Experimental Investigation of Juncture Vortex

ABSTRACT

A Particle Image Velocimetry（P.I.V.）techniques was used in a circulation water tank to measure the juncture vortex which is formed near the intersection of two different models ( circular cylinder and NACA0018) on a flat plate. Four cases with different Reynolds numbers were tested. The results show a vortex system occurs at the symmetry plane of the flow field. It was found the center of main vortex is no fixed. However no obvious relation was found between the center positions and Reynolds numbers. It showed that the main vortex centers are distributed closer to models in NACA0018 cases than in cylinder cases. Therefore, it is concluded that the model geometry affects the locations of main vortex center.
Based on the measured velocity field, the vorticity and total circulations were calculated. It shows that the maximum vorticity and total circulation increase as Reynold number increases. It also found that the total circulations obtained in NACA0018 cases are smaller than in the cylinder cases.