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Auswahl der wissenschaftlichen Literatur zum Thema „Central lubrication system“
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Zeitschriftenartikel zum Thema "Central lubrication system"
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Wu, Zhi Qiang, und Jun Fang Zhao. „The Design of Plate Mills Hydraulic Lubricating and Monitoring System“. Advanced Materials Research 1006-1007 (August 2014): 643–49. http://dx.doi.org/10.4028/www.scientific.net/amr.1006-1007.643.
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Plate mills hydraulic system is made up of several hydraulic stations, lubrication stations and grease stations, these hydraulic stations and lubrication stations are distributed around the mills. Each hydraulic station possesses qualities of successive long working time, high reliability and signal complexity, and it can satisfy diverse demands of high grade pressure or temperature control, etc. This paper is based on these demands, assembling control missions of hydraulic and lubricating stations. Several PLC S7-300 were chosen to match the need of controlling mills hydraulic and lubricating system for a certain plate factory, and the HMI monitoring system for mill hydraulic and lubricating stations was developed by WINCC, which achieved central control and monitoring the hydraulic and lubricating system of plate mills.
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Neville, A., A. Morina, T. Liskiewicz und Y. Yan. „Synovial joint lubrication — does nature teach more effective engineering lubrication strategies?“ Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 221, Nr. 10 (30.09.2007): 1223–30. http://dx.doi.org/10.1243/09544062jmes724.
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Nature shows numerous examples of systems which show energy efficiency, elegance in their design and optimum use of materials. Biomimetics is an emerging field of research in engineering and successes have been documented in the diverse fields of robotics, mechanics, materials engineering, and many more. To date little biomimetics research has been directed towards tribology in terms of transferring technologies from biological systems into engineering applications. The potential for biomimicry has been recognized in terms of replicating natural lubricants but this system reviews the potential for mimicking the synovial joint as an efficient and durable tribological system for potential engineering systems. The use of materials and the integration of materials technology and fluid/surface interactions are central to the discussion.
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Czarny, Ryszard. „THE EFFECT OF THE TYPE OF WALL MATERIAL AND GREASE COMPOSITION PAIRING ON SHEAR STRESSES IN BOUNDARY LAYER“. Tribologia 284, Nr. 2 (30.04.2019): 27–36. http://dx.doi.org/10.5604/01.3001.0013.4146.
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The paper presents the results of research on the influence of fillers introduced into plastic greases on the rheological properties of the boundary layer of the resultant lubricant compositions. The fillers were PTFE and MoS2 powders. They are added to lubricants to improve their tribological properties; however, these fillers also affect the rheological properties of the composition. This affects the change of the shear stress value in the lubricant during its flow in the lubrication system. Knowledge of this value, especially during the flow of the lubricant composition in the boundary layer, has a significant impact on the operation of automated central lubrication systems in which these compositions can be used. Measurements were carried out by means of a rotary rheometer (Rheotest 2.1). Tests were performed on lithium and bentonite greases (without additives) as well as compositions of these greases containing various percentage of the fillers mentioned above. Test results showed that both the type of grease and the type of filler introduced into this grease affect the rheological properties in the boundary layer of the produced lubricating compositions.
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CZARNY, Ryszard. „INFLUENCE OF FILLERS ON THE RHEOLOGICAL PROPERTIES OF THEIR COMPOSITIONS WITH LUBRICATING GREASES“. Tribologia 273, Nr. 3 (30.04.2018): 47–55. http://dx.doi.org/10.5604/01.3001.0010.6120.
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The paper presents the results of studies on the influence of fillers, introduced into lubricating greases, on the rheological properties of resultant grease compositions. These fillers were graphite and PTFE powders. They are added to greases in order to improve their tribological properties. They also affect their rheological properties, and they mainly change the value of the shear stress in grease during its flow in a lubrication system. Knowledge of this value is important in designing automated central lubrication systems in which these compositions may be used. Measurements during experimental tests were performed by means of a rotary rheometer Rheotest 2.1. Tests were performed on pure lithium and bentonite greases, with the addition of oxidation and corrosion inhibitors as well as compositions of these greases with different shares of the above mentioned fillers. These tests were performed by changing the gradient of shearing rate. Test results have shown that both the kind of grease and the kind of filler introduced into this grease affect the rheological properties of produced grease compositions.
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Li, Feng, Feng Guo, Guan Gyuan Liu und Zhang Gang. „Design and Experiment Study on a New Type of Lubrication Simulation System for Thrust-Ball Bearing in Confined Space“. Applied Mechanics and Materials 873 (November 2017): 303–7. http://dx.doi.org/10.4028/www.scientific.net/amm.873.303.
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Many machine components work within an elastohydrodynamic lubrication (EHL) regime. Unconfined space is widely used in EHL formulas for to evaluate film thickness, which is related to operating conditions and material properties. In classical theoretical EHL studies, film pressure matches the loading balance and the location of the lubricated components can be adjusted. In the present study, the lubrication performance is analyzed based on a confined space. A thrust ball bearing lubrication simulation system is designed and used to examine the relationship between velocity and film thickness. It was found that the central film thickness and minimum film thickness increased as entrainment velocity increased. Fluctuations in the film thickness curve were observed, which may have arisen from slight gap variations in the ball-plate contact area.
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Huo, Junzhou, Jianjun Zhou, Tao Li, Zhichao Meng und Wei Sun. „Thermal EHL Characteristics Investigation on Axle Box Bearings of Railway Vehicle Based on Slicing Method“. Shock and Vibration 2019 (02.04.2019): 1–14. http://dx.doi.org/10.1155/2019/6981482.
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Lubrication failures of axle box bearings can lead to accidents, such as bearing burnout and hot axle cutting. Presently, the modeling of the vehicle-track system dynamics rarely considers the nonlinear contact load of axle box bearings, and this leads to imperfection in the vehicle-track system dynamics calculation. And then, the load distribution and lubrication characteristics of axle box bearings are difficult to obtain. Therefore, in this paper, we fully consider the time-varying nonlinear contact load of bearings and track irregularity in establishing the bearing-wheel-rail system coupling-dynamics model. The dynamic response of axle box bearings is obtained by taking the vertical, strong impact-time-varying load on the carrying saddles as the external excitation. The load-balance equation of dynamic pressure lubrication is then obtained, according to the slicing method of bearing rollers. Finally, the elastohydrodynamic lubrication (EHL) model of axle box bearings is established considering thermal and scale effects. The results show that the central film thickness under thermal EHL was decreased by 13.61% compared with that under isothermal EHL. As the velocity of the contact pair increases, the thickness difference between thermal and isothermal EHL became larger. Thermal effects should be considered in the EHL model, in order to truly reflect the characteristics of EHL under a high speed.
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Glazunov, D. V. „Development of the lubricant for side-mounted rail flange lubricators for traction rolling stock“. Vestnik of the Railway Research Institute 78, Nr. 1 (13.05.2019): 59–64. http://dx.doi.org/10.21780/2223-9731-2019-78-1-59-64.
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Specificity of operating conditions of the rolling stock defines a number of requirements for lubricants intended for the wheel-rail tribosystem. Lubricants are used for “wheel — rail” contact, the aggregate state of which varies from liquid to solid. When evaluating the lubrication properties of these materials, a significant number of factors must be taken into account, in particular, influence of the environment, method of application, condition of the rail surface. The paper discusses the main operational requirements for lubricants operating in a wheel-rail tribosystem. Temperature ranges of the lubricants used for the “wheel — rail” contact on the railway network of the Russian Federation are given. As a result of the research, it was determined that none of the materials used for lubrication of the wheel-rail system satisfies the operating temperature conditions of the traction rolling stock. To solve this problem a lubricant was developed and tested in an industrial environment at the Rostov State University of Railway Transport. Its lubricant composition allows to significantly expand the temperature range of the lubricant. Complex of experimental studies and method of orthogonal central composite plan of the 2nd order established the optimum values of the thickness of the working shell of the 0.846 mm lubricating rod and the 50.411 % percentage of plastic lubricant, allowing to extend the temperature range of lubricant rods and, in particular, completely eliminate the lubricant flow to achieve a temperature of 126.034 °C. Proposed composition of the lubricant was tested on a freight electric locomotive of the VL80T series, equipped with non-power lubricators, under the conditions of the Bataysk — Likhaya section of the North Caucasus Railway. Intensity of wear of the wheel flanges of the traction rolling stock lubricated by the proposed material, compared with the intensity of wear of the wheel flanges without the use of lubrication systems is reduced by 2 times.
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Zhai, Liming, Zhengwei Wang, Yongyao Luo und Zhongjie Li. „TEHD analysis of a bidirectional thrust bearing in a pumped storage unit“. Industrial Lubrication and Tribology 68, Nr. 3 (11.04.2016): 315–24. http://dx.doi.org/10.1108/ilt-07-2015-0092.
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Purpose The purpose of this paper is to analyze lubrication characteristics of a bidirectional thrust bearing in a pumped storage, considering the effect of the thermal elastic deformation of the pad and collar. Design/methodology/approach This study used the fluid–solid interaction (FSI) technique to investigate the lubrication characteristics of a bidirectional thrust bearing for several typical operating conditions. The influences of the operating conditions and the thrust load on the lubrication characteristics were analyzed. Then, various pivot eccentricities were investigated to analyze the effects of the pivot position. Findings It is found that the effect of the radial tilt angle of the collar runner on the oil film is compensated for by the radial tilt of the pad. The central pivot support system is the main factor limiting the loads of bidirectional thrust bearings. Originality/value This paper has preliminarily revealed the lubrication mechanism of bidirectional tilting-pad thrust bearings. A three-dimensional FSI method is suggested to evaluate the thermal–elastic–hydrodynamic deformations of thrust bearings instead of the conventional method, which iteratively solves the Reynolds equation, the energy equation, the heat conduction equation and the elastic equilibrium equation.
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Lu, Junjie. „Theoretical optimization and experiment on lubrication of floating microgroove cylindrical seal“. Industrial Lubrication and Tribology 72, Nr. 10 (10.06.2020): 1217–26. http://dx.doi.org/10.1108/ilt-02-2020-0048.
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Purpose The purpose of this paper is to analyze and improve the lubrication performance of a floating cylindrical seal by investigating micro spiral groove. Design/methodology/approach The lubrication model of is solved by finite difference, considering the influence of convergence eccentricity and Rayleigh step on the gas film period. A lubrication model, which is a gas film of floating microgroove cylindrical seal, is solved under high-precision central difference (finite-difference method-center) for the critical problems of convergence eccentricity and Rayleigh step. And then, an idea on the opening-leakage ratio is proposed, and a multiobjective optimization model is established. Finally, an experiment is conducted on a narrow gap to determine the gas film opening force and leakage by the modules of testing system, and the theoretical results are verified by real tests. Findings The theoretical calculation results agree well with the experimental data, which proves the correctness of the lubrication optimization model, and the optimized groove has better lubrication performance. On the other hand, the sealing pressure plays a more important role in the seal operation. Originality/value The theoretical model carries out low complexity and high sparseness, thus being very suitable for large-scale gas film problems. A multiobjective optimal function is established based on the opening-leakage ratio for optimizing groove. Finally, a curved groove of high precision and gas film opening force is obtained completely. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2020-0048/
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KOWALEWSKI, Piotr, Anna BROŃCZYK und Wojciech WIELEBA. „A TRIBOLOGICAL TEST RIG FOR FIBRES, CABLES, AND PLAITINGS“. Tribologia 271, Nr. 1 (28.02.2018): 51–55. http://dx.doi.org/10.5604/01.3001.0010.6363.
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The paper presents a description of the mechanical construction, measuring and control systems and the possibilities of a new type tribological testing device. The design was developed and built at the Department of Fundamentals of Machine Design and Tribology of Wroclaw University of Science and Technology. Described tester allows the investigate a friction and wear of components such as fibrous tapes, ropes, plaitings or fibers themselves in contact with solid materials. The paper describes in detail the construction of drive and the load pneumatic system. The innovative system of the device such measurement equipped with piezoelectric sensors and an experimental fixing unit of tested components also have been described. Work includes diagrams of used control and measurement systems and the central lubrication system. As a test the polyethylene cable in contact with brass rods has been examined. The results of this studies were been also presented in the paper.
Dissertationen zum Thema "Central lubrication system"
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Sikora, Vojtěch. „Optimalizace mazacího systému pro mazání ložisek válcovacích stolic“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443758.
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The thesis focuses on the optimization of the central lubrication system for the lubrication of rolling bearings of rolling mills in the operation continuous wire rod mill. The work is divided into theoretical and practical part. The first part of the theoretical work is focuses on the search of rolling and tribodiagnostics. The next part focuses on the description of modern central lubrication systems, explanation of their principle and practical use. The practical part explains the function of the old lubrication system for rolling mill bearings with an analysis of its problems. Next is described the technical design of a new central lubrication system, its application into operation and its actual commissioning are described. The last part of the thesis is the conclusion and evaluation of the benefits of the new central lubrication system compared to the old one.
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Belinelli, Marjorie Maria. „Desenvolvimento de método para seleção de política de lubrificação de máquinas centrada em confiabilidade: aplicação na indústria alimentícia“. Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-15072016-162939/.
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Em indústria de alimentos são aplicados máquinas e equipamentos para processamento de alimentos, os quais exigem lubrificação para garantir seu pleno estado de funcionamento. Porém o mesmo lubrificante que auxilia o funcionamento do maquinário é considerado um risco potencial de contaminação do produto em suas etapas de processamento, vindo a interferir em sua qualidade. Além deste fator, uma inadequada gestão do processo de lubrificação de máquinas e equipamentos podem gerar eventos de falhas, impactando na disponibilidade e confiabilidade operacional do sistema industrial como todo. O objeto da pesquisa desenvolvida nesta tese de doutorado é o desenvolvimento de um método de seleção de política de lubrificação industrial centrada em confiabilidade voltada especificamente para maquinário empregado na fabricação de alimentos, e visa analisar os eventos de falhas ocorridos no maquinário, os quais relacionados com o processo de lubrificação industrial, bem como, a relação das atividades de lubrificação na geração de foco de potencial risco que propicie perda de qualidade e inocuidade do produto. O método é estruturado na identificação das variáveis envolvidas no processo de lubrificação industrial e análise de seus impactos sobre a geração de eventos de falhas e potencial foco de risco de perda de qualidade e inocuidade do produto, Esta análise visa direcionar a tomada de decisão quanto a estrutura da política de lubrificação industrial adequada a cada ativo industrial instalado na indústria de alimentos. A validação do método de seleção de política de lubrificação centrada em confiabilidade deu-se através da aplicação de sua metodologia em um sistema reparável, uma máquina cobrideira, instalada em uma indústria de alimentos, localizada na região metropolitana de Curitiba. A análise estatística do comportamento da tendência de falhas neste ativo industrial conjuntamente com a análise funcional dos modos de falhas relacionados com o processo de lubrificação industrial, possibilitou estruturar uma política de lubrificação industrial adequada para máquina cobrideira. Esta política de lubrificação contempla ações que resultaram no aumento de produtividade anual da máquina cobrideira em 0,16%, isto significa 280.830 unidades (equivalente a 7,02 toneladas) produzidas a mais no ano de 2014 em relação a 2013, e na melhoria dos indicadores de desempenho de manutenção e disponibilidade operacional da máquina cobrideira. Além disto, a aplicação do método desenvolvido estruturou procedimentos de modo de execução e monitoramento das atividades de lubrificação, os quais visam garantir a qualidade do produto durante as etapas de fabricação conjuntamente com a melhoria de desempenho e produtividade do sistema industrial.In the food industry, machinery and equipment for food processing are used. They require lubrication to ensure they\'re working properly. However, the same lubricant which assists the operation of the machinery is considered a potential contamination to the product in its processing steps, impacting on their quality. The improper management of the lubrication process of machinery and equipment may lead to fault events, impacting on the availability and operational reliability of the industrial system as a whole. The research object developed in this doctorate thesis shows the development of a selection method of an industrial lubrication policy focused on reliability. Such policy is designed specifically for machinery used in the manufacture of foods. It analyzes the failure events in the machinery due to the lubrication process and. It also analyzes the connection between the lubricating activities and the potential risk of loss product quality and safety. The method is structured to identify the variables involved in the industrial lubrication process and analyzes their impact they have on fault events and potential source of risk of product quality loss. This analysis aims to guide decision-making regarding the structure of the adequate industrial lubrication policy to each industrial asset installed in the food industry. The validation of the lubrication policy selection method focused on reliability occurred through the application of its methodology in a repairable system, a coating machine, installed in a food industry located in the metropolitan region of Curitiba. The statistical analysis of the fault trend behavior in this industrial asset together with the functional analysis of failure modes related to the industrial lubrication process made it possible to structure a suitable policy for the industrial lubrication of the coating machine. This lubrication policy includes actions that resulted in the increase of the annual productivity of the coating machine by 0.16%. It means 280,830 more units (equivalent to 7.02 tons) were produced in 2014 than in 2013. It also improved the maintenance performance indicators and the operational availability of the coating machine. Furthermore, the application of the method structured procedures of execution mode and monitoring of lubrication activities. The aim was to ensure the quality of the product during the manufacturing steps together with the improvement of the performance and productivity of the industrial system.
Buchteile zum Thema "Central lubrication system"
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„Central Lubrication Systems for Vehicles“. In Encyclopedia of Lubricants and Lubrication, 225. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-22647-2_100095.
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Adaikan, Ganesh. „Female sexual dysfunction“. In Oxford Textbook of Obstetrics and Gynaecology, herausgegeben von Sabaratnam Arulkumaran, William Ledger, Lynette Denny und Stergios Doumouchtsis, 743–52. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198766360.003.0060.
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According to the World Health Organization, sexual health as a state of physical, emotional, mental, and social well-being in the context of sexuality, excludes the mere absence of disease, dysfunction, or infirmity. Thus a woman’s sexual function encompasses many areas; the construct of a normal function as a quality of life indicator often but not always conforms to the sexual response cycle, which is an endogenous process contributed by hormonal, vascular, neuronal, and psycho-emotional factors. Clinical and scientific evidence abounds about the physiological role of sex steroids viz. oestrogen, testosterone, and also progesterone in facilitating and maintaining the woman’s sexual parameters. The neurophysiology extends from the central and peripheral nervous systems to the targeted genital structures resulting in coordinated vascular and non-vascular smooth muscle relaxation, to be accompanied by pelvic vasocongestion, vaginal lubrication, and labial and clitoral engorgement. Any detrimental impact on this normal cycle of concerted responses can result in a functional impairment or ‘female sexual dysfunction’ (FSD). Sexual changes, psychogenic or organic, are common in women at any age; such complaints are frequently accompanied by quality-of-life concerns, varying levels of personal distress, anxiety, depression, and also fertility concerns in younger women. With FSD as a medically diagnosable entity, fewer drugs have met the safety and efficacy criteria for global approval and clinical utility. In order to appreciate the diverse range of FSD and the extent of its physical, physiological, and psychological implications, it is important to understand the fundamentals as well as the changing paradigms in a woman’s sexual functioning.
Konferenzberichte zum Thema "Central lubrication system"
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GÖK, Selva, und Mahmut FIRAT. „Analysis of Faults in Sewage Systems with Geographical Information Systems“. In 4th International Conference of Contemporary Affairs in Architecture and Urbanism – Full book proceedings of ICCAUA2020, 20-21 May 2021. Alanya Hamdullah Emin Paşa University, 2021. http://dx.doi.org/10.38027/iccaua2021tr0050n9.
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Wastewater systems are one of the most important infrastructure elements in terms of human and environmental health. In such systems, failures are observed depending on various factors. These failures increase operating and maintenance-repair costs and create threats to human and environmental health. For this reason, these systems should be monitored regularly and the factors causing malfunction should be analyzed. In this study, it is aimed to evaluate and analyze failures occurring in sewerage systems with geographical information systems. For this, the failures in the sewage system of Malatya province between year 2015-2019 were taken into account. It has been determined that the most common types of failure are misuse, in-line sag and deformation, and in-line lubrication. In addition, the highest failure rate occurred in pipes with a diameter of 100-200 mm. In the spatial analysis of faults, inline collapse is generally observed in the central regions, while misuse faults are found to be in the system. It has been observed that factors such as pipe diameter and length, season, traffic load, ground feature, and improper use are effective in the increase in fault density.
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Fenton, Marcus B. M., und Ali Veshagh. „Fluid Flow Modelling of an Automotive Engine Lubrication System“. In ASME 1993 International Computers in Engineering Conference and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/cie1993-0024.
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Abstract A computer model has been developed to provide a design analysis tool for assessing the flow characteristics of an engine lubrication system. Parametric studies can be conducted to predict the pressure and flow of oil throughout the lubrication system and to study the effects of various design parameters and operating conditions. This paper reports on the development of the engine lubrication system flow model at the Advanced Technology Centre in collaboration with Jaguar Cars. The results of the simulation model are assessed and its future potential as a computer aided analysis tool for engine development programmes is examined.
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Wang, Zhan-jiang, Yuan-zhong Hu, Wen-zhong Wang und Hui Wang. „Numerical Analysis of Point Contact EHL on Coated Substrates“. In ASME/STLE 2009 International Joint Tribology Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/ijtc2009-15038.
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Performances of point contact EHL on multilayered or coated substrates have been analyzed in this paper via computer simulations, with emphasis on comparing the effects of Newtonian and non-Newtonian lubricants. The lubrication system consists of a rigid ball in contact with a smooth coated flat. The coating is perfectly bonded to an elastic substrate and it has a uniform thickness. The rigid ball has surface velocity U relative to the contact point. The hydrodynamic pressure p is governed by a generalized Reynolds equation in which the non-Newtonian effects of lubricants are characterized by two factors whose values are determined based on lubricant rheology. The Papkovich-Neuber potentials were employed to get the response functions in frequency domain for layered contact problems, and the influence coefficients relating pressure to surface displacements and stresses can be obtained via invert Fourier transform. The surface deformation was then calculated in terms of the pressure-displacement influence coefficients and the DC-FFT method was used to speed up the computation. The distributions of pressure, film thickness and subsurface stress have been analyzed for lubricants with different rheological behaviors, from which pressure and film thickness profiles along the rolling direction are calculated for Newtonian and Non-Newtonian lubricants. The central film thickness become thicker for stiffer coatings in the case of Newtonian lubricants, but the trend is reversed for Non-Newtonian lubricants. The surface stresses along the rolling direction show a spike corresponding to the pressure, which is more significant with stiffer coatings in the Newtonian case, but the spike is less visible for Non-Newtonian lubricants.
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Deng, Xin, Cori Watson, Minhui He, Roger Fittro und Houston Wood. „Response Surface Mapping and Multi-Objective Optimization of Crowning and Tapers in Water-Lubricated Thrust Bearings“. In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91984.
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Abstract Fluid film bearings for turbomachinery are designed to support the loads applied by the rotor system. Oil-lubricated bearings are widely used in high speed rotating machines. However, environmental issues and risk-averse operations have made water lubricated bearings increasingly popular. Due to different viscosity properties between oil and water, the low viscosity of water decreases film thickness significantly. Crowning and tapers are two main ways to maintain the film thickness requirements in water lubrication, but no studies about the influence of these parameters on the film thickness in water-lubricated bearings have been reported. Therefore, further understanding of the performance associated with optimizing the bearing design with different weighted performance and their relationships to bearing design variables could be invaluable to bearing design engineers. This study explores the impact of three crowning and taper design variables on the performance of one tilting pad thrust bearing using the design of experiments techniques applied to a thermoelastohydrodynamic (TEHD) bearing model. The bearing design variables analyzed in this study include the radius of the ground-in crown, taper circumferential angle offset, and the vertical taper distance at the inner and outer radii. Each of the design variables is first varied over five levels, each in central composite design. The outputs from the TEHD numerical simulations used as performance measures for each bearing design point were the minimum film thickness, the film thickness at the pivot location, maximum film pressure and power loss. Multi-objective optimization was performed. A range of weighting parameters was selected for the optimization function to find a bearing design that maintains the minimum film thickness criterion while minimizing power loss. The resulting optimum design points allowed for a comparison between the design optimization at different weightings. This study demonstrates how designers can use these approaches to view the relationships between design variables and important performance metrics to design better bearing for a wide range of applications.
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Prabhakar, Arun, Stephen Ambrose und Herve Morvan. „Numerical Investigation of Two Phase Flow in a Dual Drive Booster (DDB)“. In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90347.
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Abstract Recent efforts have been devoted in developing cutting edge methods and technologies to overcome the complications involved in extracting power from the spools in turbofan engines to drive the power systems in aircraft. In a contemporary turbofan engine design, a Dual Drive Booster turbofan (DDBTF) summation gear box is employed to derive power from the low pressure (LP) and high pressure (HP) spools. This paper aims to investigate the scavenging of lubrication oil from the Dual Drive Booster gearbox. It is essential that that the scavenging of oil from the gearbox is efficient to eradicate risks that may arise when oil resides in the gear box for prolonged durations. Longer residence times of oil in the gearbox can lead to rapid oil degradation. Simulations were conducted on a previously optimized geometry and the work in this paper will focus on investigating the effect of different operating conditions on the scavenging performance of the scavenge chamber. The effect of attitude, altitude and the inlet flow rate of oil have been simulated to understand their influence on the oil flow behavior. Emphasis is given on the predicting potential oil churning, recirculation and pooling behaviors in the scavenge chamber that encloses the gear box. Numerical Investigations are carried out using ANSYS Fluent. The Volume of Fluid (VOF) multiphase model is employed to model the multiphase flow arising between air and oil in the system and the effects of turbulence are modelled using the standard k-ϵ model. The computational domain is discretized using a polyhedral grid comprising of 4 million cells which was adopted based on grid independency tests that were conducted prior to the main simulations. Validation against published experimental data for similar flow regimes was also carried out. Results indicate that the scavenging performance is not affected significantly under the various operating conditions and scenarios that were investigated. This is because the effects of the windage outweigh the effects caused by the different operating conditions that are imposed to the scavenge chamber. The windage in the system drives the oil efficiently out from the chamber with the aid of the tangential sump (shown in Figure 4). Oil is distributed in an axially central section of the chamber and the total residence mass of oil is compared and under 0.5 kg for all the cases presented in this paper.
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Kudish, Ilya I. „Uniform Equations in the Inlet and Exit Zones of Heavily Loaded Point EHL Contacts Involved in Various Steady Motions“. In ASME 2014 12th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/esda2014-20388.
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Heavily loaded point EHL contacts involved in steady purely transitional, skewed transitional, and transitional with spinning motions are considered. It is shown that in the central parts of the inlet and exit zones of such heavily loaded point EHL contacts the asymptotic equations governing the EHL problem along the lubricant flow streamlines for the above types of contact motions can be reduced to two sets of asymptotic equations: one in the inlet and one the exit zones. The latter sets of equations are identical to the asymptotic equations describing lubrication process in the inlet and exit zones of the corresponding heavily loaded line EHL contact [1]. For each specific motion of a point contact a separate set of formulas for the lubrication film thickness is obtained. For different types of contact motions these film thickness formulas differ significantly [1]. For heavily loaded contacts the discovered relationship between point and line EHL problems allow to apply to point contacts most of the results obtained for line contacts [1,2].
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Rahmani, Ramin, Gema Styles und Homer Rahnejat. „Meniscus Formation in the Piston Compression Ring-Cylinder Liner Inlet Zone“. In ASME 2012 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icef2012-92123.
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The piston compression ring-cylinder liner contact experiences a transient regime of lubrication. This comprises hydrodynamic, mixed (partial) or boundary interactions. The regime of lubrication is influenced by contact kinematics, loading, mechanical and topographical properties of the bounding solid surfaces, as well as lubricant rheology and its supply to feed the conjunction. Ideally, a sufficient volume of lubricant would exist at the conjunctional inlet, which acts as a meniscus, from which a film of lubricant is entrained into the contact area. However, often there is an insufficient volume at the inlet to the contact or unfavourable kinematic conditions exist, such as at the dead centre reversals in the piston system. Such conditions are generally regarded as the underlying reasons for mixed or boundary regimes of lubrication. Whilst, these are the main reasons for failure to form a coherent lubricant film at dead centre reversals, poor hydrodynamic lubrication can also occur elsewhere in the piston cycle due to the lack of an inlet meniscus. This may be as the result of poor ring-bore conformability, where a meniscus cannot be formed in an increasing clearance space. Numerical analyses reported in open literature often assume an idealised fully flooded or drowned inlet. Other analyses assume starved inlet boundaries, usually based on a lubricant availability model, which itself is based on an assumed supply of lubricant on free surfaces ahead of the contact. It is, however, important to establish the limiting clearance space which would allow the lubricant to adhere to the adjacent boundary solids and, thus form a meniscus bridge. The current study is aimed at establishing inlet meniscus conditions. This would depend on the lubricant surface tension, affected by the free surface energy of liquid-vapour interface and the contact angle made between the lubricant and the bounding solids. It also depends on the solid surfaces, any coatings and their topography. In general, the results indicate the dependence of the meniscus force on surface material and topography, through measurement of contact angles made by the various compression rings against the various cylinder liner surfaces, using an especially developed rig and in conjunction with a goniometer. Obviously, the measurements do not exactly replicate those existing in a fired engine. Nonetheless, this initial study provides a good insight into oil-surface combination in separating gaps, which is far more representative than the usually assumed idealised inlet conditions.
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Yang, Limin, und Torgeir Moan. „Cylinder Bore Wear Damage Analysis of a Heaving-Buoy Wave Energy Converter With Hydraulic Power Take-Off“. In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20164.
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Wave energy is a non-polluting and renewable source of energy. Among several wave energy converters (WEC), an oscillating body with a hydraulic power take-off (PTO) is commonly used for energy conversion. For such a hydraulic system, the piston ring and cylinder play very important roles in achieving desired energy converting performance and durability. Among the failure modes of the ring-bore components, wear is a prevailing one. Compared with the ring wear, cylinder wear is more important to the manufacturer and user, because cylinders are more expensive to replace than the rings. Since the floating body is exposed to irregular incident waves, the dynamic response of the PTO is also random. The position of maximum accumulated wear damage along the cylinder bore cannot be as easily determined as the engine bores where the maximum wear occurs near the Top Dead Centre (TDC). It is controlled by the characteristic dynamics of the system together with the lubrication of the interface which can be modelled by the well-known Stribeck curve. The purpose of this paper is to establish and apply a method for estimating the wear damage along the cylinder bore. The dynamic response of the WEC system is based on the nonlinear mathematical model established by Yang et al [1]. A particular issue in this research is to calculate the dimensionless film thickness λ (the ratio between the oil film thickness h and the composite surface roughness σ) in the lubricated contacts and then determine the lubrication regime according to the Stribeck curve. Combining the wear coefficient which is related to the lubrication regime and the contact pressure, the bore wear damage along the cylinder wall is predicted. In this paper, the bore wear damage is estimated on the basis of time domain simulations. The results show that the bore wear distribution is affected by two main factors: sea state condition and the nonlinearity of the PTO system. The position of the bore where the maximum accumulated wear occurs is predicted. Finally, the relative contribution of wear damage from different sea states is obtained.
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Anand, M., M. Hadfield, JL Viesca und B. Thomas. „Experimental Study on the Effect of Marine Engine Lubricant Degradation on Tribological Performance of Cylinder Liner and Piston Rings Contact Using a Tuning Fork Technology Based Oil Sensor“. In International Conference on Marine Engineering and Technology Oman. London: IMarEST, 2019. http://dx.doi.org/10.24868/icmet.oman.2019.009.
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An investigation was carried out to study the effect of changes in oil quality on its tribological performance using a tuning fork technology based oil sensor. In this research, a tribological testing system was commissioned, to simulate the piston ring-cylinder liner sliding contact, and to measure the lubricant condition in real-time using an oil sensor. Tribological contact between cylinder liners and piston rings in marine engines is the most affected region due to excessive thermo-mechanical stresses. At top dead centre, the effect of such stresses is at a maximum where piston-sliding speed is lowest, while the temperature is high due to fuel combustion, and radial load behind the piston rings compressing against the cylinder liner surface is at a maximum due to gas pressure and the compression fit of piston rings within the cylinder liner. At bottom dead centre, this effect is less severe due to a reduction in temperature and gas pressure on the piston rings, as the piston is positioned away from the combustion chamber. These two regions experience boundary lubrication conditions, where anti-wear and anti-friction additives are responsible for forming a protective lubricious film on sliding surfaces. At mid-stroke, piston-sliding speed is maximum, therefore, a full hydrodynamic film is formed in this region separating the piston rings and cylinder liner. The formation of oil film depends upon, the physical properties of oil (such as viscosity and density) under hydrodynamic lubrication conditions, and the oil chemistry (such as presence of additives in oil) under mixed or boundary lubrication conditions. Lubricants in marine engines undergo intense degradation in quality due to contamination with wear particles, water, soot, un-burnt fuel, coolant, and additives depletion. Such degradation of lubricants leads to a reduction in their capability to form a minimum thickness of oil film between two moving engine components to avoid direct metal-to-metal contact, which may cause wear. Therefore, monitoring the condition of marine engine lubricants is vital in order to predict any significant change in its quality. The results obtained from tribology testing and oil condition monitoring in the current research showed a good correlation and are useful to understand the performance of lubricants for piston ring-liner contacts.
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Rundo, Massimo, und Nicola Nervegna. „Geometry Assessment of Variable Displacement Radial Pumps“. In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95807.
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The paper brings to evidence the effect that geometry of the stator ring of variable displacement radial pumps bears on performance characteristics of these units. The type of motion of the stator ring (linear or rotational), the location of the centre of rotation, the porting plate integral with the casing or with the stator ring all have remarkable effects on the pump steady state and dynamic performance. At steady state, an influence exists on the attainable minimum displacement and on the deviation of discharge pressure from the desired setting when displacement is being controlled. In turn, dynamic performance is affected by changes in port plate timing as stator position and displacement undergo transitions. Specific attention is then committed to variable displacement vane pumps for internal combustion engines lubrication where an additional and foremost effect is investigated concerning the issues entailed by internal forces distribution on the stator ring that originate from incomplete chambers filling at high rotational pump speed.