In centrifugal rotary blood pumps (RBP), clearances are a critical parameter in determining blood trauma. This study investigates the effect of axial clearance (Cax) and radial clearance (Crad) on the hydrodynamic and hemolytic performance of a centrifugal RBP. A centrifugal pump was parameterized so that it could be defined by geometric variables Cax and Crad. Optimal Latin hypercube sampling was used to determine design points based on Cax, Crad, and rotor speed (ω). For each design point, a computational simulation was conducted to determine efficiency (η) and normalized index of hemolysis (NIH). Next, a response surface (RS) was created to estimate these performance parameters based on the design variables. The results show that for a given Cax, when Crad is decreased, η increases until Crad = 0.15 mm, beyond which η deceases. For a given Crad, Cax has a unimodal relationship with η. The NIH has a unimodal relationship with both Cax and Crad. The mechanisms behind these relationships were investigated by various analytical methods. It was found that vortices in the secondary flow paths were a critical factor in determining efficiency and hemolysis. The optimal clearance values discerned in this study are only valid for the specific impeller geometry and operating conditions analyzed.
From the *School of Engineering and Materials Science, Queen Mary University of London, London, United Kingdom
†Department of Cardiology, Barts and the London NHS Trust, London Chest Hospital, London, United Kingdom
‡Parks College of Engineering, Aviation and Technology, Saint Louis University, St. Louis, Missouri.
Submitted for consideration February 2017; accepted for publication in revised form September 2017.
This report is an independent research funded by the National Institute for Health Research (i4i, Turbocardia, II-LB-1111–20007). Principal Investigator for the grant is Prof. T. Korakianitis. The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health.
Disclosure: The authors have no conflicts of interest to report.
Correspondence: Theodosios Korakianitis, Parks College of Engineering, Aviation and Technology, Saint Louis University, St. Louis, MO 63103. Email: email@example.com.