Axial-Flow Fan Blade Roughness for Higher Airflow Pressure
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Solution Overview
Problem
Axial-flow fans used for heat dissipation suffer from low flow field pressure, necessitating improvements to enhance airflow characteristics.
Innovation Solution
Adjusting the surface roughness of the front and rear surfaces of the blades to create a pressure difference, with the rear surface roughness being greater than the front, to optimize airflow direction and concentration without altering the blade shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the number and structure of blades are adjusted to improve air supply characteristics, then noise is reduced and airflow optimization is achieved, but the pressure of the flow field remains too small
Solution Approach 1:
The patent applies different surface roughness treatments to different regions of the blade surfaces. Specifically, the front surface has a first surface roughness while the rear surface has a second surface roughness that is different from the first. This local differentiation allows each surface to perform its specific function: the front surface optimizes for reduced noise and smooth airflow, while the rear surface is designed to enhance pressure generation through controlled turbulence and vortex formation.
Solution Approach 2:
The patent changes the surface roughness parameter of the blade surfaces to improve flow field pressure. By adjusting the surface roughness values (Ra1 for front surface, Ra2 for rear surface) within specific ranges, the patent achieves better pressure generation without changing the blade geometry. This parameter modification allows the rear surface to create beneficial turbulence that increases pressure while the front surface maintains laminar flow for noise reduction.
2Stress or pressure
If the surface roughness of blade surfaces is adjusted to improve pressure, then flow velocity difference and pressure difference are enhanced, but the blade shape must remain unchanged
Solution Approach 1:
Instead of changing the overall blade shape, the patent applies local quality modifications by treating the front and rear surfaces with different surface roughness characteristics. The front surface maintains a smoother finish (first surface roughness) for optimal airflow attachment and noise reduction, while the rear surface receives a different treatment (second surface roughness) to enhance pressure generation through controlled flow separation and vortex creation.
Solution Approach 2:
The patent modifies the surface roughness parameter (Ra values) as a design variable to achieve the desired pressure difference without altering blade geometry. By specifying different roughness parameters for the front and rear surfaces, the patent creates the necessary pressure differential that improves heat dissipation performance while keeping the blade structural design simple and manufacturable.
3Object-affected harmful factors
If various designs and tests are carried out on the structure of air flow to reduce noise, then air supply characteristics are improved, but the flow field pressure remains insufficient
Solution Approach 1:
The patent applies different surface quality characteristics to different blade surfaces to simultaneously address noise and pressure requirements. The front surface is designed with a first surface roughness that promotes laminar flow and reduces turbulence-induced noise, while the rear surface has a second surface roughness that generates beneficial turbulence for pressure enhancement. This spatial differentiation of surface qualities allows both noise reduction and pressure improvement.
Solution Approach 2:
The patent uses surface roughness parameter modification as the primary design variable to achieve both noise reduction and pressure improvement. By carefully selecting the Ra values for the front and rear surfaces, the patent creates optimal flow conditions: smooth flow attachment at the front for noise reduction, and controlled flow separation at the rear for pressure generation, all without changing blade geometry.
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
Enhances airflow pressure and reduces noise by controlling fluid separation and turbulence, meeting heat dissipation requirements effectively.
Implementation Method 1
A surface roughness of the front surface is different from a surface roughness of the rear surface... adjusts the surface roughness of the front surface and the rear surface of the blades, and then reaches the effect of adjusting the pressure on the blade surface
Data Source
AI summary
An axial-flow heat dissipation fan including a frame, a hub, and a plurality of blades is provided. The frame has an air inlet and an air outlet. The hub is rotatably arranged in the frame. The blades disposed at side of the hub respectively and rotate along with the hub. Each of the blades has a front surface facing toward the air inlet and a rear surface facing toward the air outlet. A surface roughness of the front surface is different from a surface roughness of the rear surface.