Vortex disc of vortex expander

The invention discloses a vortex disc of a vortex expander. The central initiating end of the vortex disc is an arc. The outer wall of the vortex disc is in an involute type that is tangent to the external endpoint of the arc at the central initiating end of the vortex disc and extends outward. The inner wall of the vortex disc comprises an involute segment and a linear segment that are parallel to the outer wall of the vortex disc. The initiating end of the involute segment is in connection with the internal endpoint of the arc at the central initiating end of the vortex disc through the linear segment, which is respectively tangent to the initiating end of the involute segment and the internal endpoint of the arc at the central initiating end of the vortex disc. Therefore, the volume ofa central cavity of the vortex disc is increased, i.e. the inspiratory volume of the vortex expander is increased, thus improving the output power of the vortex expander.