A THEORETICAL CONTRIBUTION TO THE INVESTIGATION OF THE HUB INFLUENCE IN PROPELLER DESIGN

Propeller design on a theoretical basis usually does not consider the displacement effect of the hub body. However, a theoretical investigation of this subject shows clearly that the radial distribution of the hub induced effective wake demands corrections of the hydrodynamic advance coefficients close to the hub, which are of the order of lifting surface corrections. Based on a special hub form, a procedure for obtaining these hub corrections is outlined and the results of an example are presented. The special hub form in question allows the bound circulation of the lifting line to be finite at the hub. Introducing a simplified hub representation for the down stream part of the hub body, the vortex theory is shown to provide the same flow pattern at the lifting line as is given by the momentum theory at the sink disc for an optimum propeller. Therefore, both propeller representations are iteratively used for the purpose of determining the potential wake of the hub. Basic relationships, derived for the wake adapted actuator disc, are applied to the lifting line representation of the propeller and the validity of this procedure is numerically confirmed. Investigations based on the sink disc representation of the propeller allow the treatment of arbitrary hub forms. In this manner, the influence of hub form, hub contour and hub radius on thrust, deduction, efficiency and radial distribution of wake is studied. However, the behaviour of the pressure gradient over the hub boundary in the axial direction indicates that the treatment of practical hub forms by means of a potential theory would be questionable.

  • Corporate Authors:

    University of Michigan, Ann Arbor

    Department of Naval Architects and Marine Engineers
    Ann Arbor, MI  USA  48109
  • Authors:
    • Ostergaard, Carsten
  • Publication Date: 1970-11

Media Info

  • Features: Appendices; Figures; References;
  • Pagination: 58 p.
  • Serial:
    • Issue Number: 100

Subject/Index Terms

Filing Info

  • Accession Number: 00015539
  • Record Type: Publication
  • Source Agency: University of Michigan, Ann Arbor
  • Files: TRIS
  • Created Date: May 19 1973 12:00AM