Dissertations / Theses on the topic 'Theory of lubrication'
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Tsandzana, Afonso Fernando. "Homogenization with applications in lubrication theory." Licentiate thesis, Luleå tekniska universitet, Matematiska vetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18727.
Full textGodkänd; 2014; 20140415 (afotsa); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Afonso Fernando Tsandzana Ämne: Matematik/Mathematics Uppsats: Homogenization with Applications in Lubrication Theory Examinator: Professor Peter Wall, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Professor Anders Holmbom, Mittuniversitetet, Östersund Tid: Onsdag den 11 juni 2014 kl 10.00 Plats: E231, Luleå tekniska universitet
Chien, Ssu-Ying. "Compressible Lubrication Theory in Pressurized Gases." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/88868.
Full textDoctor of Philosophy
Lubrication theory plays a fundamental role in all mechanical design as well as applications to biomechanics. All machinery are composed of moving parts which must be protected against wear and damage. Without eective lubrication, maintenance cycles will be shortened to impractical levels resulting in increased costs and decreased reliability. The focus of the work presented here is on the lubrication of rotating machinery found in advanced power systems and designs involving micro-turbines. One of the earliest studies of lubrication is due to Osborne Reynolds in 1886 who recorded what is now regarded as the canonical equation governing all lubrication problems; this equation and its extensions have become known as the Reynolds equation. In the past century, Reynolds equation has been extended to include three-dimensional eects, unsteadiness, turbulence, variable material properties, non-newtonian uids, multi-phase ows, wall slip, and thermal eects. The bulk of these studies have focused on highly viscous liquids, e.g., oils. In recent years there has been increasing interest in power systems using new working uids, micro-turbines and non-fossil fuel heat sources. In many cases, the design of these systems employs the use of gases rather than liquids. The advantage of gases over liquids include the reduction of weight, the reduction of adverse eects due to fouling, and compatibility with power system working uids. Most treatments of gas lubrication are based on the ideal, i.e., low pressure, gas theory and straightforward retro-tting of the theory of liquid lubrication. However, the 21st Century has seen interest in gas lubrication at high pressures. At pressures and temperatures corresponding to the dense and supercritical gas regime, there is a strong dependence on gas properties and even singular behavior of fundamental transport properties. Simple extrapolations of the intuition and analyses of the ideal gas or liquid phase theory are no longer possible. The goal of this dissertation is to establish the correct form of the Reynolds equation valid for both low and high pressure gases and to explore the dynamics predicted by this new form of the Reynolds equation. The dissertation addresses ve problems involving our new Reynolds equation. In the rst, we establish the form appropriate for the simple benchmark problem of two-dimensional journal bearings. It is found that the material response is completely determined by a single thermodynamic parameter referred to as the eective bulk modulus. The validity of our new Reynolds equation has been established using solutions to the full Navier-Stokes-Fourier equations. We have also provided analytical estimates for the range of validity of this Reynolds equation and provided a systematic derivation of the energy equation valid whenever the Reynolds equation holds. The next three problems considered here derive local and global results of interest in high speed lubrication studies. The results are based on a perturbation analysis of our Reynolds and energy equation resulting in simplied formulas and the explicit dependence of pressure, temperature, friction losses, load capacity, and heat transfer on the thermodynamic state and material properties. Our last problem examines high pressure gas lubrication in thrust bearings. We again derive the appropriate form of the Reynolds and energy equations for these intrinsically threedimensional ows. A nite dierence scheme is employed to solve the resultant (elliptic) Reynolds equation for both moderate and high-speed ows. This Reynolds equation is then solved using perturbation methods for high-speed ows. It is found that the ow structure is comprised of ve boundary layer regions in addition to the main core region. The ow in two of these boundary layer regions is governed by a nonlinear heat equation and the ow in three of these boundary layers is governed by nonlinear relaxation equations. Finite dierence schemes are employed to obtain detailed solutions in the boundary layers. A composite solution is developed which provides a single solution describing the ow in all six regions to the same accuracy as the individual solutions in their respective regions of validity. Overall, the key contributions are the establishment of the appropriate forms of the Reynolds equation for dense and supercritical ows, analytical solutions for quantities of practical interest, demonstrations of the roles played by various thermodynamic functions, the rst detailed discussions of the physics of lubrication in dense and supercritical ows, and the discovery of boundary layer structures in ows associated with thrust bearings.
Noronha, Noel John. "Analysis of lubrication groove geometry." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4317.
Full textThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 20, 2007) Vita. Includes bibliographical references.
Tsandzana, Afonso Fernando. "Homogenization of some new mathematical models in lubrication theory." Doctoral thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-59629.
Full textBryant, Benjamin. "Modeling Moving Droplets: A Precursor Film Approach." Scholarship @ Claremont, 2003. https://scholarship.claremont.edu/hmc_theses/142.
Full textCampbell, Craig Maurice. "Signature analysis techniques for needle bearing defect detection." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/19539.
Full textFabricius, John. "Homogenization of some problems in hydrodynamic lubrication involving rough boundaries." Doctoral thesis, Luleå tekniska universitet, Matematiska vetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25734.
Full textGodkänd; 2011; 20110408 (johfab); DISPUTATION Ämnesområde: Matematik/Mathematics Opponent: Professor Guy Bayada, Institut National des Sciences Appliquées de Lyon (INSA-LYON), Lyon, France, Ordförande: Professor Lars-Erik Persson, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Tisdag den 7 juni 2011, kl 10.00 Plats: D2214/15, Luleå tekniska universitet
Takagi, Daisuke. "Spreading of viscous fluids and granular materials on slopes." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/228707.
Full textManoylov, Anton. "Modelling of mixed lubrication in plain bearings based on the theory of flow factors and incorporating a dry contact analysis." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/59971/.
Full textUlusoy, Suleyman. "The Mathematical Theory of Thin Film Evolution." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16213.
Full textWong, Jeffrey. "Simulations of Surfactant Spreading." Scholarship @ Claremont, 2011. http://scholarship.claremont.edu/hmc_theses/1.
Full textWhite, Jonathan Charles. "HIGH-FRAME-RATE OIL FILM INTERFEROMETRY." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/572.
Full textZhang, Yuanyuan. "Friction prediction for rough surfaces in an elastohydrodynamically lubricated contact." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI063.
Full textThe friction of interfacial surfaces greatly influences the performance of mechanical elements. Friction has been investigated experimentally inmost studies. In this work, the friction is predicted by means of numerical simulation under an elastohydrodynamic lubrication (EHL) rough contact condition. The classical Multigrid technique performs well in limiting computing time and memory requirements. However, the coarse grid choice has an important influence on code robustness and code efficiency to solve the rough problem. In the first part of this work, a coarse grid construction method proposed by Alcouffe et al. is implemented in the current time-independent EHL Multi-Grid code. Then this modified solver is extended to transient cases to solve the rough contact problem. The friction curve is usually depicted as a function of “lambda ratio”, the ratio of oil film thickness to root-mean-square of the surface roughness. However this parameter is less suitable to plot friction variations under high pressure conditions (piezoviscous elastic regime). In the second part of this work, the friction coefficient is computed using themodified EHL code for many operating conditions as well as surface waviness parameters. Simulation results show that there is no single friction curve when the old parameter "lambda ratio" used. Based on the Amplitude Reduction Theory, a new scaling parameter depends on operating condition and waviness parameters is found, which can give a unified friction curve for high pressure situation. For more complex rough surfaces, a power spectral density (PSD) based method is proposed to predict friction variations in the third part of this work. The artificial surface roughness is employed to test the rapid prediction method firstly. Good agreement is found between the full numerical simulation and this rapid prediction. Then the rapid prediction method is applied to analyze the friction variation of measured surface roughness. Both the new scaling parameter and the friction increase predicted by the PSD method show good engineering accuracy for practical use
Nizkaya, Tatiana. "Transport and deposition of inertial particles in a fracture with periodic corrugation." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0410/document.
Full textIt is well-known that inertial particles tend to focus on preferential trajectories in periodic flows. The goal of this thesis was to study the joint effect of particle focusing and sedimentation on their transport through a model 2D fracture with a periodic corrugation. First, single-phase flow though the fracture has been considered: the classical results of the inertial lubrication theory are revisited in order to include asymmetric fracture geometries. Cubic corrections to Darcy's law have been found analytically and expressed in terms of two geometric factors, describing channel geometry. For weakly-inertial particles in a horizontal channel it has been shown that, when inertia is strong enough to balance out the gravity forces, particles focus to some attracting trajectory inside the channel. The full trapping diagram is obtained, that predicts the existence of such attracting trajectory regime depending on the Froude number and on geometric factors. Numerical simulations confirm the asymptotic results for particles with small response times. The influence of the lift force on particle migration has also been studied. In a vertical channel the lift is induced by gravity and leads to complex trapping diagrams. In the absence of gravity the lift is caused by inertial lead/lag of particles and can lead to chaotic particle dynamics. Finally, for dust particles in a vortex pair it has been shown that particles can be trapped into one or two equilibrium points in a reference frame rotating with the vortices. A full trapping diagram has been obtained, showing that any pair of vortices can trap particles, independently of their strength ratio and the direction of rotation
Xie, Kebin. "Dimensioning of a cutter wheel bearings." Thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik (from 2013), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-80154.
Full textMaimouni, Houda. "Suivi des échanges d’eau dans un mortier de sable recyclé modèle à l’état frais par une approche rhéologique." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0045.
Full textThe increased interest in concrete recycling results from a willingness to reconcile the construction industry with sustainability. Recycled concrete aggregates (RCA) consist of a mix of natural aggregates and attached cement. The high porosity of RCA modifies the effective water content of a recycled concrete at the expense of its fresh and hardened performances. A testing method based on spread measurements is suggested to follow quantitatively water transfers between RCA sand and a fresh cement paste. This protocol is tested on cement paste sands (CPS) having 0.3, 0.5 and 0.7 water/cement ratios (W/C). Results show that the saturation degree of CPS embedded in a filler paste reaches a maximum no later than 6 minutes then remains quasiconstant. The saturation degree increases with the W/C of CPS ratios but remains less than 1. Moreover, similar water transfer kinetics are found whether initially dry CPS are immersed in a filler or a cement paste. The established protocol assumes a correlation between spread and effective water content of a mortar. In order to study this correlation, on the one hand, under the lubrication approximation, the yield stress of mortars is calculated from their spread radius. On the other hand, yield stress of mortars is calculated using a biphasic modelling of mortars viewed as non-colloidal suspensions in a yield stress fluid. Consistency between the two approaches is examined
Разаві, Сейед Фаршад. "Гідродинамічні особливості потока аномально-в'язких рідин у конічної поверхні ковзання." Doctoral thesis, Київ, 2019. https://ela.kpi.ua/handle/123456789/29180.
Full textDočekal, Václav. "Chlazení a mazání rotujících kuličkových matic." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-379022.
Full textHsiang-ChinJao and 饒翔進. "Lubrication Theory for Micro-Bearings." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/z2h8ek.
Full text國立成功大學
材料科學及工程學系
105
In this study, a lubrication theory that includes the coupled effects of anisotropic slip on both the solid-liquid interface, rheology and surface roughness on the lubrication (journal bearing) performance is proposed. A modified average Reynolds equation (modified ARE) as well as Poiseuille and Couette flow rate correctors and the related factors (pressure and shear flow factors, and shear stress factors) are then derived by applying the rheology model, Navier slip boundary conditions and flow factor with orthogonal principal slip lengths ( b ix , b iy ). The results show that the existence of boundary slip can dilute the effects of surface roughness. And contours of constant load ratios are plotted and then the parameters in flow rheology and boundary slip can be located while designing functional surfaces in journal bearings. Finally,a bearing with desired performance can be designed by the processing method of the surface texture.
Sheng-TengHuang and 黃勝騰. "Analysis of Asymmetric Electric Double Layer and Water Lubrication Theory on Pure Squeeze." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/5umd82.
Full text國立成功大學
材料科學及工程學系
107
Debye Huckel and nonlinear Poisson-Boltzmann solution is classical solution derived by semi-infinite space boundary conditiom. In this research, Our electric double layer model want to deviate from the topic of classic assumption, and developed a numerical solution for electrical double layer with asymmetric boundary condition instead of symmetric boundary condition. In past study, the electric conductivity in classic Reynold is constant, In our new modified Reynold equation, the electric conductivity varies with temperatue and ionic coconcentration, at the same time, our new modified Reynold equation is derived with asymmetric boundary condition and ionic conservation rule.
Stocker, Roman, and A. E. Hosoi. "Corner Flows in Free Liquid Films." 2004. http://hdl.handle.net/1721.1/10742.
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