Abstract: A centrifugal fan includes: an impeller driven by a drive motor to rotate; a scroll casing including an inlet-port face having an opening and a wall portion having positions at which distances from an axis line that is a rotation center of the impeller differ from each other, and changing an air flow in a centrifugal direction generated by rotation of the impeller into an air flow in one direction; an air admitting portion including a bell mouth portion having a large-diameter side end placed on an inlet-air-flow upstream side of the inlet-port face; and a protruding portion extending from the air admitting portion in a direction orthogonal to the axis line, which is the rotation center of the impeller, and in a direction away from the rotation center and surrounding part of the bell mouth portion.

Abstract: A centrifugal fan includes: an impeller driven by a drive motor to rotate; a scroll casing including an inlet-port face having an opening and a wall portion having positions at which distances from an axis line that is a rotation center of the impeller differ from each other, and changing an air flow in a centrifugal direction generated by rotation of the impeller into an air flow in one direction; an air admitting portion including a bell mouth portion having a large-diameter side end placed on an inlet-air-flow upstream side of the inlet-port face; and a protruding portion extending from the air admitting portion in a direction orthogonal to the axis line, which is the rotation center of the impeller, and in a direction away from the rotation center and surrounding part of the bell mouth portion.