Research on drag reduction of underwater vehicle shape based on deterministic and robust optimization

Objectives In order to improve the endurance and performance stability of autonomous underwater vehicles. Methods Three common rotating bodies were selected as candidates for the main body shape of the AUV. Three models were first established to obtain the volume of the models, and hydrodynamic analysis was conducted to obtain the resistance of the models. The preferred choice was the Myring line type as the main body shape of the AUV. According to the Myring line equation, the range of line parameters was determined. The Latin hypercube experimental design method was used to sample the design variables and obtain the response values of the sample points. Based on the sample points, an approximate model was constructed. After the approximate model was established, fitting degree analysis, sensitivity analysis, and response surface analysis were carried out. After the fitting degree of the approximate model reached the standard, a multi-objective optimization model was established for deterministic optimization, and the optimal solution was obtained. The reliability analysis of the optimal solution was carried out, and then robustness optimization was carried out to improve the reliability of the optimized solution. Results After deterministic optimization, the resistance decreased by 5.96% compared to the initial external resistance, and the volume decreased by 0.78%; Compared to deterministic optimization, robust optimization has increased resistance by 0.35%, increased volume by 0.14%, and achieved a reliability level of 6 σ. Conclusions Deterministic optimization and robust optimization both reduce the resistance of underwater vehicles, while robust optimization improves the stability of design variables.