Contact and wear modelling of rotary seals under mixed lubrication in piston pumps for aerospace electro-hydrostatic actuators

High-pressure piston pumps are a critical component of electro-hydrostatic actuators in aerospace applications. High-speed Rotary lip/Shaft Seals (RSS) are utilised in piston pumps under low medium pressure to prevent leakage of the oil medium from the pump chamber. Although the wear behaviour of RSS has been investigated, existing studies are mainly based on the classical Archard wear model under dry contact conditions and do not account for the dynamic stiffness of surface asperities on micro-scale convex bodies. This approach characterises RSS lubrication behaviour under Mixed Lubrication (ML) conditions without considering micro-scale convex body behaviour. Thus, this study establishes a radial shaft seal model to simulate lubrication performance and tangential contact wear behaviour over a rotational speed range of 5000–10 000 r/min and a temperature range of 5–60 °C. A fluid–solid–wear coupling method is applied to the RSS to simulate micro-scale convex body deformation and its associated wear rate. The wear-induced deformation and volume loss of micro-scale convex bodies are evaluated using the roughness probability density function and interpolation. Furthermore, the description of the RSS failure mechanism associated with the leakage rate is modified beyond the classical Couette flow theory based on wear simulations. This study also re-examines the lubrication mechanism of the RSS in the ML region to clarify its role in maintaining stable suction in piston pumps, thereby extending previous studies.