Micron-scale clearance high-pressure deformation and leakage flow characteristics in line seal plunger pair

The line seal plunger pair (LSPP) is one of the critical structural components for achieving high efficiency and low noise in the novel floating-chamber plunger pump, and it also presents a major design challenge. This study investigates the high-pressure deformation and leakage flow characteristics of micron-scale clearance in LSPP, filling the theoretical gap of line seal leakage flow in clearance flow theory. A mathematical model for the clearance deformation of the LSPP was developed by leveraging the structural features of the LSPP and incorporating the elastoplastic deformation theory of metallic materials. The accuracy of the clearance deformation mathematical model was validated through multi-parameter deformation simulations, with a precision of 98.7%. Due to the high sensitivity of the micron-scale clearance to various parameters, it was identified that the sealing line position, the plunger spherical head surface contour accuracy, and floating chamber internal cylindricity significantly influence the leakage flow rate of the LSPP. To precisely analyze the leakage flow characteristics, a dedicated experimental setup was designed to measure the leakage flow rate of the LSPP. Combining experimental data with machine learning regression algorithms and traditional annular clearance flow theory, the impact of relevant variables on the leakage flow rate was evaluated. Experimental data was trained through the CatBoost regression algorithm, and the accuracy of the prediction model was approximately 95.4%, satisfying engineering requirements. This research enriches non-contact clearance sealing flow theory and provides theoretical guidance for the design of line-sealing clearance and coordinated control of leakage flow in line seal structures.