Propeller Fan Blade Tip Vortex Reduction
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Solution Overview
Problem
In propeller fans, the design to reduce blade tip vortex generation compromises fan efficiency, particularly at the outer peripheral portion where peripheral speed is high.
Innovation Solution
The propeller fan design includes a ring connected to each blade tip, with a first portion inside the radial direction having a constant axial height at the maximum camber location, and a second portion outside with increasing axial height towards the blade tip, enhancing workload and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the maximum camber location ratio is increased toward the blade tip to reduce blade tip vortex, then blade tip vortex generation is reduced, but fan efficiency is degraded due to reduced workload on the blade tip side
Solution Approach 1:
The blade is divided into two portions with different axial heights at the maximum camber location. The first portion (inner side) has substantially constant axial height to reduce blade tip vortex, while the second portion (outer side) has increasing axial height toward the blade tip to maintain workload and fan efficiency. This local differentiation resolves the contradiction by applying different design characteristics to different regions of the blade.
Solution Approach 2:
The blade is segmented into two distinct portions along the radial direction: an inner portion with constant axial height and an outer portion with increasing axial height. This segmentation allows each portion to independently address different requirements - the inner portion focuses on vortex reduction while the outer portion maintains productivity, thereby resolving the technical contradiction.
2Ease of manufacture
If the axial height at maximum camber location is kept constant across the blade to simplify manufacturing, then manufacturing complexity is reduced, but fan efficiency is compromised due to insufficient workload on the blade tip side
Solution Approach 1:
Instead of applying a uniform axial height design across the entire blade, the invention applies different axial height characteristics to different regions. The inner portion maintains constant axial height for manufacturing simplicity, while the outer portion increases axial height toward the blade tip to enhance workload and fan efficiency, thus resolving the contradiction between ease of manufacture and productivity.
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 blade tip vortex generation while enhancing fan efficiency by increasing workload on the blade tip side and optimizing static pressure efficiency.
Implementation Method 1
The blade tip vortex is a vortex flow generated by air that flows back around a blade tip from a positive pressure surface side to a negative pressure surface side of the blade
Data Source
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AI summary
A propeller fan includes a plurality of blades (14) extending outward in the radial direction of rotation from the outer peripheral surface of the cylindrical hub (12). A ring (16) provided so as to surround the plurality of blades (14) is connected to each blade tip (20) of the blades (14). Each blade (14) has a first portion (30) which is provided inside in the radial direction of rotation and whose axial height at a maximum camber location (X) is substantially constant, and a second portion (32) which is provided outside in the radial direction of rotation and whose axial height at the maximum camber location (X) increases toward the blade tip (20).