Analysis of flow characteristics for different blade outlet angle in LVAD

Abstract

Mechanical heart assist device is an emerging treatment for end stage of heart failure which is an alternative to heart transplant due the shortage of heart donors. Despite the clinical success of Left Ventricular Assist Devices (LVAD), the development still continue as new designs are progressively being tested to address the ever existing complications. Developing centrifugal blood pumps requires determination between adequate pump performance while giving attention to possible occurrence of blood clot and damage. This study utilized a proposed design concept of different impeller angle geometry and evaluate its merits of adapting the concept from a perspective of computational fluid dynamic (CFD) approach. Theoretically, two types of impeller angle design feature were chosen for this study, the radial type 90° and backward facing type (50° and 70°) impellers of the blood pump to provide data on both the flow characteristics and pressure distribution of the blood pump (LVAD). Three model variations were constructed from the design parameters for comparison with experimental data. Shear Stress Transport (SST) turbulent model under steady state analysis was used to simulate 3 impeller blade angles with initial boundary setup was known for operating speed and flowrates. Evaluation involved assessing the model variants based on several performance criteria. Ranked selection method was used to rate and select the best performing model variation with a good compromise between the pressure head produced and the percentage of hydraulic efficiency as output level among the geometries. CFD results showed that impeller with blade outlet angle of 50° has the most efficient blood pump configuration among the three types of impeller blades. Pressure gradient drop for this impeller angle is the lowest compared with 90° and 70°. Ranking and selection of the model variants resulted in the backward facing 50° impeller blade ranked as the best performing configuration that gives the good compromise of pump performance setup.