Positive-negative-rotation fan for clothes dryer, and clothes dryer

A clothes dryer, comprising:

• a positive-negative rotation fan including multiple first fan blades arranged on a periphery of an outer frame of the fan, multiple second fan blades arranged on the periphery of the outer frame of the fan;
• a volute, wherein a chamber of the volute is of a symmetrical structure, the fan is located in the chamber of the volute and a center of the fan is located on a symmetry axis of the chamber of the volute;
• and
• a flow guide device arranged on one side of the fan towards an outlet of the volute, and a clearance is formed between the flow guide device and a periphery of the fan, wherein
• the flow guide device is symmetrical in structure and a center of the flow guide device is set on the symmetry axis of the chamber of the volute,
• the flow guide device is of an inverted T shape, and includes a bottom plate and a vertical part connected with the bottom plate and located in a middle of the bottom plate,
• wherein a base surface of the bottom plate is toward the fan, a free end of the vertical part is away from the bottom plate and toward the outlet of the volute, the vertical part is perpendicular to the base surface of the bottom plate, and the base surface of the inverted T-shaped flow guide device is an arc surface which extends along the periphery of the fan.