Propeller Fan Trailing Edge Segmentation to Reduce Vortex Energy Loss
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Solution Overview
Problem
Propeller fans with existing blade designs suffer from strong vortex formation at the trailing edge, leading to increased turbulence and energy loss, as the axis of vortexes generated at the trailing edge aligns with the airflow direction, causing these vortices to persist downstream.
Innovation Solution
The propeller fan design features a trailing edge configuration where the second connection point is forward of the reference line in the rotation direction, and the second trailing edge is rearward, allowing vortexes generated at the first and second trailing edges to weaken each other, reducing their strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the trailing edge is designed to extend along the flow direction to increase blade area and static pressure, then the static pressure increases, but vortexes are generated at the trailing edge and persist downstream causing turbulence and energy loss
Solution Approach 1:
The trailing edge is divided into two distinct segments: a first trailing edge portion extending forward from the inner peripheral side, and a second trailing edge portion extending rearward from the outer peripheral side. These segments are positioned at different axial locations, creating separate vortex generation zones that interfere with each other, thereby reducing overall vortex strength and energy loss while maintaining adequate blade area for static pressure generation
Solution Approach 2:
The design accepts that vortexes will be generated at the trailing edge but positions them strategically so that vortexes from the first and second trailing edge portions interact and weaken each other. The harmful vortexes are converted into a beneficial interference pattern that reduces overall turbulence and energy loss downstream
2Stress or pressure
If the trailing edge is extended along the flow direction to increase blade area, then the static pressure increases, but noise levels increase due to persistent vortexes
Solution Approach 1:
The trailing edge is segmented into two portions positioned at different axial locations, creating separate vortex generation zones. The interference between vortexes from these segments reduces the intensity and persistence of vortex-induced noise, thereby lowering overall noise levels while maintaining the blade area necessary for adequate static pressure
Solution Approach 2:
The design converts the potentially harmful persistent vortexes into a beneficial interference pattern where vortexes from the first and second trailing edge portions weaken each other, reducing noise generation from vortex persistence downstream
3Area of moving object
If the trailing edge configuration creates vortexes parallel to airflow direction, then the blade area is maximized, but turbulence increases due to vortex persistence
Solution Approach 1:
The trailing edge is segmented into two portions extending in opposite axial directions, creating separate vortex generation zones. This segmentation allows the blade to maintain adequate area while the resulting vortexes interfere with each other, reducing their persistence and improving airflow stability downstream
Solution Approach 2:
The design accepts vortex generation as inevitable but strategically positions the trailing edge segments so that vortexes from each segment interfere and weaken each other, converting the harmful persistent turbulence into a beneficial interference pattern that stabilizes airflow downstream
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 effectively reduces the strength of trailing edge vortices, minimizing turbulence and energy loss, and subsequently decreases noise levels.
Implementation Method 1
vortexes generated at the first trailing edge and vortexes generated at the second trailing edge weaken each other
Implementation Method 2
The noise and energy loss of air-sending devices are made by the turbulence of airflow
Data Source
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AI summary
A propeller fan according to an embodiment of the present invention includes a shaft provided a rotation axis of the propeller fan, and a blade provided on an outer peripheral side of the shaft. The blade has a trailing edge on a rear side of the blade in a rotation direction of the propeller fan. The trailing edge includes a first trailing edge located on an innermost side of the trailing edge, and a second trailing edge adjacent to and outward of the first trailing edge. Where an innermost point of the first trailing edge is a first connection point, a connection point between the first trailing edge and the second trailing edge is a second connection point, and a straight line that extends through the rotation axis and the first connection point is a reference line, the second connection point is located forward of the reference line in the rotation direction, or located on the reference line, and the second trailing edge is located rearward of the second connection point in the rotation direction.