1. A fan consisting of a disk-type wheel within a cylinder, with a set of air guide vanes located either before or after the wheel; may be either belt-driven or connected directly to a motor.
2. An axial-flow fan which incorporates downstream guide vanes. It has a higher efficiency than any other type of axial-flow fans.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.