DUCT EFFECTS ON THE DYNAMIC FAN CHARACTERISTICS OF AIR CUSHION SYSTEMS

During dynamic operation of an air cushion system, the fan operating point as seen at the cushion does not move along a static characteristic. Instead, it moves on a loop. It is shown that loop type behavior can be predicted theoretically. The theory models the fan-duct-plenum system as a one dimensional acoustic vibration system. It uses the method of characteristics and a finite difference technique known as the method of specified time intervals to solve for the pressure and flow variations which occur along the duct during unsteady operation. Several practical situations where the loop behaviour may be of importance are discussed.

• Supplemental Notes:
  • Also available from Engineering Societies Library.
• Corporate Authors:

  University of Toronto

  Institute for Aerospace Studies, 4925 Dufferin Road
  Toronto, Ontario  Canada  M5S 1A1
• Authors:
  • Hinchey, M J
  • Sullivan, P A
• Publication Date: 1977-6

Media Info

• Pagination: 49 p.

Subject/Index Terms

• TRT Terms: Air cushion vehicles; Atmospheric pressure; Confined flow; Ducted propellers; Dynamics; Fans; Finite differences; Flow measurement
• Uncontrolled Terms: Dynamic characteristics
• Old TRIS Terms: Air cushion dynamics; Ducted fans; Method of characteristics; Pressure gradient
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00175009
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: UTIAS-TN-211
• Files: TRIS
• Created Date: Apr 26 1978 12:00AM