An Average Flow Model for Determining Effects of Three-Dimensional Roughness on Partial Hydrodynamic Lubrication

1978 ◽  
Vol 100 (1) ◽  
pp. 12-17 ◽  
Author(s):  
Nadir Patir ◽  
H. S. Cheng
Keyword(s):  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Rough Surfaces ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Surface Characteristic ◽  
Correlation Lengths ◽  
Lubricated Contacts ◽  
Empirical Relations ◽  
Numerical Flow Simulation

A new approach is utilized to determine the effects of surface roughness on partially lubricated contacts. An average Reynolds equation for rough surfaces is defined in terms of pressure and shear flow factors, which are obtained by numerical flow simulation. Through the use of measured or numerically generated rough surfaces, any three dimensional roughness structure can be analyzed with this method. The average Reynolds equation is obtained for isotropic surfaces, and for surfaces with directional patterns. The flow factors for these surfaces are expressed as empirical relations in terms of h/σ and a surface characteristic γ defined as the ratio of x and y correlation lengths.

scholarly journals Hydrodynamic lubrication of rough surfaces

1982 ◽  
Vol 383 (1785) ◽  
pp. 439-446 ◽  
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Rough Surfaces ◽  
Homogenization Method ◽  
Squeeze Film ◽  
Spatial Average

Using the two-space homogenization method we derive an averaged Reynolds equation that is correct to O (< H 6 > — < H 3 > 2 ), where H is the total film thickness and the angle brackets denote a spatial average. Applications of this mean Reynolds equation to a squeeze-film bearing with a sinusoidal or an isotropic surface roughness are discussed.

Pressure and Shear Flow Factors Calculation for Orthotropic Rough Surfaces

2007 ◽  
Author(s):  
Ramona Dragomir ◽  
Dominique Bonneau ◽  
Patrick Ragot ◽  
Franc¸ois Robbe-Valloire
Keyword(s):  
Surface Roughness ◽  
Shear Flow ◽  
Reynolds Equation ◽  
Rough Surfaces ◽  
Cross Flow ◽  
Lubricated Contacts ◽  
General Average ◽  
The Cross

In general, average Reynolds equation is defined in terms of shear flow factors in order to determine the effects of surface roughness on partially lubricated contacts. This paper is essentially devoted to the application of flow factors model to real shaft and bearing surfaces, obtained by metrological measures. Additionally, the average Reynolds equation is completed by “cross” flow factors. The “cross” flow factors may have an important role if model is applied on either longitudinally or transversely oriented surfaces (surfaces with directional patterns oriented with an angle).

ESTIMATION OF MECHANICAL LOAD ON RUBBER MIXING ROTORS BY USING A PARTIALLY FILLED FLOW SIMULATION IN CHAMBER

2021 ◽  
Author(s):  
Kazuhisa Fukutani ◽  
Kousuke Higashi ◽  
Hodaka Miura ◽  
Yasuaki Yamane
Keyword(s):  
Mechanical Load ◽  
Three Dimensional ◽  
Estimation Method ◽  
Flow Simulation ◽  
Radial Force ◽  
Operational Parameters ◽  
Mixing Condition ◽  
Rotor Design ◽  
Numerical Flow Simulation ◽  
Proper Estimation

ABSTRACT Mixing characteristics and mechanical loads of rubber-mixing rotors are considered to be the two most important factors in actual rotor design. For the design of highly reliable production mixers, there is a great need for a proper estimation method of mechanical load, such as radial force or rotation torque of the rotors. The mechanical load of tangential mixing rotors and surrounding flow are mainly discussed by using partially filled numerical flow simulation. Operational parameters of the mixing condition were set to be fill factor and rotor phase angle of two rotors rotating at an even speed. The Carreau model was applied to the shear rate dependence of viscosity. The volume-of-fluid method was used for free surface simulation. Both two-dimensional and three-dimensional simulations were carried out to discuss mechanical load and its fluctuation mechanisms. For the numerical results, radial force on rotors, pressure, and the velocity distribution around the rotors and their fluctuations are presented and discussed. It was found that the radial force of the rotors could be estimated using this kind of flow simulation, and the fluctuation phenomena could be explained by the movement of a high-pressure region between the front of the rotor wings and the chamber wall.

Three-Dimensional Hydrodynamic Lubrication Analysis of Cylinder Liner-Piston Ring

2013 ◽  
Vol 871 ◽  
pp. 27-31
Author(s):  
Shi Feng Zhang ◽  
Shu Hua Cao ◽  
Jiu Jun Xu
Keyword(s):  
Piston Ring ◽  
Reynolds Equation ◽  
Variable Viscosity ◽  
Hydrodynamic Lubrication ◽  
Three Dimensional ◽  
Cylinder Liner ◽  
Asperity Contact ◽  
Crank Angle ◽  
Minimum Film Thickness ◽  
Friction Analysis

This paper constructs a three-dimensional transient hydrodynamic lubrication model for cylinder liner-piston ring based on the three-dimensional transient average Reynolds equation and asperity contact model. A computer program was written with FORTRAN to calculate hydrodynamic lubrication, in which the surface roughness, the variable viscosity effect and the deformation of the circumferential direction of the cylinder liner are taken into account. The film pressure distribution in different crank angle during the stroke, minimum film thickness and friction are computed and analyzed with this program. This three-dimensional transient hydrodynamic lubrication model provides a design basis for the friction analysis of cylinder liner-piston ring.

Isothermal hydrodynamic pressure and load carrying capacity of parallel rough surfaces based on FFT techniques

2020 ◽  
Vol 44 (4) ◽  
pp. 602-612
Author(s):  
Wan Ma
Keyword(s):  
Carrying Capacity ◽  
Hydrodynamic Lubrication ◽  
Rough Surfaces ◽  
Hydrodynamic Pressure ◽  
Radius Of Curvature ◽  
Real Surface ◽  
Load Carrying Capacity ◽  
Time Saving ◽  
Lubricated Contacts ◽  
Load Carrying

In lubricated contacts, the component macrogeometry (radius of curvature) determines the pressure generation, and the surface microgeometry (i.e., roughness) alters it somewhat. However, for parallel surfaces, the microgeometry completely determines the hydrodynamic lubrication. This paper extends earlier work to numerically solve the isothermal hydrodynamic pressure generation and load carrying capacity (LCC) of surfaces with more complicated roughness features. A fast Fourier transform (FFT)-based method is described to quickly obtain the pressure distribution. The method is applicable to both real surface topographies and artificially generated rough surfaces. Results show that it enables one to predict the hydrodynamic pressure, when cavitation is negligible. The relative error of the LCC over the central domain is smaller than 8% and a 500× time saving, compared with the numerical method, is obtained.

Numerical and Experimental Research of the Slurry Film in Chemical Mechanical Polishing (CMP)

2010 ◽  
Vol 102-104 ◽  
pp. 669-674
Author(s):  
Fei Yan Lou ◽  
Qian Fa Deng ◽  
Ju Long Yuan
Keyword(s):  
Film Thickness ◽  
Chemical Mechanical Polishing ◽  
Applied Load ◽  
Reynolds Equation ◽  
Rotation Speed ◽  
Hydrodynamic Lubrication ◽  
Three Dimensional ◽  
Mechanical Polishing ◽  
Film Pressure ◽  
Minimum Film Thickness

A three-dimensional hydrodynamic lubrication model for chemical-mechanical polishing is presented based on the Reynolds equation and Reynolds boundary condition. By solving the Reynolds equation, the slurry film pressure distribution has been obtained. The effects of minimum film thickness and the wafer tile angle on the film pressure are analyzed, and the influence of the polishing applied load and rotation speed on slurry film thickness and tilt angle are discussed. At last, by experiment, it is found that the simulation results are similar to experiment results which film thickness is increasing with the increasing of rotation speed, decreasing of the applied load. It is proved that the simulation is reliable.

scholarly journals Effect of Relative Velocity Between Rough Surfaces: Hydrodynamic Lubrication of Rotary Lip Seal

2017 ◽  
Vol 22 (2) ◽  
pp. 321-332 ◽  
Author(s):  
I. Lahjouji ◽  
M. El Gadari ◽  
B. El Fahime ◽  
M. Radouani
Keyword(s):  
Relative Motion ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Rough Surfaces ◽  
Friction Torque ◽  
Deterministic Approach ◽  
Lip Seal ◽  
Numerical Studies ◽  
The Sixties ◽  
The Subject

Abstract Since the sixties, most of numerical studies that model the rotary lip seal lubrication have been restricted by assuming that one of the two opposing surfaces is smooth: either the lip or the shaft. This hypothesis, although it is verified only for a shaft roughness ten times smaller than that of the seal, is the best solution to avoid the transient term “∂h/∂t” in the deterministic approach. Thus, the subject of the present study is twofold. The first part validates the current hydrodynamic model with the international literature by assuming the asperities on the lip and shaft as a two-dimensional cosine function. In the second part the Reynolds equation for rough surfaces with relative motion is solved. The numerical results show that the relative motion between rough surfaces impacts significantly the load support and the leakage rate, but affects slightly the friction torque.

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