Blower Fan Blade Serrations for Noise Reduction
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Solution Overview
Problem
Existing blower fans experience noise generation due to air flow separation at the base end portion of the blades, despite serrations on the leading edges reducing noise by limiting air separation.
Innovation Solution
The blower fan design includes a hub, blades, and a ring with serrations on the leading edges of the blades. Each blade is shaped to direct air flow towards the serrations of an adjacent blade, enhancing the effectiveness of the serrations in limiting air separation and noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If serrations are formed on the leading edge of the blade, then air flow separation is limited and noise is reduced, but air flow rate may be compromised
Solution Approach 1:
The blade is designed with different local characteristics: the leading edge has serrations for noise reduction, while the rear portion has a specific shape to direct air flow toward adjacent blade serrations. This local differentiation allows each part to optimize its function without compromising overall performance.
Solution Approach 2:
The air flow itself acts as an intermediary that connects adjacent blades. By shaping the blade rear to direct air flow toward the next blade's serrations, the system creates a cooperative effect where multiple blades work together to enhance noise reduction while maintaining smooth air flow.
2Object-affected harmful factors
If the blade shape directs air flow toward adjacent blade serrations, then noise reduction is enhanced, but blade shape complexity increases
Solution Approach 1:
The blade exhibits asymmetric design where the leading edge serrations and rear portion shape work together in a non-uniform configuration. This asymmetry allows the blade to direct air flow specifically toward adjacent blade serrations, enhancing noise reduction through a coordinated asymmetric structure rather than uniform design.
3Object-affected harmful factors
If serrations are formed from center portion to distal end portion of the blade, then air flow separation is reduced, but manufacturing complexity increases
Solution Approach 1:
The serrations are segmented and positioned specifically at the leading edge from the center portion to the distal end portion of the blade, rather than covering the entire blade surface. This selective segmentation reduces manufacturing complexity while maintaining the noise reduction function where it is most needed.
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 configuration effectively limits noise generation while maintaining appropriate air flow rates by ensuring air flows easily towards the serrations of adjacent blades, thereby enhancing the noise-reducing effect of the serrations.
Implementation Method 1
a flow of the air is less likely to be separated from a negative pressure surface of the blade at the time of rotating the blower fan
Implementation Method 2
Each blade among the plurality of blades has a shape that directs a flow direction of the air passing through each blade to the separation limiting structure of an adjacent blade
Data Source
AI summary
A blower fan includes a hub, a plurality of blades and a ring. The blades are arranged along and extend outwardly from an outer periphery of the hub. The ring is shaped in a circular ring form and couples a distal end portion of each blade. The distal end portion of each blade has a separation limiting structure that limits separation of a flow of air from the blade. Each blade has a shape that directs a flow direction of the air passing through the blade to the separation limiting structure of an adjacent blade which is an adjacent one of the plurality of blades located on a rear side of the blade in a fan rotational direction.