Development of the Multistage Centrifugal Blood Pump for the Extended Use of Rotary Blood Pumps

本文研究了一种新型多级叶轮离心泵的研制。多级叶轮的使用可以在不增加电机转速的情况下产生高压。这种结构的直接优势将是减少设备中血细胞破坏（血液创伤）的数量。第一台样机是在流量为3.0 L/min、压差为500 mmHg的虚拟工况下设计的。原型机采用了以下设计特点，以确保高压的产生。入口通道中的吸入蜗壳。叶轮外形为高压型。双蜗壳，以尽量减少径向推力对叶轮的第一个原型证明了足够的泵的性能。通过对该装置内部流场的CFD分析，揭示了该装置在血细胞破坏和血栓形成方面的设计改进需求。1 .在叶轮上增加前叶冠2 .在双蜗壳的舌部使用更大的间隙3 .使用带冠的回流叶片2 .经过上述改进的第二个原型机的水力性能略有下降，这是由于设计变化增加了内部泄漏流量，从而提高了设备的冲洗条件。然而，我们成功地降低了超过血细胞破坏致死值的最大剪切应力，并消除了可能导致血栓形成的停滞区域。

The present study deals with the development of a novel centrifugal pump which consists of the multistage impeller. The use of a multistage impeller leads to generation of high pressure without increasing the rotational speed of the motor. The direct advantage of this structure will be the decreased amount of the blood cell destruction(blood trauma) in the device.The first prototype was designed for the virtual working condition of the flow rate of 3.0 L/min and the pressure difference of 500 mmHg. The prototype employs the following design features to ensure generation of high pressure.1. the suction volute in the inlet passage2. the impeller profile for high pressure3. the double volute to minimize the radial thrust on the impellerThe first prototype demonstrated the sufficient pump performance. The CFD analysis of the internal flow field of the device has revealed the need for design improvement in terms of the blood cell destruction and thrombus formation in the device.1 addition of the front shroud to the impeller2 use of the wider gap in the tongue of the double volute casing3 use of the shrouded return vaneThe second prototype with the above improvements demonstrated a bit lower hydraulic performance due to the increase in the internal leakage flow associated with the design change to enhance the wash-out condition of the device. However, we succeeded in decreasing the maximum shear stress over the lethal value for blood cell destruction and in elimination of the stagnant area which possibly leads to the thrombus formation.