Fan Impeller Blade Tip Barrier Structure for Vortex Noise Reduction
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Solution Overview
Problem
Conventional axial fans produce strong tip vortices and loud noise due to pressure differences across the tip portions of the fan blades, leading to unsteady flow fields and reduced air flow efficiency.
Innovation Solution
A fan impeller structure with barrier zones on the blades, comprising lifted and declined sections, prevents fluid turnover by pressure differences, maintaining constant airflow and reducing vortices and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional axial fan blades are used, then the fan can move air, but strong tip vortices are generated causing loud noise and unsteady flow fields
Solution Approach 1:
The blade tip is segmented into multiple functional zones: a barrier zone that blocks pressure equalization and prevents vortex formation, a lifted section that extends the blade tip upward, and a declined section that extends downward. This segmentation allows different portions of the blade tip to perform different functions, maintaining air flow while eliminating harmful vortices.
Solution Approach 2:
The barrier zone acts as an intermediary structure between the high-pressure lower surface and low-pressure upper surface of the blade tip. It prevents direct fluid turnover between these surfaces, thereby eliminating the mechanism that generates tip vortices and associated noise while preserving the overall air moving capability of the fan.
2Object-generated harmful factors
If barrier zones are added to blade tips, then vortices and noise are reduced, but device complexity increases
Solution Approach 1:
The barrier zone, lifted section, and declined section are merged into a single integrated blade tip structure. This combining of multiple functional elements into one unified component achieves vortex reduction and noise elimination without requiring separate additional parts, thereby limiting the increase in device complexity.
Solution Approach 2:
The blade tip geometry is modified by changing parameters such as the height of the lifted section, the extent of the declined section, and the positioning of the barrier zone. These parameter adjustments allow optimization of vortex reduction performance while controlling structural complexity through systematic geometric variation rather than adding complex mechanisms.
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 fan impeller structure maintains constant airflow and static efficiency while significantly reducing aerodynamic noise and vortices at the blade tips.
Implementation Method 1
pressure distributed over the upper surface and the lower surface of a tip portion of the fan blade is different. The lower surface of the tip portion of the fan blade has a higher pressure relative to the pressure at the upper surface of the tip portion of the fan blade
Data Source
AI summary
A fan impeller structure includes a hub having a top and a sidewall; and a plurality of blades being circumferentially spaced on the sidewall. Each of the blades has a barrier zone formed at a tip portion of the blade; the barrier zone is used to prevent or block fluid at a lower side of the blade to turn over to an upper side of the blade owing to a difference in the pressure distributed over the upper and the lower side of the blade. Therefore, when a fan using the fan impeller structure is operating, the fan is able to maintain constant air flow and static efficiency to largely reduce vortices formed at the tip portions of the blades (also referred to as wingtip vortices) and accordingly, to reduce the occurrence of aerodynamic noise.