CFD Simulation of the slipper dynamics during variable displacement operations in a swash-plate type axial piston pump

This paper investigates the effects of the displacement variation in swash plate type axial piston pumps on the dynamics of a vented grooved slipper. A previously validated methodology based on the combined Dynamic Fluid Body Interaction (DFBI) and morphing approach is exploited to continuously update the position of the slipper with respect to the swash plate. The separate contributions of both slipper tilting and axial translation to the instantaneous clearance height are presented, and their consequences on the pressure distribution within the gap are pointed out. Moreover, the pressure induced hydraulic lift on the slipper surfaces is monitored, and a specific balance coefficient is introduced. The impact of the slipper-swash plate interface on the volumetric efficiency of the pump is quantified by means of local measures of the leakage flow through the coupling clearance. Finally, a detailed comparison of the results at different pumps displacements highlights the most critical conditions.