extinction limits and spreading rates in opposed and concurrent spreading flames over thin solids. Combust. Flame 132, 667–677 (2003)
Loh, H.T., Fernandez-Pello, A.C.: A study of the controlling mechanisms of flow assisted flame spread. Proc. Combust. Inst. 20, 1575–1582 (1984)
Olson, S.L.: Mechanisms of microgravity flame spread over a thin solid fuel: oxygen and opposed flow effects. Combust. Sci. Tech. 76, 233–249 (1991)
Olson, S.L., Kashiwagi, T., Fujita, O., Kikuchi, M., Ito, K.: Experimental observations of spot radiative ignition and subsequent three-dimensional flame spread over thin cellulose fuels. Combust. Flame 125, 852–864 (2001)
Olson, S.L., Hegde, U., Bhattacharjee, S., Deering, J.L., Tang, L., Altenkirch, R.A.: Sounding rocket microgravity experiments elucidating diffusive and radiative transport effects on flame spread over thermally thick solids. Combust. Sci. Tech. 176, 557–584 (2004)
Olson, S.L., Miller, F.J., Jahangirian, S., Wichman, I.S.: Flame spread over thin fuels in actual and simulated microgravity conditions. Combust. Flame 156, 1214–1226 (2009)
Ramachandra, P.A., Altenkirch, R.A., Bhattacharjee, S., Tang, L., Sacksteder, K., Wolverton, M.K.: The behavior of flames spreading over thin solids in microgravity. Combust. Flame 100, 71–84 (1995)
Shih, H.Y., T’ien, J.S.: A three-dimensional model of steady flame spread over a thin solid in low-speed concurrent flows. Combust. Theory Model 7, 677–704 (2003)
T’ien, J.S., Shih, H.Y., Jiang, C.B., Ross, H.D., Miller, F.J., Fernandez-Pello, A.C., Torero, J.L., Walther, D.: Mechanisms of flame spread and smolder wave propagation. In: Ross, H.D. (ed.) Microgravity Combustion: Fire in Free Fall. Academic Press, San Diego (2001)
West, J, Tang, L, Altenkirch, R.A., Bhattacharjee, S., Sacksteder, K., Delichatsions, M.A.: Quiescent flame spread over thick fuels in microgravity. Proc. Combust. Inst. 26, 1335–1343 (1996)
Xiao, Y., Ren, T., Wang, S.F., Hu, J., Zhao, J.F.: Flame spread over thermally thick fuels in narrow channel apparatus. J. Eng. Thermophys. 31, 1423–1426 (2010). (in Chinese)
Zhang, X., Yu, Y.: Experimental studies on the three-dimensional effects of opposed-flow flame spread over thin solid materials. Combust. Flame 158, 1193–1200 (2011)
Zhao, X.Y., T’ien, J.S.: A three-dimensional transient model for flame growth and extinction in concurrent flows. Combust. Flame 162, 1829–1839 (2015)
Acknowledgments
This work is funded by the Strategic Pioneer Program on Space Science, Chinese Academy of Sciences, under grant No. XDA04020410. The authors thank Mr. Suide Wang for his assistance in conducting the experiments.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Zhu, F., Lu, Z. & Wang, S. Flame Spread and Extinction Over a Thick Solid Fuel in Low-Velocity Opposed and Concurrent Flows. Microgravity Sci. Technol. 28, 87–94 (2016). https://doi.org/10.1007/s12217-015-9475-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12217-015-9475-4