Variable Cross-Section Impeller Channels for Centrifugal VAD
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Solution Overview
Problem
Existing centrifugal blood pumps face challenges in reducing shear stress, hydraulic losses, and thrombosis risk due to inefficient blood flow and impeller design, particularly in implantable ventricular assist pumps.
Innovation Solution
The impeller features blades of variable thickness with arch-shaped interblade channels that maintain uniform cross-sections and increasing dimensions along the length, optimizing flow angles and hydraulic radius to minimize shear stress and turbulence, allowing for contactless suspension and reduced pump size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional impeller designs with constant cross-section channels are used, then manufacturing is simpler, but shear stress and hydraulic losses increase
Solution Approach 1:
The patent applies the dynamics principle by transitioning from static, constant cross-section channels to dynamic, variable cross-section channels that adapt their geometry along the flow path. The channel cross-section varies continuously from inlet to outlet, with the ratio of width to height increasing along the length, optimizing flow characteristics at different positions and reducing hydraulic losses throughout the impeller.
Solution Approach 2:
The patent implements parameter changes by systematically varying multiple geometric parameters of the channel cross-section along its length. The width, height, and width-to-height ratio all change continuously from inlet to outlet, creating an optimized flow path that minimizes shear stress and hydraulic losses while managing the increased manufacturing complexity.
2Volume of moving object
If impeller size is reduced for implantability, then pump dimensions decrease, but flow capacity and performance may be compromised
Solution Approach 1:
The patent applies local quality by optimizing different regions of the impeller channels with locally adapted geometries. The variable cross-section channels provide different flow characteristics at different positions - narrower at the inlet to control flow angles and wider at the outlet to maximize flow capacity - allowing the small impeller to achieve optimal performance throughout its volume.
Solution Approach 2:
The patent utilizes curvature principles by implementing arch-shaped channels with smooth curved transitions instead of sharp angles. The rounded corners and continuous curved surfaces in the variable cross-section channels reduce flow separation and turbulence, maximizing flow capacity within the limited space of a compact implantable impeller.
3Strength
If blade thickness is increased to improve structural strength, then mechanical strength increases, but flow channel cross-section decreases and hydraulic losses increase
Solution Approach 1:
The patent applies dynamics by making the blade thickness a variable parameter rather than a constant value. The blades have variable thickness that changes along their length, providing maximum thickness where structural strength is most needed while maintaining thinner sections where flow channel cross-section is prioritized to minimize hydraulic losses.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances blood flow stability, reduces hydraulic losses, and decreases thrombosis risk by minimizing shear stress and turbulence, while enabling a more compact pump for implantation.
Implementation Method 1
suspending the impeller during rotation within the pump chamber is performed by means of magnetic and hydrodynamic bearings
Implementation Method 2
suspending the impeller during rotation within the pump chamber is performed by means of magnetic and hydrodynamic bearings
Implementation Method 3
The present invention relates to an impeller for a centrifugal implantable ventricular assist pump
Data Source
Figure 1
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AI summary
An impeller (1) for a centrifugal implantable ventricular assist pump comprises a body, blades (3) and closed interblade flow channels (2) with variable cross-sections. The blades (3) of the impeller (1) are of variable thickness. Each channel (2) along the entire length thereof is arch-shaped. The inflow angle (α) onto the blade at the inlet of the channel (2) ranges between 18° and 25°. The outflow angle (β) from the blade (3) at the outlet of the channel (2) does not exceed 30°. The cross-sections (10) of the channel along the entire length thereof from the inlet to the outlet are uniform in shape, and the width (s) and height (h) of the channel (2) along the entire length thereof from the inlet to the outlet increase continuously. The ratio of the width (s) to the height (h) of the channel (2) along the entire length thereof from the inlet to the outlet increases continuously, and the hydraulic radius of the channel (2) along the entire length thereof from the inlet to the outlet increases continuously.