Browse Prior Art Database

Lead Septum/Foam Scroll for Centrifugal Fans

IP.com Disclosure Number: IPCOM000035146D
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Gaunt, DS: AUTHOR

Abstract

Aerodynamic noise from centrifugal fans is reduced with a minimum loss of fan performance by use of a modified fan scroll. The device permits standard centrifugal fans to be operated at lower noise levels or higher speeds with increased air flow but without proportional increase in noise.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Lead Septum/Foam Scroll for Centrifugal Fans

Aerodynamic noise from centrifugal fans is reduced with a minimum loss of fan performance by use of a modified fan scroll. The device permits standard centrifugal fans to be operated at lower noise levels or higher speeds with increased air flow but without proportional increase in noise.

The device shown in the figure comprises a metal fan scroll 1 with a window- section 2 of metal removed and replaced by a thin lead sheet 3 sandwiched between two layers of foam 4 outside the finger guard 5. Air is forced out of scroll orifice 6.

The lead septum 4 acts as a floating barrier isolated from the main body of the scroll by the foam. The aerodynamic noise is reduced in part by the increased attenuation of the floating barrier over that of the removed metal and in part by the absorption of the foam.

The mean LW acoustic reduction, shown as the average of four fans in db per octave, is given in the table below. Hz Octave : 250 500 1K 2K 4K 8K dB : - 1.73 - 2.70 - 3.4 - 6.15 - 6.5 - 2.78

The embodiment described was for the replacement of a steel section, as shown in the figure, but the principal can be extended to other fan blower geometries employing materials other than steel and in area sizes other than described.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]