NUMERICAL-SIMULATION OF INCIDENCE AND SWEEP EFFECTS ON DELTA-WING VORTEX BREAKDOWN

The structure of the vortical flowfield over delta wings at high angle s of attack was investigated. Three-dimensional Navier-Stokes numerica l simulations were carried out to predict the complex leeward-side flo wfield characteristics, including leading-edge separation, secondary s eparation, and vortex breakdown. Flows over a 75- and a 63-deg sweep d elta wing with sharp leading edges were investigated and compared with available experimental data. The effect of variation of circumferenti al grid resolution in the vicinity of the wing leading edge on the acc uracy of the solutions was addressed. Furthermore, the effect of turbu lence modeling on the solutions was investigated. The effects of varia tion of angle of attack on the computed vortical flow structure for th e 75-deg sweep delta wing were examined. At moderate angles of attack no vortex breakdown was observed. When a critical angle of attack was reached, bubble-type vortex breakdown was found. With further increase in angle of attack, a change from bubble-type breakdown to spiral-typ e vortex breakdown was predicted by the numerical solution. The effect s of variation of sweep angle and freestream Mach number were addresse d with the solutions on a 63-deg sweep delta wing.