Centrifugal fan

摘要

A centrifugal fan is described. The centrifugal fan is suitable for a portable electrical apparatus. A tongue shape is formed from a volute sidewall of a casing of the centrifugal fan and non-parallel to a rotational axis of blades. Therefore, when the blades rotate to generate a wake flow to blow on a surface of the volute sidewall at the tongue shape, noise generated by the centrifugal fan can be decreased.