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    Validation of the first Turkish axial-flow left-ventricular assist device (LVAD) using particle image velocimetry (PIV)
    (Bahçeşehir Üniversitesi Fen Bilimleri Enstitüsü, 2014-12) Dadgar, Sina; Özharar, Sarper
    Heart Failure (HF) is a major cause of mortality in 21st century modern life. HF is the case when human cardiovascular system cannot satisfy body’s metabolic needs with enough pressure and flow. End Stage Chronic Heart Failure (ES-CHF) can only be treated by Heart Transplantation (HT), but due to insufficient number of available donor hearts, Mechanical Circulatory Support Systems (MCSS) have been used to support ES-CHF patients. Left-Ventricular Assist-Devices (LVAD) being one type of MCSSs, support Left Ventricle’s (LV) function by pumping blood from LV to aorta in one direction. Depending on the patient’s situation, LVADs can be implanted on patient’s body for different purposes. Mostly, LVADs are developed in a few 1st world countries and lack of local LVADs in Turkey results in high expanses for importing them. As a result, developing countries like Turkey should design its own LVAD and properly learn its management during R&D phase. So, a study was initiated to construct an innovative domestic LVAD in 2009. A virtual prototype was designed in SolidWorks CAD software and its hemodynamic and hemolysis characteristics were tested in Computational Fluid Dynamics (CFD). Then, physical prototype is constructed based on that design to validate the virtual results. Hemodynamics of the prototype including head pressure and hydraulic efficiency will be tested in actual laboratory environment over a Cardio Vascular Mock Circuit (CVMC). This thesis mainly focuses in flow field acquisition (hemocompatibility) over the physical prototype using Particle Image Velocimetry (PIV) method. In the design process of an LVAD, flow field acquisition is an important stage since it can inspect the presence of backflow, eddies, flow separation, and high shear stress which may cause hemolysis or stagnant and statis which may cause coagulation. Instantaneous flow field acquisition is also helpful to observe transition time and calculate the velocity vectors in different parts of physical prototype. PIV is a high speed photography-based flow visualization technique which is used to evaluate fluid velocity patterns at high spatial resolution. It’s a quantitative method who develops the velocity streamlines of the flow in every single point of flow by tracking suspended particles in fluid. What makes this study unique in its own kind is this project employs a 2-D PIV system to characterize the flow field inside a pump where both axial and tangential velocities exist throughout the pump. Whereas, most of similar studies in literature are using 3-D stereoscopic PIV systems which are much more expensive than 2-D PIV systems. Probe inside the pump requires transparent shroud to allow laser light access the floating particles and illuminate them and camera look into those particles. This desires the pump to be motor-less and make it dependent on an External Driving Mechanism (EDM).