Influence of the Thermal Field on the Resistance Law in the Turbulent Bearing-Lubrication Theory

1984 ◽  
Vol 106 (3) ◽  
pp. 368-374 ◽  
Author(s):  
F. Di Pasquantonio ◽  
R. Sala
Keyword(s):  
Pressure Distribution ◽  
Thermal Field ◽  
Type Equation ◽  
Research Programme ◽  
Mass Conservation ◽  
Staggered Grid ◽  
Arbitrary Distribution ◽  
Slider Bearing ◽  
Lubricating Film ◽  
Plane Normal

In recent years, a joint theoretical and experimental research programme has been carried out by ANSALDO, ENEL, and the Department of Mechanics of the Milan Polytechnic. The purpose of this paper is to investigate the effects of the thermal field on the resistance law. In particular, a study is made of the behavior of the lubricating film of an infinite and inclined-plane slider-bearing, using a turbulence model similar to that employed by Launder and Leschziner. In our method, the complete boundary layer equations of mass, momentum, and energy are solved numerically, by a finite-difference technique in the plane normal to the sliding surface. The equations are discretized on a staggered grid, in which the scalar quantities (pressure, viscosity, and temperature) are located at the nodes and the velocity components between them. Having assumed arbitrary distribution of velocity at the inlet and pressure distribution, the set of conservation equations can be solved at the downstream stations. Since the velocity field obtained does not satisfy the global mass conservation law at every station, a Poisson-type equation for pressure correction is derived by imposing such a mass conservation condition. Velocity and pressure distribution at the inlet are then corrected, and a new computation performed. This iterative procedure is repeated until the solution is no longer significantly modified. The numerical results show that the resistance coefficients obtained taking into account the thermal field, are lower than those obtained in isothermal conditions.

A Comparison of Porous Structures on the Performance of a Slider Bearing with Surface Roughness in Couple Stress Fluid Film Lubrication

2015 ◽  
Vol 813-814 ◽  
pp. 921-937
Author(s):  
P.S. Rao ◽  
Santosh Agarwal
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Couple Stress ◽  
Type Equation ◽  
Random Variable ◽  
Couple Stress Fluid ◽  
Load Carrying Capacity ◽  
Porous Structures ◽  
Slider Bearing ◽  
Load Carrying

This paper presents the theoretical study and analyzes the comparison of porous structures on the performance of a couple stress fluid based on rough slider bearing. The globular sphere model of Kozeny-Carman and Irmay’s capillary fissures model have been subjected to investigations. A more general form of surface roughness is mathematically modeled by a stochastic random variable with non-zero mean, variance and skewness. The stochastically averaged Reynolds type equation has been solved under suitable boundary conditions to obtain the pressure distribution in turn which gives the expression for the load carrying capacity, frictional force and coefficient of friction. The results are illustrated by graphical representations which show that the introduction of combined porous structure with couple stress fluid results in an enhanced load carrying capacity more in the case of Kozeny-Carman model as compared to Irmay’s model.

Hydrodynamic Analysis of the Flow in a Rotary Lip Seal Using Flow Factors

2004 ◽  
Vol 126 (1) ◽  
pp. 156-161 ◽  
Author(s):  
Richard F. Salant ◽  
Ann H. Rocke
Keyword(s):  
Flow Field ◽  
Pressure Distribution ◽  
Reynolds Equation ◽  
Present Approach ◽  
Operating Parameters ◽  
Pumping Rate ◽  
Hydrodynamic Analysis ◽  
Lip Seal ◽  
Lubricating Film ◽  
Computationally Intensive

The flow field in the lubricating film of a rotary lip seal is analyzed numerically by solving the Reynolds equation with flow factors. The behavior of such a flow field is dominated by the asperities on the lip surface. Since previous analyses treated those asperities deterministically, they required very large computation times. The present approach is much less computationally intensive because the asperities are treated statistically. Since cavitation and asperity orientation play important roles, these are taken into account in the computation of the flow factors. Results of the analysis show how the operating parameters of the seal and the characteristics of the asperities affect such seal characteristics as the pressure distribution in the film, the pumping rate and the load support.

Non-Axisymmetric Flows and Rotordynamic Forces in an Eccentric Shrouded Centrifugal Compressor—Part 2: Analysis

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Jieun Song ◽  
Seung Jin Song
Keyword(s):  
Pressure Distribution ◽  
Centrifugal Compressor ◽  
Axisymmetric Flow ◽  
Mass Conservation ◽  
Labyrinth Seal ◽  
Operating Conditions ◽  
New Model ◽  
Flow Coupling ◽  
Order Of Magnitude ◽  
Rotordynamic Forces

AbstractAn integrated analytical model to predict non-axisymmetric flow fields and rotordynamic forces in a shrouded centrifugal compressor has been newly developed and validated. The model is composed of coupled, conservation law-based, bulk-flow submodels, and the model takes into account the flow coupling among the blades, labyrinth seals, and shroud cavity. Thus, the model predicts the entire flow field in the shrouded compressor when given compressor geometry, operating conditions, and eccentricity. When compared against the experimental data from part 1, the new model accurately predicts the evolution of the pressure perturbations along the shroud and labyrinth seal cavities as well as the corresponding rotordynamic stiffness coefficients. For the test compressor, the cross-coupled stiffness rotordynamic excitation is positive; the contribution of the shroud is the highest; the contribution of the seals is less than but on the same order of magnitude as that of the shroud; and contribution of impeller blades is insignificant. The new model also enables insight into the physical mechanism for pressure perturbation development. The labyrinth seal pressure distribution becomes non-axisymmetric to satisfy mass conservation in the seal cavity, and this non-axisymmetry, in turn, serves as the influential boundary condition for the pressure distribution in the shroud cavity. Therefore, for accurate flow and rotordynamic force predictions, it is important to model the flow coupling among the components (e.g., impeller, shroud, labyrinth seal, etc.), which determines the non-axisymmetric boundary conditions for the components.

Film Thickness and Friction Investigations in a Fluid Film Thrust Bearing Employing A New Conceived Micro-Texture on Pads

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
J. C. Atwal ◽  
R. K. Pandey
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Mass Conservation ◽  
Fluid Film ◽  
Element Formulation ◽  
Algebraic Equations ◽  
Pocket Depth ◽  
Lubricating Film ◽  
Minimum Film Thickness ◽  
Radial Length

Abstract This paper presents the performance behaviors (coefficient of friction, minimum film thickness, and pressure distributions) of a fluid film thrust bearing using a newly conceived micro-texture on pads. In the numerical investigation, the Reynolds equation has been discretized using the finite element formulation followed by the solution of algebraic equations employing the Fischer-Burmeister-Newton-Schur (FBNS) algorithm, which satisfies the mass-conservation phenomenon arising due to the commencement of cavitation in the lubricating film. The effects of parameters (micro-texture/pocket depth, circumferential/radial length of micro-texture and pocket, etc.) of new texture on the performance behaviors of the thrust bearing have been explored and presented herein for the range of input data. It has been found that the minimum film thickness has increased up to 48%, and the friction coefficient reduced up to 24% in comparison to conventional plain pad case.

An Aid to Learn Computational Fluid Dynamics: Immersed-Boundary-Based Simulation of 2D Flow

Volume 1 ◽  
2004 ◽  
Author(s):  
Sungsu Lee ◽  
Kyung-Soo Yang ◽  
Jong-Yeon Hwang
Keyword(s):  
Complex Geometry ◽  
Mass Conservation ◽  
Computational Method ◽  
Staggered Grid ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Step Method ◽  
Fractional Step Method ◽  
Navier Stokes Equation ◽  
Finite Volume Approach

Development of geometry-independent computational method and educational codes for simulation of 2D flows around objects of complex geometry is presented. Referred as immersed boundary method, it introduces virtual forcing to governing equations to represent the effect of physical boundaries. The present method is based on a finite-volume approach on a staggered grid with a fractional-step method to solve Navier-Stokes equation and continuity equation. Both momentum and mass forcings are introduced on and inside the object to satisfy no-slip condition and mass conservation. Since Cartesian grid lines in general do not coincide with the immersed boundaries, several interpolation schemes are employed. Several examples are simulated using the method presented in this study and the results agree well with other results. Both user-friendly preprocessor with GUI and FORTRAN-based solver are open to the public for educational purposes.

An Improved Three-Dimensional Level Set Method for Gas-Liquid Two-Phase Flows

2004 ◽  
Vol 126 (4) ◽  
pp. 578-585 ◽  
Author(s):  
Hiroyuki Takahira ◽  
Tomonori Horiuchi ◽  
Sanjoy Banerjee
Keyword(s):  
Level Set Method ◽  
Level Set ◽  
Stokes Equations ◽  
Interpolation Method ◽  
Density Ratio ◽  
Three Dimensional ◽  
Mass Conservation ◽  
Staggered Grid ◽  
Two Phase ◽  
Level Set Function

For the present study, we developed a three-dimensional numerical method based on the level set method that is applicable to two-phase systems with high-density ratio. The present solver for the Navier-Stokes equations was based on the projection method with a non-staggered grid. We improved the treatment of the convection terms and the interpolation method that was used to obtain the intermediate volume flux defined on the cell faces. We also improved the solver for the pressure Poisson equations and the reinitialization procedure of the level set function. It was shown that the present solver worked very well even for a density ratio of the two fluids of 1:1000. We simulated the coalescence of two rising bubbles under gravity, and a gas bubble bursting at a free surface to evaluate mass conservation for the present method. It was also shown that the volume conservation (i.e., mass conservation) of bubbles was very good even after bubble coalescence.

An Approximate Solution for the Infinitely Long, Gas Lubricated Slider Bearing

1965 ◽  
Vol 87 (4) ◽  
pp. 1085-1086
Author(s):  
H. J. Sneck
Keyword(s):  
Exact Solution ◽  
Approximate Solution ◽  
Pressure Distribution ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Slider Bearing ◽  
Load Carrying ◽  
Numerical Design ◽  
The One ◽  
Design Calculations

The only exact solution for the infinitely long, gas-lubricated slider bearing is the one obtained by Harrison [1] for the plane wedge isothermal film. The resultant formulas for the pressure distribution and load-carrying capacity are complicated and therefore quite cumbersome in numerical design calculations. In the analysis to follow, a simplified, approximate solution is developed which can be applied to any infinitely long slider geometry.

Calculation Method of Lubricant Film Pressure Distribution of Axial Piston Pump Slippers

2013 ◽  
Vol 328 ◽  
pp. 629-633
Author(s):  
Ya Jun Wang
Keyword(s):  
High Pressure ◽  
Pressure Distribution ◽  
Mass Conservation ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Shearing Flow ◽  
Pump Speed ◽  
Pressure Area ◽  
The Difference ◽  
Axial Piston

A method is implemented to get the pressure distribution of the axial piston pump slipper. Slipper was seen as translating thrust bearing, taking slipper tilt and spin in account, based on finite volume method, hydrodynamic and hydrostatic pressure has been calculated by using the mass conservation principle. For a representative element volume, the difference flow was averaged by the difference flow between the tilting planes, and the shearing flow by slipper translating was averaged by the shearing flow between the tilting planes. The numerical calculating result based two liquid resistance assume was compared, the results showed that two methods have got the same pressure distribution schematics, and the high pressure area locates at the slipper titling direction, but for the pressure values at high pressure area, the second method is slightly higher than the first method, and that the higher pump speed were, the higher the pressure values, and at the same pump speed, the slipper spin speed affects slightly the pressure, and at the lower pump speed, the lubricant pressure tends to the hydrostatic lubrication.

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