Mixing pot comprising a mixing unit with a surface-structured bearing body which interrupts a boundary layer
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Solution Overview
Problem
The existing mixing bowls with smooth-walled agitators suffer from the formation of laminar boundary layers, which hinder effective mixing due to diffusion-controlled mass transport, resulting in inefficient mixing of liquids.
Innovation Solution
The introduction of a surface structure with ribs, grooves, or indentations on the bearing body of the agitator, extending 1-3 mm in height, disrupts the laminar boundary layer, promoting the formation of vortices and convective mass transport for improved mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a smooth-walled surface is used on the bearing body, then the surface is easy to clean, but a laminar boundary layer forms that hinders effective mixing
Solution Approach 1:
The surface of the bearing body is designed with locally different properties: most of the surface remains smooth for easy cleaning, while specific localized regions contain three-dimensional structures (ribs, grooves, or protrusions) that disrupt the boundary layer and enhance mixing. This local modification approach maintains overall ease of cleaning while creating targeted flow disruption zones.
Solution Approach 2:
The surface geometry is modified by introducing three-dimensional structures with specific height parameters (1-3 mm) that change the flow characteristics. These structural parameters are optimized to be sufficient to disrupt the laminar boundary layer but not so large as to create significant cleaning difficulties, thus changing the surface parameters to achieve both mixing efficiency and cleanability.
2Ease of manufacture
If a smooth-walled bearing body is used, then manufacturing is simpler, but mass transport is diffusion-controlled and mixing is inefficient
Solution Approach 1:
Instead of making the entire bearing body complex, only localized three-dimensional structures are introduced on the surface. The bulk of the bearing body remains simple in shape, maintaining ease of manufacture, while the localized surface features provide the necessary flow disruption for enhanced mass transport.
Solution Approach 2:
The surface is modified by adding three-dimensional structures that extend in the radial dimension (1-3 mm height) from the nominal surface. This dimensional addition creates flow disruption without requiring complex internal structures or changing the overall bearing body geometry, thus maintaining manufacturing simplicity while enhancing mixing.
3Productivity
If three-dimensional surface structures are added to disrupt the boundary layer, then mixing efficiency improves, but surface complexity increases
Solution Approach 1:
The complexity is confined to localized surface regions rather than the entire bearing body. The three-dimensional structures are concentrated in specific zones where boundary layer disruption is most needed, while other regions remain smooth, thus limiting the overall increase in device complexity.
Solution Approach 2:
The surface structures are segmented into discrete elements (individual ribs, grooves, or protrusions) distributed across the bearing body surface. This segmentation allows the complexity to be distributed and managed as separate features rather than a single complex structure, facilitating both manufacturing and cleaning.
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
The surface structure enhances mixing efficiency by detaching the boundary layer and creating turbulent flow zones, leading to better mixing and cleaning capabilities while maintaining easy cleanability.
Implementation Method 1
a hydrodynamic laminar boundary layer forms on the smooth-walled surface of the bearing body. Such stationary boundary layers are disadvantageous for good mixing of the liquid in the mixing bowl, since mass transport across the course of the boundary layer is essentially diffusion-controlled.
Implementation Method 2
Vortices form downstream of the three-dimensional structures. The detachment of the boundary layer that occurs in this way ensures better mixing of the liquid in the mixing bowl in the area of the surface of the bearing body.
Implementation Method 3
The surface structure enhances mixing efficiency by detaching the boundary layer and creating turbulent flow zones, leading to better mixing and cleaning capabilities while maintaining easy cleanability.
Implementation Method 4
Convective mass transport takes place in the area of the vortex zones that form between the individual three-dimensional structures.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates firstly to a mixing vessel with an agitator (2) arranged on a wall, particularly on the bottom side, of the mixing vessel. The agitator has a bearing body (7) fixed to the wall for supporting an agitator shaft (5) for rotating a stirring element (6), which may include a set of blades, to create a circulating flow of a liquid located in the mixing vessel. To improve the mixing of the liquid near the bearing body, it is proposed that a surface (8) of the bearing body (7) in contact with the liquid have a surface structure (9) that interferes with the formation of a laminar boundary layer. Furthermore, the invention relates to an agitator (6) for use on a mixing vessel with a bearing body (7) supporting an agitator shaft (5).