Lifting surface method for modelling ship rudders and propellers

Abstract

The theoretical basis for a lifting surface model using Morino's formulation is given in this report. The various choices made previously for modelling rudder and propeller interactions are described and the reasons for using, in this investigation, a lifting surface perturbation potential method. An explicit trailing edge pressure Kutta-Joukowsky condition is used to ensure that there is no pressure loading at the trailing edge. A frozen wake or an adaptive wake model can be chosen for both the rudder and propeller simulations.

A flexible scheme for geometry definition was developed to allow flow over a wide variety of geometries and multiple body lifting-surface problems. This surface definition scheme uses parametric cubic splines which require a minimal amount of data to accurately define quadrilateral panels on a three-dimensional surface.

The proposed Interaction Velocity Field method separately models the lifting surfaces. In this case, a rudder and propeller. The flow interaction between them is accounted for by modifying their respective inflow velocity fields. Expressions were derived to allow the velocity at any point within the flow domain to be calculated using the solution to the perturbation potential method. This process is used to generate the respective inflow velocity field. It can also be used to produce flow visualisation information important for design purposes.

Verification of the lifting-surface method was carried out to compare the results obtained with previously published numerical and experimental results.

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Identifiers

ORCID for S.R. Turnock: orcid.org/0000-0001-6288-0400

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