Effects of inclined cylinder ports on gaseous cavitation of high-speed electro-hydrostatic actuator pumps: a numerical study

Raising the rotational speed of electro-hydrostatic actuator (EHA) pumps is a useful way to improve their power density. However, gaseous cavitation tends to occur in the displacement chambers at high speed, reducing the effective delivery flow rate of EHA pumps. It is a common approach to reduce the gaseous cavitation by increasing the inlet pressure. However, this conventional approach requires additional devices to boost the inlet line, which decreases the EHA pump's power density. The contribution of this study is to reduce the gaseous cavitation by introducing inclined cylinder block ports for EHA pumps, which only modifies the cylinder ports and needs no additional devices. A computational fluid dynamics (CFD) model was developed to investigate the effects of the inclined direction of cylinder ports on the gaseous cavitation. The simulation results showed that the inward-inclined design of cylinder ports could effectively decrease the gaseous cavitation using centrifugal effects of rotating fluid. Compared with a standard cylinder block, the cylinder block with inward-inclined ports could increase the effective delivery flow rate by 4% at an inlet pressure of 1 MPa and a rotational speed of 20,000 r/min.