Fire Safety Science Digital Archive

Among various aspects dealing with the influence of flow structure on the combustion characteristics of solid fuels, the effect of turbulent heat and mass transfer in the flame zone is studied in the present paper. The combustion in turbulent flow is considered by developing a model of interaction between turbulent and chemical reaction of combustion. Transport equation for turbulence heat flux defined in the Reynolds time-averaged form is taken into account including a source term describing the influence of chemical reaction. another mechanism of combustion reaction effect on turbulent heat transfer is analyzed by introducing a new characteristic period for the turbulent fluctuations, i. e. only fluctuations having a characteristic period that is smaller than corresponding characteristic period of reaction can affect the heat transfer in the flame zone. The local-isotropic assumption is carried out to reduce full transport equation for turbulent fluctuations of temperature to simple formulae. Hence, a new correlation for effective coefficient of turbulent heat transfer affected by chemical reaction is formulated. The effect of erosive burning (increase of burning rate of solid fuel under blowing of burning surface) is studied numerically by boundary layer approach. Satisfactory agreement with measurements is obtained using proposed approach for the full transport equation as well as for the local-isotropic assumption.