Dynamic Pressure Lubrication Simulation And Experimental Research On Micro-texture On Piston Surface Of Diesel Engine Cylinder Liner

There are many factors that affect the operation efficiency and service life of machinery.Tribological performance is a key factor.Reducing wear and controlling friction is of great significance to improve production efficiency and reduce resource consumption.Surface texture technology,that is to say,to process regular and arranged microstructure on the surface of friction pair,has become a new and effective method to improve the tribological properties of contact surface in recent years.In this thesis,the mathematical model of surface microtexture is simulated,and the simulation experiment of fluid flowing through microtexture is simulated by using fluent 16.0software.By changing the shape and arrangement of microtexture,the flow field inside the microtexture and the surface friction coefficient reflected by the microtexture are discussed,and the optimal patterns circular(cylinder)and arrangement three rows and three holes are obtained.In addition,the influence of the aspect ratio and the size of different micro textures on the lubrication performance is analyzed by numerical simulation.The results show that when the aspect ratio is about 1,the oil film bearing capacity is enhanced to a certain extent,that is to say,in a certain range,the oil film bearing capacity is enhanced,Increasing the depth and width of microtexture can increase the bearing capacity of oil film.Increasing the depth has a greater influence on the increase of oil film bearing capacity.There is an optimal depth to width ratio of microtexture,which makes the bearing capacity of oil film maximum.In this simulation,the optimal depth to width ratio is 4.In addition,cavitation effect can not be ignored when analyzing the influence of micro texture on lubrication performance.Compared with other factors,when cavitation effect is considered,the load-carrying capacity of oil film decreases by 62% at the micro texture.Finally,the experimental platform is built to test the micro texture of different arrangement of circular structure,and the results are compared with the simulation data.After the experiment,there are obvious massive substances in the micro pits on the surface of the cylinder liner.According to the energy spectrum analysis,the main elements of the substance are Fe,O and C.It is inferred that it is the wear debris produced in the reciprocating motion of the cylinder liner or piston ring,which indicates that the micro texture plays a role in collecting wear debris and reducing wear debris.From the experimental results,the friction coefficient of the untreated cylinder liner sample is about 0.1272,the friction coefficient of the cylinder liner sample with one row of three holes is 0.1218,which is 4.2% lower than that of the untreated cylinder liner sample,and the friction coefficient of the cylinder liner sample with three rows of three holes is 0.1127,which is 11.4% lower than that of the untreated cylinder liner sample.The experimental results show that the multi row microtexture has a significant anti-wear effect compared with the single row microtexture and no microtexture.Compared with the experimental results and the numerical analysis results,the error between the experimental results and the simulation results is within 3%,which is within the acceptable range.This further verifies the effectiveness of the simulation numerical analysis results,and provides the theoretical basis for further research.