(266e) High Speed PIV of Flow Fields in An Impeller Driven Respiratory Assist Catheter

A new high speed particle image velocimetry (PIV) system developed at the USDOE National Energy Laboratory (NET) was applied to visualize and measure flow fields in a novel respiratory catheter being developed at the McGowan Institute of Regenerative Medicine. The novel respiratory catheter consists of a series of small impellers (4 mm dia.) surrounded by a 1 cm diameter bundle of 300 micron diameter of hollow fiber membranes (HFM). The catheter is inserted percutaneously into the femoral vein for placement in the vena cava. To enhance gas exchange, the impellers spin at rates from 5000 to 20,000 rpm to force flow over the HFM's. Many different impeller designs have been tested using measurements of total gas exchange rates over the entire catherer device. In this study, high speed PIV is applied to visualize and measure flow fields produced by the impeller design that produced maximum gas exchange rates. Impeller rotational speeds were varied from 0 to 20,000 rpm and external flow over the HMF was either on or off. Fluorescent particles with a diameter of 30 microns were used as flow markers. High speed PIV produced both qualitative visualization as well as quantitative two dimensional velocity maps of flow fields over the catheter fibers. To resolve time dependence and turbulence, high resolution (1280 x 800 pixel) PIV velocity maps (over a camera frame) were acquired at rates from 1000 to 10,000 velocity maps per second. The PIV velocity maps were used to derive values for permeability constants needed in CFD simulations of flow fields produced in the respiratory catheter.