Integrated-Wing Propeller Fan Rib Design to Reduce Airflow Separation
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Solution Overview
Problem
Integrated-wing propeller fans face significant airflow separation and stagnation on the downstream side of the rotation-axis part, leading to reduced air-sending efficiency and increased separation areas, despite previous attempts to improve strength with ribs.
Innovation Solution
The propeller fan design incorporates first ribs that project towards the center of rotation and surround the rotation-axis part, along with second ribs that extend axially from the rotation-axis part towards the first ribs, with the second ribs' ends projecting further than the first ribs' ends, to diffuse airflow effectively towards the inner and downstream sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ribs are added to strengthen blades, then blade strength is improved, but airflow separation and stagnation on the downstream side of the rotation-axis part worsen
Solution Approach 1:
The rib structure is divided into two distinct segments: first ribs that extend radially from the rotation-axis part to provide structural support, and second ribs that extend axially from the first ribs to manage airflow. This segmentation allows each rib type to perform its specific function without interfering with the other, resolving the contradiction between structural support and airflow management.
Solution Approach 2:
The second ribs act as intermediary structures that bridge the gap between the first ribs (structural support) and the airflow path. By extending axially from the first ribs, the second ribs mediate the interaction between the reinforced blade structure and the surrounding airflow, guiding air toward the downstream side and reducing stagnation.
2Weight of moving object
If an integrated-wing propeller fan without boss part is used, then weight is reduced, but blade strength becomes insufficient leading to large deformation
Solution Approach 1:
The support function previously provided by a single boss part is segmented into multiple first ribs distributed around the rotation-axis part. This segmentation maintains the weight advantage of the integrated-wing design while providing sufficient structural support through the distributed rib system.
Solution Approach 2:
The rib structure combines structural support function (first ribs) with airflow management function (second ribs) in a composite configuration. This functional integration allows the lightweight integrated-wing design to achieve both structural integrity and aerodynamic performance.
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 configuration significantly reduces the separation area on the downstream side of the rotation-axis part, enhancing airflow diffusion and reducing vortex creation, thereby improving air-sending efficiency and minimizing noise.
Implementation Method 1
The outdoor unit is provided with a propeller fan, serving as an air-sending device, having blades (propeller). By rotating the propeller fan to generate an airflow, an air-sending operation, such as cooling or heat release, is performed.
Implementation Method 2
The propeller fan design incorporates first ribs that project towards the center of rotation and surround the rotation-axis part, along with second ribs that extend axially from the rotation-axis part towards the first ribs, with the second ribs' ends projecting further than the first ribs' ends, to diffuse airflow effectively towards the inner and downstream sides.
Data Source
AI summary
A propeller fan includes: a rotation-axis part that serves as a center of rotation; and a plurality of blades provided on an outer circumferential side of the rotation-axis part, the plurality of blades being joined to adjoining blades at leading edges and trailing edges thereof. A first rib projecting towards the center of rotation of the rotation-axis part to surround the rotation-axis part, and second ribs projecting towards the center of rotation to extend from the rotation-axis part toward the first rib are provided on pressure surfaces of the plurality of blades. Among ends of the second ribs in the direction of the center of rotation, the ends distant from the pressure surfaces project away from the pressure surfaces farther than an end of the first rib distant from the pressure surfaces, among the ends of the first rib in the direction of the center of rotation.