Synchronous PIV analysis of a self-powered blood turbine- pump couple

A magnetically-coupled blood turbine and pump system (iATVA) that resembles a turbocharger can provide mechanical circulatory support without external power to right-heart failure patients[1]. In this study, the fluid dynamics of the turbine and turbine-pump coupling efficiency are studied for the first-time in the literature. Optically clear prototypes are 3D printed. A time-resolved particle image velocimetry set-up equipped with a beam splitter allowed simultaneous velocity field acquisition from both impellers. The system is triggered with impeller rotation and velocity data is acquired at 6 different impeller orientations. Background subtraction, and multi-pass cross correlation were utilized as a pre and post-processing. The experimental pipeline is first verified through experiments with the FDA pump prototype, where two recirculation regions are observed, and impeller orientations affect the nozzle flow (0.25 to 0.42 m/s +-3.5% error). Coupled impellers operated synchronously. The peak velocity of the turbine span ~25% of the inter blade passage is operating at impulse mode. Backflow at the turbine exit tip reached 3/5 of peak flow. While turbine flowrates increase from 1.6 to 2.4 LPM, the relative inlet flow angle and rotation speed of the turbine change from 38 to 55% and from 630 to 900 rpm. Tip clearance leakage is localized at impeller inlets. Another recirculation region is observed in the coupled pump. Results will be used in CFD validation and to optimize iATVA system.