Experimental Studies on Thermoelastic Effects in Hydrodynamically Lubricated Face Seals

1979 ◽  
Vol 101 (3) ◽  
pp. 275-281 ◽  
Author(s):  
B. N. Banerjee ◽  
R. A. Burton
Keyword(s):  
Thermal Effects ◽  
Thermal Equilibrium ◽  
Axial Load ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Surface Waviness ◽  
Thermal Growth ◽  
Face Seals ◽  
Theoretical Predictions ◽  
Thermoelastic Effects

Experiments are reported where face-seat specimens were operated hydrodynamically at conditions close to thermal equilibrium. Changes in surface waviness and mean film thickness were monitored, and compared with theoretical predictions of thermal growth of waviness. Discrepancies were attributed to imperfect response of the gimbals to axial run-out. This run-out was increased by thermal effects at high sliding speeds and led to interactions which influenced the growth of two-lobed waves on the contact face. Operation proved stable, as predicted, under the carefully controlled operating conditions of fixed axial load and self aligning contact.

Hydrodynamic Lubrication and Wear in Wavy Contacting Face Seals

1978 ◽  
Vol 100 (1) ◽  
pp. 81-90 ◽  
Author(s):  
A. O. Lebeck ◽  
J. L. Teale ◽  
R. E. Pierce
Keyword(s):  
Surface Roughness ◽  
Hydrodynamic Lubrication ◽  
Surface Profile ◽  
Operating Conditions ◽  
Face Seal ◽  
Hydrodynamic Load ◽  
Surface Waviness ◽  
Wear Rates ◽  
Elastic Deflection ◽  
Face Seals

A model of face seal lubrication is proposed and developed. Hydrodynamic lubrication for rough surfaces, surface waviness, asperity load support, elastic deflection, and wear are considered in the model. Predictions of the ratio of hydrodynamic load support to asperity load support are made for a face seal sealing a low viscosity liquid where some contact does occur and surface roughness is important. The hydrodynamic lubrication is caused by circumferential surface waviness on the seal faces. Waviness is caused by initial out of flatness or any of the various distortions that occur on seal ring faces in operation. The equilibrium solution to the problem yields one dimensional hydrodynamic and asperity pressure distributions, mean film thickness, elastic deflection, and friction for a given load on the seal faces. The solution is found numerically. It is shown that the fraction of hydrodynamic load support depends on many parameters including the waviness amplitude, number of waves around the seal, face width, ring stiffness, and most importantly, surface roughness. For the particular seal examined the fraction of load support would be small for the amount of waviness expected in this seal. However, if the surface roughness were lower, almost complete lift-off is possible. The results of the analysis show why the initial friction and wear rates in mechanical face seals may vary widely; the fraction of hydrodynamic load support depends on the roughness and waviness which are not necessarily controlled. Finally, it is shown how such initial waviness effects disappear as the surface profile is altered by wear. This may take a long or short time, depending on the initial amount of hydrodynamic load support, but unless complete liftoff is achieved under all operating conditions, the effects of initial waviness will vanish in time for steady state conditions. Practical implications are drawn for selecting some seal parameters to enhance initial hydrodynamic load support without causing significant leakage.

scholarly journals Results of theoretical and experimental studies on determining the coefficient of subgrade reaction of sleepers for the conditions of main railways with axial loads of 30-35 tons per axle

2018 ◽  
Vol 230 ◽  
pp. 01003
Author(s):  
Oleksandr Darenskiy ◽  
Eduard Bielikov ◽  
Olexii Dudin ◽  
Alina Zvierieva ◽  
Anatolii Oleshchenko
Keyword(s):  
Sustainable Development ◽  
Reinforced Concrete ◽  
Axial Load ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Railway Track ◽  
Rolling Stock ◽  
Subgrade Reaction ◽  
Axial Loads ◽  
Interaction Dynamics

The article considers obtaining numerical values of the coefficient of subgrade reaction of wooden and reinforced concrete sleepers with axial loads up to 30-35 tons per axle. It has been concluded that using the rolling stock with axial loads of up to 35 tons per axle is necessary in order to ensure sustainable development of the railway complex. The performance of the railway track thus should be investigated in order to predict its operation in such conditions. Generally, such studies are performed using numerical methods. One of the parameters that are required for such calculations is the parameter which is commonly called the coefficient of subgrade reaction. Empirical dependencies of the coefficient of subgrade reaction of wooden and reinforced concrete sleepers on the axial load and on the operating conditions of the track have been obtained. The obtained results can be used in studies of the interaction dynamics of the track of main railways with rolling stock with axial loads of 30-35 tons per axle, which will give an opportunity to provide well-grounded recommendations on the rules for the arrangement and maintenance of the track in such conditions.

Numerical Modelling of High Pressure Gas Face Seals

2005 ◽  
Author(s):  
Se´bastien Thomas ◽  
Noe¨l Brunetie`re ◽  
Bernard Tournerie
Keyword(s):  
High Pressure ◽  
Thermal Effects ◽  
Operating Conditions ◽  
Compressible Fluids ◽  
Face Seal ◽  
Choked Flow ◽  
Exit Boundary ◽  
Face Seals ◽  
Gas Face Seal ◽  
Comparison With Experimental Data

A numerical model of face seals operating with compressible fluids at high pressure is presented. Inertia terms are included using an averaged method and thermal effects are considered. The real behaviour of gases at high pressure is taken into account. An original exit boundary condition is used to deal with choked flow. The model is validated by comparison with experimental data and analytical solutions. Finally, the influence of the operating conditions on the performance of a high-pressure gas face seal is analysed.

Elastohydrodynamic Film Thickness in Concentrated Contacts: Part 2: Correlation of Experimental Results with Elastohydrodynamic Theory

1986 ◽  
Vol 200 (3) ◽  
pp. 219-226 ◽  
Author(s):  
R J Chittenden ◽  
D Dowson ◽  
C M Taylor
Keyword(s):  
Film Thickness ◽  
Experimental Studies ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Techniques ◽  
Dimensionless Parameters ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Computational Procedures

The existence of a coherent film of lubricant between highly loaded machine elements has been recognized for many years. Over this period of time measurements of film thickness have gone hand in hand with theoretical analyses in the field now known as elastohydrodynamic lubrication. The experimental techniques of capacitance, electrical resistance and X-ray measurement have been supplemented by the use of optical interferometry while the analytical expressions obtained with the use of elegant simplifications have been superseded by those developed from extensive and comprehensive computational procedures. These developments in experimental techniques have yielded a substantial number of measurements of both minimum and central film thickness. Likewise, the advent of the digital computer has allowed the derivation of a large number of solutions to the problem of elastohydrodynamic lubrication of concentrated contacts. All these results, covering a wide range of geometrical conditions, are to be found in the literature, yet little attempt appears to have been made to assemble a representative set of experimental data to permit a detailed evaluation of the theoretical formulae for elliptical contacts. The second part of this paper therefore considers the correlation between a number of experimental studies covering a wide range of operating conditions and geometries, and the predictions of recent elastohydrodynamic theory. Some of the important aspects of each set of experimental results are then considered and examples are provided which illustrate the following points: 1. Good estimates of lubricant film thickness may be obtained from the theoretical expressions recently derived, even when the dimensionless parameters involved are outside the ranges considered in the derivation of the formulae. 2. The discrepancies which exist between theoretical predictions and some of the measured film thicknesses are nevertheless quite large, even when the dimensionless parameters are within their usual limits. On the whole there is good agreement between experiment and theory, while the general trend of the results indicates that theoretical predictions may underestimate the minimum film thickness by about 10 per cent and the central film thickness by about 25 per cent. This measure of agreement is quite remarkable when the extreme difficulty of interpreting the magnitudes of effective and very thin mean film thicknesses between machined components in various forms of experimental equipment is considered.

Thin-Film Flows with Thermoelastically Deformed Boundaries

1978 ◽  
Vol 20 (5) ◽  
pp. 239-245 ◽  
Author(s):  
B. N. Banerjee ◽  
R. A. Burton
Keyword(s):  
Film Thickness ◽  
Point Contact ◽  
Operating Conditions ◽  
Wave Number ◽  
Fluid Viscosity ◽  
Equilibrium Solutions ◽  
Surface Waviness ◽  
Long Wavelength ◽  
Thermoelastic Effects ◽  
Film Flows

Equilibrium solutions are given for the thermoelastic displacements of an initially wavy, moving surface subjected to non-uniform viscous heating derived from a hydrodynamic lubricant film. The configuration studied is similar to a flexibly mounted face seal with one metallic face running against a thermal insulator. Changes in mean film-thickness with changing speed are discussed with reference to earlier analyses which predicted thermoelastic instability and to experiments which illustrated this. The operating conditions approach those where instability was predicted for conditions of fixed mean film thickness; however, no instability is predicted for present conditions where axial load is fixed. Thermoelastic effects upon growth of surface waviness become significant when the sliding speed exceeds u*, given by u* = h1k √( K/µ), where h1 is the initial waviness amplitude, K is the wave number (κ = π/Λ, where Λ is half the wavelength of a sinusoidal waviness), K is the thermal conductivity of the metal, μ is the fluid viscosity, and α is the coefficient of expansion. Past experience has shown that the product h1 k is such that long-wavelength waviness is associated with the lowest u* and therefore magnified relative to shorter wavelength components of the surface topography. Thermal deformations appear to be favourable in their influence on film thickness—except where the unexplained but experimentally observed transition to point contact occurs.

Numerical Modelling of High Pressure Gas Face Seals

2005 ◽  
Vol 128 (2) ◽  
pp. 396-405 ◽  
Author(s):  
Sébastien Thomas ◽  
Noël Brunetière ◽  
Bernard Tournerie
Keyword(s):  
High Pressure ◽  
Thermal Effects ◽  
Operating Conditions ◽  
Compressible Fluids ◽  
Face Seal ◽  
Choked Flow ◽  
Exit Boundary ◽  
Face Seals ◽  
Real Behavior ◽  
Gas Face Seal

An axisymetric numerical model of face seals operating with compressible fluids at high pressure is presented. Inertia terms are included using an averaged method and thermal effects are considered. The real behavior of gases at high pressure is taken into account. An original exit boundary condition is used to deal with choked flow. The model is validated by comparison with experimental data and analytical solutions. Finally, the influence of the operating conditions on the performance of a high-pressure gas face seal is analyzed. It is shown that when the flow is choked, the mass flow rate is reduced and the behavior of the seal becomes unstable.

scholarly journals Ethanol/Gasoline Blends as Alternative Fuel in Last Generation Spark-Ignition Engines: A Review on CO and HC Engine Out Emissions

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4034
Author(s):  
Paolo Iodice ◽  
Massimo Cardone
Keyword(s):  
Physicochemical Properties ◽  
Alternative Fuels ◽  
Experimental Studies ◽  
Alternative Fuel ◽  
Exhaust Emissions ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Spark Ignition Engines ◽  
The Impact

Among the alternative fuels existing for spark-ignition engines, ethanol is considered worldwide as an important renewable fuel when mixed with pure gasoline because of its favorable physicochemical properties. An in-depth and updated investigation on the issue of CO and HC engine out emissions related to use of ethanol/gasoline fuels in spark-ignition engines is therefore necessary. Starting from our experimental studies on engine out emissions of a last generation spark-ignition engine fueled with ethanol/gasoline fuels, the aim of this new investigation is to offer a complete literature review on the present state of ethanol combustion in last generation spark-ignition engines under real working conditions to clarify the possible change in CO and HC emissions. In the first section of this paper, a comparison between physicochemical properties of ethanol and gasoline is examined to assess the practicability of using ethanol as an alternative fuel for spark-ignition engines and to investigate the effect on engine out emissions and combustion efficiency. In the next section, this article focuses on the impact of ethanol/gasoline fuels on CO and HC formation. Many studies related to combustion characteristics and exhaust emissions in spark-ignition engines fueled with ethanol/gasoline fuels are thus discussed in detail. Most of these experimental investigations conclude that the addition of ethanol with gasoline fuel mixtures can really decrease the CO and HC exhaust emissions of last generation spark-ignition engines in several operating conditions.

scholarly journals Analysis of a Cantilevered Piezoelectric Energy Harvester in Different Orientations for Rotational Motion

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1206 ◽  
Author(s):  
Wei-Jiun Su ◽  
Jia-Han Lin ◽  
Wei-Chang Li
Keyword(s):  
Theoretical Model ◽  
Resonant Frequency ◽  
Rotational Motion ◽  
Axial Load ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
Experimental Studies ◽  
Piezoelectric Energy ◽  
Piezoelectric Cantilever ◽  
Tip Mass

This paper investigates a piezoelectric energy harvester that consists of a piezoelectric cantilever and a tip mass for horizontal rotational motion. Rotational motion results in centrifugal force, which causes the axial load on the beam and alters the resonant frequency of the system. The piezoelectric energy harvester is installed on a rotational hub in three orientations—inward, outward, and tilted configurations—to examine their influence on the performance of the harvester. The theoretical model of the piezoelectric energy harvester is developed to explain the dynamics of the system and experiments are conducted to validate the model. Theoretical and experimental studies are presented with various tilt angles and distances between the harvester and the rotating center. The results show that the installation distance and the tilt angle can be used to adjust the resonant frequency of the system to match the excitation frequency.

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