Interaction of low aspect ratio, cantilevered, chamfered cylindrical pins with a laminar boundary layer

The flow field associated with cantilevered, low aspect ratio cylindrical pins having different chamfered free-ends were investigated using oil flow visualizations and stereoscopic particle image velocimetry at ${\text{Re}}_D=8\times {10}^3$. Two chamfered pins, where the chamfer encompassed either half of the pin's planform or its full planform, were analyzed with the chamfer at various skew angles with respect to the freestream and were compared with a pin without a chamfer. All pins exhibited a complex flow field, including an array of streamwise vortical structures. The chamfered pins resulted in two additional counter-rotating streamwise vortices, named chamfered induced vortices (CIVs). It was shown that changing the skew angle resulted in a change in the strength of these vortical structures, their direction of rotation, and as a result, the net circulation produced. Comparing the two chamfered pins, the pin where the chamfer encompassed half of its planform produced stronger CIVs. These effects are discussed in detail to provide insight into a future use of these pins as flow control devices.