Numerical Simulation Study On Thermo-Fluid-Solid Coupling Of Valve Pair In Axial Piston Pump

As one of the three friction pairs affecting the reliability and life of axial piston pumps,the distribution pair is composed of the cylinder block,the distribution plate and the oil film between the two.Under the working state,the distribution pair is affected by multiple physics factors such as pressure,temperature and elastic deformation in the solid domain,and it is very difficult to solve this problem by theoretical modeling.Therefore,this paper uses finite element numerical simulation to establish a thermal fluid-solid interaction calculation model for the distribution pair of axial piston pumps,analyzes the working mechanism of the distribution pair under the coupling of multiple physical fields,and studies the effects of different load pressures,cylinder speed and oil film wedge angle on the pressure field,velocity field,temperature field and stress field in the solid domain.Provide the basis for the design and optimization of subsequent axial piston pumps.The main research contents are as follows:(1)Taking the port pair in the axial piston pump as the research object,the three-dimensional model of the axial piston pump was established,the working principle of the axial piston pump and the port pair and the formation of the wedge-shaped oil film were analyzed,the kinematics of the piston pump was analyzed,and the velocity and acceleration equations in the process of the plunger movement were established for the subsequent UDF programming.The film thickness data and wedge angle values were obtained through the three-point oil film thickness test of the distribution pair,further determining the oil film structural parameters of the numerical model.(2)The solution process of the finite volume method in computational fluid dynamics is analyzed for the thermal-hydraulic-solid coupling problem,the computational control equations of fluid domain,solid domain and fluid-solid coupling in multi-physics field coupling are established,the solution route of the multi-physics field coupling problem of the flow distribution sub is analyzed,and the numerical solution model of the thermal-hydraulic-solid coupling of the flow distribution sub is established using the commercial software ANSYS Workbench platform.(3)Construct a three-dimensional model of an axial piston pump in the fluid domain,and simplify and split the fluid domain structure.The ICEM CFD and Mesh modules were used to mesh the fluid and solid domains of the flow distribution pair,forming a simulation model of the axial piston pump flow distribution pair.Using the Fluent module to compile UDF programs for multi plunger motion and oil viscosity temperature characteristics,select a solution model and method,apply boundary conditions,and simulate cylinder rotation around the axis and plunger axial reciprocating motion through sliding and layering dynamic grid technology.By optimizing control parameters,numerical calculation errors are reduced.Utilize system modules such as Fluent and Transient Structure to numerically solve the fluid and solid domains of the port pair under different load pressures,cylinder speed,and oil film wedge angles.(4)Based on the numerical solution results,the fluid domain pressure,temperature flow,velocity,oil film leakage,and stress and deformation in the solid domain of the distribution pair under different operating conditions were analyzed.The results show that as the load pressure increases,the oil film flow rate increases,the overall temperature of the oil film increases,the leakage on the inner and outer sides of the oil film increases,and the maximum pressure and pulsation of the oil film also increase.As the rotational speed of the cylinder increases,the maximum pressure pulsation peak of the oil film increases,and the impact on the oil film temperature and leakage rate is relatively small.As the wedge angle increases,the leakage on the inner and outer sides of the oil film increases significantly,and the maximum pressure pulsation of the oil film decreases.The deformation and stress magnitude of the solid domain are less affected by the cylinder speed and wedge angle,while the load pressure is the main factor affecting the deformation of the solid domain.The greater the load pressure,the greater and more concentrated the equivalent stress and deformation of the material at the minimum gap between the cylinder block and the port plate.