Cross Flow Fan Blade Protrusions to Reduce Vortex Noise and Vibration
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Solution Overview
Problem
Cross flow fans in air conditioners generate vortices during air discharge, leading to noise, vibration, and reduced suction and discharge efficiency, which affect user convenience and overall performance.
Innovation Solution
The design incorporates protrusions and projections on the outer edge of blades, with specific shapes and orientations to reduce vortex formation, enhance air flow, and improve discharge efficiency, including protrusions extending from the outer edge toward the blade's bottom surface and projections protruding outward with curved ends, to scatter vortices and maintain air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional smooth blades are used in the cross flow fan, then the manufacturing is simple, but vortices are generated in the discharged air flow causing noise and vibration
Solution Approach 1:
The blade design applies local quality by adding protrusions only at specific locations (outer edges and tip regions) rather than modifying the entire blade structure. This localized modification targets the vortex generation zones while keeping the rest of the blade simple and easy to manufacture.
Solution Approach 2:
The protrusions create asymmetric features on the blade edges, breaking the symmetric smooth profile of conventional blades. This asymmetry disrupts the vortex formation mechanism by creating intentional flow separation points that prevent large-scale rotational vortices from developing in the discharged air.
2Productivity
If conventional smooth blades are used in the cross flow fan, then the blade structure is simple, but the suction and discharge efficiency of air is reduced due to vortex formation
Solution Approach 1:
The protrusions are strategically placed at the outer edges and tip regions of the blades where vortices naturally form during air discharge. This localized modification optimizes the flow control exactly where it is needed most, improving discharge efficiency without requiring complex modifications to the entire blade structure.
Solution Approach 2:
The protrusions convert the harmful vortex formation into a beneficial flow control mechanism. By intentionally creating small controlled disturbances at the blade edges, the design prevents larger harmful vortices from forming, thereby improving overall discharge efficiency.
3Reliability
If protrusions and projections are added to the blade outer edges, then vortex formation is reduced and discharge efficiency is improved, but the manufacturing complexity increases
Solution Approach 1:
The protrusions and projections are confined to specific local regions (outer edges and tip areas) rather than requiring complex modifications throughout the entire blade. This localized approach maintains manufacturing simplicity while achieving the performance benefits of vortex reduction.
Solution Approach 2:
The blade structure is segmented into distinct regions: the main blade body remains simple and easy to manufacture, while the outer edges and tip regions contain the protrusions and projections. This segmentation allows different manufacturing approaches for different regions, optimizing both ease of manufacture and performance.
Data Source
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AI summary
Provided is a cross flow fan. The cross flow fan includes a fixing member (120) having a plate shape, a plurality of blades (110) fixed to one surface of the fixing member (120), the plurality of blades (110) being arranged spaced apart from each other in a circumference direction, an inner edge (111) defining an end of a side of each of the blades (110), the inner edge (111) extending toward a rotation shaft of the blades (110), an outer edge (112) defining an end opposite to the inner edge (111), and a protrusion (113) protruding from the outer edge (112) in one direction.