Abstract:By designing different concave bionic nonsmooth surface on lowspeed and hightorque hydraulic motors valve plate pair, and with the establishment of full water flow deputy hydrodynamic lubrication models, the impact of internal fluid flow and its impact on the rule of hydrodynamic lubrication performance by different shapes and crosssectional shape of the opening of the concave were studied with use of computer flow dynamics (CFD) method. The results show that under the condition of the same crosssectional shape of the concave, the concave depth and opening size, the pressure distribution of fluid film surface of the round shape of the opening of concave bionic nonsmooth surface is slightly better than that of the opening shape of square and triangle. When the opening shapes of concave are circular, hemisphere concave of semicircular crosssectional shape as compared with a rectangular concave circular columns and a circular cone concave of triangular crosssectional shape, whose surface pressure distribution of fluid film is better, the carrying capacity of liquid film surface is slightly larger, and better hydrodynamic lubrication performance is better.