Patent ID: 8231331

Claim:
A centrifugal blowing apparatus for reducing flow-induced noise, the apparatus comprising: a blower housing having a scroll wall arcuately extending thereabout to define a scroll section formed about a rotational axis, the scroll section having a circular opening formed therein, the opening defining an inlet configured to draw in air, the scroll section commencing with a reduced cross-sectional area at a first end and expanding to an increased cross-sectional area at a second end, wherein the reduced cross-sectional area defines a cutoff, the blower housing further having an outlet wall extending from the scroll wall to define an exhaust section, the exhaust section defining an outlet in fluid communication with the inlet; an impeller disposed in the opening about the rotational axis, the impeller comprising an outer surface having impeller blades radially disposed thereon, wherein the impeller is configured to rotate the impeller blades to direct a flow of air from the inlet through the scroll section to the outlet; and a plurality of indentations formed along an inner surface of the scroll section at the cutoff, wherein an entire surface of each indentation is formed by the inner surface of the scroll wall.