Abstract: In view of problems of very big axial thrust caused by the flowing water during the operation of ocean current turbines, hydrodynamics, blade element momentum and fluid-solid coupling simulation methods are used to calculate the thrust force by solving subsections of the blade and addition of them. The calculation results are compared with the simulation results in Bladed software and both prove that variation of water velocity and fluid-solid coupling cause the random nonlinear variation of the axial force. According to the characteristic of the regular change of axial thrust, a novel hydraulic equilibrator for axial thrust is designed, and its system model is constructed in AMESim and Bladed software are studied. The results show that the hydraulic equilibrator can well counteract the fluctuation of axial thrust, thereby protecting the bearing structure.

Key words: Axial thrust, Horizontal axis, Hydraulic equilibrator, Ocean current turbine