Numerical and experimental studies on flow performances and hydraulic radial forces of an internal gear pump with a high pressure

Unbalanced radial force is one of the most urgent issues for internal gear pumps (IGPs) working at high working pressures. A numerical model for the prediction of the unbalanced radial force is essential for the structural design of gear pumps, facing the challenges of gear engagement description, dynamic mesh method, and so on. In this work, a three-dimensional computational fluid dynamics model of an IGP with a high working pressure was established based on the 2.5-dimensional dynamic mesh method, with cavitation and gear engagements included. The flow behavior and the hydraulic radial force of the high-pressure IGP were studied, and experiments for pump performances were conducted for comparisons. Results indicated that the numerical model could provide a reasonable solution of the flow rate and pressure pulsation for the high-pressure IGP, verified by the experimental data. The circumferential pressure distribution of the pump does not increase linearly, but presents a stepped increase. The hydraulic radial force fluctuates with gear rotation, and its value increases with the working pressure