Cross-Flow Fan Flow Guide Member to Reduce Backflow and Surge Noise
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Solution Overview
Problem
The air supply efficiency of cross-flow fans is reduced and abnormal surge sounds are generated due to backflow of airflow between the cross-flow fan wheel and the volute, especially when the air outlet opening is small.
Innovation Solution
Incorporating a flow guide member within the air outlet duct of the cross-flow fan, which is designed to increase air pressure near the end of the cross-flow fan wheel and guide airflow, thereby preventing backflow and enhancing air supply efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the air outlet opening of the volute is small, then the air supply efficiency decreases and abnormal surge sound is generated, but reducing the air outlet opening is necessary for certain operating conditions
Solution Approach 1:
A flow guide member is introduced as an intermediary component between the cross-flow fan wheel and the volute wall. This flow guide member actively guides the airflow along the volute wall, preventing backflow to both ends of the fan wheel while maintaining small air outlet openings. The flow guide member acts as a mediator that directs flow patterns to eliminate harmful backflow effects.
2Object-affected harmful factors
If the air outlet opening is small, then abnormal surge sound is generated, but small opening degree is required for certain applications
Solution Approach 1:
The flow guide member serves as an intermediary that enables the system to maintain small air outlet openings without generating abnormal surge sounds. By actively guiding the airflow along the volute wall, the flow guide member prevents the flow separation and backflow that cause surge sounds, thus allowing the system to operate adaptably at various opening degrees including small openings.
3Productivity
If no flow guide member is provided, then the structure is simple, but airflow backflow occurs reducing efficiency
Solution Approach 1:
The flow guide member is a relatively simple intermediary component that can be integrated into the volute structure. While it does increase structural complexity slightly, it dramatically improves air supply efficiency by preventing backflow. The flow guide member can be designed as a simple protrusion or attachment on the volute wall, minimizing the increase in complexity while achieving the desired flow control.
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 implementation of the flow guide member effectively reduces backflow and abnormal surge sounds, improving the air supply efficiency of the cross-flow fan while maintaining airflow volume and reducing wind resistance.
Implementation Method 1
a flow guide member is disposed at a side wall of the air outlet duct close to an end of the cross-flow fan wheel
Implementation Method 2
the flow guide member is configured as a boss, a necking is disposed at the air outlet duct, and a distance between the surrounding plate and the volute tongue is minimal at the necking
Implementation Method 3
the flow guide member is a platform, and the height of the flow guide member is 3-6 mm
Implementation Method 4
improving the air supply efficiency of the cross-flow fan while maintaining airflow volume and reducing wind resistance
Data Source
AI summary
A cross-flow fan includes a volute internally provided with an air supply duct, a cross-flow fan wheel disposed in the air supply duct and dividing the air supply duct into an air inlet duct located upstream of the cross-flow fan wheel and an air outlet duct located downstream of the cross-flow fan wheel, and a flow guide member disposed at a side wall of the air outlet duct close to an end of the cross-flow fan wheel.