Investigation of hydraulic performance in an axial-flow blood pump with different guide vane outlet angle

This article investigates the effect of the guide vane outlet angle on the hydraulic performance and pressure fluctuation of the blood pump. In this study, an implantable two-stage axial-flow blood pump with guide vanes was used as the research model, and the guide vane outlet angle beta(4) was designed to be 20 degrees, 15 degrees, 10 degrees, and 5 degrees. The whole flow field in the pump under different guide vane outlet angles was unsteady and simulated by commercial code FLUENT. The simulation results were validated by experimental results, which use Xanthan gum solutions with concentration of 0.6 wt.parts per thousand as working fluid. The results indicate that the pump head and efficiency of the pump are the best when the guide vane outlet angle is 10 degrees. Then, the effects of guide vane outlet angle on the pressure fluctuation of blood pump were analyzed. In one rotation period, all the pulsations of the pressure fluctuation are periodic and there are one large peak and one small peak; the decrease in the guide vane outlet angle beta(4) makes the internal flow in the pump more uniform, which would lead to higher head and efficiency of the pump. But if the beta(4) is too small, the flow passage of the guide vane will become too narrow, thus the flow velocity in the guide vane is extremely high that causes the guide vane unable to convert kinetic energy into pressure energy well, which implies more hydraulic loss in the pump. According to the simulation, the minimum pressure pulsation amplitude appears at beta(4) = 10 degrees and the corresponding value is 0.0016, the decrease of which reaches as much as 18.8% of maximum pulsation amplitude 0.00197.