On the numerical calculation of wake fraction and thrust deduction in a propeller and a hull interaction

Article type: Research Article

Authors: Korvin-Kroukovsky, B.V.

Abstract: A ship-propeller interaction theory is presented in the form of computational procedure for evaluation of the nominal and effective wake fractions and of propeller thrust deduction, taking into account the contributions of potential flow, viscous boundary layer and ship wave-making. This method will give the distribution of the effective wake, and thereby will permit a more precise design of wake adapted propellers, the action of which heretofore had to be inferred from the experimental data on the distribution of nominal wake. Calculations are based on representing the propeller race by an array of cylindrical vortex sheets, thus accounting correctly for mean axial and radial flows, but neglecting the time fluctuations and rotation of the propeller race. Any form of the radial thrust distribution can be specified. The hull is represented by distribution of sources and sinks, in the evaluation of which the velocity field of the propeller and the ship wave flow are taken into account. The ratios of computed effective and nominal wakes can be used then as correction factors to observed nominal wakes. For submerged bodies of revolution, calculations can be made using desk machines. For a surface ship the use of punched card computing machines is visualized.

DOI: 10.3233/ISP-1954-1402

Journal: International Shipbuilding Progress, vol. 1, no. 4, pp. 170-178, 1954