Abstract

The spiral vortex pump (SV), an innovative, penumatically-driven ventricular assist device, was tested using flow visualization technique and laser Doppler anemometry to study effect of the inlet valve orientation under steady flow condition. The pump was operated in a purposely constructed steady flow circuit aimed at obtaining flow field data both qualitatively and quantitatively. Qualitative information was obtained using flow visualization technique. Slit lighting technique and florescent bees provided clear flow field view at desired location. The flow fields were photographed using 35mm SLR camera and Hi8 type 8mm video camera, clearly capturing vortex nature of the flow field. Quantitative informations in terms of mean velocity and fluctuating velocity profile were obtained using Kanomax single channel FLV system (Fiberoptic Laser Velocitimeter: Nihon Kagaku Kogyo, Model 8801 with Model 8015 Frequency Tracker). Three diametrical traverse locations (immediately downstream; 45° downstream and 90° downstream from the inlet valve) and three vertical locations (5, 10, and 15 mm from the diaphragm at neutral location) were selected for measurements. Both qualitative and quantitative comparison of the records demonstrated vortex nature of the flow field and confirmed relatively high velocity at HD junction (Housing-Diaphram junction). It also showed clear influence of the inlet valve orientation on the flow field inside the pump. Based on the experimental data, the following general conclusions can be made: (i) the SV pump created vortex flow field inside the pump; (ii) the inlet valve orientation sharply influence the flow inside the SV pump; (iii) the minimum flow disturbance was observed when the major orifice of the inlet valve is situated towards upward (pump outlet direction); and (iv) the maximum flow disturbance was observed when the major orifice of the inlet valve is situated towards downward (diaphragm direction).