AXIAL FLOW FAN

PURPOSE:To enable stable operation by making a mixture of a circulating flow and a main flow satisfactory at the outlet of a circulating flow circuit in a range where the variable angle of an inlet guide vane is throttled. CONSTITUTION:An axial flow fan incorporating a circulating flow circuit composed of rectifying vanes and an air separator 18, is provided therein with a circulating flow control means composed a drive cone 20 which is axially moved by the shaft 14 of inlet guide vanes 13 and a lever 19 in accordance with a variable angle of the inlet guide vanes 13. The flow rate of the circulating flow through the circulating flow circuit is adjusted to a value in accordance with a variable angle of the inlet guide vanes 13 that is, a flow rate of a gas stream (main stream) 23 flowing through the main flow passage.