Transient Analysis of Heterogeneous and Homogeneous Combustion in Boundary Layer Flow

Abstract-The present effort is an analytical study of combined homogeneous and catalytic combustion. Numerical solutions are obtained for the transient combustion of a mixture of fuel and oxidizer in boundary layer flow. The effects of an isothermal as well as an adiabatic catalyst on homogeneous combustion are examined. For an isothermal plate, the addition of the catalyst delays the ignition process, increases the ignition distance and lowers the gas phase temperatures. However, shorter concentration conversion distances and more uniform plate energy flux distributions are obtained. In general, increasing the plate temperature lowers the ignition distance while the influence of chemical parameters depends on the relative importance of each mode of combustion. The effects of surface activation energy and frequency factor are dependent on the relative importance of each mode of combustion. In the two limits of reaction limited or diffusion limited cases. catalyst activity has little effect on the ignition distance. However, when both effects are important, increasing catalyst activity increases the zero temperature gradient point. For an adiabatic plate, the addition of catalyst enhances the gas phase combustion. Increasing the catalyst activity causes a reduction of both ignition distance and ignition delay time.