CORRELATION STUDIES ON PROPELLER CAVITATION MAKING USE OF A LARGE CAVITATION TUNNEL

Significant advances have been made in recent years in the understanding and modelling of propeller cavitation. Considerations in bubble dynamics and model/full scale comparisons indicate that model propellers operating at high rotational speeds in a circulating tunnel with a closed test section yield better results regarding cavitation than can be obtained in free surface facilities. Although Froude's modelling law requires a free surface tunnel with slowly turning propellers, scale effects can be minimised by operating model propellers at as high a Reynolds' number as possible while suppressing the free surface. The paper describes the results of extensive measurements for three single screw container vessels and a twin screw frigate recently performed in a cavitation tunnel. The vessels and their propellers represent state of the art designs. In the investigations the main emphasis was placed on the realistic simulation of the wake field and the resulting cavitation behaviour of the propellers. The same models as used for resistance and propulsion tests in the towing tank were used in the large cavitation tunnel. In order to obtain a correctly scaled boundary layer thickness the investigations were repeated with shortened hull models, i.e. a shortened bow fitted to the model scale stern. The wake results are compared to model test results from the towing tank as well as to results from full scale measurements and theoretical calculations. The cavitation behaviour of the models at different speeds as well as the pressure fluctuations are also compared to results from full scale investigations and to model test results from conventional tunnels. It is shown in the paper that the three-dimensional wake simulation - particularly when using of shortening of the model - brings considerable improvement regarding the pressure fluctuations. The paper concludes with a brief description of cavitation inception investigations for the frigate. Also here, model to full-scale correlations showed considerable improvement as compared to traditional modes of investigation, especially regarding tip vortex cavitation.

• Supplemental Notes:
  • SNAME, Annual Meeting, 28-31 Oct 1992, New York, USA, Pprs. Ppr No. 2 [15 p, 23 ref, 2 tab, 20 fig]
• Authors:
  • Friesch, J
  • PAYER, H G
• Publication Date: 1992

Language

• English

Subject/Index Terms

• TRT Terms: Cavitation (Mechanics); Cavitation erosion; Performance; Propellers; Propulsion
• Old TRIS Terms: Propulsive performance
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00704241
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Aug 14 1995 12:00AM