Modulation of aerodynamic force on a 2D elliptic body via passive splitter pitching under high turbulence

Abstract

The mean and fluctuating aerodynamic force on an elliptic body of infinite aspect ratio with hinged splitters were experimentally studied under high incoming turbulence for various angle of attack AoA of the body, Reynolds numbers and splitter length. High-resolution load cell was used to measure the mean and unsteady lift and drag forces of the body; whereas a hotwire anemometry was employed to characterize the incoming turbulence and get insight on the wake flow. Results show that the attached splitters reduce the lift and drag coefficients for AoA well beyond stall. Interestingly, the splitter length did not play a noticeable role on the mean aerodynamic force; this parameter just induced minor effects on the fluctuation counterpart. Such phenomenon appear to be inherently related to the background turbulence levels. Compared to the bare body, the force coefficients exhibit stronger dependence on Reynolds number due to the dynamics induced by the splitter pitching. In general, the force fluctuations are dominated by the natural frequency of the setup under the high turbulence. The joint distribution of the instantaneous lift and drag forces reveals that under sufficiently high AoA, the vortex shedding dominates the force fluctuations along the major axis of the body; whereas the splitters can efficiently dampen the vortex shedding and mitigate the overall force fluctuations.