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  • Study of velocity and shear stress distributions in the impeller passages and the volute of a bio-centrifugal ventricular assist device.

Study of velocity and shear stress distributions in the impeller passages and the volute of a bio-centrifugal ventricular assist device.

Artificial organs (2008-05-13)
Leok Poh Chua, Kang Shiu Ong, Guoliang Song
ABSTRACT

The velocity fields within the impeller passages of three different impellers of the Kyoto-NTN bio-centrifugal ventricular assist device are measured using laser Doppler velocimetry in this study. The 16 forward-swept-blade impeller has better performance than the 16 straight-blade and 8 backward-swept-blade impellers in terms of smooth flow pattern, and has less high-shear-stress regions in the passages. The flow distributions are found to be similar with those measured by Yu et al. Through-flow characteristics are found in the impeller when the passages open to the biggest volute space. The flow fields in the blade channels of the impeller were found to be axis symmetrical due to the double volute design with the objective of minimizing the imbalance of the radial thrust when the impeller is magnetically suspended. In addition, the high-intensity vortex which was detected by Yu et al. at the discharge channel of the pump is effectively reduced when the end of the splitter plate is modified by increasing the taper ratio from 4 to 20. The new design would reduce the hemolysis of blood due to the high shear rate of the vortex.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Ammonium thiocyanate solution, 0.1 M, 1/10 N
Sigma-Aldrich
Ammonium thiocyanate, SAJ special grade, ≥99%
Sigma-Aldrich
Ammonium thiocyanate, powder
Sigma-Aldrich
Ammonium thiocyanate, ACS reagent, ≥97.5%
Supelco
Ammonium thiocyanate, 99.99% trace metals basis