Impeller Blade Tip Profile for Axial Fan Backflow Reduction
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Solution Overview
Problem
Axial fans face performance limitations due to a manufacturing process-induced gap between the blade tip and the frame, leading to a backflow phenomenon that cannot be significantly improved, affecting airflow efficiency.
Innovation Solution
The geometric profile of the impeller's negative and positive pressure surfaces near the blade tip is modified, with a convex arc surface and plane in one region and a convex or concave arc surface in another, reducing pressure differences and mitigating backflow by ensuring airflow velocities and pressures are comparable between surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the gap between blade tip and frame is reduced, then airflow backflow is reduced, but manufacturing precision requirements become excessively high and are difficult to achieve
Solution Approach 1:
The patent applies local quality by modifying only the geometric profile of the pressure surfaces near the blade tip region, while keeping the rest of the blade structure unchanged. This localized modification reduces backflow at the critical tip area without requiring high-precision manufacturing across the entire blade, thus resolving the contradiction between reducing backflow and maintaining manufacturability
Solution Approach 2:
The patent employs curvature by changing the geometric profile of the pressure surfaces from flat or simple curved surfaces to specifically designed convex and concave arc surfaces near the blade tip. This curvature modification optimizes airflow attachment and reduces backflow phenomenon without requiring reduction of the physical gap between blade tip and frame, thereby solving the manufacturing precision problem
2Productivity
If the geometric profile of pressure surfaces is modified to reduce backflow, then airflow efficiency is improved, but blade design complexity increases
Solution Approach 1:
The patent segments the blade into two distinct regions: a first region from blade root to blade tip with a simple convex arc and plane profile, and a second region near the blade tip with modified convex and concave arc profiles. This segmentation allows the complex geometric modification to be applied only where necessary (near the tip) while keeping the majority of the blade structure simple and easy to manufacture, thus improving airflow efficiency without excessive design complexity
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 reduces airflow backflow, enhancing the overall performance of the fan by minimizing pressure differences between the surfaces, thereby improving airflow efficiency.
Implementation Method 1
In the second region extending from the blade tip to the blade root by a second length smaller than the first length, the negative pressure surface and the positive pressure surface are respectively a convex arc surface and a concave arc surface or both convex arc surfaces
Data Source
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AI summary
A fan (10) including a frame (11) and an impeller (100) is disclosed. The frame (11) has an air inlet (11a) and an air outlet (11b). The impeller (100) is disposed in the frame (11) and includes a hub (110) and multiple blades (120). Each blade (120) has a negative pressure surface (121), a positive pressure surface (122), a blade root (123), and a blade tip (124). In a first region (101) extending from the blade root (123) to the blade tip (124) by a first length (L1), the negative pressure surface (121) and the positive pressure surface (122) area convex arc surface and a plane. In a second region (102) extending from the blade tip (124) to the blade root (123) by a second length (L2), the negative pressure surface (121) and the positive pressure surface (122) are convex arc and concave arc surfaces or are convex arc surfaces.