A Hydrodynamic Theory of Radial-Face Mechanical Seals

1973 ◽  
Vol 15 (1) ◽  
pp. 17-24 ◽  
Author(s):  
B. Stanghan-Batch ◽  
E. H. Iny
Keyword(s):  
Experimental Evidence ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Fluid Pressure ◽  
Fluid Film ◽  
Hydrodynamic Theory ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Substantial Agreement ◽  
Seal Design

The existence of a lubricating fluid film between the faces of a mechanical seal has been amply demonstrated, but the mechanisms of lubrication and sealing have yet to be convincingly established. Experimental evidence to show that mechanical seal faces are most probably lubricated by a hydrodynamic action induced by the waviness of one of the surfaces has recently been published by the authors. Following this work a modified form of the narrow bearing approximation to Reynolds' equation for hydrodynamic lubrication has been applied to an idealized wavy faced seal. The resulting theory of seal face lubrication has been extended to include radial flows in the fluid film and predicts a net inward flow of fluid which may be utilized to oppose the flow due to the sealed fluid pressure. Predicted lubrication and sealing characteristics are in substantial agreement with measured values. It is suggested that the performance of mechanical seals can be improved by giving one face an appropriately wavy surface at the time of manufacture; a number of other observations on mechanical seal design are also made.

scholarly journals Multifield Coupling Model and Performance Analysis of a Hydrostatic Mechanical Seal

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5159
Author(s):  
Guiyue Kou ◽  
Xinghu Li ◽  
Yan Wang ◽  
Chunsen Tan ◽  
Kanran Zhou ◽  
...  
Keyword(s):  
Fluid Pressure ◽  
Coupling Model ◽  
Outer Diameter ◽  
Mechanical Seal ◽  
Design And Optimization ◽  
Seal Design ◽  
Mechanical Deformations ◽  
Deformation State ◽  
Inner Diameter ◽  
And Performance

A two-dimensional axisymmetric thermal-fluid-solid coupled mathematical model of a contact mechanical seal is established. The finite difference method is used to solve the control equations for the fluid pressure and temperature of the seal end face, and the finite element method is used to determine the thermal deformation state of the seal. The seal’s performance at different working speeds was studied and verified by experiments. The results show that under the combined actions of thermal and mechanical deformations, the seal end face forms a convergent leakage gap from the outer diameter to the inner diameter. The minimum film thickness is observed on the inner diameter side of the seal end face, and the highest end face temperature coincides with this location. With increasing working speed, the contact force at the inner diameter side increases, the temperature difference between the inner diameter and the outer diameter of the end face increases, and the leakage rate correspondingly increases. The numerical simulation results are in good agreement with the experimental results. The model and calculation method can be applied to other forms of mechanical seal design and optimization.

Analysis of Carrying Capacity and Friction Torque of Friction Pair Fluid-Film for High Parameter Bellows Mechanical Seal

2013 ◽  
Vol 455 ◽  
pp. 207-211
Author(s):  
Mutellip Ahmat ◽  
Zhi Wei Niu ◽  
Guzaiayi Abudoumijiti
Keyword(s):  
Carrying Capacity ◽  
High Speed ◽  
Influence Factor ◽  
Friction Pair ◽  
Scientific Basis ◽  
Friction Torque ◽  
Fluid Film ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
The Relationship

The friction pair for bellows mechanical seal as a friction element is one of the key components for it. In this research, by based on the computational fluid dynamics (CFD) numerical theory, using the Fluent software, corresponding model and parameters, the fluid-film between the clearance of the sealing ring friction pair for the bellows mechanical seal under such the high-temperature, high-pressure, high-speed as complex working conditions is numerically simulated, the relationship between the carrying-capacity of the fluid-film and the temperature, the viscosity of the fluid-film, the relationship between friction torque of the fluid-film and the speed, viscosity of the fluid-film, the influence factor of leakage are obtained. The researching results provide the scientific basis for the optimization designing of the high parameter bellows mechanical seals.

Optimum Design of Flat End Face Mechanical Seal Based on Coupling Analysis

2010 ◽  
Vol 37-38 ◽  
pp. 819-822 ◽  
Author(s):  
Jian Feng Zhou ◽  
Bo Qin Gu ◽  
Chun Lei Shao
Keyword(s):  
Optimum Design ◽  
Thermal Deformation ◽  
Coupling Effect ◽  
Design Method ◽  
Fluid Film ◽  
Outer Side ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Friction Heat ◽  
Bearing Force

The flat end face mechanical seals are widely used in shaft sealing at moderate rotational speed. The thermal deformation of the rotating and stationary rings initiated by friction heat of fluid film should be primarily considered in the design of mechanical seal. In consideration of the coupling effect among the thermal deformation of sealing rings, the fluid flow in the gap composed by end faces of sealing rings and the heat transfer from fluid film to sealing rings, the optimum design method for flat end face mechanical seal is established. The end faces are fabricated to form a divergent gap at the inner side of the sealing rings, and a convergent gap will occur at the outer side and a parallel gap will be obtained at where the original divergent gap is due to the thermal deformation. After optimization, the leakage rate can be reduced while the bearing force of fluid film is still large enough to keep the fluid lubrication of the end faces.

Stability Analysis of Mechanical Seals With Two Flexibly Mounted Rotors

1998 ◽  
Vol 120 (2) ◽  
pp. 145-151 ◽  
Author(s):  
J. Wileman ◽  
I. Green
Keyword(s):  
Dynamic Properties ◽  
Equations Of Motion ◽  
Closed Form Solution ◽  
Form Solution ◽  
Fluid Film ◽  
Mechanical Seals ◽  
Stability Threshold ◽  
Seal Design ◽  
The Stability ◽  
Gyroscopic Effects

Dynamic stability is investigated for a mechanical seal configuration in which both seal elements are flexibly mounted to independently rotating shafts. The analysis is applicable to systems with both counterrotating and corotating shafts. The fluid film effects are modeled using rotor dynamic coefficients, and the equations of motion are presented including the dynamic properties of the flexible support. A closed-form solution for the stability criteria is presented for the simplifled case in which the support damping is neglected. A method is presented for obtaining the stability threshold of the general case, including support damping. This method allows instant determination of the stability threshold for a fully-defined seal design. A parametric study of an example seal is presented to illustrate the method and to examine the effects of various parameters in the seal design upon the stability threshold. The fluid film properties in the example seal are shown to affect stability much more than the support properties. Rotors having the form of short disks are shown to benefit from gyroscopic effects which give them a larger range of stable operating speeds than long rotors. For seals with one long rotor, counterrotating operation is shown to be superior because the increased fluid stiffness transfers restoring moments from the short rotor to the long.

The Study of Mechanical Seal Leakage Detection System

2013 ◽  
Vol 387 ◽  
pp. 296-300
Author(s):  
Ze Gang Sun ◽  
Chang Niu Yang ◽  
Lei Chen
Keyword(s):  
Control System ◽  
Data Acquisition ◽  
Detection System ◽  
Fluid Pressure ◽  
Mechanical Seal ◽  
Leakage Detection ◽  
Mechanical Seals ◽  
Test Platform ◽  
Data Acquisition And Processing ◽  
Design And Testing

The mechanical seal bench is the test platform for the leakage of the mechanical seal.The mechanical sealing leaking are closely related to the fluid pressure and temperature.The control system of the fluid pressure and temperature be designed to meet the needs of mechanical seals working in defferent conditions and the system of the leakage data acquisition and processing are designed based on C51 and C++BUILDER. The data collected be output on curve fitting.The test stand is certain guiding significance for the design and testing of the mechanical seal.

scholarly journals Research on the Dynamic Characteristics of Mechanical Seal under Different Extrusion Fault Degrees

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1057
Author(s):  
Yin Luo ◽  
Yakun Fan ◽  
Yuejiang Han ◽  
Weqi Zhang ◽  
Emmanuel Acheaw
Keyword(s):  
Film Thickness ◽  
Dynamic Characteristics ◽  
Fluid Film ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Rotating Speed ◽  
Analysis Process ◽  
Fluid Film Thickness ◽  
Object Of Study ◽  
Fault Mechanism

In order to explore the dynamic characteristics of the mechanical seal under different fault degrees, this paper selected the upstream pumping mechanical seal as the object of study. The research established the rotating ring-fluid film-stationary ring 3D model, which was built to analyze the fault mechanism. To study extrusion fault mechanism and characteristics, different dynamic parameters were used in the analysis process. Theoretical analysis, numerical simulation, and comparison were conducted to study the relationship between the fault degree and dynamic characteristics. It is the first time to research the dynamic characteristics of mechanical seals in the specific extrusion fault. This paper proved feasibility and effectiveness of the new analysis method. The fluid film thickness and dynamic characteristics could reflect the degree of the extrusion fault. Results show that the fluid film pressure fluctuation tends to be more intensive under the serious extrusion fault condition. The extrusion fault is more likely to occur when the fluid film thickness is too large or too small. Results illustrate the opening force is affected with the fluid film lubrication status and seal extrusion fault degrees. The fluid film stiffness would not always increase with the rotating speed growth. The seal fault would occur with the increasing of rotating speeds, and the leakage growth fluctuations could reflect the fault degree.

A Bubble Dynamics Based Approach to the Simulation of Cavitation in Lubricated Contacts

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Thomas Geike ◽  
Valentin L. Popov
Keyword(s):  
Numerical Simulations ◽  
Experimental Evidence ◽  
Reynolds Equation ◽  
Bubble Dynamics ◽  
Simulation Models ◽  
Compressible Fluids ◽  
Fluid Film ◽  
Tensile Stresses ◽  
Lubricated Contacts

The negative squeeze lubrication problem is investigated by means of numerical simulations that account for the dynamics of vaporization. The model is based on bubble dynamics, governed by the Rayleigh–Plesset equation, and the Reynolds equation for compressible fluids. Unlike most existing simulation models our model can predict tensile stresses in the fluid film prior to its rupture, which is in accordance with experimental evidence.

Relationship Between Vibrations and Mechanical Seal Failures in Centrifugal Pumps

2005 ◽  
Author(s):  
David B. Stefanko ◽  
Robert A. Leishear
Keyword(s):  
Industrial Applications ◽  
The Other ◽  
Fluid Film ◽  
Operating Speed ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Centrifugal Pumps ◽  
Radial Vibrations ◽  
The Common ◽  
Bearing Design

A reduction of radial vibrations in mechanical seals increases the life of the seals in centrifugal pumps. Mechanical seals consist of two smooth seal faces. One face is stationary with respect to the pump. The other rotates. Between the faces a fluid film evaporates as the fluid moves radially. Ideally, the film evaporates as it reaches the outer surface of the seal faces, thereby preventing leakage from the pump and effectively lubricating the two surfaces. Relative vibrations between the two surfaces affect the fluid film, damage the faces, and decrease the life of the seals. In a series of industrial applications, different techniques were used to minimize vibration, and the life of the seals was shown to significantly increase. The operating speed was controlled in one case, the bearing design was replaced in another case, and the stiffness of the pump was altered in still another case. The common corrective action in each case was a reduction in vibration.

Analysis of Mechanical Seal Leakage within Hydrostatic on Nuclear Reactor Coolant Pump

2014 ◽  
Vol 496-500 ◽  
pp. 990-994 ◽  
Author(s):  
Hai Yang Zhang ◽  
Wei Bing Zhu ◽  
Zhou Gang
Keyword(s):  
Centrifugal Force ◽  
Nuclear Reactor ◽  
Hydrodynamic Lubrication ◽  
Structural Characteristics ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Coolant Pump ◽  
Turning Angle ◽  
Hydrodynamic Lubrication Theory ◽  
Turning Radius

According to the fluid hydrodynamic lubrication theory, and the structural characteristics of the convergence gap seal is combined, the effect of differential pressure and centrifugal force should be considered, then the convergent wedge gap mechanical seals flow field numerical model is established and the influence of the leakage factors are researched, including the geometric parameters and operating parameters. Research has shown that the amount of leakage and the seal clearance were positively correlated. And the larger turning Angle is, the bigger correlation becomes, however, it is negatively correlated with speed and turning radius, the seal leakage is impeded by the centrifugal force and the larger turning radius is, the smaller leakage becomes.

The Rotordynamic Coefficients of Mechanical Seals Having Two Flexibly Mounted Rotors

1991 ◽  
Vol 113 (4) ◽  
pp. 795-804 ◽  
Author(s):  
J. Wileman ◽  
I. Green
Keyword(s):  
Degrees Of Freedom ◽  
Reynolds Equation ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Rotordynamic Coefficients ◽  
Damping Coefficients ◽  
Rotating Shafts ◽  
Stiffness And Damping ◽  
Three Degrees Of Freedom ◽  
Degenerate Cases

The Reynolds equation is derived for a mechanical seal in which both elements are flexibly mounted to rotating shafts. Stiffness and damping coefficients for the fluid film are calculated for the three degrees of freedom of each element based upon a small perturbation analysis. The analogous coefficients for simpler configurations (e.g., flexibly mounted rotor, flexibly mounted stator) contained in the literature are shown to be obtainable as degenerate cases of the more general results presented in this work.

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