Radial Fan Casing Asymmetric Air Guide Noise Reduction
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Solution Overview
Problem
Radial fans used in vehicle air conditioning systems produce significant low-frequency noise, which is unpleasant and difficult to mitigate with existing designs, especially when operating in air recirculation mode.
Innovation Solution
A radial fan housing design featuring an air guiding device that is tangentially oriented, wedge-like, and asymmetrically arranged, with a sloping front edge and a rounded upper side, which influences airflow to reduce noise levels by minimizing turbulence and air resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the inner wall of the receiving recess is extended to guide air tangentially, then air flow guidance is improved, but air resistance increases and operating noise increases
Solution Approach 1:
The air guide device is designed with asymmetric geometry, where the leading edge is inclined at a specific angle (45-85 degrees) relative to the axial direction. This asymmetric configuration optimizes airflow guidance while minimizing turbulence and air resistance, thereby reducing operating noise compared to symmetric designs.
Solution Approach 2:
The air guide device features a rounded upper surface that smoothly transitions into the receiving recess. This curved geometry eliminates sharp edges and corners, reducing airflow separation and turbulence. The rounded shape guides air more smoothly through the receiving area, decreasing air resistance and associated noise.
2Speed
If the air guide device has a steep leading edge to guide air quickly, then air flow direction is improved, but air resistance and turbulence increase
Solution Approach 1:
The leading edge of the air guide device is inclined at a specific angle range (45-85 degrees) relative to the axial direction. This optimized angle parameter balances airflow directionality with minimal air resistance. The specific angular range ensures air is guided efficiently while avoiding excessive turbulence that would occur with steeper angles.
3Area of stationary object
If the air guide device is made taller to cover more area, then air guidance coverage is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The air guide device extends partially into the receiving recess rather than fully occupying it. The height of the air guide is optimized to provide sufficient airflow guidance coverage without excessive extension. This partial action approach achieves effective air guidance while maintaining simpler geometry and easier manufacturing.
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 proposed design significantly reduces operating noise, particularly in the low-frequency range, allowing the radial fan to operate at lower power while maintaining sufficient air pressure for air conditioning applications.
Implementation Method 1
which influences airflow to reduce noise levels by minimizing turbulence and air resistance
Data Source
Figure 1
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AI summary
The housing (2) has a spiral-shaped accommodating recess (5) for accommodating a radial fan wheel, and an air conductive guide (4) for guiding air flow from the recess to an air outlet (9). The guide sustains a contour (11) of the recess on an inner side (14) of the guide, where the inner side faces the recess. The guide has an inclined leading edge (13) with a blade angle (alpha) that amounts to 63 degrees to 67 degrees, where the leading edge linearly runs at the constant blade angle.