Structure and transient behavior of radiation-controlled flame in a highly porous medium.

Abstract

The structure and transient behavior of a radiation-controlled flame both in and behind a highly porous medium, which has a finite length along the flow direction, have been clarified in detail through numerical calculation on the basis of the rigorous treatment of the radiative transfer and of the simplified one-dimensional flame theory. The results have disclosed that the flame is sustained in the region from about the middle to the upstream end of the porous medium over a wide mixture velocity range from about one-fifth to several times as high as the burning velocity of the ordinary gas phase flame because of the energy feedback by radiation. In addition, the flame is held at the downstream end of the porous medium under the condition of the mixture velocity below the burning velocity of the ordinary flame. Further, the radiation plays an important role in the transient phenomena for the flame propagation in both the upward and downward directions in the porous medium.