Optimization scheme for the selection of the propeller in ship concept design
In this study, an optimization scheme is presented coupling an open-source parametric design and analysis tool for propellers, Open Prop, and a nonlinear optimizer. This developed model, implemented in Matlab, is used to optimize different parameters of the geometry of the propeller to maximize the propeller efficiency and to verify the limits of cavitation. Propeller diameter, rotation speed, number of blades, expanded area ratio, skew and the hub diameter are the parameters optimized. The optimization procedure was tested as follows: first, a container ship was selected and the resistance of the ship was computed, then the propeller was optimized for the specified ship design speed, taking into account the power losses from the engine to the propeller, wake fraction and thrust deduction fraction. The optimization model is constructed, including the objective and the boundary conditions, while the fitness function is proposed employing penalty functions to express constraints. The model developed can be further used to optimize the parameters of any fixed pitch propeller for a given vessel.