间隙环流作用下的泰勒涡演化及环流速度分布特性研究

Evolution of Taylor Vortex in Annular Gap Flow and Its Velocity Distribution Characteristics

屏蔽电机运转过程中由于粘性旋转流体所受到的离心力作用,间隙内部出现泰勒涡结构,使得间隙环流有着复杂的速度分布特性.这种速度分布特性不仅对屏蔽电机水力损耗及散热特性具有重要影响,而且也是屏蔽电机转子动力学所关注的基础科学问题.本文借助间隙环流流动性能实验平台,采用高速摄像机拍摄观测了湍流核心区泰勒涡的演化过程,面向工程应用阐明了间隙环流湍流核心区流动对边界层速度的影响规律,可为设计屏蔽电机间隙流道的尺度提供理论依据.采用计算流体动力学软件建立间隙环流仿真模型,研究了定间隙条件下泰勒涡的演化过程与环流速度分布特性,初步探讨了变间隙比对间隙环流速度结构的影响规律.研究结果表明,泰勒涡随间隙比及转子转速演化的仿真计算结果与实验测试结果的变化趋势较吻合.泰勒涡在径向与轴向方向上的速度分布具有显着差异,间隙环流涡的流动方向会改变流动边界的速度结构.当转速增大时,间隙环流由层流转变为湍流,速度形状不再沿间隙径向线性分布,而是产生畸变,呈现出壁面周围速度快速减小,中间速度渐趋平稳的轮廓.

In the working process of the shield motor,the Taylor vortex structure appears in the gap due to the centrifugal force acting on the viscous fluid,leading to the complex velocity distribution characteristics of the gap circulation.This velocity distribution characteristic not only has an important impact on the hydraulic loss and the heat dissipation characteristics of the shielded motor,but is also a basic scientific problem concerned by the community of the rotor dynamics of shielded motor.In this paper,the evolution process of Taylor vortex in the turbulent core region has been captured by a high-speed camera through the experiment platform of gap circulation flow performance.The effects of the flow in the turbulent core region of the gap circulation on the boundary layer velocity has been elucidated for engineering applications,which can provide a theoretical basis for the design of the gap flow channel size of shielded motor.The computational fluid dynamics(CFD)software has been used to establish the gap circulation simulation model.The evolution of Taylor vortex in gap circulation and the velocity distribution characteristic under the fixed gap condition have been studied.The influence of the varied gap ratio on the velocity distribution structure of gap circulation has been explored.It shows that the simulation results are in good agreement with the experimental results.The velocity distributions of Taylor vortex in the radial and axial directions are significantly different,and the flow direction of the gap circulation vortex will change the velocity structure of the flow boundary.With the increase of rotating speed,the gap circulation transforms from laminar flow to turbulent flow.Its velocity shape also becomes distorted,developing from a linear distribution along the radial direction of the gap to a velocity profile where the velocity near the walls decreases rapidly and the intermediate velocity tends to be flat.