Particle image velocimetry study of parameter influence for synthetic-jet application

• The synthetic jet is positioned at the front stagnation point to control flow around a circular cylinder.
• Particle image velocimetry is used to measure the global flow field.
• The individual role of different excitation parameters, including the stroke length, the excitation frequency, and the momentum coefficient, in the control effect is studied.
• The control mechanism for the present control configuration is revealed.

Flow separation control of a circular cylinder using a synthetic jet positioned at the front stagnation point is experimentally investigated by the particle image velocimetry (PIV) technique. The control results for different excitation parameters, including the stroke length, the excitation frequency, and the momentum coefficient, are compared to distill the essential control parameters, and the influence of the cylinder Reynolds number on the control effect is discussed. The separation control mechanism for the present control configuration is also revealed. It is suggested that the effective control ability of the synthetic jet is attributed to the increment of the turbulent kinetic energy (TKE) and the dissipation rate surrounding the circular cylinder. High level of TKE enhances the dynamics of the fluids and thus flow around the leeward surface is endured a considerable vertical acceleration pointing to the centerline from both sides, which is more resistant to flow separation.