Detecting Separation and Reattachment Points of a NACA0012 Airfoil by using Expanded Phase-Turbulence Intensity

抄録

Phase-turbulence intensity can be used to visualize the separation and reattachment points of an airfoil, which are closely related to its stall. In this paper, we detect these points above the surface of a NACA0012 airfoil by using threedimensional phase-turbulence intensity. Moreover, because the previous intensity could not discriminate between separation and reattachment points, we introduce an expanded phase-turbulence intensity that includes the velocity gradient normal to the airfoil surface in order to solve this problem. Using this intensity, we can discriminate between separation and reattachment points. We measure the three-dimensional phase-averaged velocity field around a NACA0012 airfoil by means of stereoscopic PIV in multiple cross-sections in a periodic flow for Reynolds number R_e=4542 and reduced frequency k=3.68.