PIV STUDY OF AIRFOIL NEAR WAKE FLOW PARTⅡ DYNAMIC MECHANISM

Detailed 2D velocity and vorticity fields were measured to investigate the turbulent near wake flow of NACA0012 airfoil with on-line cross-correlation PIV in a low-speed wind tunnel.The Reynolds number on chord length is 2.39×10⁵,the angles of attack are 0° and 4°.The experimental results indicate that ordered vortex streets exist in the turbulent near wake,the vortex streets created at the airfoil trailing edge region will fully develop and finally break up downstream,and the ordered wake flow turns into disordered.The near wake flow is dominated by the kinetic characteristics and dynamic mechanism of vortices.As the second part of the investigation,the paper mainly discusses the formation of the vortex streets,the dynamic mechanism of the near wake,and the fluid instability of the vortex and vortex streets.