The effect of piston grooves performance in an axial piston pumps via CFD analysis

In the design of high pressure piston pumps/motors, some manufacturers use pistons which have grooves being cut along the piston length, while others do not use grooves at all. The present paper clarifies the effect of grooves cut along the pistons surface via studding the effect of the number of grooves and their location over the piston surface. Piston force, torque, leakage, areas where cavitation might appear and piston stability, will be, in the present paper and for a set of piston/grooves configurations, carefully evaluated. A finite volume based Reynolds equation model has been formulated for the piston–cylinder clearance which considers the piston eccentricity and the relative tangential movement between piston and barrel. Different grooves configurations have been evaluated in search of finding minimum leakage, minimum appearance of cavitation and maximum restoring torque. Design instructions to optimize the piston behavior are also given, therefore the information and methodology presented in the present paper, is expected to be used as a designing tool for future machines. The piston/cylinder leakage is considered as laminar under all working conditions. The Fluid used is hydraulic oil ISO 32.