Propeller curvature of flow

Article type: Research Article

Authors: Bahgat, F.

Affiliations: Naval Architecture and Marine Engineering Department, Alexandria University, Egypt

Abstract: A brief survey is given for published information on the curvature of flow of marine propellers particularly that connected with the Ludwieg – Ginzel – Lerbs method. An attempt is made to determine the change of the curvature of flow for moderately loaded propellers over each blade section and at each point of the blade. Use is made of the theoretical axial distribution of both the axial and the tangential induced velocities; from which induced velocity diagrams are drawn for each case. The curvature camber and the curvature correction are arrived at, by means of the B-Method, through graphical integrations of the resultant induced velocity curve. The curvature of flow curve can then be traced for each blade section. Comparison with other existing methods both theoretical and empirical, show that the calculated curvature of flow fits within their respective range. For practical application to less important propellers, a simplified B-Method is commended. Both the curvature camber and the curvature correction are determined through the use of the chart given on (fig. 18); drawn for the moderately loaded marine propellers. Close agreement has been found by the application of both the B-Method and the simplified B-Method in the case of a free-running and a wake-adapted propeller. They suggest the use of more camber than that provided for by the use of the Ludwieg – Ginzel method particularly near the root; while adopting smaller camber near the blade tip. Finally, the application of the calculated curvature of flow to the propeller blade section design is demonstrated.

DOI: 10.3233/ISP-1965-1212701

Journal: International Shipbuilding Progress, vol. 12, no. 127, pp. 101-126, 1965