The Effects of the Initial Geometrical Errors on the Piston Friction and Sealing Performance in a Buoyancy Regulator of an Underwater Glider

As an important power component of an underwater glider, the energy consumption of the buoyancy regulator directly affects the endurance of the underwater glider. The accurate calculation and prediction methods for the friction forces can be helpful for improving the working performance of the buoyancy regulator. The traditional friction prediction models consider the cylinder as perfect cylinder without any geometric error, which cannot accurately reflect the effects of the initial geometric defects on the friction force and sealing performance of the cylinder of the piston type buoyancy regulator. This article proposes a new friction force calculation method considering the initial geometrical defects of the cylinder. By using the theoretical analysis and finite element calculations, the effects of the initial geometrical defects on the friction force and sealing performance of the piston type buoyancy regulator can be more accurately analyzed. The effect of the ovality and taper on the friction force and sealing performance is analyzed. In addition, the friction force calculation method proposed in this article is validated by an experiment. This article can provide an accurate cylinder friction force calculation method considering the initial geometrical errors for the piston type buoyancy regulators.