Mixed Lubrication Modelling in Mechanical Face Seals

2008 ◽  
Author(s):  
C. Minet ◽  
N. Brunetie`re ◽  
B. Tournerie
Keyword(s):  
Friction Coefficient ◽  
Numerical Model ◽  
Hydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Mechanical Seal ◽  
Deterministic Approach ◽  
Lubrication Regimes ◽  
Face Seals ◽  
Non Gaussian

This paper presents a numerical model of mechanical seal operating in mixed lubrication. It is based on a deterministic approach using realistic roughness description. This model is able to simulate the transition from mixed to hydrodynamic lubrication regimes corresponding to a minimum of the friction coefficient. Moreover it is able to work with non Gaussian surfaces and oriented surfaces.

A Deterministic Mixed Lubrication Model for Mechanical Seals

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Christophe Minet ◽  
Noël Brunetière ◽  
Bernard Tournerie
Keyword(s):  
Flow Model ◽  
Hydrodynamic Lubrication ◽  
Industrial Applications ◽  
Mixed Lubrication ◽  
Asperity Contact ◽  
Mechanical Seals ◽  
Optimal Point ◽  
Lubrication Regimes ◽  
Face Seals ◽  
Stribeck Curves

Mechanical seals are commonly used in industrial applications. The main purpose of these components is to ensure the sealing of rotating shafts. Their optimal point of operation is obtained at the boundary between the mixed and hydrodynamic lubrication regimes. However, papers focused on this particular aspect in face seals are rather scarce compared with those dealing with other popular sealing devices. The present study thus proposes a numerical flow model of mixed lubrication in mechanical face seals. It achieves this by evaluating the influence of roughness on the performance of the seal. The choice of a deterministic approach has been made, this being justified by a review of the literature. A numerical model for the generation of random rough surfaces has been used prior to the flow model in order to give an accurate description of the surface roughness. The model takes cavitation effects into account and considers Hertzian asperity contact. Results for the model, including Stribeck curves, are presented as a function of the duty parameter.

Unsteady Analysis of a Mechanical Seal Using Duhamel’s Method

2004 ◽  
Vol 127 (3) ◽  
pp. 623-631 ◽  
Author(s):  
Richard F. Salant ◽  
Bin Cao
Keyword(s):  
Thermal Analysis ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Model ◽  
Numerical Experiment ◽  
Auxiliary Function ◽  
Mixed Lubrication ◽  
Mechanical Seal ◽  
Element Analysis ◽  
Semiempirical Approach

An unsteady numerical model of a mechanical seal, with mixed lubrication, has been developed. The thermal analysis is performed using Duhamel’s method in combination with a numerical experiment to determine Duhamel’s auxiliary function. The results using this semiempirical approach compare well with those from a finite element analysis. The model has been used to predict the performance of a mechanical seal during startup and shutdown.

A New Approach to Determine Lubrication Regimes of Piston-Ring Assemblies

1997 ◽  
Vol 119 (4) ◽  
pp. 808-816 ◽  
Author(s):  
Naeim A. Henein ◽  
Shengqiang Huang ◽  
Walter Bryzik
Keyword(s):  
Piston Ring ◽  
Hydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Spark Ignition Engine ◽  
Frictional Torque ◽  
New Approach ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime ◽  
And Shifts

A new approach is developed to determine piston-ring assembly lubrication regimes from the instantaneous frictional torque measured for the whole engine. This is based on the variation of the friction coefficient with the duty parameter in the Stribeck diagram over the mixed and hydrodynamic lubrication regimes. The derived equation determines the lubrication regimes from the slope of the line in the Stribeck diagram. A single cylinder spark ignition engine was instrumented to determine the total instantaneous frictional torque of the engine. Experiments were conducted under different loads at a constant speed. Results show that the regime is mixed lubrication near the top dead center (TDC) and shifts to the hydrodynamic lubrication regime as the piston moves away from TDC. The extent of the mixed lubrication regime depends on engine load and speed.

The comprehensive effect of surface texture and roughness under hydrodynamic and mixed lubrication conditions

2017 ◽  
Vol 231 (10) ◽  
pp. 1307-1319 ◽  
Author(s):  
Chenbo Ma ◽  
Yanjun Duan ◽  
Bo Yu ◽  
Jianjun Sun ◽  
Qiaoan Tu
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Hydrodynamic Lubrication ◽  
Diameter Ratio ◽  
Mixed Lubrication ◽  
Textured Surface ◽  
Texture Parameters ◽  
Lubrication Condition ◽  
Lubrication Conditions ◽  
Effect Of Surface

A theoretical study is carried out to investigate the comprehensive effect of the machined roughness and fabricated textures, by solving the average Reynolds equation coupled with a mass-conservative cavitation algorithm and taking into account asperity contact. We analyzed the influence of surface roughness, which is represented by the combined root-mean-square roughness σ and surface pattern parameter γ on the optimum texture parameters including the dimple depth-over-diameter ratio and area density under hydrodynamic and mixed lubrication conditions. The results show that the effect of surface roughness on load-carrying capacity can be ignored under hydrodynamic lubrication condition. Furthermore, the optimum texture parameters under hydrodynamic lubrication condition and the optimum dimple depth-over-diameter ratio under mixed lubrication condition are determined at minimized friction coefficient, which can be taken as the same for smooth-textured surface and rough-textured surface. The corresponding minimum friction coefficient increases with increasing σ and γ, and decreasing dimple area density under mixed lubrication condition.

FULL NUMERICAL SIMULATION TO THE PERFORMANCE OF MICRO-TEXTURED MECHANICAL FACE SEALS

2008 ◽  
Vol 07 (02) ◽  
pp. 267-270 ◽  
Author(s):  
XIAO WANG ◽  
HUIXIA LIU ◽  
WEI CHEN ◽  
CHANGJING LIU ◽  
YONGHONG FU ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Friction Coefficient ◽  
Reynolds Equation ◽  
Grid Method ◽  
Numerical Approach ◽  
Polar Coordinates ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Face Seals

A mathematical model is established based on a modified Reynolds equation in polar coordinates, and solved by the multi-grid method to demonstrate the performance of micro-texturing mechanical seal surface. Sample cases of cylinder-shaped, square-shaped and diamond-shaped micro-asperity are studied to show the performance of micro-texturing mechanical seals. The results show that geometry has a vital influence on the friction coefficient and leakage. Diamond-shaped micro-texturing asperities have better performance than the others. And the performance is sensitive to the area density than the micro-texturing depth. The numerical approach can be a useful engineering tool, analyzing and optimizing the performance of micro-texturing mechanical face seals.

Parametric Study of the Behavior of a Mechanical Face Seal Operating in Mixed and TEHD Lubrication Regimes

2012 ◽  
Author(s):  
André Parfait Nyemeck ◽  
Noël Brunetière ◽  
Bernard Tournerie
Keyword(s):  
Heat Transfer ◽  
Friction Coefficient ◽  
Mixed Lubrication ◽  
Operating Conditions ◽  
Fluid Viscosity ◽  
Face Seal ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Mechanical Face Seal ◽  
Mixed Lubrication Regime

In this paper, the behavior of a mechanical face seal is analyzed for different operating conditions and designs. For that, a theoretical model including a multiscale approach of the mixed lubrication regime, heat transfer and deformation of the seal rings is used. It has been possible to clearly identify the three different lubrication regimes of a mechanical seal: the mixed lubrication where the friction coefficient decreases, the rough hydrodynamic regime corresponding to an increasing friction and then the thermo-elasto-hydrodynamic (TEHD) regime for which the coefficient of friction is approximately constant. In this work, the influence of the fluid pressure, the seal roughness height, the balance ratio, the rings materials, the dry friction coefficient and viscosity are respectively examined. Generally speaking, the variation of these parameters affects the location of the optimum value of the friction coefficient in the mixed lubrication regime. In the TEHD regime, the temperature is mainly influenced by the materials and the fluid viscosity, which control the amplitude of deformation and heat transfer. A dimensionless parametric analysis has been carried out in order to perform an overall discussion of the results. It is shown that the mixed and rough hydrodynamic lubrication regimes are controlled by the modified duty parameter, while the TEHD regime is controlled by the sealing parameter.

Experimental Investigation of Lubrication Regimes of a Water-Lubricated Bearing in the Propulsion Train of a Marine Vessel

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Dov Avishai ◽  
Groper Morel
Keyword(s):  
Experimental Investigation ◽  
Friction Coefficient ◽  
Hydrodynamic Lubrication ◽  
Low Cost ◽  
Pollution Prevention ◽  
Elastohydrodynamic Lubrication ◽  
Sliding Bearings ◽  
Naval Vessel ◽  
Lubrication Regimes ◽  
Lubrication Regime

Abstract Sliding bearings, operating in a full hydrodynamic lubrication regime, exhibit a low friction coefficient and extended life. In recent years, with the increase in environmental awareness and pollution prevention, attention is being directed to oil spills, which pollute the environment. This is extremely prominent in ships and submarines whose propeller shafts are typically supported by oil-lubricated sliding bearings. To reduce pollution risk and also to obtain a simpler and low-cost maintenance system, the propeller shafts of numerous modern marine vessels are supported by water-lubricated bearings. An experimental investigation into the lubrication regime of a water-lubricated bearing in the propulsion train of a naval vessel is presented. A test rig was designed and built to allow testing of a scaled water-lubricated composite bearing supporting a naval vessel propeller shaft. Experimental results quantifying the effect of the rotational speed on the operating eccentricity, the friction coefficient, and the bearing’s lubrication regimes are presented. The experimentally obtained results are compared with an elastohydrodynamic lubrication (EHL) model solved by employing comsol multiphysics modeling software, and the differences are addressed. Finally, conclusions that may assist in better understanding the operation profile of the bearing and thus improving the vessel’s operability are presented.

The Lubrication Regimes of Mechanical Face Seals

2014 ◽  
Vol 630 ◽  
pp. 255-266
Author(s):  
Noël Brunetiere
Keyword(s):  
Friction And Wear ◽  
Hydrodynamic Lubrication ◽  
Rotation Velocity ◽  
Operating Conditions ◽  
Thermal Gradients ◽  
Lubrication Regimes ◽  
Seal Design ◽  
Lubrication Regime ◽  
Face Seals ◽  
Static Conditions

Mechanical face seals are usually described as contacting seals because their faces are in partial contact during static conditions. However, many experiments demonstrated that this contact is not maintained during operation. Indeed a full fluid film can separate the seal surfaces leading to lower friction and wear. In this paper, the mechanisms of lubrication taking place at the seal interface are reviewed and analyzed through simulations and experiments. It is shown that several lubrication regimes can be experienced, depending on the operating conditions and on the seal design. At low speed values the lubrication regime is mixed and turns to hydrodynamic lubrication regime when the speed is increased. At higher rotation velocity, the dissipated power generates thermal gradients and leads to thermally controlled lubrication regime. The transition between the lubrication regimes is also discussed and dimensionless parameters controlling the transition are proposed.

scholarly journals Two-scale homogenization of hydrodynamic lubrication in a mechanical seal with isotropic roughness based on the Elrod cavitation algorithm

2021 ◽  
pp. 135065012110176
Author(s):  
Yanxiang Han ◽  
Qingen Meng ◽  
Gregory de Boer
Keyword(s):  
Surface Topography ◽  
Carrying Capacity ◽  
Hydrodynamic Lubrication ◽  
Tribological Performance ◽  
Stribeck Curve ◽  
Polar Coordinate System ◽  
Load Carrying Capacity ◽  
Mechanical Seal ◽  
Macro Scale ◽  
Load Carrying

A two-scale homogenization method for modelling the hydrodynamic lubrication of mechanical seals with isotropic roughness was developed and presented the influence of surface topography coupled into the lubricating domain. A linearization approach was derived to link the effects of surface topography across disparate scales. Solutions were calculated in a polar coordinate system derived based on the Elrod cavitation algorithm and were determined using homogenization of periodic simulations describing the lubrication of a series of surface topographical features. Solutions obtained for the hydrodynamic lubrication regime showed that the two-scale homogenization approach agreed well with lubrication theory in the case without topography. Varying topography amplitude demonstrated that the presence of surface topography improved tribological performance for a mechanical seal in terms of increasing load-carrying capacity and reducing friction coefficient in the radial direction. A Stribeck curve analysis was conducted, which indicated that including surface topography led to an increase in load-carrying capacity and a reduction in friction. A study of macro-scale surface waviness showed that the micro-scale variations observed were smaller in magnitude but cannot be obtained without the two-scale method and cause significant changes in the tribological performance.

Effect of shape/size and distribution of microgeometries of textures on tribo-performance of crankpin bearing

2021 ◽  
pp. 135065012110105
Author(s):  
Nguyen Van Liem ◽  
Wu Zhenpeng ◽  
Jiao Renqiang
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Contact Force ◽  
Distribution Density ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Combined Model ◽  
Obvious Effect ◽  
Area Density

The effect of the shape/size and distribution of microgeometries of textures on improving the tribo-performance of crankpin bearing is proposed. Based on a combined model of the slider-crank mechanism dynamic and hydrodynamic lubrication, the distribution density, area density, and shape of spherical textures, square-cylindrical textures, wedge-shaped textures, and a hybrid between spherical texture and square-cylindrical texture on the crankpin bearing's tribo-performance are investigated under different operating conditions of the engine. The tribological characteristic of the crankpin bearing is then evaluated via the indexes of the oil film pressure p, asperity contact force, friction force, and friction coefficient of the crankpin bearing. The research results show that the distribution density with n = 12 and m = 6, and area density with α = 30% of various microtextures have an obvious effect on ameliorating the crankpin bearings tribo-performance. Concurrently, at the mixed lubrication region, the shape of the square-cylindrical texture on improving the tribo-performance is better than the other shapes of the spherical texture, wedge-shaped texture, and spherical and square-cylindrical texture. Particularly, all the average values of the asperity contact force, friction force, and friction coefficient with a square-cylindrical texture are significantly reduced by 14.6%, 19.5%, and 34.5%, respectively, in comparison without microtextures. Therefore, the microtextures of the spherical texture applied on the bearing surface can contribute to enhance the durability and decrease the friction power loss of the engine.

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