The influence of forcing frequency and amplitude to effectiveness of synthetic jets on laminar separation control

Comsol Multiphysics
Publication Type:
Conference Proceeding
17th Australasian Fluid Mechanics Conference, 2010, pp. 1 - 4
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A synthetic jet actuator (SJA) is regarded to be effective if the separating bubble is eliminated in the control of boundary layer separation. One novel idea is to use the flow instability as internal energy to enhance the effectiveness of synthetic jets. To explore this idea, a three-dimensional large eddy simulation (LES) was performed and the influence of forcing frequency and amplitude to the SJA's effectiveness was investigated. The numerical model was verified by experimental results in a laminar separation zone in a boundary layer with adverse pressure gradient. The numerical results of the SJA's effectiveness were compared to identify the significance in changes made by varied forcing frequency at fixed forcing amplitude and by varied forcing amplitude at a fixed forcing frequency. Consistent with the wind tunnel experiments, LES results showed that the effectiveness of the SJA depends more on the forcing frequency than on the forcing amplitude. They support the inference from the experiments that the non-frictional Kelvin-Helmholtz (K-H) instability associated with the laminar separation is a source for enhancing the frictional Tollmien-Schlichting (T-S) instability which resists the laminar separation.
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