Effects of end condition on aerodynamic force distribution on a skewed circular cylinder

The change of the end conditions has significant influences on the aerodynamic forces when a finite length cylinder is tested in the wind tunnel for its aerodynamic forces. In the present study, the characteristics of aerodynamic forces on an oblique cylinder with various end conditions at Reynolds number of 6.43×10⁴ are studied through a rigid model pressure test in a wind tunnel. Using the wind pressure distribution along the length of the cylinder, the effects of end conditions on aerodynamic forces on the oblique circular cylinder are revealed. The results show that the wind pressure on the oblique cylinder could be classified into three states along the length of the cylinder, that the state near the upstream end plate, the state at the middle and the state near the downstream end plate. The wind pressure on the leeward near upstream end plate has a significant variation (convex) due to the existence of the horseshoe vortex. The existence of the end plates significantly influences the strength of the horseshoe vortex. At the middle state, the wind pressure on the leeward varies alternately along the length, which is probably induced by the motion of the horseshoe vortex through the axial flow. The end conditions also influence the amplitude of the alternative wind pressure at the leeward and the local drag coefficient on the cylinder. Near the downstream end plate state, wind pressure on the windward and leeward varies sharply when the downstream end plate is closed. The downstream end plate has a more significant influence on the wind pressure distribution at the windward than at the leeward.