NUMERICAL INVESTIGATION OF VORTEX BREAKDOWN ON A DELTA-WING

A numerical investigation of leading-edge vortex breakdown on a delta wing at high angles of attack is presented. The analysis has been restricted to low-speed flows on a flat-plate wing with sharp leading edges. Both Euler and Navier-Stokes (assuming fully laminar and turbulent flows) equations have been used in this study and the results are compared against experimental data. Predictions of vortex breakdown progression with angle of attack with both Euler and Navier-Stokes equations are shown to be consistent with the experimental data. However, the Navier-Stokes predictions show significant improvements in breakdown location at angles of attack where the vortex breakdown approaches the wing apex. The location of the primary vortex and the level of vorticity in the prebreakdown regions are affected very little by the viscous effects. In the postbreakdown regions, however, the levels of vorticity in the primary vortex have increased differences between the Euler and Navier-Stokes solutions. Navier-Stokes solutions indicate the presence of a secondary vortex even after the primary vortex is burst. The predicted trajectories of the primary vortex are in very good agreement with the test data with the laminar solutions providing the overall best comparison.