| 摘要 |
<p>In a multi-blade centrifugal fan (1) in which an impeller (17) is provided in a scroll casing (2) in a freely rotatable manner, the scroll casing (2) is provided with an axially expanded portion that forms an air channel (9A) at a bottom surface thereof which is expanded in a rotation-axis direction at a radially outer side of an annular flange portion (8) which supports the impeller (17); and is provided, in a region of an outlet (14) between a tongue portion (12) and a spiral-end portion (13) of the scroll casing (2) in the axially expanded portion, with a protrusion (24) that protrudes radially outward from a radially inner side surface by a predetermined amount so as to directly face an airflow in a circumferential direction.</p> |
