Cross-Flow Fan Stabilizer Geometry for Quiet Airflow Control
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Solution Overview
Problem
Conventional air conditioners face challenges in maintaining flow stability and reducing broad band noise while preventing reverse inhalation and wind noise, as narrower gaps improve blowing efficiency but increase noise, and broader gaps destabilize airflow and generate backflow.
Innovation Solution
The air conditioner incorporates a cross-flow fan design with concave-convex portions on the stabilizer and casing surfaces, arranged apart in the rotational axis direction, to generate turbulences and stabilize eddies, thereby preventing reverse inhalation and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gap between the impeller and stabilizer is narrowed to improve blowing efficiency, then the air flow stability is improved, but broad band noise increases due to collision of high-speed air with the stabilizer
Solution Approach 1:
The stabilizer surface is segmented into multiple regions with different gap distances from the impeller. The upstream side has a larger gap while the downstream side has a smaller gap, allowing different portions to serve different functions: noise reduction upstream and flow stability downstream.
Solution Approach 2:
Different regions of the stabilizer are given different local properties regarding gap distance. The upstream region maintains a larger gap to reduce noise, while the downstream region maintains a smaller gap to stabilize flow, optimizing performance locally in each region.
2Object-generated harmful factors
If the gap between the impeller and stabilizer is broadened to reduce broad band noise, then the noise is reduced, but the air flow becomes unstable and back flow is generated
Solution Approach 1:
The stabilizer is divided into upstream and downstream regions with different gap characteristics. This segmentation allows the upstream side to reduce noise while the downstream side maintains flow stability, preventing back flow.
Solution Approach 2:
The gap distance is varied in the axial direction (another dimension) rather than maintaining a uniform radial gap. This creates a gradient in gap distance that simultaneously achieves noise reduction and flow stability.
3Object-generated harmful factors
If concave portions are formed on the rear guider to reduce interference sound, then the interference sound is reduced, but the draft resistance increases when the gap is reduced to maintain flow stability
Solution Approach 1:
The stabilizer is segmented into upstream and downstream regions with different functions. The upstream region focuses on noise reduction while the downstream region maintains flow stability with minimal draft resistance.
Solution Approach 2:
Instead of forming concave portions that increase draft resistance, the invention uses a different approach by varying the gap distance in the axial direction, achieving noise reduction without significantly increasing draft resistance.
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 design stabilizes cross-flow eddies, prevents reverse inhalation, and significantly reduces broad band and wind noise, enhancing blowing performance and user comfort.
Implementation Method 1
a plurality of concave portions or convex portions which are arranged on the upstream side of the projection so as to disturb the gas stream flowing along the opposing surface
Data Source
AI summary
In an air conditioner, reverse inhalation is prevented while broad band noise and wind sound are reduced. A projection arranged at the leading end of a stabilizer on the downstream side of an air stream flowing along a surface of the stabilizer opposing an impeller and protrudes toward the impeller to define the shortest distance to the impeller. A plurality of grooves or projections are provided on the opposing surface on the upstream side of the projection to disturb the air stream flowing along the opposing surface. The positions of the grooves or the projections are arranged apart in a rotational axis direction. A plurality of convex portions are provided to disturb an air stream flowing along a surface of a casing opposing the impellers. The positions of the convex portions are arranged apart in the rotational axis direction of the impeller.