Research on Bubble Monitoring Method of Lubricating Oil System Based on DPM Model

Wear particles are the most common pollutants in lubricating oil, and they are also the direct product of most component failures. Monitoring the wear particles in the aero-engine lubricating oil system can infer the wear status of the parts and predict the wear failure in time; In addition to the wear particles, there are also suspended bubbles in the lubricating oil. These bubbles will affect the quality of the oil and also interfere with the identification of solid particles. Electrostatic sensors, inductive sensors, and other sensors currently are used to monitor the wear particles, but they are likely to misidentify bubbles as particles, resulting in a high false alarm rate for the sensors. This article aims to distinguish wear particles and bubbles using their different motion characteristics from the perspective of solid-liquid two-phase flow. Firstly, the types and sources of bubbles and particles in the oil are analyzed. Then, the forces of the particles are studied under the Lagrangian coordinate system. Finally, the movement of gas-solid particles in the oil under different working conditions is simulated using the Discrete Phase Model (DPM) in the software Fluent. It is found that the movement trajectories and stable positions of solid particles and bubbles in the pipeline are significantly different. This provides a new research idea for reducing the false alarms of various sensors in the online monitoring of lubricating oil systems.