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TRB Annual Meeting

SOME ASPECTS OF HUB VORTEX CAVITATION

This study is concerned with the test procedures for identifying inception, vortex breakdown phenomenon, and gas content and roughness effect on hub vortex cavitation (HVC). The tests were made with the ITTC foil/headform combination at the large cavitation tunnel for the NSMB Laboratories of MARIN. During the round-robin tests of the ITTC combination it was found that HVC inception was significantly delayed by applying sand roughness on the leading edge of the foils. A hub instrumented with five pressure taps was mounted to the ITTC combination. Cavitation tests at two gas content ratios, pressure measurement and flow visualisation by dye injection were made for two different hub tip radii, with and without sand roughness on the leading edge of the foils. The cavity pressure at the hub tip, the cavitating core radii, and some parameters of vortex breakdown were measured. It was found that the roughness could cause a pressure increase, which was a main reason for the delay of HVC inception, and roughness may promote weak vortex breakdown at extremely low speeds. Based on the Rankine vortex model, using two measured cavitating core radii at two cavitation numbers, a method has been developed to calculate an ideal cavitation inception number corresponding to a zero cavitating core radius. This value seems to be more objective than the cavitation inception number measured by different observers. The predicted cavitating core radii for the limited and developed HVC agree well with the experimental data. This method can also be used for identifying and predicting the limited and developed tip vortex cavitation of propellers.

  • Supplemental Notes:
    • Scientific Ship Research Centre (China), Rpt. No. 87003, Mar. 1987 [43 pp., 34 ref., 8 tab., 14 fig., 2 phot.]
  • Authors:
    • Ye, Y P
  • Publication Date: 1987

Language

  • English

Subject/Index Terms

  • TRT Terms: Cavitation
  • Subject Areas: Marine Transportation;

Filing Info

  • Accession Number: 00693759
  • Record Type: Publication
  • Source Agency: British Maritime Technology
  • Files: TRIS
  • Created Date: Aug 14 1995 12:00AM