Identifying Dynamic Coefficients Of Lubricant Film Based On Different Frequency Disturbance And CFD Technology

Sliding bearing and squeeze film damper based on the principle of dynamic pressure lubrication have been widely used in engineering practice.The dynamic coefficients of sliding bearing and squeeze film damper directly affect the vibration characteristics and operation safety of its supporting shafting.At present,oil film dynamic coefficients of simple structure are analyzed by solving Reynolds equation of fluid lubrication in engineering.However,for sliding bearing and squeeze film damper with complex structure and working conditions in practical engineering,this calculation method will lead to certain errors and even no longer has applicability.CFD method has been developed quite mature,which provides a new idea for the identification and calculation of oil film dynamic coefficients.Based on this,this paper studies the dynamic coefficients identification method of oil film based on CFD technology.The main research contents and achievements of this paper are as follows:Firstly,the complex variable function between disturbance displacement and disturbance force is studied when the journal is disturbed with different frequency in two directions of the bearing.A different frequency disturbance method considering initial phase and inertia term is developed.The dynamic coefficients of sliding bearing or squeeze film damper can be identified by combining CFD technology.Then an example of sliding bearing is used to verify the feasibility of the developed identification method and CFD technology to calculate the dynamic coefficients of sliding bearing.Compared with the theoretical solution of short bearing,the results show that the maximum errors of main stiffness and cross stiffness of oil film are 2.1%and 18.6%respectively,and the maximum errors of main damping and cross damping are 30.8%and 54.6%respectively.Finally the feasibility of the identification method is verified by an example of squeeze film damper.Through numerical simulation calculation of the damper,the dynamic coefficients of squeeze film damper are identified through CFD calculation results,and the result is compared with the theoretical solution.The results show that the main damping error in the x direction is 5.6%,and the main damping error in the y direction is 11.4%.In this paper,the feasibility of the lubricating oil film identification method is verified by the results of dynamic coefficients identification of sliding bearing and squeeze film damper under the condition of small eccentricity ratio,but the applicability of the method remains to be verified under the condition of large eccentricity ratio.