Dynamic-thermal modeling and motion analysis for deep-sea glider with passive buoyancy compensation liquid

Abstract The passive buoyancy compensation liquid (PBCL) has been widely used in underwater vehicles operating in deep-sea environments to reduce buoyancy loss caused by hull deformation and seawater density variation. The heat transfer process of PBCL is an important factor that affects the net buoyancy and motion performance of the deep-sea glider (DG), which was commonly neglected. A comprehensive dynamic-thermal model for Petrel-4000 deep-sea glider (PDG) with PBCL is established in this paper. A model which considers the heat transfer process is proposed to estimate the volume change of PBCL. These models are verified by comparing the numerical results with experimental data. The effect of the heat transfer process on the motion performance of PDG is fully analyzed by comparisons with those not considering heat transfer process. Then, the effect of PBCL distribution is discussed, which shows that the reasonable PBCL distribution can facilitate a more stable gliding attitude of PDG. Energy consumption analysis is carried out and the results indicate that the application of PBCL is beneficial for energy saving, especially under the lower power of the control system and measurement system. The results and conclusions would provide a valuable reference for the design and engineering applications of DG.