Control of a Blunt Trailing Edge Profiled Body using Unsteady Distributed Forcing

Blunt trailing edges are often used to improve the structural characteristics of airfoils in high load situations and/or reduce wave drag on transonic wings. However, the wake generated behind blunt trailing edges can lead to higher-pressure drag, unsteady aerodynamic loading and higher noise emission. This presentation will consider dynamically important features of the blunt trailing edge wake behind a non-lifting body as a precursor for their control. Of particular interest will be the presence of three-dimensionality in the von Karman vortex street generated in the wake – even when the geometry is nominally two-dimensional. This will be followed by the presentation of “distributed forcing”, which is a flow control approach that promotes three-dimensionality to achieve a large change in the blunt trailing edge wake with minimal energy input. Implementations of this flow control system using synthetic jets will be presented. Results from these experiments will highlight the change in the wake dynamics and reduction in pressure drag.