NUMERICAL STUDIES OF AN AXIAL FLOW BLOOD PUMP WITH DIFFERENT DIFFUSER DESIGNS

Most axial flow blood pumps basically consist of a straightener, an impeller, and a diffuser. The diffuser plays a very important role in the performance of the pump to provide an adequate pressure head and to increase the hydraulic efficiency. During the development of an axial flow blood pump, irregular flow field near the diffuser hub is not desirable as it may induce thrombosis. In order to avoid this phenomenon, two approaches were adopted. In the first approach, the number of the diffuser blades was increased from three (B3, baseline model) to five (B5 model). It was observed that the flow field was improved, but the irregular flow patterns were not completely eliminated. In the second approach, we detached the blades from the diffuser hub (B3C2 model), which was integrated and rotated with the impeller hub. It was found that the rotary diffuser hub significantly improved the flow field, especially near the diffuser hub. Besides the detailed flow fields, the hydraulic and hematologic performances at various flow conditions were also estimated using computational fluid dynamics (CFD). Although each design has its own advantages and disadvantages, the B5 model was superior based on a comparative overview.

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Multi-parameter analysis of the effects on hydraulic performance and hemolysis of blood pump splitter blades

Advances in Mechanical Engineering ◽

10.1177/1687814020921299 ◽

2020 ◽

Vol 12 (5) ◽

pp. 168781402092129

Author(s):

Zheqin Yu ◽

Jianping Tan ◽

Shuai Wang

Keyword(s):

Flow Field ◽

Axial Length ◽

Axial Flow ◽

Hydraulic Performance ◽

Parameter Analysis ◽

Blood Pump ◽

Computational Fluid Mechanics ◽

Structural Improvement ◽

Axial Flow Blood Pump ◽

And Performance

The splitter blade can effectively optimize pump performance, but there is still insufficient research in blood pumps that cover both hydraulic and hemolysis performance. Thus, the aim of this study was to investigate the effect of key factors related to splitter blade on the performance and flow field of axial flow blood pump. In this study, the number of splitter blades, the axial length, and the circumferential offset were chosen as three objects of study. An analysis of the flow field and performance of the pump by orthogonal array design using computational fluid mechanics was carried out. A set of hydraulic and particle image velocimetry experiments of the model pumps were performed. The result showed that the pump had greater hydraulic performance without sacrificing its hemolytic performance when it had two splitter blades, the axial length ratio was 0.6, and the circumferential offset was 15°. Based on these reference data, the splitter blade may contribute to greater hydraulic performance of the pump and cause no side effect on the velocity distribution of the flow field. This finding provides an effective method for the research, development, and application of structural improvement of the axial flow blood pump.

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Analysis of flow field and hemolysis index in axial flow blood pump by computational fluid dynamics–discrete element method

The International Journal of Artificial Organs ◽

10.1177/0391398820917145 ◽

2020 ◽

Vol 44 (1) ◽

pp. 46-54

Author(s):

Lizhi Cheng ◽

Jianping Tan ◽

Zhong Yun ◽

Shuai Wang ◽

Zheqin Yu

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Numerical Calculation ◽

Flow Field ◽

Discrete Element Method ◽

Axial Flow ◽

Discrete Element ◽

Blood Pump ◽

Axial Flow Blood Pump ◽

Element Method

To fully study the relationship between the internal flow field and hemolysis index in an axial flow blood pump, a computational fluid dynamics–discrete element method coupled calculation method was used. Through numerical analysis under conditions of 6000, 8000, and 10,000 r/min, it was found that there was flow separation of blood cell particles in the tip of the impeller and the guide vane behind the impeller. The flow field has a larger pressure gradient distribution, which reduces the lift ratio of the blood pump and easily causes blood cell damage. The study shows that the hemolysis index obtained by the computational fluid dynamics—discrete element method is 4.75% higher than that from the traditional computational fluid dynamics method, which indicates the impact of microcollision between erythrocyte particles and walls on hemolysis index and also further verifies the validity of the computational fluid dynamics–discrete element coupling method. Through the hydraulic and particle image velocimetry experiments of the blood pump, the coincidence between numerical calculation and experiment is analyzed from macro and micro aspects, which shows that the numerical calculation method is feasible.

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Design of Implantable Axial-Flow Blood Pump and Numerical Studies on Its Performance

Journal of Hydrodynamics ◽

10.1016/s1001-6058(08)60170-5 ◽

2009 ◽

Vol 21 (4) ◽

pp. 445-452 ◽

Cited By ~ 8

Author(s):

Hui-min Fan ◽

Fang-wen Hong ◽

Lian-di Zhou ◽

Yin-sheng Chen ◽

Liang Ye ◽

...

Keyword(s):

Axial Flow ◽

Blood Pump ◽

Axial Flow Blood Pump ◽

Numerical Studies

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COMPARISON AND EXPERIMENTAL VALIDATION OF TURBULENCE MODELS FOR AN AXIAL FLOW BLOOD PUMP

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519419400633 ◽

2019 ◽

Vol 19 (08) ◽

pp. 1940063

Author(s):

SHUAI WANG ◽

JIANPING TAN ◽

ZHEQIN YU

Keyword(s):

Velocity Field ◽

Flow Field ◽

Axial Flow ◽

Turbulence Models ◽

Internal Flow ◽

Reynolds Stress Model ◽

Blood Pump ◽

Axial Flow Blood Pump ◽

Standard Formula ◽

Text Model

Computational fluid dynamics (CFD) has become an essential tool for designing and optimizing the structure of blood pumps. However, it is still questionable which turbulence model can better obtain the flow information for axial flow blood pump. In this study, the axial flow blood pump was used as the object, and the influence of the common turbulence models on simulation was compared. Six turbulence models (standard [Formula: see text]–[Formula: see text] model, RNG [Formula: see text]–[Formula: see text] model, standard [Formula: see text]–[Formula: see text] model, SST [Formula: see text]–[Formula: see text] model, Spalart–Allmaras model, SSG Reynolds stress model) were used to simulate the pressure difference and velocity field of the pump. In parallel, we designed a novel drive system of the axial flow blood pump, which allowed the camera to capture the internal flow field. Then we measured the flow field in the impeller region based on particle image velocimetry (PIV). Through the comparison of experiments and simulation results, the average errors of velocity field obtained by the above models are 30.97%, 19.40%, 24.25%, 15.28%, 28.51%, 23.00%, respectively. Since the SST [Formula: see text]–[Formula: see text] model has the smallest error, and the streamline is consistent with the experimental results, it is recommended to use SST [Formula: see text]–[Formula: see text] model for numerical analysis of the axial flow blood pump.

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PIV experimental study on the flow field characteristics of axial flow blood pump under three operating conditions

The Journal of Engineering ◽

10.1049/joe.2018.9003 ◽

2019 ◽

Vol 2019 (13) ◽

pp. 155-158

Author(s):

Zhiyong Xiao ◽

Jianping Tan ◽

Shuai Wang ◽

Zheqin Yu ◽

Weiqiang Wu

Keyword(s):

Experimental Study ◽

Flow Field ◽

Axial Flow ◽

Operating Conditions ◽

Blood Pump ◽

Axial Flow Blood Pump ◽

Flow Field Characteristics

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Five Month Survival in a Calf Supported With an Intraventricular Axial Flow Blood Pump

ASAIO Journal ◽

10.1097/00002480-199507000-00025 ◽

1995 ◽

Vol 41 (3) ◽

pp. M333-M336 ◽

Cited By ~ 8

Author(s):

Steven M. Parnis ◽

Michael P. Macris ◽

Robert Jarvik ◽

John L. Robinson ◽

Jeffrey W. Kolff ◽

...

Keyword(s):

Axial Flow ◽

Blood Pump ◽

Axial Flow Blood Pump

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Large-Eddy and Unsteady Reynolds-Averaged Navier-Stokes Simulations of an Axial Flow Pump for Cardiac Support

Volume 2B: Turbomachinery ◽

10.1115/gt2017-65250 ◽

2017 ◽

Cited By ~ 1

Author(s):

Benjamin Torner ◽

Sebastian Hallier ◽

Matthias Witte ◽

Frank-Hendrik Wurm

Keyword(s):

Flow Field ◽

Axial Flow ◽

Pressure Head ◽

Damage Parameter ◽

Ventricular Assist Devices ◽

Navier Stokes ◽

Mean Velocity ◽

Blood Damage ◽

Large Eddy ◽

Reynolds Averaged Navier Stokes

The use of implantable pumps for cardiac support (Ventricular Assist Devices) has proven to be a promising option for the treatment of advanced heart failure. Avoiding blood damage and achieving high efficiencies represent two main challenges in the optimization process. To improve VADs, it is important to understand the turbulent flow field in depth in order to minimize losses and blood damage. The application of the Large-eddy simulation (LES) is an appropriate approach to simulate the flow field because turbulent structures and flow patterns, which are connected to losses and blood damage, are directly resolved. The focus of this paper is the comparison between an LES and an Unsteady Reynolds-Averaged Navier-Stokes simulation (URANS) because the latter one is the most frequently used approach for simulating the flow in VADs. Integral quantities like pressure head and efficiency are in a good agreement between both methods. Additionally, the mean velocity fields show similar tendencies. However, LES and URANS show different results for the turbulent kinetic energy. Deviations of several tens of percent can be also observed for a blood damage parameter, which depend on velocity gradients. Possible reasons for the deviations will be investigated in future works.

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