Experimental and Numerical Analysis of an Axial Piston Pump: A Comparison Between Lumped Parameter and 3D CFD Approaches

In this paper an axial piston pump is studied using numerical and experimental approaches. The pump, manufactured by the company Continental Hydraulic Inc., has a maximum operating pressure limit of 280 bar and a displacement of 65.9 cm3/rev; it is a variable swashplate design with nine-piston, suitable for open circuit application, medium to high pressure. Two numerical approaches have been compared to simulate the pump units. First of all, an accurate 3D -CFD model has been built up putting emphasis on the description of the detailed features of the flow through the unit. Specific attention has been reserved to the flow losses due to cavitation. Then a fast-lumped parameter approach has been built up focusing the attention on the valve plate geometry. Using the proposed numerical approaches, it is possible to fully understand the unit operation with, obviously, different assumptions and level of result details. Numerical models have been validated with an experimental data performed by the pump manufactured on their test ring with high agreement. As results, the proposed analysis permit to gain a high level of understanding of the operation of the unit finding the critical aspects and giving important information to the designer in order to improve the pump performance. By the end a new valve plate has been designed to improve the pump volumetric efficiency and to reduce the flow ripples and the reverse flow.