ASYMMETRIC TURBULENT VORTICAL FLOWS OVER SLENDER BODIES

Time-accurate numerical solutions have been obtained for equations modeling turbulent subsonic flows over a slender ogive-cylinder body of revolution in the high-angle-of-attack regime where a large asymmetry in the mean flow has been observed experimentally. A modified algebraic eddy-viscosity turbulence model was utilized to correctly compute the effects of the asymmetric vortices on the underlying viscous layers. To reproduce any one of the experimentally observed asymmetric flowfields, it was found necessary to add a small geometrical disturbance near the body apex. By determining an appropriate size of the disturbance, it was possible to obtain excellent agreement between numerical results and experimental data for angles of attack of 30 and 40 deg, Reynolds numbers of Re(D) = 3.0 x 10(6) and Re(D) = 4.0 x 10(6), and several roll angles. When the disturbance was removed, the calculated flowfield returned to its original symmetric shape. These results are similar in behavior to solutions obtained previously for laminar flows. As in the laminar case, results suggest that the origin of the asymmetry is a convective-type instability of an originally symmetric flow.