Bearing Oil Film Research Articles

Combined Influence of Misalignment and Orifice Diameter on the Static Performances of Hydrostatic, Water-Lubricated Journal Bearings

The water-lubricated bearings have gained an increasing focus to overcome the disadvantages of the oil film bearings and gas bearings. In this paper, the influences of orifice diameter in aligned and misaligned conditions on the static performance of two hydrostatic, four-recess, water-lubricated journal bearings used to support a rigid rotor, are investigated. The steady Reynolds equation for the journal bearing for the turbulent bulk flow and the film thickness expression considering tilting angles are used and numerically solved by finite difference method. Results demonstrate that the static performances, such as the quality, power loss and temperature rise are affected by the tilting angles, orifice diameter to some degree.

An On-Line Condition Monitoring System for Oil Film Bearings of Cold Rolling Mill

An on-line monitoring system of hydrodynamic lubricant supply conditions for the back-up roll’s oil film bearing of 1420mm cold rolling mill was developed for providing real time monitoring so as to avoid unexpected breakdown of the production line. The monitoring parameters of supply pressure, supply temperature and supply flow rate show that the monitoring system software with real-time event trigger mechanism and intelligent storage algorithm solves the issue of data overflow in the continuous record and ensure the safety of data transmission. Test results for hydrodynamic lubricant supply conditions in the industrial production are reported, which indicated that established software architecture and programming methods construct a stable and reliable monitoring system, which provides early warnings for the safe production.

Flow Criterion Research on Fluid in Hydrostatic Bearing from Laminar to Turbulent Transition

The multi- pad circular guide hydrostatic bearing of heavy-duty CNC machine is taken as the research object. Based on the lubrication properties of the heavy hydrostatic bearing, viscosity-temperature equation of interstitial fluid is established in various viscosities. In accordance with factory actual production, the fluid critical from laminar to turbulent is calculated by finite volume method. The inner flow field of hydrostatic bearing is simulated, when the rotating speed of workbench is 6r/min at different flow. The simulation results reveal flow distribution low and verify the reliability of the calculation. The results show that, the transition critical inlet fluid flow from laminar to turbulent of fluid in hydrostatic bearing is 22L/min. Through the above analysis and research, reveals the flow rule of the hydrostatic bearing oil film bearing gap, provides a theoretical basis for actual hydrostatic bearing for engineering structural optimization design.

Study on creep characteristics of oil film bearing Babbitt

According to the creep deformation of oil film bearing Babbitt in operation process, the creep test method of Babbitt was put forward, the factors about influencing the results of creep test were analysed, and the creep test research of Babbitt was carried out. The test data were processed, and the creep characteristics of SnSb11Cu6 and SnSb8Cu4 were acquired based on Graham creep equation and the wheat quarts method and global optimisation algorithm. The relationship between creep coefficients and stress has been obtained, and a group of creep curves under different stress has been speculated through calculating stress related indexes. At the same time, the accuracy and reliability of creep deformation of Babbitt were verified through finite element numerical simulation on the test specimens based on ANSYS. Then the creep characteristics of Babbitt of oil film bearing were carried out by finite element numerical simulation.

The Fault Analysis and Research of Turbine Generator Sliding Bearing Oil Film Instability

This article are discussed Sliding Bearing for Turbine instability failure research status in detail; Gives the theoretical analysis On sliding bearing oil film instability failure mechanism, to further explore the oil whirl and oil whip manifestations and signal spectral characteristics. And analysis of the oil whirl speed changes the vibration characteristics of typical regions, given the time-domain waveform oil whirl and oil whip axis trajectory. Details of the turbine generator film and the main reason for the instability factors and made a film instability fault governance approach. It helped for Fault Diagnosis of Turbine film and achieving security and stability of Turbine provides technical reference.

Viscosity monitoring and control on oil-film bearing lubrication with ferrofluids

Ferrofluid application in the oil-film bearing can improve the viscosity and the load-carrying capacity in a magnetic field. A solenoid was developed to provide magnetic field for ferrofluid, using which the distribution of magnetic induction intensity was calculated. The viscosity equation of ferrofluid was derived. The effects of oil-film temperature T, oil-film pressure P and magnetic intensity H on ferrofluid viscosity ηf was analyzed and tested by an unifactor experiment method. The control equations and transfer functions of each variable were given based on a large-scale oil-film bearing test rig. The variations of P, T, H and ηf were simulated and monitored by a reasonable control strategy. The results suggest that the viscosity increment by magnetic intensity could compensate the viscosity decrement by temperature rise.

Effect of unbalanced magnetic pull and hydraulic seal force on the vibration of large rotor-bearing systems

The influence of unbalanced magnetic pull (UMP) and hydraulic seal force on the vibration of large rotor-bearing systems is studied. The UMP caused by rotor eccentricity imposes important effects on rotating machinery, especially for large generators such as water turbine generator sets, because these machines operate above their first critical speed in some instances and are supported by oil film bearings. A magnetic stiffness matrix for studying the effects of the UMP is proposed. The magnetic stiffness matrix can be generated by decomposing the expression of air gap magnetic field energy. Two vibration models are constructed using the Lagrange equation. The difference between the two models lies in the boundary support condition: one has rigid support and the other has elastic bearing support. The influence of the magnetic stiffness and elastic support on the critical speed of the rotor is studied using Lyapunov nonlinear vibration stability theory. The vibration amplitude of the rotor is calculated, taking the magnetic stiffness and horizontal centrifugal force into account. The unbalanced hydraulic seal force is produced because of the asymmetry of seal clearance. This imbalance is one of the factors that causes self-excited vibration in rotating machinery, and is as important as the UMP for large water turbine generator sets. The rotor-bearing system is supported by an oil film journal bearing, whose characteristic also impose considerable influence on vibration. On the basis of the above-mentioned conditions, a three-dimensional finite element model of the rotating system that includes the oil film journal bearing is constructed. The effect of the UMP and unbalanced hydraulic seal force is considered in the construction, and studied in relation to the magnetic parameters, seal parameters, journal bearing stiffness, and outer diameter of the rotating machine critical speed. Conclusions may benefit the dynamic design and optimized operation of large rotating machinery.

The Effect of Unbalance on the Cyclic Stresses of a Flexible Rotor Mounted on Oil-Film Bearings Using Finite Elements Technique (ANSYS)

Eccentricity problem is considered as one of the most important and common repeated problems in rotary shafts in all machines. This will lead to generation of vibration and extra loads on bearings. Also a non-uniformity can occur in distribution of applied load on all the surface of the bearing which being concentrated on one or two sides of the bearing surface.The purpose of this research is to investigate the effect of the unbalance on the values of stresses and deflections for a flexiblerotor supported by oil film bearings. Various rotational speeds and unbalance effects has been taken in to consideration. A dynamical model of the system has been built. The parameters of journal bearing have been determined using MATLAB/ simulink software. ANSYS program has been used for the analysis of the stresses produced during rotation. تأثير عدم اتزان عمود الدوران المرن المثبت على محامل مزيتة على قيمة الاجهادات الدورية المتولدة فيه باستخدام تقنية العناصر المحددة (الانسز) خالد الياس حمو احمد محمود عبدالله عمرعبدالرحمن محمد (مدرس مساعد) قسم الهندسة الميكانيكية / كلية الهندسة / جامعة الموصل الخلاصة تعد مشكلة الاختلاف المركزي في الأعمدة الدوارة من أهم المشاكل الشائعة والمتكررة الحدوث في معظم المكائن الدوارة إذ تؤدي إلى توليد اجهادات وأحمال إضافية على المحامل, والى عدم انتظام توزيع الحمل المسلط على سطح المحمل بتركزه على جانب واحد أو جانبين من جوانب المحمل.الغرض من هذا البحث هو معرفة تأثير عدم الاتزان لعمود الدوران على قيم الاجهادات والانحرافات المتولدة فيه والمثبت بواسطة محامل مزيتة. تم اخذ تأثير كلا من عدم التوازن ولعدة سرع دورانية مختلفة بنظر الاعتبار.تم بناء النموذج الديناميكي للنظام. بعد تحديد العوامل المؤثرة في المحامل والتي تم من خلالها حساب القوى عن طريق استخدام برنامج الماتلاب. استخدم احد برامج تحليل الاجهادات وهو برنامج الانسز من اجل معرفةتوزيع الاجهادات والانحرافات أثناء الدوران. الكلمات المفتاحية: عدم الاتزان، الاختلاف المركزي ، التمثيل، عمود دوار

Parameter variation and data mining of oil-film bearings: a stochastic study on the Reynolds’s equation of lubrication

The modeling and simulation process of oil-film bearing dynamics constitutes a rather essential task integrated in the workflow of various mechanical products. Specifically, in the turbo charger industry, the correct capture and understanding of the associated nonlinear rotating dynamics is of utmost importance, since the system’s efficiency and lifetime span depends on it. The root cause of the nonlinear rotordynamic effects is the oil-film concentrated in the rotor’s journal bearings. Its behavior is highly coupled with both the system’s geometric and dynamic configuration. The dynamics of the oil-film are described by the well-known Navier–Stokes equation, which under a series of assumptions and simplifications results to the, so-called, Reynolds equation. In this paper, the Reynolds equation is numerically solved based on a finite difference scheme and several parameter variation studies are conducted in an effort to pinpoint the most influential parameters—journal bearing geometric dimensions, oil-film properties and rotor-velocity-driven inputs—with respect to designated responses—friction, oil-film pressure force, minimum oil-film thickness and boundary oil-flow—all of which are regarded as important in terms of the aforementioned system’s efficiency and lifetime span. Based on multivariate analysis algorithms, correlation outcomes and global sensitivity results are presented. In an effort to capture possible nonlinear phenomena, which might not be possible via linear data mining tools, the Spearman rank-order coefficient and self-organizing maps methodology are applied.

Review of the Study on Load Capacity of Oil-Film Bearings

The oil-film bearings are widely used in mechanical transmission due to the good performance. In normal operating conditions, the journal and bearing shell are separated by the oil film, which contributes to the reduction of wear. And the stability and reliability of oil film has a great effect on load capacity. The paper briefly introduces research methods of the load capacity of oil-film bearings and points out some aspects of large oil-film bearings for in-depth study. Then combining dynamic simulation with experimental test on the scaled model of whole machine, a dynamic research idea is presented for large oil-film bearings.

Experimental Research on Cavitation Characteristics of a Novel Hybrid Journal Bearing

Under high and super high speed, the oil film of a journal bearing is easy to crack and then becomes cavitation. The existence of cavitation has a great effect on the work performance of the bearing. The cavitation mechanism of a spiral oil wedge journal bearing was investigated on the experimental rig. The effects of rotating speed and supply pressure on the cavitation shape of oil film and the number of cavitation strip in the rupture zone were analyzed. The results show that the cavitation shape of oil film is a long strip. The number of cavitation strip increases when supply pressure has been improved, and the location of oil outlet must be designed optimally.

Experimental Investigation on Cavitation Characteristics of a Three-Groove Journal Bearing

Under high and super-high speed, oil film of the journal bearing is easy to crack and then becomes cavitation. The existence of cavitation has an important effect on the work characteristics of the shaft. On the journal bearing experiment rig the cavitation characteristics of the three-groove journal beaing were studied. The influences of the shaft rotating speed and supply pressure on cavitation shape were investigated. The results show that rotating speed and supply pressure have a clear effect on the cavitation shape, and the number of cavitation strip in the rupture zone decreases when the supply pressure increases.

Experimental Study on Cavitation Boundary of Journal Bearing

Under high and super-high speed conditions, oil film of the journal bearing is easy to crack and then becomes cavitation. The existence of cavitation has a great effect on the work characteristics of the bearing. Cavitation boundary of a three-groove journal beaing was investigated on the journal bearing experimental rig. The influences of rotating speed and supply pressure on cavitation boundary were studied. And experimental equations of reformation location and the percent of rupture area are established. The results show that rupture location of oil film is not related with rotating speed and supply pressure, otherwise reformation location of oil film is effected greatly by them. The experimental equations lay foundations for next research on cavitation theory model and stability.

Nonlinear Analysis of Rotor-Stator-Bearing System Unsteady Oil Film Force

According to the LaGrange energy equation, the establishment of the unsteady oil film force of the rotor - stator - bearing system dynamics model, the application of numerical method, the system with the speed change time domain waveforms, amplitude spectra and Axis Orbit, the results show that: the unsteady oil film force and speed of change is closely related to changes in the process of oil film force oil whirl Oil Whip. Provide a theoretical basis for effective diagnosis of rotor - stator - bearing oil film instability fault research.

Nonlinear dynamic analysis of a rotor-bearing-seal system under two loading conditions

The operating speed of the rotating machinery often exceeds the second or even higher order critical speeds to pursue higher efficiency. Thus, how to restrain the higher order mode instability caused by the nonlinear oil-film force and seal force at high speed as far as possible has become more and more important. In this study, a lumped mass model of a rotor-bearing-seal system considering the gyroscopic effect is established. The graphite self-lubricating bearing and the sliding bearing are simulated by a spring-damping model and a nonlinear oil-film force model based on the assumption of short bearings, respectively. The seal is simulated by Muszynska nonlinear seal force model. Effects of the seal force and oil-film force on the first and second mode instabilities are investigated under two loading conditions which are determined by API Standard 617 (Axial and Centrifugal Compressors and Expander-compressors for Petroleum, Chemical and Gas Industry Services, Seventh Edition). The research focuses on the effects of exciting force forms and their magnitudes on the first and second mode whips in a rotor-bearing-seal system by using the spectrum cascades, vibration waveforms, orbits and Poincaré maps. The first and second mode instability laws are compared by including and excluding the seal effect in a rotor system with single-diameter shaft and two same discs. Meanwhile, the instability laws are also verified in a rotor system with multi-diameter shaft and two different discs. The results show that the second loading condition (out-of-phase unbalances of two discs) and the nonlinear seal force can mainly restrain the first mode instability and have slight effects on the second mode instability. This study may contribute to a further understanding about the higher order mode instability of such a rotor system with fluid-induced forces from the oil-film bearings and seals.

Research on Load-Carrying Performances of Magnetic-Fluid Lubrication for Mill Oil-Film Bearing

The FEM model of lubricating oil film was built with mill oil-film bearing as the research target, the analysis system of magnetic-fluid lubricating oil film for oil-film bearing was developed. APDL and CEL languages were applied to compile the inner analytical programs, and the combination of VB, ANSYS Mechanical with ANSYS CFX was perfectly realized. Through the numerical simulation of magnetic-fluid lubricating film, the load-carrying performances of oil-film bearing with magnetic-fluid lubrication were analyzed, and the relationship among magnetic field intensity with oil-film pressure and temperature was quantitatively calculated. The numerical results have shown that the magnetic-fluid lubrication has obvious influences on oil-film pressure when magnetic field was applied on oil-film bearing, the lubricating viscosity increases with the magnetic-fluid intensity, and the oil-film pressure and temperature also increase with magnetic-field intensity. However, the increasing increment of oil-film temperature is far lower than that of oil-film pressure. The above conclusions prove that magnetic fluid with proper magnetic field can effectively improve the load-carrying capacity of lubricating oil film and enhances the stability of oil-film pressure. Moreover, the adjustable intelligent oil-film pressure with magnetic field is deduced to be feasible.

자동차용 연료펌프의 진동 저감에 대한 연구

This article presents the reduction of vibration generated by an automobile fuel pump. In order to analyze the vibration of the fuel pump, a simplified dynamic model is established, which is composed of a rigid rotor and a equivalent springs. The equivalent stiffnesses of the upper and lower assemblies are evaluated by the comparison of modal testing results and the finite element analysis. The stiffness for the oil film of the journal bearing is extracted by using Reynold's equation. In addition, the time responses for the vibration of the fuel pump are computed by using a commercial multi-body dynamics software, RecurDyn. Based on these results, some design suggestions are proposed to reduce the vibration of an automobile fuel pump.

Vibrations caused by noncircular shaft journals — a mathematical model for rotordynamic analysis of electrical motors with sleeve bearings

The paper presents a mathematical model for theoretical rotordynamic analysis of electrical motors with sleeve bearings, regarding excitation due to noncircular shaft journals. It is shown, that noncircular shaft journals lead to kinematic constraints regarding the movement of the shaft journals on the oil film of the sleeve bearings and therefore excite the rotordynamic system to vibrate. The rotordynamic system is mathematically described by a system of linear differential equations, considering the rotor mass, the rotor structural stiffness, the oil film stiffness and damping of the sleeve bearings, the structural stiffness of the sleeve bearing housings with the end shields, the electromagnetic coupling between rotor and stator in the air gap and the excitation due to noncircular shaft journals. The solution of this differential equation system leads to the mathematical description of the movement of the rotor centre, the shaft journals and the sleeve bearing housings. Additionally, the relative movements between the shaft journals and the bearing housings can be calculated, as well as the bearing housing vibration velocities. A four-pole induction motor is analyzed, to also show numerical results.

Research on Hydrostatic Supporting Temperature-Rise of Heavy NC Machine Tool

With heavy NC machine tool is widely used in many oil pad round guide hydrostatic bearing as the research object, in the under condition of variable viscosity, establish oil film viscosity-temperature equation. Adopt finite volume method, simulation the hydrostatic bearing internal fluid temperature field under different flow rates on the speed of 6R / min. Numerical simulation hydrostatic thrust bearing oil film temperature field, can find a general high temperature region, and then take effective control temperature. It can achieve the hydrostatic thrust bearing oil film temperature field prediction for engineering practical oil chamber structure, offer the theoretical foundation for optimization design.

Temperature Field of Hydrostatic Supporting Disk in Different Viscosity and Rotational Speed

With heavy hydrostatic bearing as the research object, establish oil film viscosity-temperature equation. Adopt finite volume method, respectively calculates the oil film temperature field under different rotate velocity in Invariant viscosity and variable viscosity, revealing the oil film temperature arise influence rule of hydrostatic bearing on the viscosity and rotate velocity. The results show that the viscosity and rotate velocity have a great influence on the hydrostatic bearing oil film temperature rise, but the effect regularity varied. The calculated results that provide a theoretical basis for the hydrostatic bearing structure design and bearing deformation calculation, and have very important significance on improve the reliability and precision of the whole machine tools.