Axial Fan Blade Tip Member for Low-Noise Airflow
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Solution Overview
Problem
Large industrial axial fans face challenges in reducing noise levels due to manufacturing limitations of extrusion and pultrusion techniques, which restrict shaping and result in increased blade dimensions and reduced rotation speed, failing to effectively minimize noise generation.
Innovation Solution
The design of a blade with a terminal member having a rounded front and rear portion, a tapered shape, and a lobe at the trailing edge, which reduces turbulence by modifying the air trajectory and overlapping with adjacent blades to deflect recirculating air, combined with a manufacturing process involving extrusion or pultrusion followed by cutting to achieve aerodynamic shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If extrusion and pultrusion techniques are used to manufacture large fan blades, then cost-effectiveness and mechanical strength are improved, but the ability to shape blades for noise reduction is worsened
Solution Approach 1:
The blade is divided into two functional parts: an extruded/pultruded hollow structure providing mechanical strength and cost-effectiveness, and an aerodynamic skin layer providing noise-reducing shaping. This segmentation allows each part to fulfill its specific function optimally.
Solution Approach 2:
The blade combines a hollow structural core (from extrusion/pultrusion) with an aerodynamic skin layer, creating a composite structure that integrates both mechanical strength requirements and aerodynamic noise reduction requirements in a single component.
2Object-generated harmful factors
If blade rotation speed is reduced to decrease noise, then noise levels are improved, but airflow performance is worsened
Solution Approach 1:
The terminal member features rounded contours including a rounded leading edge, rounded trailing edge, and rounded tip end. These curved surfaces guide air flow smoothly around the blade tip, reducing turbulence and vortex formation that cause noise, while maintaining aerodynamic efficiency for airflow performance.
3Productivity
If blade dimensions are increased to maintain airflow at reduced speed, then airflow performance is improved, but noise reduction effectiveness is worsened
Solution Approach 1:
The aerodynamic skin layer with specific rounded contours is applied locally at critical areas (terminal member, leading edge, trailing edge) where turbulence generation is most significant. This localized aerodynamic treatment effectively reduces noise without requiring overall blade dimension changes.
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 solution significantly reduces noise levels by minimizing turbulence and vortices, achieving noise reduction comparable to moulding techniques while maintaining cost-effectiveness and mechanical strength, and is adaptable for large industrial fans.
Implementation Method 1
The rounding facilitates the circulation of air around the terminal member, thus reducing the turbulence. In particular, the angle of the trajectory of the leading point in relation to the air, is gradually modified around the tip side of the blade, avoiding sudden changes and the creation of vortices.
Data Source
AI summary
A blade for an industrial axial fan includes an extruded or pultruded airfoil, extending along a blade axis and having a leading edge, a trailing edge, a root side and a tip side, an intrados and an extrados. A terminal member is arranged to close the tip side and has a rounded front portion in a plan view at the leading edge and a rounded rear portion in a plan view between the front portion and the trailing edge.