CFD analysis and experiment study on the lubrication behaviours of dimpled surfaces under seawater lubrication

In order to introducing the bionic surface technology into high pressure seawater axial piston pump to improve the lubrication performance of cylinder/port plate pair, computational fluid dynamics (CFD) simulations on the surface with three types of dimples, which imitates the bionic surface, were present. The pressure and velocity distributions, total normal force and skin friction coefficient on the sliding surface were obtained. The corresponding experiments of the friction samples were carried on a MMU-5G ring-on-disc tester with rotational speed of 1200 r/min and normal load of 60N under natural seawater lubrication. The CFD analysis and the test result show that, compared with smooth surface, the friction coefficient of dimpled surface are lower, the surface with semi-spherical pits has the lowest friction coefficient as 0.093 from the test results. In addition, the existence of the dimples which can store seawater in it and produce the dynamic effect was consider as the main reason of the lubrication improvement. In this study, some ideas were provided for exploring lubrication improvement mechanism of dimpled surface and the numerical simulation can guide the selection of dimple type to manufacture the port plate.