Blood damage and turbulence: in vitro study of the turbulence-induced hemolysis in a Taylor-Couette-System

点击翻译按钮获取中文摘要

Blood damage caused by turbulence is a huge problem in the clinical use of cardiovascular implants such as ventricular assist devices. Objective: The objective of the project is to investigate the blood damage caused by turbulence in-vitro. This has not yet been achieved, as turbulence chambers commonly used in fluid mechanics are not suited for investigation of blood flows. Using an experimental turbulence chamber, a Taylor-Couette system (TCS) with counter-rotating cylinders, turbulence can be generated, and blood damage caused by turbulent flow features can be investigated experimentally. State of the art: The importance of blood damage for ventricular assist devices is judged as an important issue in the international literature. A variety of damage models is presented, but there is a lack of consensus between the respective models as well as between models and underlying experiments. Currently, there is no in-vitro model known, which permits to subject a limited blood volume to a defined turbulence. Hypothesis: The hypothesis is, that blood damage caused by turbulence can be experimentally investigated in a special TCS. In this flow chamber the inner and the outer cylinder can be rotated independently from each other. When counter rotating with distinct rotational speeds, featureless turbulence is generated in the gap between both cylinders. So far, this effect was not yet used for the investigation of blood damage due to turbulence flows. Furthermore, a nearly homogenous laminar shear flow with similar average shear rates can be generated in the same Couette flow chamber. Using this feature, a direct comparison between laminar and turbulent flow conditions can be performed. Methods: Using the TCS with counter rotating cylinders, a turbulent flow is generated in the gap. Using the same flow chamber, the fluid in the gap can be subjected to laminar and turbulent shear flow with the same average shear rate. The flow characters are investigated using a test fluid modelling the multiphasic behavior of blood and a two velocity-component LDA probe. Characteristic turbulence parameters are assessed as a function of rotational speed and effects of flow conditions, turbulence intensity, time will be investigated as well as the variance of those turbulent parameters. For the assessment of blood damage, blood samples of animals and healthy volunteers are investigated with current clinical standard methods. Finally, a model for prediction of blood damage based on turbulence parameters will be developed.