<![CDATA[The formation and development of a single vortex is investigated in a wind tunnel. The wake from a lifting rectangular wing based on CLARK-Y profile of 11.7% is studied up to 80 chords downstream. Digital particle image velocimetry is used to measure the velocity field in the cross stream plane from which is the vortex is measured. Two different experimental test were carried out in two different conditions of the tunnel, without and with grid. From the first condition, the vortex is observed to be quite stable and long-lived. A correlation for the peak tangential velocity uθ,max and the vortex core rc has been compared with the Lamb-Oseen model, and it gives a good agreement. The circulation Γ is observed to be proportional to the free-stream U∞ (range 8 − 20 m/s) and the angle of attack α (range 1−12 deg). The vorticity ω, however, diffuses over time within the growth of the vortex core rc. This growth can be approached by the Squire model. Apparently, the vortex characteristics become weaker when the experiments are performed under grid turbulence condition. Due to the influence of the grid turbulence, some experiments give inconsistent result. This makes difficult to draw conclusions. However, still some interesting information is found in this case.]]>
Copyrights © 2020
