THE CAVITATION TUNNEL AS AN AID TO PROPELLER DESIGN

After outlining the history of cavitation tunnel testing, the Author, of SMM Propellers Ltd, discusses the ways in which the cavitation tunnel can aid the propeller designer, under the headings:--Uniform Flow Experiments; Simulated Wake Distributions; Vibratory Forces; and Spindle Torques. Two case histories are then described, in order to illustrate how tunnel tests can be of practical use in propeller design. The first case concerned a large twin-screw passenger liner, with a maximum of 55,000 shp per shaft at 174 rpm (This appears to be Queen Elizabeth 2--Ed.). After tests, a six-bladed propeller design was selected. The propellers have required minor attention because of cavitation erosion, but were in reasonable condition ten years after entering service. The cavitation tunnel tests for them were carried out in uniform flow. The second case was an early 230,000-dwt tanker series, with an installed power of 32,450 shp at 86 rpm on one shaft. There were cavitation-erosion difficulties with the six-bladed propeller before an acceptable solution was found. If the paint-test technique (a significant step forward in cavitation tunnel testing and model/ship correlation) had been proved and accepted at the time of the original (simulated-flow) experiments, a strong case could have been made out for changes to the propeller and/or hull design, and these erosion problems might then have been avoided. A brief account is given of experiments (in the Newcastle University tunnel) with different shapes of cone, fitted to a model of a naval-type c.p. propeller, for the suppression of the strong vortex core that occurs at the boss of many propellers. Cavitation tunnel tests have materially assisted the propeller designer, but they would not have been sufficient alone; results must be related in a systematic way to full-scale experience. For the future, progress is expected in the development of techniques for measuring vibration impulses and relating the results to full-scale measurements and calculated predictions, with possibly an extension of this type of work towards predicting noise emissions from cavitating propellers, particularly those of warships. Order from BSRA as No. 53,401.

• Supplemental Notes:
  • From the Proceedings of the Stone Manganese Marine/Newcastle University Conference "Model Experiments as an Aid to Advanced Propulsion", 24-27 September 1979.
• Corporate Authors:

  Newcastle upon Tyne University, England

  Claremont Tower, Claremont Road
  Newcastle NE1 7RU, Tyne and Wear,   England 
• Authors:
  • Hawdon, L
• Publication Date: 1979

Media Info

• Features: References;
• Pagination: 11 p.

Subject/Index Terms

• TRT Terms: Cavitation (Mechanics); Cavitation erosion; Propellers; Simulation; Vehicle design; Vibration; Wakes
• Old TRIS Terms: Model testing; Propeller design; Propeller vibration; Simulated wake; Wake analysis
• Subject Areas: Design; Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00316729
• Record Type: Publication
• Source Agency: British Ship Research Association
• Report/Paper Numbers: Paper No. 10 Conf Paper
• Files: TRIS
• Created Date: Oct 8 1980 12:00AM