A Characterization of Pulsatile Flow by Positron Emission Particle Tracking

Multi-positron emission particle tracking (M-PEPT) is a Lagrangian measurement technique that can be used to evaluate flow attributes. This study seeks to characterize steady flow in a tube, pulsatile flow in a circular and pinched cross section tube and explore particle detection uncertainties of our M-PEPT measurement. A pump driven flow loop and motorized ball valve are designed to create the pulsatile flow of frequency 2.1 Hz in a 19 mm diameter and 3.2 mm thick Masterkleer PVC tube. Anion exchange resins of 600-800 microns are labeled with fluorine-18 (half-life: 109.8 minutes) and pumped through the flow loop at flow velocity near 1 m/s, Womersley number near 70 and approximate Reynolds number of 20,000. Bulk flow velocity and pressure are measured to define the pulsatile flow features. In addition, particle trajectories are collected using M-PEPT and synchronized to a trigger signal produced by laser-photodiode mounted on the motorized ball valve. Trajectories are divided into 20 equally spaced time gated frames in each pulse cycle. A three-dimensional velocity field is generated at each phase of the pulse cycle by integrating time gated data from several hundred pulse cycles. The average location uncertainty in the M-PEPT measurement is calculated to be near 0.31 mm in the x and y-direction and 0.2 mm in z. The turbulent kinetic energy and diffusion characteristics of a steady flow is also presented.