An Analysis of Shock Structure and Nonequilibrium Laminar Boundary Layers Induced by a Normal Shock Wave in an Ionized Argon Flow.

摘要

An analytical study was made to describe the structure of a strong normal shock wave moving into argon and the nonequilibrium flow of partially ionized argon in the laminar boundary layers induced behind the shock wave on the shock-tube walls and over a flat plate. The subsequent interaction of the laminar boundary layer with a corner-expansion flow was also considered. In order to determine the shock structure, the ionization and relaxation processes were based on a two-step model of the collisional processes. The excitation (or ionization) cross-section constant for the argon atom-atom collisions was determined to be 3.5 x 10 to the -20th power sq cm/ev from a comparison of theoretical and experimental shock-structure data. The effects of a small amount of hydrogen impurity in the argon test gas on shock-wave structure was evaluated and discussed, as the hydrogen impurity can markedly reduce the total relaxation length. A study of this effect was required in connection with stabilizing the experimental shock waves. An integral method was used in the analysis to study both the shock induced nonstationary laminar boundary layer on the shock-tube walls and the quasi-steady flat-plate laminar boundary layer for an ionized argon flow. The frozen, equilibrium and nonequilibrium flow solutions were obtained and compared with some existing experimental results.