Numerical Solutions of the Navier-Stokes Equations for Laminar and Turbulent Supersonic Mixing Flows.

摘要

A modification of MacCormack's two step computational method is applied to flow of a perfect gas with constant thermal properties between parallel, free boundaries. The complete Navier-Stokes equations were applied. Such flow predictions are fundamental to later extension of computer programs to include the kinetics and diffusion for flow downstream of the nozzle stacks with a chemical laser or a downstream mixing gasdynamic laser. A laminar flow program was constructed first and checked out by application to flow problems with exact solutions. The checkout of the laminar flow program indicated that satisfactory results could be obtained at reasonable expense. This program was extended to produce two turbulent flow programs. One program utilizes a mixing length model while the other applies the Saffman-Wilcox-Alber turbulence model. Application of the turbulent programs to nozzle exit flows with smooth profiles at the exit plane of the nozzles produced satisfactory results. However, if these profiles have the discontinuous profiles characteristic of the ideal mixing of two parallel streams, a relatively small amplitude, steady state oscillation develops. Further investigations are in process to remove this oscillation and to extend these programs to treat downstream mixing gasdynamic lasers.