Study on CFD Solution Method for Static Characteristics of Hybrid Oil Film Bearing

2012 ◽  
Vol 155-156 ◽  
pp. 236-240
Author(s):  
Da Ying Li
Keyword(s):  
Boundary Condition ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Reynolds Equation ◽  
Solution Method ◽  
Fundamental Equation ◽  
Static Characteristics ◽  
Oil Film ◽  
Static Performance ◽  
Fluent Software

Reynolds equation is the fundamental equation to solve the static performance for sleeve bearings. For hydrodynamic and hydrostatic oil film bearing with three oil recesses, the specific expressions of the fluid mechanics lubrication Reynolds equation are presented. The gridding model of the bearing is proposed, the boundary condition of the bearing is set, the static characteristics are solved and the pressure distribution of the bearing is plotted by using FLUENT software. The computation results from FLUENT are considerably accordance with the computation results from finite difference method.

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

2014 ◽  
Vol 607 ◽  
pp. 608-611
Author(s):  
Hui Hui Feng ◽  
Chun Dong Xu ◽  
Feng Feng Wang
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Film Thickness ◽  
Power Loss ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Orifice Diameter ◽  
Rigid Rotor ◽  
Static Performance

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.

Study on the Oil Film Static Performance of Sliding Bearings with Different Throttling Methods

2012 ◽  
Vol 155-156 ◽  
pp. 519-525
Author(s):  
Da Ying Li ◽  
Gui Yun Jiang
Keyword(s):  
Carrying Capacity ◽  
Continuity Equation ◽  
Reynolds Equation ◽  
Vital Role ◽  
Static Characteristics ◽  
Sliding Bearings ◽  
Oil Film ◽  
Numerical Solution Methods ◽  
Solution Methods ◽  
Static Performance

The restrictors of fluid lubricated sliding bearings play vital role in oil film rigidity and carrying capacity of bearings. The mathematical models for solution of the oil film static performance of the bearings with four different restrictors were presented and the numerical solution methods were analyzed. The solutions for oil film static characteristics in many aspects such as discretization of Reynolds equation, building clearance function, determinating boundary conditions, constructing continuity equation, deducing the models of oil inlet flow, solving the carrying capacity were conducted. The computational results show that the bearings with capillary or orifice restrictor have lower carrying capacity and oil film rigidity than those with sliding valve feedback or film feedback restrictors.

Analysis of Infinitely Short and Infinitely Long Hydrodynamic Journal Bearings Under Micro-Polar Fluid by Direct Integration Method

2017 ◽  
Author(s):  
Bikash Routh
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Integration Method ◽  
Pressure Profile ◽  
Journal Bearings ◽  
Direct Integration ◽  
Polar Fluid ◽  
Direct Integration Method

In the present paper Reynolds equation of lubrication under micro-polar fluid for journal bearing is solved by direct-integration method under infinitely long and infinitely short journal bearing assumptions [1]. Infinitely long-bearing and infinitely short bearing solutions are the two available approximate closed form solutions for journal bearings. In the present investigation, solution of Reynolds equation i.e. pressure profile is compared with pressure profile obtained by previously used approximate method like finite difference method (FDM). Mentionable here that any approximation method needs lots of calculation and computer programing to get the result. In the present work it has been found that direct-integration method leads the almost same result as the conventionally used complex finite difference method. CFD analysis is also presented in the present work to justify the profile obtained by direct numerical method. It has seen here that theoretical and simulation results are in good agreement to each other’s.

Heat Diffusion in Heterogeneous Bodies Using Heat-Flux-Conserving Basis Functions

1988 ◽  
Vol 110 (2) ◽  
pp. 276-282 ◽  
Author(s):  
A. Haji-Sheikh
Keyword(s):  
Heat Flux ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Diffusion Equation ◽  
Difference Method ◽  
Solution Method ◽  
Basis Functions ◽  
Heat Diffusion ◽  
Simple Geometry ◽  
The Finite Difference Method

The generalized analytical derivation presented here enables one to obtain solutions to the diffusion equation in complex heterogeneous geometries. A new method of constructing basis functions is introduced that preserves the continuity of temperature and heat flux throughout the domain, specifically at the boundary of each inclusion. A set of basis functions produced in this manner can be used in conjunction with the Green’s function derived through the Galerkin procedure to produce a useful solution method. A simple geometry is selected for comparison with the finite difference method. Numerical results obtained by this method are in excellent agreement with finite-difference data.

Averaging effect on pitch errors in hydrostatic lead screws considering helical recess layout and nut misalignment

2017 ◽  
Vol 232 (9) ◽  
pp. 1181-1192
Author(s):  
Yongtao Zhang ◽  
Changhou Lu ◽  
Yunpeng Liu
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Radial Displacement ◽  
Continuity Equation ◽  
Reynolds Equation ◽  
Spatial Frequencies ◽  
The Finite Difference Method ◽  
Low Speeds ◽  
Flank Surface

The hydrostatic nut usually has different helical recess layouts and the nut misalignment (including radial displacement and tilt) may occur during movement, which will influence the averaging effect on pitch errors, i.e. the motion accuracy of the hydrostatic nut. This paper researches the averaging effect on pitch errors in capillary compensated hydrostatic lead screws, under low speeds and considering the helical recess layout and the nut misalignment. Based on the equivalent plane of the flank surface of threads, whose normal clearance is calculated by vector operations, the Reynolds equation and the flow continuity equation are solved using the finite difference method. The results show that (a) the averaging coefficient presents bulges at corresponding spatial frequencies for the hydrostatic nut with discontinuous helical recesses, (b) the positions of the first and second periodical fluctuations of the averaging coefficient are the same for the hydrostatic nut with symmetric continuous helical recesses, symmetric discontinuous helical recesses, or asymmetric continuous helical recesses, and (c) The nut misalignment has little influence on the averaging coefficient.

Accuracy analysis of narrow groove theory for spiral grooved gas seals: A comparative study with numerical solution of Reynolds equation

2018 ◽  
Vol 233 (6) ◽  
pp. 899-910
Author(s):  
Wanjun Xu ◽  
Jiangang Yang
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Reynolds Equation ◽  
Compressible Fluids ◽  
Accuracy Analysis ◽  
Performance Parameters ◽  
Typical Performance ◽  
Gas Seals ◽  
Film Stiffness

This study examined the accuracy of narrow groove theory for spiral grooved gas seals. Designed for compressible fluids, a finite difference method was proposed to solve the two-dimensional compressible Reynolds equation. The predictions of narrow groove theory were compared with those of the Reynolds equation. The typical performance parameters including gas film force, leakage, gas film stiffness, and torque were analyzed. The results show that the predictions of narrow groove theory generally agree with those of finite difference method when the number of grooves is more than eight. The gas film force, leakage, and gas film stiffness were slightly overestimated by narrow groove theory, with better accuracy for gas film force, leakage, and torque than for gas film stiffness. Although some cases showed deviation for gas film stiffness of as much as 52%, most deviations can be effectively ignored. Therefore, it is feasible to use narrow groove theory for qualitative analysis such as groove shape optimization. The present analysis provides the optimum groove parameters for the investigated seal.

Analysis of Hybrid (Hydrodynamic/Hydrostatic) Journal Bearing

2013 ◽  
Vol 650 ◽  
pp. 385-390 ◽  
Author(s):  
Vijay Kumar Dwivedi ◽  
Satish Chand ◽  
K.N. Pandey
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Gas Turbines ◽  
High Speed ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Natural Boundary Condition ◽  
Dimensional Solution

The Hybrid (hydrodynamic/ hydrostatic) journal bearing system has found wide spread application in high speed rotating machines such as compressors, gas turbines, steam turbines, etc. The present studies include solution of Reynolds equation for hydrodynamic journal bearing with infinitely long approximation (ILA), infinitely short bearing approximation (ISA) and finite journal bearing approximation. Further Finite Journal bearing approximation considers two dimensional solution of Reynolds equation with natural boundary condition, which cannot be solved by analytical method. So, here the solutions for finite journal bearing have been done with finite difference method (a MATLAB® code is prepared for finite difference method) to get bearing performance parameters such as load capacity, Sommerfeld no., etc.

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