Nonequilibrium Flow over a Reactive Surface

Abstract

A reacting flow situation is considered wherein a gas mixture initially in a state of chemical equilibrium flows over a surface having a chemical affinity for one of the components in the flowing gas. A gas‐solid reaction results which, in turn, upsets the gas phase equilibrium so that a reaction starts there also. Evolution of gaseous products of the wall reaction serves to lower skin friction and to further complicate the situation. The flow is taken to be over a flat plate, and the simplest forms for the two reactions are used. The interactions among the processes are viewed in terms of an interaction parameter G, which is the ratio of the square of the characteristic time for wall reaction processes to the product of characteristic times for the gas phase and diffusion processes, and a stoichiometric factor K̄. The latter represents the mass of wall material that can react with unit mass of the free‐stream gases. Typical results for drag show that when G = 1 and K̄ = 5, a 45% reduction occurs; when G = 5 and K̄ = 5, a 55% reduction is obtained. Even greater differences are found between values of skin friction when K̄ varies at constant G.