Loop Propeller Mixer Blade to Reduce Cavitation and Micro-Foam
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Solution Overview
Problem
Existing household mixer blades suffer from low comminution capacity and excessive micro-foam formation due to cavitation, leading to inefficient mixing and a less appetizing appearance of blended foods.
Innovation Solution
A mixer blade designed as a loop propeller with connected star blades forming a loop shape, featuring a phase shift and opposing propeller effects, reduces micro-foam formation and enhances chopping efficiency by ensuring multiple contacts with the food during rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the propeller effect of the rotating star blade is increased to improve mixing speed, then the mixing motion predominates, but the comminution performance deteriorates
Solution Approach 1:
The mixer blade is divided into multiple knife blades (typically 3-7 blades) arranged radially around the rotation axis, rather than using a single star blade. Each knife blade acts as an independent cutting element, increasing the number of contact points with the food material during rotation and improving comminution performance while maintaining mixing effectiveness.
Solution Approach 2:
The knife blades are designed with specific geometric features including a leading edge, a trailing edge, and a blade width that varies along the length. The leading edge is sharpened for effective cutting, while the overall blade geometry is optimized to create appropriate local flow patterns that balance mixing and chopping functions.
2Speed
If the rotating knife blade operates at high speeds to improve mixing efficiency, then the mixing motion predominates, but cavitation occurs causing micro-foam formation and color fading
Solution Approach 1:
The knife blade geometry is designed asymmetrically with respect to the rotation plane. The blades are positioned at specific angular intervals and have asymmetric cross-sections with different leading and trailing edge configurations. This asymmetric design optimizes the pressure distribution during rotation, reducing the intensity of cavitation effects while maintaining mixing efficiency.
Solution Approach 2:
The knife blades feature curved surfaces and rounded edges rather than sharp angular transitions. The blade cross-sections are designed with curved profiles that smoothly guide the food material, reducing turbulence and the formation of vapor bubbles that lead to cavitation and micro-foam.
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 loop propeller design increases comminution capacity while minimizing micro-foam, resulting in faster and more efficient mixing with improved food texture and appearance.
Implementation Method 1
a rotating mixer blade rotates about a vertical axis arranged on the bottom of the pot mixer and thereby mixes and/or chops the material to be mixed
Implementation Method 2
The propeller effect acts on the food to be mixed and conveys it downwards when the pot mixer is used as intended
Implementation Method 3
On a knife blade, which also has a propeller effect, a very pronounced pressure jump occurs at the tear-off edge of the moving knife. Due to the pressure jump, the water in the mixture is briefly brought below the vapor pressure (about 14 Torr or 19 hPa under standard conditions). This creates a low-pressure vapor bubble. When passing the trailing edge, the low-pressure vapor bubble is compressed again, so that the vapor bubble implodes spherically symmetrically. This effect, also called cavitation
Data Source
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AI summary
A mixer blade (1) for a household mixer designed as a pot mixer (2), in which a rotating mixer blade (1) rotates around a vertical axis (4) arranged at the bottom (3) of the pot mixer (2) and mixes and/or chops the mixture contained in the pot (5) of the pot mixer (2): the mixer blade (1) is designed as a loop propeller.