Assessment of Parameters Influencing the Prediction of Shear-Layer Mixing

Abstract

A multi-site team has completed an investigation of modeling high speed mixing layers using the computational methods currently being applied to predict HSCT nozzle flow fields. The objectives of this investigation were to: (1) calibrate the codes used by the various team members against benchmark experimental data, and (2) assess the accuracy of the Navier-Stokes codes in calculating turbulent flows having flow characteristics similar to those of HSCT engine nozzles. Two flow geometries were investigated using the five codes of NASTAR, PAB3D, GIF3D, NASTD, and NPARC. The first was the heated supersonic round jet of Seiner. For this configuration, with a jet exit Mach number similar to that of the primary flow from mixer chutes, three nozzle flow temperatures were investigated with the five codes. Using the same grid, boundary conditions, and k-e turbulence model (in the mixing region), very similar results were obtained for all codes, but the solutions did not agree well with the experimental velocity and temperature profiles. Further calculations using different turbulence models, compressibility corrections, and axisymmetric dissipation corrections improved the agreement with experimental data, but the corrections are not universally applicable. The second configuration was the two-dimensional supersonic mixing layer of Goebel & Dutton. For the flow case examined, with two supersonic streams, the five codes again produced very similar results using the same grid, boundary conditions, and turbulence model. The agreement with experimental data was better than for the Seiner round nozzle.