电加热圆柱尾迹涡的流动显示

本文在低湍流度风洞及水槽中，就低雷诺数范围内对加势圆柱尾迹涡进行流动显示研究，实验表明在水介质中均匀加热圆柱时可促进其尾涡的脱落、而沿展向局部加热时，其局部涡脱落频率增大，导致原准二维卡门涡街三维化；相反空气中加热圆柱对旋涡脱落有扼制作用，本文首次观察到加热诱发的圆柱尾迹不稳定性的展向波，表现为Ｒｅ＾＊〈Ｒｅ（临界涡脱落雷诺数）时双子涡展向断裂成间距为展向波长λ的涡段。圆柱加热增强了尾迹近区的不稳

Flow Visualization of the Wake behind Electrically Heated Circular Cylinder

Flow visualization experiments of the wake behind a heated circular cylinder in the low Reynolds number range are conducted to study the effect of heat transfer on the downstream evolution of the wake. Water channel visualization photographs show that the heat transfer along the whole model promotes the vortex shed-ding, and the local heat transfer at the centre of the model leads to form the three-dimensional structures. On the contrary, experiments carried out with a heated circular cylinder located in a wind tunnel show that complete suppression or modification of the vortex shedding phenomenon can be achieved with the increase of heat input. Flow visualization of the heated circular cylinder suggests that the heat transfer has significant influence on the two-dimensional and three-dimensional instabilities in wakes. The visualization photographs of cells in steady wake region and netting pattern and vortex ring in downstream region are pressented in this paper.