Vortex Flow and Aerodynamic Performance of a Reverse Delta Wing

摘要

The unsteady flow past a reverse delta wing is simulated numerically to characterize the structure of the vortical flow and associated unsteady phenomena, and quantify the impact of such structures on the aerodynamic performance. The most cost-effective grid-size/time-step combination is selected by performing a coupled sensitivity analysis. This numerical approach is successfully validated against well-established results for a delta wing. It is established that the flow past a reverse delta wing is always unsteady even at small angles of attack. The shear layer separating at the leading edge of the reverse delta wing rolls up into spanwise vortical structures that, as they are convected downstream, pair, realign, and reorganize, generating suction that contributes substantially to the lift produced by a reverse delta wing. The tip vortices confine the vortical structures to the leeward side and contribute to a less extent to lift. Power spectral density analysis shows that the unsteadiness of the lift coefficient is related to vortex shedding and reorganization of the vortical structures. Finally, it is confirmed that the lift-to-drag ratio of a delta wing and a reverse delta wing is, surprisingly, about the same.