Investigation and optimization of appendage influence on the hydrodynamic performance of AUVs

Navigational range is an important attribute of autonomous underwater vehicles (AUVs), and drag reduction efforts have been pursued to improve overall efficiency. Improved efficiency results in a more capable vehicle over all. Historically, the majority of research focused on drag reduction has been concentrated on the optimization of vehicle hull geometry. The influence of the hull appendages on drag, however, has been largely ignored owing to their smaller size. In this study, the impacts of appendage size and position on vehicle drag are investigated using a computational fluid dynamics method. The results indicate that appendages increase more drag because of their impact on the development of turbulence. The investigation of the interactions between multiple appendages fixed on a vehicle hull shows that optimization is necessary for drag reduction. This paper presents an arrangement optimization method for AUV appendages based on the Kriging approximation model and the multi-island genetic algorithm. The results of the optimization show that appendage influence on hydrodynamic performance is directly proportional to its size, and that a distributed arrangement is beneficial for drag reduction.