Propeller Fan Blade Layout for Uniform Radial Wind Speed
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Solution Overview
Problem
The wind speed distribution in the radial direction of propeller fans is non-uniform, leading to surging phenomena, noise, and damage, with the inner peripheral portion contributing minimally to air blowing, thus limiting air flow rate and efficiency.
Innovation Solution
The propeller fan design incorporates specific ratios for the radius and wind speed between the inner and outer peripheral portions, along with strategically positioned blade elements and holes to maintain uniform wind speed distribution, suppressing surging and enhancing air flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the diameter and rotation speed of the propeller fan are increased to improve air flow rate, then the air flow rate is improved, but the wind speed difference between the outer peripheral portion and inner peripheral portion of the blade increases, causing surging phenomenon and noise
Solution Approach 1:
The patent applies local quality by making the blade chord length vary along the radial direction. The chord length is designed to be longer at the inner peripheral portion and shorter at the outer peripheral portion, creating localized geometric variations that compensate for the non-uniform wind speed distribution. This geometric optimization ensures more uniform wind speed across the blade span, suppressing surging phenomenon while maintaining high air flow rate.
2Productivity
If the propeller fan operates at high speed to improve air flow rate, then the air flow rate is improved, but the inner peripheral portion of the blade where wind speed is slow does not contribute substantially to air blowing, reducing blade surface utilization efficiency
Solution Approach 1:
The patent applies parameter changes by optimizing the chord length parameter along the radial direction of the blade. By varying the chord length from the inner peripheral portion to the outer peripheral portion according to a specific distribution pattern, the design ensures that all parts of the blade operate within an optimal wind speed range. This parameter optimization enables the inner peripheral portion to contribute effectively to air blowing, improving overall blade surface utilization efficiency while maintaining high air flow rate.
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 improves air flow rate while minimizing wind speed differences across the blade, reducing noise and damage, and optimizing operational efficiency.
Implementation Method 1
a plurality of blades (12A, 12B, 12C) provided on a side surface of the hub (11)... the wind speed in the propeller fan is high at the outer peripheral portion of the blade and decreases toward the center of rotation
Data Source
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AI summary
A propeller fan includes a hub having a rotation axis, and a plurality of blades provided in a circumference direction of the hub, in which a blade includes an inner peripheral portion that is located on a side of a base within a portion from the base connected to the hub to an outer edge, and an outer peripheral portion that is located on a side of the outer edge, the outer peripheral portion is formed as one blade surface, the inner peripheral portion includes a plurality of blade elements arranged at a predetermined interval, a ratio r/R in which a radius r which is a distance from the central axis to a boundary between the inner peripheral portion and the outer peripheral portion and a radius R which is a distance from the central axis to the outer edge is 0.4 or less, and when a wind speed at the outer peripheral portion is V1 and a wind speed at the inner peripheral portion is V2, a relational formula of V1 ≤ V2 × 2.0 is established.