Axial Fan Grooved Trailing Edge for Noise–Strength Balance
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Solution Overview
Problem
Existing axial fans face challenges in reducing air flow noise and maintaining mechanical strength, particularly due to differences in wind speed between the inner and outer rear edge parts, which affect airflow direction and the effectiveness of groove configurations in reducing noise.
Innovation Solution
The axial fan design incorporates a hub with blades featuring a cutout that divides the rear edge into outer and inner parts, with distinct groove configurations on each part. The outer rear edge has deeper grooves extending along the airflow direction, while the inner rear edge has shallower grooves, and a reinforcing part is added to enhance mechanical strength without compromising noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If grooves are added to the rear edge part to reduce air flow noise, then noise reduction is improved, but mechanical strength deteriorates
Solution Approach 1:
The rear edge part is divided into outer and inner parts by a cutout, allowing different groove configurations in each segment. The outer rear edge part has grooves extending from the rear edge toward the front edge, while the inner rear edge part has a different groove pattern. This segmentation enables optimized noise reduction in each region without compromising overall structural strength.
Solution Approach 2:
Different groove configurations are applied to different regions of the blade based on local airflow characteristics. The outer rear edge part (with higher wind speed) has grooves of one configuration, while the inner rear edge part (with lower wind speed) has grooves of a different configuration. This local optimization reduces noise effectively while maintaining mechanical strength in each specific region.
2Ease of manufacture
If uniform groove configuration is used across the entire rear edge, then manufacturing is simplified, but noise reduction effectiveness deteriorates due to different wind speeds in inner and outer regions
Solution Approach 1:
The blade is segmented into outer and inner rear edge parts with distinct groove configurations tailored to each region's airflow characteristics. The outer part has grooves suitable for higher wind speeds, while the inner part has grooves optimized for lower wind speeds, maximizing noise reduction effectiveness across the entire blade.
Solution Approach 2:
Each region of the blade receives a locally optimized groove configuration based on its specific operating conditions. The outer rear edge part experiences different wind speeds and airflow directions compared to the inner rear edge part, so each region has grooves specifically designed for its local conditions to maximize noise reduction.
3Object-affected harmful factors
If the outer rear edge part has deeper grooves to handle higher wind speed, then noise reduction in outer region is improved, but mechanical strength of outer edge deteriorates
Solution Approach 1:
The outer rear edge part is separated from the inner rear edge part by a cutout, allowing independent optimization of each region. The outer part can have deeper grooves to handle higher wind speeds and reduce noise effectively, while the inner part has shallower grooves that maintain structural strength, as each segment can be designed independently for its specific requirements.
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 suppresses air flow noise and maintains proper mechanical strength by aligning grooves with airflow directions and using a reinforcing part to secure the outer rear edge, enhancing the fan's noise reduction capabilities and structural integrity.
Implementation Method 1
a vortex that has occurred in the front edge part of the blade is flown from the front edge part to the rear edge part along a blade surface of the blade, and is then caught and held by the cutout. This suppresses or reduces fluctuation and development of the vortex, thereby suppressing or reducing a noise caused by the flow of the air.
Data Source
AI summary
An axial fan includes: a hub; a plurality of blades arranged in a circumferential direction of the hub; a cutout in a rear edge part of each of the plurality of blades, the cutout divides the rear edge part into an outer rear edge part and an inner rear edge part; a first groove part disposed in the outer rear edge part, the first groove part including a plurality of grooves extending toward the front edge part; and a second groove part disposed in the inner rear edge part, the second groove part including a plurality of grooves extending toward the front edge part, the plurality of grooves of the first groove part and the plurality of grooves of the second groove part having different shapes when viewed in a rotational axis direction of the hub.