Laminar Separation Bubble Manipulation with Dynamic Roughness

Abstract

The laminar separation over a symmetric, idealized airfoil was altered by employing a leading edge roughness element ahead of the separation point. Experimental tests were performed with a dynamic roughness, with a time-dependent amplitude, in order to determine the range of control authority associated with this type of leading edge manipulation. The dynamic roughness tests demonstrated the sensitivity of the separation to frequency perturbations at the leading edge induced by the roughness element. Two low dimensional analysis techniques, Proper Orthogonal Decomposition and Dynamic Mode Decomposition, were employed to examine the coupling between the wall motion and the flow, with a view to investigating the practicality of using leading edge roughness perturbations to in future closed loop control configurations.

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