A study on lubrication characteristics of contaminated oil film and abrasive wear in fuel gear pumps based on discrete element method

Abstract

Aviation fuel gear pumps are prone to accelerated wear of friction pairs during long-term high-load operation, generating metallic particles that contaminate the sliding bearing oil film and trigger abrasive wear. To address this, a coupling solution of the discrete element method (DEM) with a two-phase flow lubrication model was employed, enabling direct dynamic simulation of contaminant particles that follow a specified distribution. The Rabinowicz wear theory was introduced to model wear caused by individual contaminant particles, which was integrated with the DEM to predict the wear process and corresponding performance degradation of the sliding bearing under specific operating conditions. Statistical characteristics of particle-induced wear and their influencing factors were also investigated. The results show that the proposed method effectively tracks particle motion paths in the bearing, with most particles aggregating in low-pressure areas and only a few maintaining sustained high-speed motion. Abrasive wear is primarily concentrated in regions with thinner oil films, and the wear depth increases over time but at a decelerating rate. Extensive sampling simulations indicate that average wear follows a truncated normal distribution. Parameter studies reveal that increases in particle size mean, shaft speed, and eccentricity enhance wear depth, and when the average wear amount reaches 0.35 μ m, the load capacity decreases by approximately 2%, threatening the long-term operational stability of the gear pump.