项目主要以实验的方式研究初始扰动场为上游物体尾迹的零压力梯度平板边界层旁路转捩，综合运用流动显示、氢气泡时间线测速等方法，对上游横向圆柱绕流尾迹形式下的边界层旁路转捩过程进行了系统研究。结果表明横向圆柱绕流尾迹能否在边界层内诱导产生二次涡将直接决定横向尾迹影响下的边界层转捩路径，二次涡的存在将使旁路转捩过程偏离高湍流度自由来流引起边界层转捩的Klebanoff模式，而呈现出完全不同的路径，以拟序结构按照"二次涡-马蹄涡-马蹄涡包-条带"的路径演化为主要特征。横向圆柱绕流影响下旁路转捩末期和转捩之后的湍流边界层与绊线引起的充分发展壁湍流在主要拟序结构-广义马蹄涡的空间形态和对流速度上具有相似之处，说明湍流产生的动力学机制在从转捩末期到建立充分发展湍流这一过程中始终保持一致，同时马蹄涡的存在对不同方式建立起来的湍流边界层均具有普适性。

With the primary aim focusing onto the bypass transition which is initiated byfree-stream wake, the present investigation studies the transition route induced by the horizontally positioned cylinder wake with flow visualization and digital hydrogen bubble line anemometer. It is found that whether the wake of the horizontally positioned cylinder is able to generate the secondary spanwise vortices inside the boundary layer is critical to the transition route. The existence of the secondary vortices may bring the transition along a way totally different to Klebanoff mode, which is characterized as the evolution route of coherent structures from secondary vortices to hairpin packets and streaks.the transition.Hairpin-like vortices in the later stage of bypass transition, the turbulence stage after bypass transition and the traditionally rode-generated turbulent boundary layer share some similarity with each other both in characteristic shape and in vortex dynamics, thus evidencing both the consistency of the dynamics of turbulence generation from transition to turbulence and the universality of the existence of hairpin-like vortices in turbulent boundary layers being set up through different transition route.

项目主要以实验的方式研究初始扰动场为上游物体尾迹的零压力梯度平板边界层旁路转捩，综合运用流动显示、氢气泡时间线测速等方法，对上游横向圆柱绕流尾迹形式下的边界层旁路转捩过程进行了系统研究。结果表明横向圆柱绕流尾迹能否在边界层内诱导产生二次涡将直接决定横向尾迹影响下的边界层转捩路径，二次涡的存在将使旁路转捩过程偏离高湍流度自由来流引起边界层转捩的Klebanoff模式，而呈现出完全不同的路径，以拟序结构按照"二次涡-马蹄涡-马蹄涡包-条带"的路径演化为主要特征。横向圆柱绕流影响下旁路转捩末期和转捩之后的湍流边界层与绊线引起的充分发展壁湍流在主要拟序结构-广义马蹄涡的空间形态和对流速度上具有相似之处，说明湍流产生的动力学机制在从转捩末期到建立充分发展湍流这一过程中始终保持一致，同时马蹄涡的存在对不同方式建立起来的湍流边界层均具有普适性。