Qian K X, Feng Z G, Ru W M, Zeng P, Yuan H Y
Biomedical Engineering Institute, Jiangsu University, Zhenjiang, PR China.
J Med Eng Technol. 2007 Jul-Aug;31(4):239-42. doi: 10.1080/03091900500219790.
Previously it has been found by pump haemolysis testing that the flow rate has a remarkable effect on index of haemolysis (IH), while pressure head does not affect IH. Recent investigation with particle image velocimetry (PIV) technology has demonstrated that IH is directly related to the flow pattern of stream field in impeller vane channels. PIV is a visible approach showing the real flow status in the pump. The different positions of a tracer particle in two PIV pictures taken at 20 micros intervals decide the velocity value and direction. The velocity vectors of many particles draw the flow pattern of the stream field. The same pictures are taken at 2, 4 and 6 l min(-1) flow rates while the pressure head is kept unchanged at 100 mmHg; then the pictures are taken at 4 l min(-1) flow with different pressure heads of 80, 100 and 120 mmHg. Results reveal that the flow rate of 4 l min(-1) (IH = 0.030) has the best stream field, and neither turbulence nor separation can be seen. In other flow rates (IH: 0.048 - 0.082), there is obviously second flow. Meanwhile, no significant difference can be seen among the PIV pictures of different pressure heads pumped, which agrees with the results of haemolysis testing showing that pressure has no effect on pump haemolysis. It may be concluded that the haemolysis property of a centrifugal pump can be assessed approximately by PIV pictures, which are much easier to take than haemolysis tests.
此前通过泵溶血试验发现，流速对溶血指数（IH）有显著影响，而压头对IH没有影响。最近利用粒子图像测速（PIV）技术进行的研究表明，IH与叶轮叶片通道内流场的流动模式直接相关。PIV是一种可视化方法，可显示泵内的实际流动状态。示踪粒子在以20微秒间隔拍摄的两张PIV图片中的不同位置决定了速度值和方向。许多粒子的速度矢量描绘了流场的流动模式。在压头保持在100 mmHg不变的情况下，分别以2、4和6 l min⁻¹的流速拍摄相同的图片；然后在流速为4 l min⁻¹、压头分别为80、100和120 mmHg的不同情况下拍摄图片。结果显示，流速为4 l min⁻¹（IH = 0.030）时流场最佳，未见湍流和分离现象。在其他流速下（IH：0.048 - 0.082），明显存在二次流。同时，不同压头泵送情况下的PIV图片之间未见显著差异，这与溶血试验结果一致，表明压力对泵溶血没有影响。可以得出结论，离心泵的溶血特性可以通过PIV图片大致评估，PIV图片比溶血试验更容易获取。
