The invention provides a double-air-inlet
centrifugal fan which comprises a
volute, double-air-inlet impellers and a motor. The double-air-inlet impellers are arranged on a rotating shaft of the motor and are arranged in the
volute. The
volute comprises a
front cover plate, a rear cover plate and a volute coaming arranged between the
front cover plate and the rear cover plate. The positions, aligned with the double-air-inlet impellers, of the
front cover plate and the rear cover plate are provided with a front air-
inlet channel and a rear air-
inlet channel respectively. The volute coaming is provided with an air outlet channel. The position, corresponding to the air outlet channel, of the volute is provided with a volute tongue. The volute tongue comprises a volute tongue curved face, and the volute tongue curved face is located on one side of the air outlet channel and is an inwards-concave and asymmetric curved face. According to the double-air-inlet
centrifugal fan, the inwards-concave and asymmetric curved face is adopted for the volute tongue curved face, on one hand, rotating
noise can be reduced, on the other hand, a deep tongue form is adopted for the volute tongue
contour line close to an
impeller front end ring and an
impeller rear end ring, a shallow tongue form is adopted for the volute tongue
contour line close to an
impeller middle disc, so that the problem caused by uneven outlet speed distribution of the impellers can be avoided, and thus
air volume and air pressure are increased, and efficiency are improved easily.