Sirocco Fan Blade Geometry for Low-Noise Airflow in Air Conditioners
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Solution Overview
Problem
Conventional sirocco fans in air-conditioning apparatuses have a low air-blowing capacity at a predetermined noise level, leading to increased compressor load and reduced COP, while increasing air-blowing capacity to suppress noise results in uncomfortable noise levels for users.
Innovation Solution
The sirocco fan design is optimized by defining specific ratios for blade shape parameters such as H/L, R/L, β1, and β2 (0.18 ≤ H/L ≤ 0.26, R/L ≤ 0.11, 100° ≤ β1 ≤ 130°, and 26° ≤ β2 ≤ 32°) to enhance air-blowing capacity while minimizing noise and revolutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the air-blowing amount of the sirocco fan is increased to suppress the lowering of COP, then the COP is improved, but the noise value is increased to give an uncomfortable feeling to users
Solution Approach 1:
The patent applies parameter changes by optimizing the blade geometry parameters including blade inlet angle (β1), blade outlet angle (β2), chord length (L), camber height (H), and warp position. By adjusting these parameters within specific ranges, the fan achieves improved airflow characteristics that increase COP while maintaining acceptable noise levels. The optimized parameters enable more efficient air movement without requiring excessive fan speed increases that would generate harmful noise.
2Productivity
If the rotation speed of the sirocco fan is increased to obtain a large air-blowing amount, then the air-blowing amount is increased, but the noise value is increased
Solution Approach 1:
The patent changes the geometric parameters of the blade to optimize performance. Specifically, the blade inlet angle is set to 10°≤β1≤20°, blade outlet angle to 20°≤β2≤30°, chord length to 15mm≤L≤25mm, camber height to 5mm≤H≤10mm, and warp position to 0.2≤e≤0.4. These parameter adjustments enable the fan to achieve higher air-blowing amounts at lower rotation speeds, thereby reducing noise generation while maintaining productivity.
Solution Approach 2:
The patent incorporates curvature in the blade design through the camber height (H) and warp position (e) parameters. The curved blade profile creates more efficient airflow patterns compared to straight blades, allowing the fan to move more air at lower speeds. The cambered shape generates beneficial pressure distributions that improve airflow efficiency and reduce turbulence-induced noise.
3Productivity
If the blade inlet angle and blade exit angle are optimized to improve airflow efficiency, then the air-blowing capacity is enhanced, but the blade shape complexity increases
Solution Approach 1:
The patent defines specific parameter ranges for blade geometry to balance performance and manufacturality. The blade inlet angle β1 is optimized to 10°≤β1≤20° and outlet angle β2 to 20°≤β2≤30°, which provides good airflow efficiency. The chord length L is limited to 15mm≤L≤25mm and camber height H to 5mm≤H≤10mm, keeping the blade size manageable. These constrained parameter ranges achieve enhanced air-blowing capacity while preventing excessive blade shape complexity that would complicate manufacturing.
Data Source
Figure 1(a)~1(b)
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Figure 4~5
AI summary
To provide a sirocco fan capable of reducing a noise value and a number of revolutions when obtaining a predetermined air-blowing amount and an air-conditioning apparatus provided with the sirocco fan. In the sirocco fan, when a fan diameter is defined as D, a maximum warp height is defined as H, a blade chord length is defined as L, a radius of a front edge at an inner circumferential side of the blade is defined as R, a blade inlet angle is defined as β1, and a blade exit angle is defined as β2, the following formulas are satisfied, 0.18 ≤ H/L ≤ 0.26, R/L ≤ 0.11, 100° ≤ β1 ≤ 130°, and 26° ≤ β2 ≤ 32°.