Propeller Fan Trailing Edge Layout for Vortex Noise Reduction
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Solution Overview
Problem
Propeller fans with existing blade designs suffer from strong vortex generation at the trailing edge, leading to increased noise and energy loss due to turbulence in airflow, as vortexes generated at the leading and trailing edges do not effectively cancel each other out.
Innovation Solution
A propeller fan design featuring a trailing edge configuration with a first and second trailing edge, where the second connection point is located forward of a reference line, and the second trailing edge is positioned rearward, allowing vortexes generated at both edges to weaken each other, thereby reducing turbulence and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the inner peripheral side of the trailing edge extends along the flow direction, then the blade area is increased and static pressure is improved, but vortexes are generated at the trailing edge that remain until air flows downstream, causing increased noise and energy loss
Solution Approach 1:
The trailing edge is divided into two distinct edges: a first trailing edge extending along the flow direction to maintain static pressure, and a second trailing edge extending in the opposite direction to generate counter-vortices. This segmentation allows each edge to perform its specific function independently, resolving the contradiction between maintaining pressure and reducing vortex strength.
Solution Approach 2:
The second trailing edge generates vortexes that rotate in the opposite direction to those generated by the first trailing edge. These counter-vortices act as anti-weight to the primary vortexes, neutralizing their harmful effects and reducing overall turbulence and noise while preserving the pressure-generating capability of the first trailing edge.
2Stress or pressure
If the trailing edge is designed to increase blade area, then static pressure is improved, but turbulence and energy loss increase due to persistent vortexes
Solution Approach 1:
The trailing edge is segmented into two functional edges with different orientations. The first trailing edge maintains the blade area and static pressure, while the second trailing edge is specifically designed to generate counter-vortices that reduce turbulence and energy loss, allowing both objectives to be achieved simultaneously.
Solution Approach 2:
The second trailing edge converts the harmful effect of vortex generation into a beneficial effect by creating counter-vortices that neutralize the primary vortexes. This transforms what would normally be a source of energy loss into a mechanism for reducing turbulence and improving overall efficiency.
3Device complexity
If the trailing edge configuration follows conventional design, then blade simplicity is maintained, but noise increases due to strong vortex generation
Solution Approach 1:
The trailing edge is divided into two distinct segments with different geometric configurations. This segmentation increases structural complexity but is minimal and can be implemented through straightforward manufacturing processes, while effectively reducing noise by generating counter-vortices that neutralize harmful turbulence.
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 design effectively reduces the strength of vortexes at the trailing edge, minimizing turbulence and energy loss, resulting in a quieter and more efficient airflow.
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, for example, vortexes
Data Source
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.