端部状态对斜置圆柱气动力分布的影响

在有限长度圆柱气动力测试风洞试验中，端部状态的变化对气动力有很大影响。在雷诺数为6.43×104时，通过刚性模型风洞测压试验对3种端部状态下的斜置圆柱气动力特性进行研究，基于平均风压系数沿斜置圆柱的轴向和周向分布规律，分析端部状态对斜置圆柱气动力测试结果的影响。结果表明:斜置圆柱表面风压沿轴向可分为近上游端部区、中间区和近下游端部区；由于马蹄涡的存在，在近上游端部区的背风面，风压沿轴向有一个突变，端部状态对马蹄涡强度有很大影响；在中间区，背风面风压沿轴向出现交替变化，可能是由于在近上游端部区形成的旋涡受到轴向流作用向中间区流动导致的，端部状态对交替风压变化的幅度和阻力系数有很大影响；当下游端部封闭时，近下游端部区的迎风面和背风面风压都会出现突变，且迎风面的突变幅度更大，下游端板对近下游端部区迎风面的风压分布影响更大。

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.