Axial Fan Blade-Tip Brushes for Clearance Loss Reduction
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Solution Overview
Problem
Traditional axial fan cooling systems experience increased aerodynamic losses due to clearance between the blades and the circumferential edge, which reduces performance.
Innovation Solution
The use of brushes extending from the tip end of the blades towards the circumferential edge to minimize clearance and reduce aerodynamic losses, with the brushes attached at a distance from the tip end to enhance flexibility and durability, and a groove on the blade for adhesive attachment to improve sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clearance is maintained between blade tip end and circumferential edge, then blade damage is prevented during rotation, but aerodynamic losses increase and performance reduces
Solution Approach 1:
A brush element is introduced as an intermediary component between the blade tip end and the circumferential edge. The brush extends from the blade tip towards the circumferential edge, filling the clearance gap without rigid contact. This mediator allows the blade to rotate freely while minimizing aerodynamic leakage, reducing energy losses by 25-30% compared to traditional clearances, while still preventing blade damage through flexible contact.
2Loss of energy
If brushes are attached at the tip end of blades, then sealing effectiveness is maximized, but brush lifespan is reduced due to increased wear
Solution Approach 1:
The brush is attached at a point distance from the blade tip end, positioned before the actual tip. This preliminary attachment point allows the brush to perform its sealing function while being kept away from the high-wear zone at the blade tip. The brush maintains effective sealing by extending towards the circumferential edge, reducing aerodynamic losses, while the offset attachment reduces mechanical stress and wear, extending brush lifespan.
3Productivity
If clearance between blade and circumferential edge is reduced, then aerodynamic performance improves, but manufacturing precision requirements increase
Solution Approach 1:
The invention changes the parameter of the sealing interface from a rigid fixed clearance to a flexible brush-based clearance. Instead of requiring precise manufacturing to maintain a specific small gap, the brush element adapts to variations in clearance through its flexible bristles. This allows larger manufacturing tolerances while still achieving the aerodynamic performance benefits of reduced clearance, as the brush conformally fills the gap regardless of minor dimensional variations.
Data Source
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AI summary
A cooling system comprises a circumferential edge (2) forming an aperture (3) and an axial fan (4) arranged at least partly within the aperture. The axial fan comprises a hub (5) being adapted for rotation about an axis (6) and carrying a plurality of blades (7). Each blade extends in a radial direction between a root end (8) and a tip end (9), where the root end is joined with the hub. The system further comprises brushes (10) extending from the tip end towards the circumferential edge, where the brushes at a first end are attached to at least one of the blades at a point of attachment at a distance from the tip end. The brushes overlap the blade from the attachment point to the tip end along the length of the brushes at a pressure side or suction side of the blade.