Abstract:By researching the relation of hydraulic pressure and output flow to the external gear pump side-plank balanced groove, the optimal size of the side-plank groove is drawn. Based on ensuring volumetric efficiency of the pump, the influence of trapping phenomenon and flow pulsation could be reduced. One type of high pressure gear pump was used as a research object, firstly the fluid pressure of gear pump was calculated by establishing the theoretical formula. Secondly, establishing the Computational Fluid Dynamics (CFD) model, the hydraulic pressure and export flow were drawn through fluid simulation. Finally, the optimal angle, depth and width of side-plank are drawn by comparison.