| The friction loss of main bearing and piston ring friction pairs of diesel engines is large.It is of great significance to explore ways to improve the lubrication characteristics and thermoelastic characteristics of the two friction pairs from the perspective of friction pair structure to reduce the mechanical loss of diesel engines.Surface texture technology is one of the ways to improve the structure of friction pairs,however,there are many types and distribution forms of surface texture.For different friction pairs,lubrication states and operating conditions,the same texture model may have opposite effects on lubrication characteristics.Therefore,it is necessary to explore the impact of different texture models on lubrication characteristics based on the actual operating conditions and structural characteristics of this two types of friction pairs.In addition,sudden changes in oil film thickness are prone to occur at the surface texture boundary,making it difficult for existing algorithms to simulate the lubrication performance of the texture boundary position.Therefore,it is necessary to seek an efficient,stable,and adaptable algorithm to study this texture problem.Adding functionally graded material（FGM）to the friction pair structure is also one of the methods to improve the friction pair structure.FGM can be used to optimize the thermal elastic characteristics of laminated structure friction pairs,thereby affecting lubrication characteristics.However,in the study of lubrication and thermal elastic characteristics of two types of friction pairs,FGM has not been effectively and deeply analyzed.Therefore,It is necessary to explore the optimization effect of FGM on the lubrication performance and thermoelastic performance of this two types of friction pairs.In addition,the finite element method（FEM）is often used in the study of the thermal elastic characteristics of FGM structures.However,when dealing with laminated structures,FEM requires special boundary settings between layers,which is more troublesome.Therefore,it is necessary to find a suitable algorithm to solve the thermal elastic characteristics of FGM friction pairs.In this paper,the unstructured cell-vertex finite volume method were firstly used to solve the Reynolds equations.And in order to improve the computational efficiency,the multigrid method were used to solve the discrete equations.Through the comparison of different lubrication models,the applicability,accuracy and efficiency of the two kinds of algorithms were verified.A transient solution model of journal bearing was established based on the CVFVM,the accuracy and efficiency of the model were verified with comparison to the results in reference.By introducing high-order elements into CVFVM,a high-order numerical model for solving Reynolds equations was established,and the accuracy and efficiency of the high-order model were explored.For the main bearing of diesel engine,a steady state lubrication model was built firstly.Through the comparative study of three texture types and 16 texture distribution schemes,it was found that the comprehensive lubrication performance was better when the elliptical cylinder pit textures were added in the range of 180°～360°along the circumferential direction.By establishing the transient analysis model of the mixed lubrication characteristics of the main bearing,the influence of the different distribution patterns of the elliptical cylinder pit texture on the lubrication characteristics was studied,which provided some reference for the optimization of the main bearing lubrication characteristics.By establishing the thermal elastohydrodynamic characteristics analysis model of FGM main bearing,the influence of FGM on the lubrication characteristics of main bearing and the thermal elastomeric properties of bearing bush was studied.For the piston ring-cylinder liner friction pair,the transient analysis model of piston ring mixed lubrication was established,the influence of different texture schemes on the piston ring lubrication characteristics was studied,and the texture schemes which can be used to improve the piston ring friction and lubrication characteristics were given.A transient thermal elasto-hydrodynamic lubrication model of FGM rings was established to research the influence of functionally graded materials on piston ring lubrication and thermal elastic properties.it was found that FGM piston rings are helpful to the formation of good lubrication state.The effects of surface materials on the thermal elastohydrodynamic characteristics of piston rings was also studied.It was pointed out that Zr O2 coating can improve the lubrication and thermal elastohydrodynamic characteristics of piston rings. |
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