不同风攻角4∶1矩形柱绕流大涡模拟OA

Using the large eddy simulation method,the overall aerodynamic parameters,surface pressure dis-tribution,mean flow characteristics,and transient flow features of a 4∶1 rectangular cylinder were studied at attack angles of α=0°-12°,Reynolds number of 1.1×10⁴,and a uniform inflow condition.The attack angle effects of the aerodynamic performance and flow field characteristics of the rectangular cylinder,as well as their flow mechanisms,were analyzed.At small attack angles α=0°-1°,the flow around the rectangular cyl-inder exhibits a reattachment flow pattern of the separated shear layers on the upper and lower surfaces,and shows a higher symmetry of the flow field.The mean and fluctuating aerodynamic force coefficients are rela-tively small.At large wind attack angles α=3°-12°,the separated shear layer remains reattaching to the upper surface,while the lower surface does not show stable reattachment,forming large recirculation zones on the lower side and in the wake.As the attack angle increases,the absolute values of the mean aerodynamic force coefficients generally show an increasing trend,and the Strouhal number decreases.Under large attack angles,the 4∶1 rectangular cylinder is subjected to stronger and longer-period cross-flow aerodynamic forces,which may induce vortex-induced vibrations(VIV)or alter the lock-in wind speed interval and amplitude of VIV.