Swept-Back Grid Fins for Transonic Drag Reduction

A swept-back grid-fin configuration was proposed in a previous study as a mean for reducing the drag associated to flow choking in the lattice cells at transonic speeds. The current follow-on study aims to further reduce the unfavorable effects of the transonic choking phenomenon by adding a 20° sharp angle to the leading edges of the lattice walls. Viscous computational fluid dynamic simulations were performed to investigate the flow of an ogive-cylinder body with conventional and with swept-back grid fins with sharp leading edges at transonic and supersonic speeds and zero angle of attack. These data were further validated with wind-tunnel measurements in the transonic regime of models of the two types of fin. The results indicate that swept-back grid fins with sharp leading edges offer a significant drag reduction.