Analyses of the Unsteady Fluid Force on the Impeller of a Centrifugal Blood Pump

离心式血泵叶轮非定常流体力分析

基本信息

批准号：
15360103
负责人：
TSUKIYA Tomonori
金额：
$ 5.38万
依托单位：
Research Institute of National Cardiovascular Center
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

The present study deals with the analyses of the rotor-dynamic fluid force acting on the impeller of a miniature centrifugal pump developed as a left ventricular assist device. The final goals are to clarify the causes of the unstable problems on the impeller motion of a magnetically-coupled centrifugal pump and to present the design standards for vibration problems. The in-house blood pump originally designed as a left ventricular assist device was selected as the object pump. The displacement of the impeller was measured using two laser displacement meters to obtain the lateral loci of the impeller under the wide range of working conditions. The average position of the impeller shifted in the direction of the outlet port as the flow rates increased at the all investigated rotational speeds (1500 - 3000 rpm). The frequencies of the whirling motion of the impeller were between 0.7 and 0.5, and the rotational velocity components around the impeller bush was influential on the frequency of the whirling motion. This flow works also as the leakage flow, which is expected to wash the bottom area of the pump casing to avoid thrombus formation inside the pump. The practical operational conditions of the pump include flow fluctuation of a large-scale, which was caused by the beatings of the native heart of the patients. The impeller displacements were also measured under the pulsatile conditions by the use of pulsatile blood pump placed at the upstream of the test pump. The results showed no significant difference from the loci of the steady flow rate conditions.For the measurements of the rotordynamic fluid forces, a 7.5 time scale-up model of -the impeller was manufactured and tested under whirling motion. The results are that the unsteady forces are generated on the impeller with the open-blades without the shroud, and that unsteady force becomes steady at the frequency ratio of 0.7 to 0.8.

本研究涉及作用在作为左心室辅助装置开发的微型离心泵叶轮上的转子动态流体力的分析。最终目标是阐明磁力耦合离心泵叶轮运动不稳定问题的原因，并提出振动问题的设计标准。选择最初设计为左心室辅助装置的内部血泵作为对象泵。采用两台激光位移计测量叶轮的位移，获得大范围工况下叶轮的横向轨迹。在所有研究的转速（1500 - 3000 rpm）下，随着流量的增加，叶轮的平均位置向出口方向移动。叶轮回转运动的频率在0.7~0.5之间，叶轮轴套周围的转速分量对回转运动的频率有影响。该流也作为泄漏流，预计会冲洗泵壳的底部区域，以避免泵内形成血栓。泵的实际运行工况包括由患者自身心脏跳动引起的大范围的流量波动。还通过使用放置在测试泵上游的脉动血泵在脉动条件下测量叶轮位移。结果表明与稳定流量条件下的轨迹没有显着差异。为了测量转子动力流体力，制造了7.5倍放大的叶轮模型并在旋转运动下进行了测试。结果表明，开式叶片、无护罩的叶轮上产生非定常力，且在频率比为0.7～0.8时非定常力变得稳定。