Lines design of underwater vehicle based on the optimization of hydrodynamic performance and energy consumption

Collaborative optimization with relaxation factor is proposed for the lines design of an underwater vehicle. The hydrodynamic performances and energy consumption are considered in optimization framework. Hydrodynamic performances include the resistance, sway force and yaw moment. The efficient power of the propeller is selected to reflect the energy consumption. Analytic hierarchy process (AHP) combined with Delphi method is used to allocate the weights of disciplines in the objective function at the top level. A gradient-based algorithm, sequential quadratic programming (SQP) in combination with an intelligent-based algorithm, the multi-island genetic algorithm (MIGA) is taken into account as the optimization algorithm. To increase the efficiency of optimization, an approximate model based on optimal Latin hypercube and radial basis function (RBF) is introduced to replace the time-consuming discipline analysis model. Full-appendage SUBOFF model is used to test the proposed optimization scheme. The optimization results show that the drag of the underwater vehicle is reduced by 2.05 %, the lateral force by 6.38 %, the yaw moment by 5.90 %, and the energy consumption by 2.15 %. Compared with a single algorithm (e.g., PSO), the proposed hybrid algorithm (MIGA-SQP) reduces the value of the comprehensive objective function by 2.5-4.8 %.The innovations of this paper are as follows: 1. The Delphi-AHP method is combined with the cooperative optimization of relaxation factors to improve the objectivity of weights; 2. An OLH-RBF surrogate model is constructed, which increases the CFD calculation efficiency by 4 times.