Direct Monte Carlo Simulations of a Binary Gas Free-Jet Flow Over a Flat Plate

Abstract

Monte Carlo simulations of low density, hypersonic free‐jet wind tunnel tests [1] are presented for comparison with test measurements, made by a laser‐induced iodine fluorescence method, of Mach 12 flow over a flat plate at zero incidence. The radially expanding free‐jet core is modeled as a 3‐dimensional (spherical) expansion. Upstream velocity, temperature, and density profiles were established directly from the Ashkenas‐Sherman correlations for jet‐centerline Mach number and off‐axis density. The flow simulations extended to the free‐jet wake and ambient test pressure and include the characteristic ‘Mach stem’ jet termination feature. The test gas was composed of a binary mixture of nitrogen with a trace quantity of iodine, and this composition was maintained in an axisymmetric flow simulation to establish the influence of diffusive separation on the accuracy of the test measurements. Velocity profiles of both species on the plate are compared to the measured iodine velocity profiles. Mole fraction profiles of iodine are presented. Rotational and translational temperature profiles of iodine from the simulation are compared with test measurements.