逆压梯度转捩边界层流动结构显示

采用氢气泡时间线方法,对逆压梯度条件下人工激发平板边界层转捩过程中扰动的发展和演化特性进行观测,其中引入计数器技术实现对不同位置的平面图及侧面图的流动显示结果在同一相位条件下进行分析.除了T-S波和发卡涡等典型的流动结构,试验结果还揭示出转捩过程中二次发卡涡的再生、展向多个发卡涡的出现以及流动破裂等重要现象的细节和机制.

Visualization study on the flow structures in the transitional boundary layer under an adverse pressure gradient

By using hydrogen bubble time-line method,the characteristics and evolution of flow structures in an excited transitional boundary layer under an adverse pressure gradient were studied.In the experiments,a digital indicator was used,by which the visualization results of plan view and side view at different position can be analyzed coherently at the same phase of the induced perturbation.Besides the T-S wave and hair-pin vortex which is typical in the transitional boundary layer,the results highlights some important detail phenomena and mechanisms of the re-generation of second hair-pin vortices,the appearance of multiple streamwise vortices,as well as the initial flow breakdown.