Figure 1: General issues relating to propulsor design.
The hydrodynamic analysis and design of marine propulsors involves several issues, some of which are shown schematically in Figure 1. The designer must develop the most efficient (and economically feasible) design which meets certain requirements (e.g. thrust, propeller RPM at given ship speed) and constraints (such as limits on cavitation extent or on the amplitudes of fluctuations of shaft forces or propeller induced hull pressures). In some situations (underwater vehicles, waterjet inlets) the hull and the propulsor have to be designed together in order to avoid strong velocity gradients at the plane of the propulsor or to help the overall efficiency of propulsion. In several contemporary propeller designs cavitation cannot be avoided without substantial sacrifice on propeller efficiency.
Numerical modeling of propeller flows (including developed cavitation) which predicts reliably the propulsor performance is crucial during the design or assessment stage of a propulsor. Reviews of existing computational methods for the analysis and the design of marine propellers may be found in [12], [13], [3], and [20].
The present work presents recent developments of a vortex-lattice method and a panel method for the analysis of unsteady propeller cavitation. The methods are applied to some propeller geometries in non-axisymmetric inflows and the results are compared to each other and to those measured in experiments.
Finally, a recent optimization technique for the design of cavitating blades is applied to a case with given requirements and various constraints and the resulting designs are compared to each other.