A mathematical leakage-friction model for deep-sea external gear pumps

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This paper investigates the effects of radial and axial clearances on the performance of external gear pumps, particularly in challenging deep-sea conditions marked by high pressure and low temperatures. These clearances lead to reduced volumetric and hydro-mechanical efficiency. To enhance the efficiency of deep-sea high-pressure gear pumps, we propose a new methodology to predict optimal clearances. The study begins by analyzing how clearances affect the volumes between gear teeth and calculating leakage rates based on pressure drops and drag flow. We identify various sources of leakage and mechanical loss, including friction at the gear tooth tips, lateral surfaces, shafts, and meshing interfaces. The model accounts for bush structure, fluid viscosity, and clearance changes from high-pressure deformation. Additionally, we propose a leakage–friction model that optimizes gear pump clearances and efficiency under both deep-sea and standard conditions, providing a comprehensive approach to improving gear pump efficiency.