PERFORMANCE ON TILTED DUCTS

The paper presents a discussion of the causes and effects of air drawing (natural ventilation) of ship propellers with special reference to ducted propellers. Model tests are described where the effects of air drawing upon thrust fluctuations and propeller-induced pressures on the hull have been measured. Various means have been tested for the purpose of reducing the tendency of air drawing of ducted propellers. It is concluded that the most efficient means of obtaining such an improvement is to tilt the duct downward at its forward end so that its axis no longer coincides with the propeller shaft axis. Further model tests are described, which indicate that such tilting of the duct may also have a beneficial effect with respect to propulsive efficiency and propeller-induced vibrations, even with the ship in a load condition where there is no danger of air drawing.

• Corporate Authors:

  Ship Research Institute of Norway

  P.O. Box 4125, Valentinlyst, Hakon Hakonsongt. 34
  N-7001 Trondheim,   Norway 
• Authors:
  • Huse, E
• Publication Date: 1974-11

Media Info

• Features: References;
• Pagination: p. 5-12

Subject/Index Terms

• TRT Terms: Ducted propellers; Performance; Propellers; Vibration
• Uncontrolled Terms: Scale effect
• Old TRIS Terms: Model testing; Propeller efficiency; Propeller induced vibration; Propeller performance; Ventilated flow
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00167714
• Record Type: Publication
• Source Agency: Ship Research Institute of Norway
• Report/Paper Numbers: R-32.74
• Files: TRIS
• Created Date: Dec 27 1977 12:00AM