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.

Coupling Analysis of Fluid Film and Thermal Deformation of Sealing Members in Spiral Groove Mechanical Seal

2007 ◽  
Vol 353-358 ◽  
pp. 2455-2458
Author(s):  
Jian Feng Zhou ◽  
Bo Qin Gu
Keyword(s):  
Thermal Deformation ◽  
Critical Speed ◽  
Fluid Film ◽  
Hydrodynamic Effect ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Spiral Groove ◽  
Coupling Analysis ◽  
Rotating Speed ◽  
Bearing Force

The thermo-hydrodynamic effect in the spiral groove mechanical seal was investigated. The coupling analysis of the fluid film and the thermal deformation of sealing rings was carried out, the separation angle obtained, and the shape of the gap between the two deformed end faces determined. The results indicate that the increase of the temperature of the fluid film and the thermal deformation of the sealing rings cause the increase of the leakage rate. There exists a critical rotating speed, when the rotating speed is lower than the critical speed, the bearing force increases with the increase of the rotating speed, and once the rotating speed is higher than the critical speed, the bearing force decreases reversely. The thermal deformation weakens the hydrodynamic effect of the spiral groove mechanical seals.

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.

Analysis of Mechanical Seal Behavior During Transient Operation

1998 ◽  
Vol 120 (2) ◽  
pp. 191-197 ◽  
Author(s):  
S. R. Harp ◽  
R. F. Salant
Keyword(s):  
Thermal Deformation ◽  
Transient Behavior ◽  
Mechanical Deformation ◽  
Contact Forces ◽  
Squeeze Film ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Pressure Distributions ◽  
Deformation Mechanics ◽  
Gas Seals

A mathematical model that predicts the transient behavior of gas or liquid lubricated hydrostatic mechanical seals has been developed. The analysis includes an evaluation of the fluid, contact, and deformation mechanics of a mechanical seal subject to constant or varying rotational speed and sealed pressure. Squeeze film effects are included. For gas seals, slip at the walls is also taken into account. Results include predictions of film thickness distributions, contact forces, leakage rates, pressure distributions, heat generation rates, thermal deformation, and mechanical deformation.

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.

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.

Design, Development and Testing of Water-Lubricated Ceramic Journal Bearing

2017 ◽  
Author(s):  
Jun Zha ◽  
Jianlei Wang ◽  
Kejia Liu ◽  
Yaolong Chen
Keyword(s):  
Expansion Coefficient ◽  
Thermal Deformation ◽  
Journal Bearing ◽  
Simulation Method ◽  
Fluid Film ◽  
Design Development ◽  
Test Rig ◽  
Friction Heat ◽  
Bearing Clearance ◽  
Hybrid Bearing

Strong shear force developed in the fluid film as the water-lubricated hybrid bearing operates at high speeds. Thus the phenomena of shaft expanding outward and bearing contracting inward happened due to the increasing temperature of the fluid film caused by the friction heat. So the bearing clearance decreases on account of the thermal deformation of the shaft and the bearing. Seriously, there will be a risk of seizure accident when the speed gets higher. Friction heat may be weakened by adopting low viscosity lubricant and thermal deformation may be reduced by adopting low expansion coefficient materials. Such as the ceramic’s expansion coefficient is 3–5 times smaller than that of typical journal bearing material like tin bronze. Thus, a ceramic journal bearing was developed in this paper to weaken the thermal influence on the bearing clearance. For improving the temperature rise of the journal bearing, a water-lubricated ceramic hydrodynamic-hydrostatic hybrid bearing test rig was designed firstly. Considering expansion coefficient and thermal conductivity effects, the simulation method was used to study the variation of bearing clearance with the speed and the original bearing clearance. Then, the water-lubricated ceramic hydrodynamic-hydrostatic hybrid bearing test rig was developed to verify the temperature characteristics at different speeds. Results indicate that the relative error of the tested temperature results and simulation results was below 10% at different speeds. Lastly, the evolution of bearing clearance with speed and the original bearing clearance was studied through FEM. The advantages of ceramic material were more obvious with the increase of the rotation speed when exceeds 8000rpm.

Predictions for Non-Contacting Mechanical Face Seal Vibration With External Excitation From Pump Vibration: Part II — Flexibly Mounted Rotor

2018 ◽  
Author(s):  
Clay S. Norrbin ◽  
Dara W. Childs
Keyword(s):  
Excitation Frequency ◽  
Harmonic Excitation ◽  
Fluid Film ◽  
Axial Distance ◽  
Mechanical Seal ◽  
Seal Ring ◽  
Mechanical Seals ◽  
Running Speed ◽  
Frequency Dependent ◽  
Frequency Independent

Stability and response predictions are presented for a Flexibly Mounted Rotor (FMR) mechanical seal ring using the model developed by Childs in 2018. The seal ring is excited by lateral/pitch vibration from the rotor/housing. The model includes a frequency dependent stiffness and damping model for the O-ring and a frequency independent model for the fluid film. The dynamic coefficients are speed and frequency dependent. The mechanical seal is modeled after a typical FMR mechanical seal. Parameters for radius, fluid film clearance, and O-Ring axial distances are varied. The axial distance between the O-Ring and seal ring inertia center doz is found to couple lateral rotor motion and seal ring pitch vibration. The predictions show a dependency on both excitation frequency and running speed. The analyzed FMR has a critical region with high transmissibility in a region around a speed and excitation frequency of 70 kRPM. Another region of high transmissibility is predicted to be with sub-harmonic excitation frequency. The FMR seal ring also has an unstable region that is sub-harmonic of 1% running speed. Running back on the HQ curve for a pump causes broadband sub-harmonic excitaiton, which can cause rub failures for FMR mechanical seals.

scholarly journals Relationship Between Vibrations and Mechanical Seal Life in Centrifugal Pumps

2007 ◽  
Author(s):  
Robert A. Leishear ◽  
David B. Stefanko
Keyword(s):  
Crack Growth ◽  
Fatigue Damage ◽  
The Other ◽  
Fluid Film ◽  
Time To Failure ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Centrifugal Pumps ◽  
Vibration Data ◽  
Cyclic Stresses

A reduction of vibrations in mechanical seals increases the life of the seals in centrifugal pumps by minimizing fatigue damage. 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 outward across the seal face. 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 and lead to stresses on the seal faces, which lead to fatigue damage. As the fluid film breaks down, impacts between the two seal faces create tensile stresses on the faces, which cycle at the speed of the motor rotation. These cyclic stresses provide the mechanism leading to fatigue crack growth. The magnitude of the stress is directly related to the rate of crack growth and time to failure of a seal. Related to the stress magnitude, vibration data is related to the life of mechanical seals in pumps.

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

2012 ◽  
Vol 522 ◽  
pp. 441-446
Author(s):  
Qiang Gao ◽  
Mutellip Ahmat ◽  
Li Chao Ren ◽  
Jing Luo
Keyword(s):  
Carrying Capacity ◽  
High Speed ◽  
Friction Pair ◽  
Scientific Basis ◽  
Fluid Film ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Numerical Theory ◽  
Sealing Ring ◽  
Relationship Of

In this research, by based on the computational fluid dynamics (CFD) numerical theory, using the Standard-Turbulence model and the Standard-Wall function, 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 was numerically simulated, the pressure fluid and the relationship of the carrying-capacity of the fluid-film between the pressure inlet of seal cavity and the width of the fluid-film, and the results of the numerical analysis was compared with the theoretical value. The researching results provide the scientific basis for the optimization designing of the high parameter bellows mechanical seals.

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