Numerical modeling of separation control by mechanical and jet vortex generators

Results are presented of numerical modeling of a turbulent boundary layer interacting with streamwise vortices created by mechanical and jet vortex generators. The computations are performed in the framework of the three-dimensional Reynolds-averaged Navier–Stokes equations with the use of the Spalart–Allmaras turbulence model sensitized to streamline-curvature effects. When modeling the mechanical vortex generators, the approach used is based on their emulation with a specially designed body force introduced in the momentum equation. It is demonstrated that this approach provides satisfactory agreement of the numerical predictions with experiments. For the jet vortex generators, the turbulence model used allows the correct qualitative description of all the details of the flow but predicts the evolution of the vortex in the boundary layer with sufficient accuracy only for a relatively short distance from the section of jet injection (about 10–15 nozzle diameters). Further downstream, it results in a tangible underestimation of the vortex dissipation rate. Based on a NACA0015 airfoil with a deflected flap as an example, the possibility is shown of applying the proposed methodology for optimization of the position of mechanical vortex generators on the airfoil surface. An example is also presented of computing the flow past a vortex generator accounting for its real geometry, which is needed for its optimization and, also, for fine-tuning of the body-force parameters.