Cross-Flow Fan Blade Thickness Layout for Lower Airflow Resistance
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Solution Overview
Problem
Conventional cross flow fans suffer from increased air flow resistance and power consumption due to non-uniform air velocity distribution and blade shape configurations, leading to inefficient fanning and energy usage.
Innovation Solution
The cross flow fan design incorporates support plates with blades divided into areas, where the inner peripheral blade end thickness is reduced in the middle portion compared to the adjacent support plate areas, optimizing air flow resistance and velocity distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the blade has the same blade shape in the impeller shaft direction, then the structure is simple, but the inter-blade distance is small creating air flow resistance
Solution Approach 1:
The blade is segmented into different sections along the impeller shaft direction: a first section adjacent to the support plate with greater thickness, and a second section at the center portion with smaller thickness. This segmentation allows the inter-blade distance to vary, creating a larger passage in the center portion that reduces air flow resistance while maintaining structural integrity near the support plate.
Solution Approach 2:
Different portions of the blade are given different local qualities through varying thickness. The first section near the support plate has greater thickness for structural support, while the second section at the center has reduced thickness to minimize air flow resistance. This local differentiation optimizes both structural strength and flow characteristics.
2Speed
If the chord length is made short in the intermediate portion to reduce air velocity and make velocity distribution uniform, then the velocity distribution improves, but the blast volume drops
Solution Approach 1:
Instead of shortening the chord length to reduce air velocity, the invention inverts the approach by reducing the blade thickness at the center portion. This maintains a longer effective chord length for generating blast volume while the reduced thickness creates a larger inter-blade passage that allows air to flow more freely, achieving uniform velocity distribution without sacrificing productivity.
Data Source
AI summary
A cross flow fan including an impeller having at least two rings arranged with intervals in a fan rotation axis O direction and a plurality of blades that are arranged, between correlated rings, with intervals in a circumferential direction of the rings, in which the blade is divided into plural areas in the fan rotation axis O direction, and both ends adjacent to the rings are denoted as the blade-ring proximate sections and the center portion of the blade is denoted as the inter-blade-ring center section. The blade is formed such that the thickness of the inner peripheral blade end of the blade that is the inner peripheral end of the impeller is smaller in the inter-blade-ring center section than in the blade-ring proximate section.