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In this work, hydrodynamic journal bearing are simulated considering the realistic deformations of the bearing with fluid structure interactions (FSI) coupled with CFD. Mixture model is used model cavitation in the bearing. Parametric modeling is used to modify the flow domain due to deformation. Both systems are coupled and multi objective genetic algorithm (MOGA) is used to get optimized solution...
This work focuses on study of tribological behavior of a commercially available polytetrafluoroethylene (PTFE) and carbon fiber reinforced PTFE hydrodynamic journal bearing. The purpose of selection of this material is due to its low coefficient of friction and enhancement of the self lubricating properties. Performance parameters like pressure distribution, load carrying capacity and deformation...
Journal misalignment often exists in grease lubricated journal bearings. Lubricating grease is a non-Newtonian liquid, and the rheological properties of grease make it difficult to analyze the lubrication performance numerically. In this paper, grease lubrication Reynolds equation is introduced based on the Herschel-Bulkley model which accurately describes the rheological properties of grease. The...
A dynamic lubrication model is built based on the lubrication theory of the oil film for optimization design of the inner radius of the sealing surface of slipper, considering the macro and micro motion of the slipper. Reasonable design criterion is presented, adopting the oil film characteristics, dynamic stiffness and minimum power loss as the optimum conditions. Furthermore, the experiments of...
This paper presents an SPH (smoothed particle hydrodynamics) model for numerical simulation of multiphase drop dynamics including liquid drop formation and deformation, coalescence and separation, liquid drop impacting, spreading and splashing. SPH is a Lagrangian, meshfree particle method. It has special advantages in modeling multiphase drop dynamics. Surface tension effects are modeled using a...
The dynamic model of the rub-impact rotor system with an parallel misalignment was set up. By the displacement constraint between rotors, the dynamic equations was developed on the Lagrange method. Simulations show that the rotor system's low frequencies with large amplitude are 1/2, 1 and 3/2 octave spetrums. If the parallel misalignment is small, the displacement is small as the parallel becomes...
High-speed hydrodynamic and hydrostatic hybrid spindle unit is a new product of spindle in recent years, and it is the most promising high-speed spindle product to be developed with our own intellectual property and brand in the field of high-speed spindle in China. By researching in the current development in high-speed hydrodynamic and hydrostatic hybrid spindle unit and the technology involved,...
Aimed at washer in planetary transmission, the wear problem of thrust washer and planet gear due to the force in axis direction was investigated. In order to reduce wear, hydrodynamic lubrication design was studied by way of machining rectangular groove in radial direction into one side of thrust washer. The purpose of hydrodynamic lubrication design is that the relative movement between planet gear...
This paper has studied the friction of main bearing on an engine by combining the multi-body dynamics and hydrodynamic lubrication model. First, the basic equations and the application on AVL-Excite software platform of multi-body dynamics have been described in detail. Then, introduce the hydrodynamic lubrication model, which is the extended Reynolds equation derived from the Navier-Stokes equation...
This paper has studied the fatigue and friction of big end bearing on an engine connecting rod by combining the multi-body dynamics and hydrodynamic lubrication model. First, the basic equations and the application on AVL-Excite software platform of multi-body dynamics have been described in detail. Then, introduce the hydrodynamic lubrication model, which is the extended Reynolds equation derived...
This paper presents a modified numerical model for Elastohydrodynamic lubrication (EHL) calculations of involute spur gears. This model considers the fluid as a Newtonian fluid. The main study performs on gear EHL properties along path of contact (POC). Using this study, the minimum film thickness and maximum pressure value as well complete film geometry and pressure distribution could be obtained...
In this paper, a modified full numerical model will be presented to calculate elastohydrodynamic line contacts in various conditions of geometry and material properties. This model can calculate results in shortest time and with best accuracy. All modifications will be applied in previously developed models to reach demanded results in desired time and accuracy. This model is helpful to get results...
Amplification of space charge waves (SCW) due to the negative differential conductivity (NDC) in n-GaN films of submicron thicknesses is investigated theoretically. An influence of nonlocal dependence of average electron velocity on the electron energy is considered. The simplest nonlocal model is used where the total electron concentration is taken into account. The relaxation momentum and energy...
This paper presents several models which can be applied to simulate the gas absorption in countercurrent packed bed columns with first-order chemical reaction. The hydrodynamic models predict the velocity profile in liquid film for both laminar and turbulent conditions by using the interfacial drag which is the result of gas side interaction on liquid flow rate. As the gas or liquid flow rates increase,...
Under the loadcase of heavy load and high speed, the elastic deformation and thermal effects heavily influence the oil film properties of bearing system. Considering the variations of oil film viscosity and density with pressure and temperature, 3D thermo-hydrodynamic lubrication model of large-scale mill bearing was built. The coupling algorithm which integrated Finite Difference Method (FEM) and...
In this paper, a thermoelastohydrodynamic model for tilting-pad bearing is developed. In our proposed model, the study of temperature field is characteristicly focused on the temperature change along the film thickness direction, and thermal-elastic deformation is calculated based on assumption that the pad is a cantilever beam. The model is described with the generalized Reynolds equation, the energy...
A micro-rotating machinery such as hard disk drive requires high efficiency and robust dynamics in high operating speed. Herringbone grooved journal bearings are widely used for this application thanks to their excellent dynamic characteristics. The clearance between sleeve and shaft is filled with fluid lubricant. However, the temperature of the fluid film rises significantly as the frictional heat,...
Based on fundamental hydrodynamic equations, according to principle of flux conservation in control volume, various field variables of every node in the whole flow field of circular thrust aerostatic bearing are resolved. Distribution of these discrete variables can substitute for solutions of the partial differential equations which describe physical phenomena of the flow in the bearing. By this...
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