Fan Blade Noise Reducer

Inactive Publication Date: 2019-05-09
SAYGER JACK MILTON
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This patent is about reducing the noise of fans by changing the shape and size of the part of the fan blades that leads them. This can be done to existing blades, during production, or directly into the blades. The result is quieter fans.

Problems solved by technology

To reduce fan size it is necessary to increase fan rpm to maintain the same airflow on such items as shop fans, ac fans, computer fans, etc.. In doing so the fan creates unwanted noise due to leading edge aerodynamic deficiencies.

Method used

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  • Fan Blade Noise Reducer

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0004]The leading edge method prototype setup used a commercial 4-blade stamped sheet metal shop fan. Fan noise was a major issue during use.

[0005]Fan Blades: 4

[0006]Blade Span: 12.75″

[0007]Chord: 6″

[0008]Blade Thickness: 0.70″

[0009]Leading edge method applied: 0.25 OD, 0.125 ID round rubber tubing, full span of each blade. Results: Noise level drop 6%. / RPM drop 0.018% / CFM drop 6%.

[0010]The flow rate drop was not significant for fan's intended application. Noise level drop was significant and greater than could be associated with RPM drop alone.

[0011]In this example, increasing the leading edge radius to 0.25″ from 0.70″ (28%) where 0.25″ is defined as Leading Edge Radius / Blade Chord Length achieved these results. Apply method along leading edge of fan. Tip region is more critical than root region but best results occur with full span treatment. Circular / tubular shape of method is simple but not required as long as leading edge radius is increased to all blades.

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PUM

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Abstract

The leading edge method improves fan blade aerodynamics, which reduces energy lost into the airflow as acoustic noise. This results in a quieter fan, with no significant change to air moving capability. This is accomplished by increasing the radius of the fan blade leading edge, and by ensuring that any laminar boundary layer existing over the fan blade is tripped into a more energetic, and less likely to separate, turbulent boundary layer. Most fan blades are not fabricated with aerodynamic (airfoil) cross sections. Typically, they are either stamped from sheet stock, or molded out of thin material, in both cases with “sharp” leading edges with small leading-edge radius compared to fan blade chord length. Airfoils designed to operate at the Reynolds-numbers applicable to fan blades eschew sharp leading edges for large, rounded leading edges to control the surface pressure distributions and permit operation over a wide angle of attack range without boundary layer separation. The leading edge treatment in this patent application serves the purpose of increasing the fan leading edge radius without scrapping the entire fan blade and replacing it with a proper low Reynolds-numbers airfoil shape.

Description

BACKGROUND[0001]To reduce fan size it is necessary to increase fan rpm to maintain the same airflow on such items as shop fans, ac fans, computer fans, etc.. In doing so the fan creates unwanted noise due to leading edge aerodynamic deficiencies. This is a simple fix to this unwanted noise.BRIEF SUMMARY[0002]Reduce fan noise by altering fan blade leading edge radius shape and size. Applicable as an aftermarket fix to fan blades, an additional step during blade production, or can be formed directly into the blade.DESCRIPTION OF DRAWING[0003]FIG. 1 Front view and end view looking at tubing attached on fan blade leading edge.DETAILED DESCRIPTION[0004]The leading edge method prototype setup used a commercial 4-blade stamped sheet metal shop fan. Fan noise was a major issue during use.[0005]Fan Blades: 4[0006]Blade Span: 12.75″[0007]Chord: 6″[0008]Blade Thickness: 0.70″[0009]Leading edge method applied: 0.25 OD, 0.125 ID round rubber tubing, full span of each blade. Results: Noise level ...

Claims

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Application Information

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IPC IPC(8): F04D29/66F04D29/38
CPCF04D29/667F04D29/384F04D29/388F04D25/08F05D2240/303
InventorSAYGER, JACK MILTON
OwnerSAYGER JACK MILTON