Numerical Simulation Research On Flow Characteristics Of High Pressure Oil Pump Valve

As an important component of the high-pressure common rail diesel engine,whether the high-pressure fuel pump can achieve stable and efficient fuel supply will have a greater impact on the work of the entire diesel engine.However,the high-pressure fuel pump has a short fuel compression cycle,high fuel flow rate,and continuous movement of the valve core causing pressure fluctuations in the cavity,resulting in intricate flow field structure.In this paper,combined with the Fluent dynamic grid technology,a numerical simulation is carried out on the working process of the fuel supply pump.The main work content is as follows:(1)The physical model required for the simulation calculation of the fuel supply pump valve is established.Based on Newton’s second law,the force balance equations of the inlet and outlet valve spools are established respectively,and the UDF program of the specified spool movement is compiled based on this to simulate the opening and closing of the valve,thereby realizing the spool movement and flow field changes.coupling.According to the given cam profile,the movement speed of the plunger is deduced,and the reciprocating movement of the plunger is realized by compiling the UDF program.The appropriate turbulence model,boundary conditions,mesh update method,discrete format,relaxation factor,etc.were selected for comparison.The feasibility of the simulation model is verified according to the theoretical flow of the pump.(2)The movement law of the spool of the oil outlet valve(ball valve)and the oil inlet valve(cone valve)is analyzed,which mainly includes the displacement,velocity and acceleration of the spool movement.The changes of the flow rate and the transient hydraulic power of the spool in the working process are analyzed.In addition,the changes in the flow field in the plunger cavity and the flow field in the valve were analyzed through visual research,and the cause of the phenomenon that the fuel jet adhered to the wall and detached from the wall was explored during the fuel intake stage.(3)The influence of the cam speed on the oil supply of the high-pressure oil pump,the movement law of the spool,the internal flow field and the hydraulic loss are explored.The results show that increasing the speed can increase the fuel supply and increase the opening of the valve,but it will aggravate the spool closing hysteresis and increase the hydraulic loss.(4)Finally,the influence of different structural parameters on the flow characteristics of the fuel supply pump is compared.It mainly includes the preload force of the spool spring,the stiffness coefficient,the weight of the spool and the maximum lift of the spool.The influence of the structural parameters on the force and movement characteristics of the spool is obtained,which can provide a reference for the reasonable selection of the structural parameters of the valve block.