Research On The Fluid-thermal-structure Coupling Characteristics Of Oil Film In The Gap Between Piston And Cylinder In Pump

Piston pump is a complex product of Fluid-Thermal-Structural coupling.It mainly consists of three friction pairs: piston pair,slipper pair and valve pair to ensure energy conversion efficiency and service life.The piston deputy is mainly composed of piston and cylinder block.The two parts cooperate with each other to realize the periodic change of the volume of the chamber,and then realize the functions of oil absorption,pressurization and drainage.However,at present,the interaction of kinematics,dynamics and hydrodynamics,materials science and thermodynamics of piston pairs is still not clear,and there is no mature theoretical support.Therefore,this paper carries out research work from both theoretical and experimental levels.The main research contents are as follows:(1)Combining the structure,movement and force of the piston pair,the motion and force model of the piston pair is established and the kinematics simulation is carried out.(2)A fluid-thermal-structure coupling oil film characteristic model of piston pair is established and the numerical solution method is given.The finite volume method and the ultra-relaxation iteration method are used to discretize and solve the Reynolds equation and the energy equation in the model.Finally,the calculation method of the piston surface deformation using the finite element method is introduced.(3)The oil film thickness field,pressure field and temperature field of the plunger pair are simulated and calculated by the combined simulation of MATLAB and COMSOL,and the variation law of the above physical field in one revolution is analyzed(4)a single piston pair type 360° oil film lubrication characteristic test table and it's data acquisition system was built and equipped.The oil film thickness,pressure and temperature test of piston pair were carried out under different load pressure,inlet oil temperature and main shaft speed.Theoretical analysis and experimental results show that:(1)the greater the load pressure,the higher the inlet temperature and spindle speed,the more obvious the decreases of minimum oil film thickness in the piston pair.When the load pressure exceeds 20 MPa,the inlet temperature higher than 40?,and the spindle speed over 2000r/min,the decreasing of the minimum oil film thickness increases trendly;(2)The thermal equilibrium temperature rise of the piston auxiliary oil film fill out with the increase of the above parameters,of which the spindle speed is the major factor that determines the thermal equilibrium temperature rise value;(3)When the inlet oil temperature rises,the dynamic pressure of the oil film in all areas except the pressure peak.When the load pressure build up and the main shaft speed rise,the dynamic pressure both increasing in the oil film.all The above conclusions prove the relative accuracy of the calculation model of multi physical parameters for oil film of piston pair,which can effectively predict the lubricating performance than guide the structural optimization of the piston pair.