Automated CFD shape optimization of stator blades for the PediaFlow pediatric ventricular assist device

TL;DR

This paper presents an automated CFD shape optimization method for stator blades in a pediatric ventricular assist device, improving pressure recovery and pump efficiency while assessing hemocompatibility effects.

Contribution

It introduces a novel automated CFD optimization approach for stator blade design that enhances performance and evaluates blood compatibility in a pediatric VAD.

Findings

Optimized design with 2 blades achieved 73 mmHg pressure recovery.

Stator stage increased pump head by 46%.

Pump efficiency improved from 21.9% to 25.7%.

Abstract

PediaFlow is a miniature mixed-flow ventricular assist device for neonates and toddlers. PediaFlow has a fully magnetically levitated rotor which improves biocompatibility, but the increased length of the rotor creates a long annular passage where fluid energy is lost. Therefore, a set of helical stator blades was proposed immediately after the impeller stage to remove the swirling flow and recover the dynamic head as static pressure. Automated computational fluid dynamics (CFD) shape optimization of the stator blades was performed to maximize pressure recovery at the operating point of 1.5 LPM and 16,000 RPM. Additionally, the effect on hemolysis and thrombogenicity was assessed using numerical modeling. The optimization algorithm favored fewer blades of greater length over a larger number of short blades. The ratio of wrap angle to axial length emerged as a key constraint to ensure the viability of a design. The best design had 2 blades and generated 73 mmHg of pressure recovery in an isolated stage. When re-introduced to the CFD simulation of the complete flow path, the added stator stage increased the pump head by 46% and improved the pump efficiency from 21.9% to 25.7% at the selected operating point. Automated CFD shape optimization combined with in silico evaluation of hemocompatibility can be an effective tool for exploring design choices and informing early development process.