The trailing vortex sheets of a marine propeller, after a short transition region, roll up into helical vortex cores and a straight hub vortex core. Photographs of the phenomenon show a partial absorption of the vortex sheet of a blade by the tip vortex core of the preceding blade. The geometry of the ultimate wake can be theoretically calculated. The new model of the propeller wake can be used for the calculation of field-point velocities and the determination of propeller interaction. The use of the rolled-up wake model is strongly suggested for the unsteady propeller theory. An example of an application of the new wake model to propeller blade design is presented. The actuator disk theory underestimates the wake contraction for light propeller loadings and overestimates it for heavy propeller loadings. The wake contraction in the tunnel is practically independent of the propeller loading. The geometry of the wake of a propeller at constant thrust is different in the tunnel and in open water. The difference in induced velocities might change the cavitation characteristics of the propeller. The validity of existing optimization criteria for propeller performance was found questionable. The geometry of the ultimate wake will become a part of any correct solution of the problem.

  • Corporate Authors:

    Massachusetts Institute of Technology

    Department of Naval Architecture and Marine Engineering
    Cambridge, MA  United States  02139
  • Authors:
  • Publication Date: 1971-5

Media Info

  • Features: References;
  • Pagination: 192 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00035113
  • Record Type: Publication
  • Source Agency: Maritime Administration
  • Report/Paper Numbers: 71-1 DR Thesis
  • Contract Numbers: 0-35466, DSR 72467
  • Files: TRIS, USDOT
  • Created Date: Oct 27 1973 12:00AM