均匀流中悬臂圆柱体气动力雷诺数效应∗

摘要

通过风洞试验对均匀来流中长径比为5的悬臂圆柱体气动力进行了研究.试验中圆柱直径为200 mm,来流风速为5~45 m/s,对应的雷诺数为0.68×105~6.12×105,涵盖了亚临界、临界与超临界区间.研究表明,尽管悬臂圆柱处于均匀流中,但其气动力特性在不同高度上仍存在显著的差异,悬臂圆柱气动力也存在着明显的雷诺数效应.其从亚临界进入临界区所对应的临界雷诺数略大于二维圆柱.悬臂圆柱阻力系数在临界雷诺数范围内的减小幅度明显小于二维圆柱.在亚临界区内,悬臂圆柱阻力系数小于二维圆柱的对应值,而在超临界区则大于后者.尽管处于均匀流中,悬臂圆柱不同高度所对应的临界雷诺数并不相同,越接近自由端越早出现从亚临界向临界区的转变.%The aerodynamic forces on a cantilevered circular cylinder with an aspect ratio of 5 were ex-perimentally investigated in a wind tunnel.The diameter of the cylinder d was 200 mm.The oncoming flow velocity ranged from 5 m/s to 45 m/s,corresponding to Reynolds number of 0.68×10 5 ~6.12×10 5 , which covered subcritical,critical and transcritical regimes.It was found that,although the cantilevered cylinder is in uniform flow,its aerodynamic forces present significant differences at various spanwise posi-tions,indicating a strong three dimensionality.Reynolds number has profound effect on the aerodynamic forces on the cantilevered cylinder.The critical Reynolds number is smaller for the cantilevered cylinder relative to that of 2D cylinder.In the critical regime,reduction in the drag coefficient (C d )of the cantile-vered cylinder is relatively smaller compared with that of 2D cylinder.In subcritical regime,C d of the can-tilevered cylinder is smaller than that of 2D cylinder.On the other hand,C d of the former is larger in tran-scritical regime.The critical Reynolds number is different at various spanwise locations for the cantilevered cylinder.Transition from subcritical to critical regimes occurs earlier near the free end of the cantilevered cylinder.