摘要:
Porous damping material (40) is attached to an entire inner circumference of the fan shroud (20) opposing to an end of a fan (4) and is exposed to opposing space without using conventional perforated metal. Accordingly, jet noise caused by strong swirl between the fan (4) and the fan shroud (20) can be damped by the damping material (40) and impulsive sound scarcely occurs. Thus, both of the impulsive sound and the jet noise can be effectively damped, thereby securely reducing noise. The pours member (401) constituting the porous damping material (40) is a die-molding product made by a die (150) having a cavity (153).