Segmented Fan Blade with Variable Setting Angles
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Solution Overview
Problem
Conventional fan structures experience aerodynamic noise and reduced efficiency due to high air flow separation and uneven air pressure distribution, particularly at the outer local region of the blade, which worsens with increased rotation speed.
Innovation Solution
A fan structure with blades comprising multiple segments, where the first and second surfaces have distinct setting angles relative to the base plane, and each segment has a specific height and radius width configuration to distribute air pressure more evenly, preventing eddy flow and enhancing aerodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the setting angle of the blade is increased to improve air flow, then the air flow increases, but aerodynamic noise increases and efficiency decreases due to flow separation
Solution Approach 1:
The blade is divided into multiple segments along its span, with each segment having a distinct setting angle. This segmentation allows the blade to maintain a higher overall setting angle for improved air flow while the variation in angles across segments prevents flow separation and reduces aerodynamic noise.
Solution Approach 2:
Different regions of the blade are assigned different setting angles tailored to local flow conditions. The root portion has a larger setting angle to generate thrust, while the tip portion has a smaller angle to prevent flow separation and reduce noise, optimizing performance locally across the blade span.
2Speed
If the rotation speed of the fan is increased to improve air flow, then the air flow increases, but vibration and noise occur
Solution Approach 1:
The blade is segmented into multiple sections with different setting angles, which distributes the aerodynamic loads more evenly across the rotation. This reduces periodic fluctuations in force that cause vibration and noise, allowing higher rotation speeds to be achieved without excessive vibration.
3Speed
If a high setting angle is used to increase air flow, then air flow increases, but eddy flow and flow separation occur reducing aerodynamic efficiency
Solution Approach 1:
The setting angle varies locally across different segments of the blade, with the root portion having a larger angle for flow generation and the tip portion having a smaller angle to maintain attached flow. This local optimization prevents eddy flow and separation, maintaining high aerodynamic efficiency while achieving increased air flow.
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 solution broadens the high air pressure gradient region on the blade, reducing noise and improving aerodynamic performance and efficiency, as evident from the comparison of pressure distribution and efficiency curves.
Implementation Method 1
the blades B can create an axial flow of air
Implementation Method 2
a high air pressure gradient usually occurs in an outer local region of the blade
Implementation Method 3
eddy flow and separation of the air flow from the blade may occur
Data Source
AI summary
A fan structure is provided, including a hub and a plurality of blades surrounding the hub. Each blade has a first segment connected to the hub and a second segment extended outwardly from the first segment. A first surface is formed between the first segment and the hub, and a second surface is formed between the first and second segments. The first and second surfaces respectively have a first and second setting angle relative to a base plane of the fan structure, wherein the first setting angle exceeds the second setting angle.