Experimental and numerical study on flow control using obliquely aligned elements.

The use of micro-electromechanical system devices (MEMS) have been studied extensively in literature for control of flow separation and transitioning to turbulent flow. However, there is limited information about how obliquely aligned roughness elements affect the boundary layer development and induce turbulence. The purpose of this study was to measure the transverse flow and turbulent intensities produced by an array of 0°, 5°, 10°, and 15° obliquely-aligned elliptical control elements in turbulent flow at 2, 5, and 10 m/s on a flat plate. The resulting boundary-layer measurements demonstrate the ability of the control elements to produce tailored secondary flows. Since the test coupon was of finite span, results demonstrate that controlled vortices can also be generated using the arrays. Additionally, CFD simulations were performed and compared to the experimental results using the realizable k-ε turbulence model in ANSYS FLUENT 12.0 with solutions converging to residuals less than 1x10⁻⁶ for flow and turbulence quantities.