The wake of a yawed circular cylinder was investigated by measuring all the velocity and vorticity components using an eight-wire vorticity probe. All experiments were performed at a Reynolds number of 7200. The tested yaw angle (a) is 0°, 15°, 30° and 45°. The measurements were conducted at different downstream positions to investigate the streamwise evolution of the wake. It is found that the effects of yaw angle on the coherent vorticity are negligibly small for a.< 15°. When a increases to 45°, the maximum of coherent spanwise vorticity reduces by about 50%, while that of streamwise vorticity increases by about 70%, indicating the suppression of spanwise vortices and the enhancement of three dimensionality of the wake with the increase of a. The streamwise decaying rate of the coherent spanwise vorticity is smaller for a larger a. It is because the streamwise spacing between the spanwise vortices is bigger for a larger a, thus this results in a weak interaction between the vortices and hence decays slowly. The coherentcontribution to u' and v! decay slower for a larger yaw angle as moving downstream, consistent with the slowly streamwise decaying rate of ok for a larger yaw angle.
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