Cross Flow Fan Blade Camber Angle Variation for Uniform Airflow
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Solution Overview
Problem
Existing cross flow fans in air conditioners and air blowers experience non-uniform wind velocity distribution along the axial direction due to variations in gap sizes between the fan and the air trunk member, leading to increased input power and noise, as well as potential airflow separation and vortex formation.
Innovation Solution
A cross flow fan design featuring annular rings and radially interposed blades with a circular arc cross-sectional shape, where the camber angle is smaller at the ring side than at the blade center, ensuring uniform wind velocity distribution and reduced airflow separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the outer diameter of the ring part is increased to assure strength, then the structural strength is improved, but the gap between the ring part and the air trunk becomes smaller, causing high-speed flow and vortex formation that increases noise and power consumption
Solution Approach 1:
The blade camber angle is made smaller at the ring side (near the high-speed flow region) and larger at the blade center, creating local quality variations that adapt to different flow conditions. This allows the blade to efficiently handle both high-speed flow near the ring and maintain overall performance without increasing structural diameter
Solution Approach 2:
The invention changes the camber angle parameter along the blade width, making it smaller at the ring side to reduce the velocity difference between fast and slow flows. This parameter variation suppresses vortex formation and reduces noise while maintaining the structural strength provided by the larger ring diameter
2Productivity
If the camber angle is increased to improve air moving capability, then the volume of air is increased, but the velocity difference between fast flow and slow flow becomes greater, causing more pronounced vortex formation and noise
Solution Approach 1:
The blade camber angle is made smaller at the ring side where high-speed flow occurs and larger at the blade center, creating local quality variations. This allows the blade to maintain good air moving capability at the center while reducing velocity differences at the ring side, thereby suppressing vortex formation and noise
Solution Approach 2:
The camber angle parameter is varied along the blade width rather than being uniform. By making the camber angle smaller at the ring side, the invention reduces the velocity difference between fast and slow flows, preventing vortex formation while maintaining overall air moving capability through the larger camber angle at the blade center
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 achieves a uniform wind velocity distribution at the exit of the air trunk, reducing input power and noise, while preventing vortex formation and airflow separation, thereby enhancing the performance of air conditioners and air blowers.
Implementation Method 1
each having a circular arc cross sectional shape
Implementation Method 2
a camber angle of the blade is smaller at the ring side than at a center area of the blade between the rings in a longitudinal direction
Data Source
AI summary
Disclosed is a cross flow fan that makes uniform a distribution of wind velocity along an axial direction of the fan at an exit of an air trunk and that lessens chance of separation of an air flow on an inlet side of the fan, and there are thereby provided a cross flow fan that accomplishes a lower input and smaller noise and an air blower and an air conditioner that use the cross flow fan. A cross flow fan being rotatably placed in a horizontally-long air trunk, and including a plurality of annular rings that are substantially parallel to each other and a plurality of blades that are radially interposed between adjacent rings, each having a circular arc cross sectional shape, and a camber angle of the blade is smaller at the ring side than at a center area of the blade between the rings in a longitudinal direction.