Hydrodynamic Optimization of Marine Propeller Using Gradient and Non-Gradient-based Algorithms

Abstract

Here a propeller design method based on a vortex lattice algorithm is developed, and two gradient-based and non-gradient-based optimization algorithms are implemented to optimize the shape and efficiency of two propellers. For the analysis of the hydrodynamic performance parameters, a vortex lattice method was used by implementing a computer code. In the first problem, one of the Sequential Unconstraint Minimization Techniques (SUMT) is employed to minimize the torque coefficient as an objective function, while keeping the thrust coefficient constant as a constraint. Also, chord distribution is considered as a design variable, namely 11 design variables. In the second problem, a modified Genetic algorithm is used. The objective function is to maximize efficiency by considering the design variables as non-dimensional blade's chord and thickness distribution along the blade, namely 22 design variables. The hydrodynamic performance analyzer code is modified by a higher order Quasi-Newton scheme. Also, a hybrid function is used to improve the accuracy of the convergence. The solution of the optimization problems showed that a nearly 13% improvement in efficiency and a nearly 15% decrease in torque coefficient for the first propeller, as well as nearly 10% improvement for efficiency of the later propeller, is possible.