Journal bearings are important parts to keep the high dynamic performance of rotor machinery. Some methods have already been proposed to analysis the flow field of journal bearings, and in most of these methods simpli...Journal bearings are important parts to keep the high dynamic performance of rotor machinery. Some methods have already been proposed to analysis the flow field of journal bearings, and in most of these methods simplified physical model and classic Reynolds equation are always applied. While the application of the general computational fluid dynamics （CFD）-fluid structure interaction （FSI） techniques is more beneficial for analysis of the fluid field in a journal bearing when more detailed solutions are needed. This paper deals with the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearings and rotor dynamics with CFD-FSI techniques. The fluid dynamics of oil film is calculated by applying the so-called ＂dynamic mesh＂ technique. A new mesh movement approacb is presented while the dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The proposed mesh movement approach is based on the structured mesh. When the joumal moves, the movement distance of every grid in the flow field of bearing can be calculated, and then the update of the volume mesh can be handled automatically by user defined function （UDF）. The journal displacement at each time step is obtained by solving the moving equations of the rotor-bearing system under the known oil film force condition. A case study is carried out to calculate the locus of the journal center and pressure distribution of the journal in order to prove the feasibility of this method. The calculating results indicate that the proposed method can predict the transient flow field of a journal bearing in a rotor-bearing system where more realistic models are involved. The presented calculation method provides a basis for studying the nonlinear dynamic behavior of a general rotor-bearing system.展开更多
Turbulence is an irregular fluid motion in which the various flow properties such as velocity and pressure show random variations with time and position.A number of authors proposed different solutions e.g.for pressur...Turbulence is an irregular fluid motion in which the various flow properties such as velocity and pressure show random variations with time and position.A number of authors proposed different solutions e.g.for pressure distribution,temperature prediction and Thermo-Hydrodynamic(THD)analyses.In a fluid film bearing,the pressure in the oil film satisfies the Reynolds equation with a variation in the thickness of the lubricating film.In the presented cases of fluid-structure interaction analyses,all important phenomena accompanying bearing operation are considered,e.g.lubricant flow,structure movements and their deformations as well as heat transfer in case of thrust bearing.In this paper,the authors have developed an empirical relationship to determine the effect of lubrication when considering thermoelastohydrodynamic(TEHD)lubrication with turbulent flow.The critical point of this work is to import the matrix data(the pressure and temperature fields...)from the fluid domain to the internal surface of the bearing with a precision of the mesh especially in the contact surface.The results are presented in the median plane as a function of the bearing angle.A parametric study deals with the influence of rotation speed and the type of turbulence model on the pressure,temperature,deformation and stress intensity fields.展开更多
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2009AA04Z413)Zhejiang Provincial Natural Science Foundation of China (Grant No. Y1110109)
文摘Journal bearings are important parts to keep the high dynamic performance of rotor machinery. Some methods have already been proposed to analysis the flow field of journal bearings, and in most of these methods simplified physical model and classic Reynolds equation are always applied. While the application of the general computational fluid dynamics （CFD）-fluid structure interaction （FSI） techniques is more beneficial for analysis of the fluid field in a journal bearing when more detailed solutions are needed. This paper deals with the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearings and rotor dynamics with CFD-FSI techniques. The fluid dynamics of oil film is calculated by applying the so-called ＂dynamic mesh＂ technique. A new mesh movement approacb is presented while the dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The proposed mesh movement approach is based on the structured mesh. When the joumal moves, the movement distance of every grid in the flow field of bearing can be calculated, and then the update of the volume mesh can be handled automatically by user defined function （UDF）. The journal displacement at each time step is obtained by solving the moving equations of the rotor-bearing system under the known oil film force condition. A case study is carried out to calculate the locus of the journal center and pressure distribution of the journal in order to prove the feasibility of this method. The calculating results indicate that the proposed method can predict the transient flow field of a journal bearing in a rotor-bearing system where more realistic models are involved. The presented calculation method provides a basis for studying the nonlinear dynamic behavior of a general rotor-bearing system.
文摘Turbulence is an irregular fluid motion in which the various flow properties such as velocity and pressure show random variations with time and position.A number of authors proposed different solutions e.g.for pressure distribution,temperature prediction and Thermo-Hydrodynamic(THD)analyses.In a fluid film bearing,the pressure in the oil film satisfies the Reynolds equation with a variation in the thickness of the lubricating film.In the presented cases of fluid-structure interaction analyses,all important phenomena accompanying bearing operation are considered,e.g.lubricant flow,structure movements and their deformations as well as heat transfer in case of thrust bearing.In this paper,the authors have developed an empirical relationship to determine the effect of lubrication when considering thermoelastohydrodynamic(TEHD)lubrication with turbulent flow.The critical point of this work is to import the matrix data(the pressure and temperature fields...)from the fluid domain to the internal surface of the bearing with a precision of the mesh especially in the contact surface.The results are presented in the median plane as a function of the bearing angle.A parametric study deals with the influence of rotation speed and the type of turbulence model on the pressure,temperature,deformation and stress intensity fields.
基金Supported by National Science and Technology Special Program(No.2011ZX04004-041)National Natural Science Foundation of China(No.90923023)Doctoral Program Foundation of Higher Education of China(No.20092302110055)
