Unpowered draught fan with support frames as wing-shaped blades

The invention discloses an unpowered draught fan with support frames as wing-shaped blades. According to an existing unpowered draught fan, strong vortexes will be formed behind plate support frames, and the turbulence degree of a flow field is intensified. The lower-end support frame of the unpowered draught fan is formed by multiple lower-end wing-shaped blades, one end of each lower-end wing-shaped blade is fixed to the bottom of a center shaft, and the other end of each lower-end wing-shaped blade is fixed to the inner wall of an angle-changing pipe diameter; the upper-end support frame of the unpowered draught fan is formed by multiple upper-end wing-shaped blades, one end of each upper-end wing-shaped blade is fixed to a positioning sleeve, and the other end of each upper-end wing-shaped blade is fixed to the inner wall of a cylinder pipe diameter; the positioning sleeve is supported to the center shaft through a bearing; the chord length of the upper-end wing-shaped blades is larger than the chord leng