Species Diffusion in the Frozen Laminar Boundary Layer on a Catalytic Flat Plate

摘要

A theoretical solution is presented for species diffusion in the compressible laminar boundary layer on a flat plate for frozen gas-phase chemistry. It is assumed that the recombination at the wall is a first-order reaction, and the chordwise concentration gradients are neglected. The solution parallels Crocco's treatment except for the assumption governing the viscosity variations with temperature. A modified Chapman-Rubesin constant is used here, and it is assumed that the product of the density and viscosity varies as a power of the static enthalpy. This makes it possible to closely approximate the actual rho mu- product in the vicinity of the wall. The solution for the species equation and the energy equation are obtained in terms of the shear in the boundary layer. The latter is determined following an empirical calculation used by Young. The result given here should be somewhat more general since the Prandtl number effects are included in a more complete fashion. The solutions for heat transfer and skin friction are compared with existing exact numerical solutions to show that they agree with typical errors of about 5 percent. (Author)