AXIAL-FLOW FAN

PURPOSE:To reduce thrust load, by providing a sealing means between an inner cylinder and an impeller, a high-pressure fluid feed pipe in an upstream section in the inner cylinder in the face of the impeller, and a discharge pipe in a downstream section in the inner cylinder in the face of the impeller. CONSTITUTION:Labyrinth seals 3, 3a-3c are provided along the contact lines of inner cylinder 6 and impellers 7, 7a of an axial-flow fan to perform sealing on them. High-pressure fluid feed pipes 1, 1a are provided in sections extending toward the upstream sides of the impellers 7, 7a, to feed high-pressure air. Discharge pipes 2, 2a are provided in sections extending toward the downstream sides of the impellers 7, 7a, and are opened into the atmosphere. As a result, the impellers 7, 7a are pushed downstream by the pressure of the high-pressure air. When the pressure in a casing 9 is increased, a downstream pulling force is applied to the impellers 7, 7a. Thrust load can thus be reduced or eliminated.