囊腔液体受挤压和抽吸时内流场PIV实验研究

Research on internal flow field of sac by squeeing and pumping based on PIV technology

主动脉旁反搏装置作为治疗心力衰竭的心脏辅助装置,装置腔内的流场结构对装置的机理分析及优化设计具有重要作用。将主动脉旁反搏装置简化为液囊模型,利用粒子成像测速仪(PIV)对液囊内流场进行测量,选取3种液囊截面,每种截面取3种抽吸频率和3种吸气量,共27种工况,采用整体平均法对实验数据进行处理,得到了平均速度矢量图和湍流切应力图。结果表明:装置腔内流场主要是以旋转的形式存在,在装置进出口附近存在二次流动,而且进出口的位置对内部流场影响较大,同时进出口附近流体的动量交换较为强烈,呈现出较大的雷诺应力,另外进出口附近流体流动能够同步响应抽吸频率,且湍涡中心点随时间在不断地移动。

Used as the adjunct device in treating heart failure,the flow field structure inside the ventricular assist device has an important role in the mechanism analysis and optimization design of the device.In the study,ventricular assist device was tested via a sac model and the flow field inside the sac was investigated by PIV（Particle Image Velocimetry）.There were twenty-seven working conditions,which include three different sections of the sac model,with every section containing three operation frequencies as well as three suction gas volumes.The average velocity vector and turbulent shear stress were computed by processing the experimental data with overall average method.It is found that the flow field structure inside the device is mainly in the form of rotation and there are secondary flow near the inlet outlet.Meanwhile,the location of the inlet outlet has significant effect on the flow filed and the fluid around the inlet outlet exchanges momentum strongly which leads to relative large Reynolds shear stress.The fluid can synchronously responded to the suction of different frequencies,and the center point of eddy moves continuously with time.