Study on Fluid Dynamic Characteristics of Turbulent Blood Flow

由人工心脏组成的心室辅助系统中的压力-流量关系有助于诊断和检测系统的异常情况，或开发省去所用装置的压力和流量传感器的间接测量系统。例如，我们开发了利用离心式血泵驱动电机的功耗进行间接流量测量的系统。然而，这种关系受制于血液的物理性质以及系统的配置。血液流动的物理性质，或血液的流变学，是实现这一目标的关键，但关于湍流状态下血液流动的物理性质的报道很少，这种情况经常在人工心脏等机械辅助装置中观察到。测量并比较了山羊血和牛顿流体在圆管内的湍流压降。羊血示威者…比牛顿流体压降略有下降，且压降下降的幅度与血细胞浓度无关。尝试用电机功耗间接测量离心式血泵的流量，考察了粘度变化对测量精度的影响。我们研究所研制的离心式血泵安装在左心尖部和降主动脉之间，进行左心转流。在已知粘度的情况下，用该方法测得的流量具有足够的精度，可用于实际应用。误差程度随术后一段时间内红细胞压积的变化而波动。通过用牛顿流体获得的校准数据，将血液的粘度测量到实际可接受的范围，可以修正这些误差。在实际应用中，由于非牛顿性质引起的湍流压降差异在湍流管流中被观察到，在这种流量测量方法中被发现是可以忽略不计的。较少

The pressure - flow rate relationship in the ventricular assist system consisting of an artificial heart is helpful in order to diagnose and detect abnormal condition of the system, or to develop indirect measurement system which saves sensors for pressure and flow rate of the device being used. For example, we have developed the indirect flow rate measurement system using the power consumption of the driving motor of the centrifugal blood pump. This relationship, however, is subject to the physical properties of blood as well as the configuration of the system. The physical properties of flowing blood, or rheology of blood, is essential for such aims, but reports on physical properties of flowing blood under turbulent state, which is often observed in the mechanical assisting devices like artificial hearts, has hardly been investigated. The pressure drop across the circular pipe of turbulent flow was measured and compared between goat blood and a Newtonian fluid. Goat blood demonstrat … More ed slight decrease in the pressure drop than the Newtonian fluid, and the magnitude of the decrease in pressure drop was independent of blood cell concentration. The indirect measurement of flow rate of a centrifugal blood pump using motor power consumption was attempted, in which the effect of viscosity change on the accuracy was investigated. The centrifugal blood pump developed in our research institute was installed between the left apex and the descending aorta making a left heart bypass. The flow rate measured by this method has demonstrated sufficient accuracy for practical use when the viscosity is known. The extent of errors fluctuated with the change of hematocrit after in the course of time after surgical operation. The errors could be corrected by measuring the viscosity of the blood to the practically acceptable range by calibration data obtained with Newtonian fluids. The difference in pressure drop in turbulence due to Non-Newtonian properties, which was observed in the turbulent pipe flow, was found to have negligible effects in this measurement method of flow rate for the practical use. Less