Experimental Study of Pressure Fluctuations from Yawed Circular Cylinders

摘要

Multipoint fluctuating wall pressure measurements are used to examine the spanwise characteristics of the vortex shedding from yawed circular cylinders for yaw angles from α = 60 to 90° and for Reynolds numbers from 2.81 × 10～4 to 5.61 × 10～4. The results indicate that yawing the cylinder to the mean flow direction causes the vortex shedding in the wake to become more disorderly. This, in turn, reduces the correlation length of the cylinder and causes the acoustic dipole sources in the cylinder wake to change from strongly tonal for α = 90° to largely broadband for α = 60°. Low-frequency pressure fluctuations were found to be associated with reasonably well organized structures that develop on the upstream end of the cylinder and span several cylinder diameters in length. These structures appear to disrupt the vortex shedding process along the span of the cylinder.