Development of an extended non-linear turbulence model and its application for analysis of three-dimensional wall jets

Abstract

In order to predict the flowfield of three-dimensional wall jets, an extended non-linear constitutive relation of the Reynolds stress is incorporated into the shear stress transport (SST) turbulence model. FaST Aerodynamic Routines (FaSTAR) developed by JAXA is used as a compressible-flow solver. Firstly, the computation of three-dimensional wall jets is performed, and the maximum velocity and its spreading rates obtained by the present extended model are compared with those by other turbulence models and experiments. Secondly, the effects of Mach and Reynolds numbers on the spreading rate of velocity in three-dimensional wall jets are examined. The ratio of vertical to lateral half-widths in the region near the nozzle exit is affected by the Mach number, and the counterpart far from the exit is affected by the Reynolds one. Moreover the ratio increases with the Mach and Reynolds numbers in the case of a fixed diameter of the nozzle exit. Concerning the effects of Mach and Reynolds numbers on the maximum velocity, the former has an effect opposite to the latter. Therefore, the effects of Mach and Reynolds numbers tend to cancel out each other in the fixed-diameter case. As the first application to jet blasts in practical airports, the computations of wall jet for double and four jets are carried out, and the computed velocity decay is in good agreement with experiments. As the second application, the computation of a single jet in crosswind is carried out, and the deformation of the velocity distribution due to crosswind is pointed out.