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Centrifugal Blower With Means to Distribute the Air More Evenly Inside the Cage for Reduced Noise in the Air at the Radially Outer Edges of the Blades

IP.com Disclosure Number: IPCOM000037682D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Maling, GC, Jr: AUTHOR [+2]

Abstract

In a conventional centrifugal blower, air flows axially into the impeller from its open end and then flows radially outward through the revolving blades. The air flowing through the blower produces noise with a loudness that is proportional to about the 5th or 6th power of the air velocity. For this reason, the noise of a blower can be reduced by making the velocity more uniform -- reducing the highest velocities to reduce noise and raising the lowest velocity to provide the same air flow rate.

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Centrifugal Blower With Means to Distribute the Air More Evenly Inside the Cage for Reduced Noise in the Air at the Radially Outer Edges of the Blades

In a conventional centrifugal blower, air flows axially into the impeller from its open end and then flows radially outward through the revolving blades. The air flowing through the blower produces noise with a loudness that is proportional to about the 5th or 6th power of the air velocity. For this reason, the noise of a blower can be reduced by making the velocity more uniform -- reducing the highest velocities to reduce noise and raising the lowest velocity to provide the same air flow rate.

The velocity of the air at the outer edges of the blades is not uniform over the axial length of the blades. It is lowest near the inlet to the cage and highest at the inside end of the cage. We attribute this difference to the fact that the inlet end of the cage is starved for air.

In one version of this rotor, the flow rate is made more uniform by tapering the radially inward edges of the blades so that the space inside the impeller has a small diameter at the inlet end and larger diameter at the inside end. This structure provides an easier flow of air at the inlet end of the cage and thereby evens the air velocity at the outer edges of the blades.

In a second version of this blower, the radially inward edges of the blades are parallel to the axis of the impeller, as is conventional. A plug is located inside the squirrel...