The guide wheel also includes a number of steady flow grooves; a number of steady flow slots are centered around the center of the impeller and set at the edge of the impeller with the side of the flow guide. Each steady flow slot is set between the two diversion channels, and the direction of the channel extension of each steady flow groove is the same as the extension direction of the channel body adjacent to the flow channel; the steady flow trough depends on it. The distance from the center of the impeller to the edge of the impeller is larger than the distance between the center of the impeller and the edge of the impeller.