Cross-flow fan auxiliary ring reduces flow path loss
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Solution Overview
Problem
Conventional cross-flow fans face a trade-off between reducing flow path loss and maintaining strength, as increasing the number of support plates enhances strength but increases flow path loss, while reducing support plates decreases strength but minimizes flow path loss.
Innovation Solution
The cross-flow fan incorporates an auxiliary ring positioned on the lengthwise direction intermediate section of the blades, with connection portions extending only to the spaces between adjacent blades, joined to the suction surfaces, and molded integrally with the blades, to reduce flow path loss while reinforcing the fan's strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple support plates are disposed to enhance fan strength, then the strength of the cross-flow fan is improved, but flow path loss increases due to air friction loss occurring at the support plates
Solution Approach 1:
The patent extracts the connection function from traditional support plates and relocates it to an auxiliary ring positioned at the intermediate section of the blades. This removes the harmful air friction loss caused by support plates while preserving the necessary structural support function through the auxiliary ring's connection portions that extend into the spaces between adjacent blades.
Solution Approach 2:
The auxiliary ring is positioned at the intermediate section of the blades in the lengthwise direction, creating a new spatial dimension for support. Instead of placing support plates at the ends (traditional approach), the auxiliary ring operates at the intermediate section, reducing interference with air flow paths while maintaining blade bundling and fan strength.
2Loss of energy
If support plates are reduced to minimize flow path loss, then flow path loss is reduced, but the strength of the cross-flow fan is reduced
Solution Approach 1:
The auxiliary ring acts as an intermediary structure that provides the necessary support function without causing the air friction loss associated with traditional support plates. Its connection portions extend into the spaces between blades to provide support, while its positioning at the intermediate section and careful design minimize interference with air flow.
3Strength
If connection portions are added to the pressure surface sides of blades, then the strength is improved, but flow path loss increases due to connection portions occupying space in the flow path
Solution Approach 1:
The connection portions are strategically positioned only on the suction surface side of the blades, not on the pressure surface side. This local differentiation allows the connection portions to provide necessary support and bonding while minimizing their presence in the high-velocity flow path region, thereby reducing flow path loss.
Data Source
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AI summary
To reduce flow path loss caused by an intermediate plate or the like without reducing the strength of a cross-flow fan. Plural blades (40) extend in a lengthwise direction from a disc-shaped or circular annular support plate. A ring portion (61) of an auxiliary ring (60) is positioned on a lengthwise direction intermediate section of the plural blades (40) and is disposed on the outside of outer ends (40a) of the plural blades (40). Plural connection portions (62) of the auxiliary ring (60) extend from the ring portion (61) as far as spaces between adjacent blades of the plural blades (40) and are joined to the blades (40) in the spaces between adjacent blades.