Browse Prior Art Database

Crescent Air - Moving Device Inlet Conditioner

IP.com Disclosure Number: IPCOM000105766D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Yeager, DM: AUTHOR

Abstract

This article describes a crescent-shaped, inlet-flow conditioner that, when attached to the fan inlet just downstream of an obstructing physical object, reduces the A-weighted noise emission level of the fan, and reduces the annoyance of the fan noise by removing the discrete frequency tones from the spectrum.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 68% of the total text.

Crescent Air - Moving Device Inlet Conditioner

      This article describes a crescent-shaped, inlet-flow
conditioner that, when attached to the fan inlet just downstream of
an obstructing physical object, reduces the A-weighted noise emission
level of the fan, and reduces the annoyance of the fan noise by
removing the discrete frequency tones from the spectrum.

      The noise generated and radiated by an axial-flow, air-moving
device (fan) is related to the circumferential uniformity of the
inlet-flow velocity.  If the flow into the fan inlet is not
circumferentially uniform (i.e., equivalent flow rate through all
sectors of the fan annulus), then discrete frequency tones are
generated which are related to the rotational frequency of the fan
and number of blades, and which cause the overall noise level of the
fan to increase.  In the design of electronic computer systems, it is
often necessary to place electronic components or other mechanical
obstructions near the inlet of a fan, due to space constraints.  This
causes a flow deficit and turbulent wake just downstream of the
obstruction, at the fan inlet, thereby increasing the noise.

      In the drawings, Fig. 1 is a front sectional view of the fan
and Fig.  2 is a side sectional view.  In operation, as a fan blade
rotates through a nonuniform inlet flow, the blade surface pressure
fluctuates as the blade passes through the flow deficit regions.
Very significant flow deficit regions can be created by...