Thermodynamic coupling in boundary layers by a rapid coupling-factor estimate

Abstract

Experiments conducted during the last decade show that thermodynamic couplings in boundary layers may result in rather unusual and appreciable changes in the values of heat fluxes in hypersonic flows or even in low-speed flows characterized by large temperature gradients. However, exact estimates of these effects in actual multicomponent boundary-layer flows require mathematical procedures which are too complicated and cumbersome to be of much routine use except in simple binary cases. Unjustifiably these effects have been therefore neglected by most investigators before estimating the expected results under the expected operating conditions. In trying to overcome the aforementioned difficulties we develop a relatively simple new iterative method to obtain rapid approximate estimates of these effects under various operating conditions. The method is amenable to rapid calculations by hand as well as for computer applications and allows also estimates of the particularly interesting coupling effects involved in mass-transfer cooling by foreign gas injection, ablation, evaporation, condensation or suction.