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1
Wu, Bo, Xiao Dong Yu, Xue Mei Chang und Chao Yin. „Influence of Working Parameters on Dynamic Pressure Effect of Heavy Constant Flow Hydrostatic Center Rest“. Applied Mechanics and Materials 274 (Januar 2013): 82–86. http://dx.doi.org/10.4028/www.scientific.net/amm.274.82.
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In order to increase the working performance of a heavy constant flow hydrostatic center rest, a theoretical study concerning the lubricating oil film dynamic pressure effect of the heavy constant flow hydrostatic center rest is described. The Computational Fluid Dynamics and the Finite Volume Method have been used to compute numerically the static pressure field and the total pressure field of the lubricating oil film. The influences of spindle rotating rate, lubricating oil dynamic viscosity and inlet flow rate on the lubricating oil film dynamic pressure effect of the heavy constant flow hydrostatic center rest were analyzed based on the computational fluid dynamics and lubrication theory, and the influencing laws were revealed. By means of this method, the reasonable data can be provided for reasonably controlling dynamic pressure and structure optimal design of the heavy constant flow hydrostatic center rest.
2
Wang, Xigui, Jian Zhang, Yongmei Wang und Chen Li. „Self-Anti-Disturbance Control of a Hydraulic System Subjected to Variable Static Loads“. Applied Sciences 12, Nr. 14 (19.07.2022): 7264. http://dx.doi.org/10.3390/app12147264.
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A hydraulic system’s lubricating oil is subject to serialized variable static loads with performance. An improved self-turbulent flow algorithm, based on the real-time acquisition and monitoring of lubricating oil static pressure in a hydraulic system to simulate variable static loads, is proposed. A mathematical model of the electrohydraulic servo control system for lubricating oil static pressure acquisition is presented, and the self-turbulent flow controller is designed for numerical analysis. The self-anti-disturbance control strategy for the lubricating oil static pressure of an electrohydraulic servo system is discussed, which is used for quadratic optimization, pole placement, PID, and self-turbulent flow control, and the lubricating oil static pressure simulation model of self-turbulent flow control is constructed by a SIMULINK module. The numerical simulation results indicate that the overshoot is significantly reduced. The proposed self-anti-disturbance control algorithm is verified by experiments, and the lubricating oil static pressure acquisition followability and monitoring accuracy are greatly improved. Variable hydraulic lubricating oil static pressure acquisition and monitoring can be effectively and stably adjusted by a predesigned electrohydraulic servo control system in the field of power hydraulic fluid lubrication.
3
Sun, Jun, Xiao Zhang, Jianxiong Zhu, Yaming Gao, Hu Wang, Xiaoyong Zhao, Qin Teng, Yanping Ren und Guixiang Zhu. „On the lubrication characteristics of piston ring under different engine operation conditions“. Industrial Lubrication and Tribology 72, Nr. 1 (09.09.2019): 101–8. http://dx.doi.org/10.1108/ilt-06-2019-0220.
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Purpose Currently, lubrication analysis of piston ring is generally done under engine rated operating condition. However, the engine (such as the vehicle engine) does not always operate in rated operating condition, and its operating condition changes frequently in actual use. In addition, the lubrication status of piston ring is generally assumed as the flooded lubrication or a certain form of poor lubrication in most of the lubrication analysis. Design/methodology/approach In this paper, based on the equations about the flow rate of lubricating oil and the variation of control volume, the flow model of lubricating oil in the piston ring-cylinder liner conjunction is established. The lubrication analysis of piston ring for a four-stroke engine under different engine operating conditions is done, in which the lubricating oil at the inlet of piston ring is considered as the lubricating oil attached on the relevant location of cylinder wall after the piston ring moves over at the previous stroke. Findings There is remarkable difference for the lubrication characteristics of the piston ring under different engine operating conditions. The worst lubrication status of piston ring may not take place under engine rated operating condition. Originality/value In this paper, based on the measured engine cylinder pressure, the lubrication analysis of piston ring for a four-stroke engine under different engine operating conditions is done in which the lubricating oil supply condition at the inlet of piston ring is considered. The results of this paper are helpful for the design and research of engine piston ring-cylinder liner conjunction.
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Liu, Guomin, Xueqiao Wu, Meng Zou, Yuying Yan und Jianqiao Li. „Experimental Study on Drag Reduction Characteristics of Bionic Earthworm Self-Lubrication Surface“. Applied Bionics and Biomechanics 2019 (23.10.2019): 1–8. http://dx.doi.org/10.1155/2019/4984756.
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In the present study, a coupling bionic method is used to study the drag reduction characteristics of corrugated surface with lubrication. In order to test the drag reduction features, bionic specimen was prepared inspired by earthworm surface and lubrication. Based on the reverse engineering method, nonsmooth curve of earthworm surface was extracted and the bionic corrugated sample was designed, and the position of lubrication hole was established by experimental testing. The lubricating drag reduction performance, the influence of normal pressure, the forward velocity, and the flow rate of lubricating fluid on the forward resistance of the bionic specimens were analyzed through a single factor test by using the self-developed test equipment. The model between the forward resistance and the three factors was established through the ternary quadratic regression test. The results show that the drag reduction effect is obvious, the drag reduction rate is 22.65% to 34.89%, and the forward resistance decreases with the increase of the forward velocity, increases with the increase of the normal pressure, and decreases first and then becomes stable with the increase of flow rate of lubricating fluid. There are secondary effects on forward resistance by the three factors, and the influencing order is as follows: normal pressure>flow rate of lubricating fluid>forward velocity.
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Yu, Xiao Dong, Xiu Li Meng, Hui Jiang, Xiao Zhong Lou, Bo Wu, Hong Jun Xiang, Xian Zhu Sun, Chang Qing Yang und Jun Feng Wang. „Numerical Simulation on Oil-Flow-State of Gap Oil Film in Sector Cavity Multi-Pad Hydrostatic Thrust Bearing“. Applied Mechanics and Materials 37-38 (November 2010): 743–47. http://dx.doi.org/10.4028/www.scientific.net/amm.37-38.743.
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Hydrostatic thrust bearing lubrication is significantly affected by the oil flow state of gap oil film, but it can not be measured by experiment and analysis. For this problem, the oil flow state of gap oil film in sector cavity multi-pad hydrostatic thrust bearing during rotation was simulated by using computational fluid dynamics, lubricating theory, and Finite Element Method. Laminar model and κ-ε turbulence model were adopted to model incompressible steady equations, and the equations were discreted by using Finite Volume Method and Second-order Finite Difference. By comparing the calculated results of numerical simulation and semi-empirical theoretical equation, the numerical simulation is proved feasible in oil film state analysis parameter prediction, which can overcome the deficiency of single model and get good effect. Streamlines and velocity vectors show that the lubricating oil flow in the resistive oil edges and oil cavities are laminar flow under the conditions of speed and flow in less than a certain value, while the flow and speed are more than a certain value, the lubricating oil flow in the resistive oil edges is also laminar flow, but the lubricating oil flow in the oil cavities is turbulent flow, then determines critical flow and critical speed. The critical flow and critical speed were determined, it provides a theoretical basis of the temperature field and thermal field deformation calculation.
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Sun, Jun, Feifei Hao, Guangsheng Liu, Hu Wang, Qin Teng, Enming Miao, Xiaoyong Zhao, Yanping Ren und Guixiang Zhu. „Research on the lubrication performance of engine piston skirt–cylinder liner frictional pair considering lubricating oil transport“. International Journal of Engine Research 21, Nr. 4 (04.06.2018): 713–22. http://dx.doi.org/10.1177/1468087418778658.
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In current lubrication analysis of piston skirt, the flooded status is generally considered in the piston skirt–cylinder liner frictional pair in all strokes of an engine operating cycle. However, the quantity of lubricating oil at the entrance of piston skirt cannot always ensure the sufficient lubrication status of piston skirt–cylinder liner frictional pair when the piston moves from the bottom dead center to the top dead center in actual engine. In this article, based on the model of piston secondary motion, fluid lubrication, and lubricating oil flow, the lubrication performance of piston skirt–cylinder liner frictional pair is analyzed, in which the quantity of lubricating oil detained on the surface of cylinder liner after the piston skirt moves from the top dead center to the bottom dead center and is considered as the quantity of lubricating oil at entrance of piston skirt when the piston moves from the bottom dead center to the top dead center. The results show that compared with current analysis, in which the sufficient lubrication of piston skirt–cylinder liner frictional pair is assumed in all strokes of engine, there are remarkable changes for the lubrication performance of piston skirt–cylinder liner frictional pair and the piston secondary motion when the lubrication status of the frictional pair in the upstroke of piston is determined by considering actual lubricating oil transport in the lubrication analysis of piston skirt.
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Ding, Yuan Fa, Wen Guo Huo, Xiang Dong Su und Lan Zhang. „A Grinding Wheel of Self-Lubrication with Solid Powder Lubricant and Centrifugal Impeller for Green Grinding Process of TC4 Alloy“. Key Engineering Materials 748 (August 2017): 269–74. http://dx.doi.org/10.4028/www.scientific.net/kem.748.269.
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A new self-lubrication concept based on the techniques including of dry grinding and solid lubricating was proposed for green grinding process. And a kind of self-lubrication grinding wheel was designed with solid powder lubricant and centrifugal impeller inside. The self-lubricating was achieved by the blow out of the solid powder lubricant from the inner cavity of the wheel by the centrifugal force to the grinding surface. The experiments were conducted to study the friction and wear properties of the new cylindrical wheel samples manufactured by the proposed concept. The results showed that the flow channel diameters of 1 to 1.5 mm are the best for the blowing out of the solid lubricant to realize the continuous lubricating. After grinding, the surface coating is even, and the sizes of the abrasive particles are relatively uniform with no peeling into blocks. Although there is a certain wear loss of the grinding surface, the wear rate of the particles on the sample wheels is less than that of the traditional grinding wheel. The computational simulation of the self-lubrication wheel is conducted with the RSM method with FLUENT software to analyze the flow field in the wheel cavity of solid lubricant inside, which is meaningful for the study of the motion of the solid lubricant and useful for optimum design of the wheel design to realize the best self-lubricating performance.
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Nainal, Razi, Muhammad Yunus und Saifuddin Saifuddin. „Analisis Kebutuhan Pelumasan saat Kegagalan Sistem Kelistrikan (Black Out) pada Kompresor Boil Off Gas (K-6801) pada Fasilitas LNG Hub“. Jurnal Teknologi 23, Nr. 2 (31.10.2023): 63. http://dx.doi.org/10.30811/teknologi.v23i2.3831.
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The lube oil system in the compressor plays an important role for any rotating equipment because it functions to provide lubrication against the effects of friction on various rotating equipment. This overhead tank works by gravity to distribute lubricating oil from operating speed to zero rpm. The large volume of lube oil provides lubrication to the compressor bearings when the normal circulating flow from the pump stops and is assisted by the backup flow from the overhead tank. The purpose of this approach is to calculate the need for lubrication when an electrical fault occurs in the Boil-off Gas compressor (K-6801). Based on the results of analysis and calculations where the Boil-Off Gas Compressor (K-6801) is the object of observation, the amount of lubricating oil needed for the remaining rounds is 1885 liters while the amount of lubricating oil available in the field is 1528,286 liters. From the calculation results, 1528,286 liters is sufficient based on the reference API Standard 614 edition 4, chapter 2, Section 1.4.10.2 because it has exceeded the 20% reduction from 1885 liters, namely 1508 liters. The height of the overhead tank that is suitable for flowing lubricating oil to the compressor bearings is 5.2588 meters above the compressor with a distribution pipe diameter of 3 inches and an orifice bore diameter of 1 inches.
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Zhang, Jingwei, Yuan Zhang, Yanling Zhao und Wenguang Han. „Research on Lubrication Characteristics of Cage-Free Ball Bearing with Local Functional Slot“. Lubricants 11, Nr. 5 (02.05.2023): 203. http://dx.doi.org/10.3390/lubricants11050203.
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The factors affecting the lubrication effect of a ball bearing without cage and containing a functional slot are analyzed, including the structural parameters of the functional slot, the speed of the rolling element, and the deformation of the contact surface, in order to establish the initial oil volume equation. Based on the multiple mesh method and Matlab programming, the established model is solved by obtaining the distribution rules of oil film pressure, oil film thickness, and oil film flow rate between the rolling element, the conventional raceway, and the functional slot under different speed conditions, and by determining the optimal functional slot depth. Finally, through an experiment performed to verify the lubrication effect of the lubricating oil in the functional slot, the results show that the lubricating oil in the functional slot can have a lubricating effect, and the initial amount of lubricating oil needed increases with an increase in speed.
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Naufal Annafi, Muhammad, Asman Ala und Jarot Delta Susanto. „Optimizing Air Compressor Productivity in Supporting Operational Activities on The Mt Ship. Gamalam“. International Journal of Advanced Multidisciplinary 2, Nr. 2 (14.09.2023): 608–11. http://dx.doi.org/10.38035/ijam.v2i2.304.
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Air compressors are auxiliary machines on board that can produce high pressure air. This research was conducted because the productivity of the air compressor was less than optimal, causing air production and the performance of the air compressor to be less than optimal and disrupting operational activities on the ship. The impact that occurs when air production is reduced in the air compressor, the ship cannot operate according to the contract specified by the company, because the initial start of the main engine or main engine on board requires compressed air. Many factors can cause reduced production of air produced by air compressors, including the lack of performance of the suction valve and exhaust valve on the high pressure section which causes less maximum or longer time for filling air into the air bottle, low flow of the lubrication system on the piston which causes no compression to produce air. This research was carried out with the aim of identifying and analyzing the causes of the lack of performance of the suction and exhaust valves on high pressure sections and low flow of the piston lubrication system which results in less optimal performance of the air compressor when filling into air bottles. The method used in this study uses a qualitative descriptive method using primary and secondary data collection approaches and techniques. The lack of performance of the inlet and exhaust valves can be corrected by cleaning the carbon deposits on the valves and leveling the valve surfaces. The low flow of the lubrication system on the piston can be done by checking the lubricating oil pump, cleaning the lubricating oil filter, changing the lubricating oil periodically according to the instruction manual book, and adding lubricating oil according to the specifications of the air compressor.
11
Bao, Heyun, Xiaonan Hou und Fengxia Lu. „Analysis of Oil-Air Two-Phase Flow Characteristics inside a Ball Bearing with Under-Race Lubrication“. Processes 8, Nr. 10 (01.10.2020): 1223. http://dx.doi.org/10.3390/pr8101223.
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Under-race lubrication can increase the amount of lubricating oil entering a bearing and greatly improve lubrication and cooling effects. The oil-air two-phase flow characteristics inside a ball bearing with under-race lubrication play a key role in lubrication and cooling performance. The motions of ball bearing subassemblies are complicated. Ball spin affects the oil volume fraction. In this paper, the coupled level set volume of fluid (CLSVOF) method is used to track the oil-air two-phase flow inside the ball bearing with under-race lubrication. The influence of various factors on the oil volume fraction inside the ball bearing with under-race lubrication is investigated, particularly rotating speeds, inlet velocity and the size of oil supply apertures under the inner ring. The influence of the ball spinning is analyzed separately. The result demonstrates that, on account of the centrifugal force, lubricating oil is located more on the outer ring raceway at rotational speeds of 5000 r/min, 10,000 r/min, 15,000 r/min and 20,000 r/min. The oil volume fraction inside the bearing gradually increases at an oil inlet velocity of 5 m/s, 10 m/s and 15 m/s. The circumferential distribution of oil is also similar. As the diameter of the oil supply aperture increases from 1.5 mm to 2 mm, the oil volume fraction increases inside the ball bearing. However, the oil volume fraction slightly decreases from 2 mm to 2.5 mm of oil supply aperture diameter. Ball spin does not affect the circumferential distribution trend of the lubricating oil, but slightly reduces the oil volume fraction. Furthermore, ball spin causes the surface fluid to rotate around its rotation axis and increases the speed.
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Chien, S. Y., und M. S. Cramer. „Load and loss for high-speed lubrication flows of pressurized gases between non-concentric cylinders“. Journal of Fluid Mechanics 867 (20.03.2019): 1–25. http://dx.doi.org/10.1017/jfm.2019.113.
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We examine the high-speed flow of pressurized gases between non-concentric cylinders where the inner cylinder rotates at constant speed while the outer cylinder is stationary. The flow is taken to be steady, two-dimensional, compressible, laminar, single phase and governed by a Reynolds lubrication equation. Approximations for the lubricating force and friction loss are derived using a perturbation expansion for large speed numbers. The present theory is valid for general Navier–Stokes fluids at nearly all states corresponding to ideal, dense and supercritical gases. Results of interest include the observation that pressurization gives rise to large increases in the lubricating force and decreases in the fluid friction. The lubrication force is found to scale with the bulk modulus. Within the context of the Reynolds equation an exact relation between total heat transfer and power loss is developed.
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Duratun Nasiqiati Rosady, Siti, Eli Novita Sari und Jauharotul Maknunah. „STUDI NUMERIK KARAKTERISTIK DISTRIBUSI ALIRAN DAN TEMPERATUR PADA PENDINGIN OLI PELUMAS DENGAN VARIASI MULTI-STEP BLOCKER“. Jurnal Inovasi Teknologi Manufaktur, Energi dan Otomotif 1, Nr. 1 (31.08.2022): 21–36. http://dx.doi.org/10.57203/jinggo.v1i1.2022.21-36.
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Lube oil cooler serves to lower the temperature of the lub eoil in the gas turbine lubrication system. The problem that often occurs is the oil exit temperature is still high. This causes process failure in the lubrication system because the working temperature exceeds the allowable temperature. This failure is caused by non-uniformity flow distribution of the lube oil cooler. Therefore, further studies are needed to improve the uniformity of flow distribution. To increase the uniformity of flow, modification of the shape of the inlet header and variations of the lubricating oil capacity on the performance of the lubricating oil cooler were carried out. The research method used is numerical simulation with ANSYS FLUENT software. The simulation is carried out in 3 dimensions with a turbulence model in the form of k-ε RNG using a pressure based solution solver. Making geometry and design specifications using GAMBIT software. Geometric data is the dimensions of the lubricating oil cooling system and data from previous studies. The simulation is carried out in the form of a base line header with a modification of the inlet header, namely a multi-step blocker with variations of the Reynolds Number of 3088, 5146, and 7616. Based on the results of numerical simulations that have been carried out, the lowest Non-uniformity flow rate is at Re = 3088 sebesar, Ф = 0.01594, Exit Temperature 76.620 oC, and Pressure Drop 639.265 N/m2.
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Liu, He, Yu Dai, Jifu Jia und Xiang Zhu. „CFD Investigation into Flow Characteristics of a Special Splash Lubrication in Light Helicopters“. Aerospace 9, Nr. 9 (29.08.2022): 482. http://dx.doi.org/10.3390/aerospace9090482.
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Lubricating oil flow characteristics are the primary concern in the main reducer of light helicopters. To improve the lubricating performance of the main reducer, a special lubrication system is innovatively constructed by adding two oil-guiding tubes to the hub of the output gear, and the influence of the oil-guiding tubes is investigated through CFD (computational fluid dynamics) techniques. A CFD model of the gearbox integrated with the VOF (volume of fluid) technique was established to explore the flow characteristics of the oil–air two-phase flow inside the gearing system. To validate the proposed CFD model, a specialized testing rig is devised and manufactured to examine the features of oil distribution. The effects of the structure parameters of the oil-guiding tubes and operating conditions on the lubrication performance are explored. Comparing experimental and numerical findings reveals that the inner diameter of the oil-guiding tube and the rotational speed of the driven gear have a significant influence on the lubrication performance. In contrast, the length of the installation end of the oil-guiding tube, its angle, and the oil-immersion depth show little impact.
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Liu, Le Min, Yong Zang und Yuan Yuan Chen. „Study on the Hydrodynamic Lubrication Behavior in Cold Rolling Process“. Advanced Materials Research 154-155 (Oktober 2010): 731–37. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.731.
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Partial lubrication in cold rolling process has been investigated. The average flow Reynolds equation for rolling lubrication is set. This equation considers the pressure-viscosity effect and the average flow effect. Lubricating factors such as inlet velocity, surface waviness, lubricant viscosity are studied in analyses. The results for lubrication equation show that inlet velocity and lubricant viscosity have some influence on the value of rolling friction. And the results also show that surface waviness has great influence on both rolling pressure and rolling friction.
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Liu, Xiyao, Zhiwei Lu, Hao Dong, Yan Cao und Xueming Qian. „Friction and Wear Characteristics of Microporous Interface Filled with Mixed Lubricants of M50 Steel at Different Loads“. Materials 13, Nr. 13 (30.06.2020): 2934. http://dx.doi.org/10.3390/ma13132934.
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Improving the tribological performance of M50 steel under the conditions of wide load range is of great significance. In this study, the interfacial structure of surface micropores filled with Sn–Ag–Cu or Sn–Ag–Cu/whisker carbon nanotubes (whiskerCNT) of M50 material was prepared by laser additive manufacturing and high-temperature infiltration. From 2 to 22 N, the lubrication characteristics of Sn–Ag–Cu and whiskerCNT in surface micropores of M50 was investigated. Results indicate that Sn–Ag–Cu can precipitate to the worn surface and form a lubricating layer, which has a good lubricating effect. Moreover, the flow behavior of Sn–Ag–Cu on a worn surface can play the role of crack healing. At higher load, the strength of the lubricating film is enhanced by whiskerCNT, which renders the lubricating film not vulnerable to premature rupture.
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Yu, Xiao Dong, Hong Jun Xiang, Xiao Zhong Lou, Xiu Li Meng, Hui Jiang, Wei Dong Ji, Chang Qing Yang und Xian Zhu Sun. „Influence Research of Velocity on Lubricating Properties of Sector Cavity Multi-Pad Hydrostatic Thrust Bearing“. Advanced Materials Research 129-131 (August 2010): 1104–8. http://dx.doi.org/10.4028/www.scientific.net/amr.129-131.1104.
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Lubricating characteristics of sector cavity multi-pad hydrostatic thrust bearing are affected significantly by velocity, poor design can cause lubricant film rupture and dry friction, even leading to failure of hydrostatic bearing tribology. For this problem, the Computational Fluid Dynamics and the lubrication theory have been used to analyze velocity characteristics of the parameters such as cavity pressure of oil, oil cavity flow and film thickness, to gain relationship between velocity and lubricating properties of sector cavity multi-pad hydrostatic thrust bearing, avoiding the occurrence of hydrostatic bearing tribological failure. It is shown that along with the speed of the worktable increasing, the flow of lubricant oil caused by inertia and centrifugal force become larger, the flow of efflux from the oil cavity also become larger, causing the pressure drop of the oil cavity, the thinning of the film thickness, the occurrence of film rupture and dry friction and failure of hydrostatic bearing tribology. The study provides the basic data for the hydrostatic thrust bearing design, the lubrication and the experiment, implements of the prediction of the hydrostatic thrust bearing lubrication velocity characteristics, and reaches the purpose of reducing economic loss.
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Czaban, Adam, und Andrzej Miszczak. „Influence of Pressure Changes on the Viscosity of Lubricating Oil in CFD Simulations of Conical Bearing Hydrodynamic Lubrication“. Journal of KONBiN 52, Nr. 3 (01.09.2022): 259–78. http://dx.doi.org/10.2478/jok-2022-0036.
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Abstract The aim of this study is to consider the effect of pressure on the viscosity of lubricating oil in the adopted model of hydrodynamic lubrication and on the calculated flow parameters and operating parameters of a conical slide bearing. The numerical analysis consisted in solving the Reynolds type equation for the process of stationary hydrodynamic lubrication.
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Li, Mao Sheng, und Qun Gui Du. „Lubricating Characteristic Analysis on Automobile Continuously Variable Transmission“. Applied Mechanics and Materials 529 (Juni 2014): 321–25. http://dx.doi.org/10.4028/www.scientific.net/amm.529.321.
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In order to conduct lubricating characteristic analysis on automobile continuously variable transmission, this paper divides overall model of transmission on the basis of the idea of blocking simulation. Then it generates shed oil model of differential mechanism and oil gathering model of oil groove. Set monitoring surface at the position of reverse gear shaft catcher groove in shed oil model of differential mechanism and oil groove in oil gathering model of oil groove to monitor its conditions of oil-taking. Consider the received flow from the two monitoring surfaces in simulation process as evaluation index of effects of transmission lubrication system, as well as conduct quantitative evaluation on lubricating effects of transmission lubrication system. The results show that all of working condition with second gear 1500rpm, reverse gear shaft and oil groove have comparative ideal lubrication effects on input axis.
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Zhang, Xiaohan, Tao Yu, Hao Ji, Feng Guo, Wenbin Duan, Peng Liang und Ling Ma. „Analysis of Water-Lubricated Journal Bearings Assisted by a Small Quantity of Secondary Lubricating Medium with Navier–Stokes Equation and VOF Model“. Lubricants 12, Nr. 1 (07.01.2024): 16. http://dx.doi.org/10.3390/lubricants12010016.
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Due to the low viscosity of water, water-lubricated bearings are susceptible to significant wear and noise in demanding operating conditions. It has been demonstrated that a small quantity of secondary lubricating medium can improve the lubrication performance of water-lubricated contact surfaces and achieve the purpose of temporary risk aversion. As a further step, the feasibility of the proposed idea is experimentally validated on a water-lubricated bearing test bench. A numerical model that couples the N–S equation and the VOF model is then developed to investigate the behavior of the flow field lubricated by pure water and water with a small quantity of the secondary lubricating medium. This model provides the predictions of important quantities such as the load-carrying capacity, the secondary lubricating medium volume fraction and the contact pressure under different lubricated conditions. The results show that the secondary lubricating medium can enter into the contact region and improve the lubrication performance of water-lubricated bearings, especially at lower shaft rotational speeds. Therefore, the feasibility of our proposed idea is verified, which provides a promising approach to reduce the wear and friction of water-lubricated bearings when they encounter short-time severe working conditions.
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Zhang, Xu. „Transient Flow Characteristics of a Pressure Differential Valve with Different Valve Spool Damping Orifice Structures“. Strojniški vestnik - Journal of Mechanical Engineering 70, Nr. 3-4 (28.03.2024): 141–58. http://dx.doi.org/10.5545/sv-jme.2023.691.
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Lubrication system failure is a significant cause of in-flight shutdown incidents in aviation engines. The pressure differential valve, an essential component of a certain type of aviation engine lubrication system, is responsible for controlling the flow rate and pressure of the lubricating oil. Comprehending the transient flow characteristics of the pressure differential valve is of paramount importance for the secure operation of lubrication systems. This paper establishes a transient flow model of a pressure differential valve based on a transient computational fluid dynamics (CFD) method, and the experimental validation demonstrates the effectiveness of the computational model. The internal flow characteristics of the differential pressure valve at different stages during the opening process were studied. Additionally, four transient lubricating oil flow models with different valve spool damping orifice were established to analyse the impact of damping orifice structure on valve spool movement characteristics, pressure control characteristics, and flow field distribution. The results indicate that when the diameter of the valve spool damping orifice increases from 0.3 mm to 1.0 mm, the valve spool displacement and fluid force increase by 88 % and 20 %, respectively. Meanwhile, the peak valve spool velocity, peak oil supply pressure, and steady-state value decreased by 15 %, 29 %, and 34 %, respectively. As the length of the valve spool damping orifice increases from 0.894 mm to 4.0 mm, the growth rate of valve spool displacement and fluid force gradually decreases, with the peak valve spool velocity decreasing by 7 %. This study has potential significance for the structural optimization and application of pressure differential valve in lubrication systems.
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Mitsuya, Y., und T. Ohkubo. „High Knudsen Number Molecular Rarefaction Effects in Gas-Lubricated Slider Bearings for Computer Flying Heads“. Journal of Tribology 109, Nr. 2 (01.04.1987): 276–82. http://dx.doi.org/10.1115/1.3261351.
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This paper presents a study into the gas lubrication capability of an ultra-thin 0.025 μm film (converted value for ambient air film). The experimental results obtained using subambient helium as the lubricating film are compared with the calculated results using the modified Reynolds equation considering flow slippage due to the molecular mean free path effects. This comparison confirms that the slip flow model holds true within the range of the present experiments, and that the modified Reynolds equation is applicable for designing the computer flying heads operating at such thin spacing. The reason for the excellent agreement is discussed considering the locality of rarefaction effects on the lubricating surfaces and the anisotropy of these effects between the film thickness and the slider width.
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Xiang, Yuhao, Tengjiao Lin und Wen Liu. „Characteristics of internal flow field and convection heat transfer in planetary gear reducer of shield machine“. Journal of Physics: Conference Series 2383, Nr. 1 (01.12.2022): 012023. http://dx.doi.org/10.1088/1742-6596/2383/1/012023.
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Based on RNG k-ε turbulence model and dynamic grid technology, the internal fluid dynamics model of splash lubrication three stage planetary gear reducer system is established. The distribution of lubricating oil and convective heat transfer characteristic in the system at different input rotational speeds are analyzed. The results show that at high speed condition, the oil gas mixing volume and the degree of atomization of lubricating oil are higher, and the convective heat transfer coefficient of tooth surface is larger, and it takes less time for the convective heat transfer coefficient to reach equilibrium. Meanwhile, the mean convective heat transfer coefficient on the tooth surface of sun gear, planetary gear and ring gear decreases successively.
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Meng, Guang Yao, Ji Wen Tan und Yi Cui. „Grinding Fluid Flow Field Modeling and Multi-Parameter Numerical Analysis Based on Smooth Model“. Advanced Materials Research 156-157 (Oktober 2010): 948–55. http://dx.doi.org/10.4028/www.scientific.net/amr.156-157.948.
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Relative motion between grinding wheel and workpiece makes the lubricant film pressure formed by grinding fluid in the grinding area increase, consequently, dynamic pressure lubrication forms. The grinding fluid flow field mathematical model in smooth grinding area is established based on lubrication theory. The dynamic pressure of grinding fluid field, flow velocity and carrying capacity of lubricating film are calculated by the numerical analysis method. An analysis of effect of grinding fluid hydrodynamic on the total lifting force is performed, and the results are obtained.
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Miszczak, Andrzej, und Krzysztof Wierzcholski. „Operating Parameters of a Slide Bearing with Parabolic-Shaped Slide Surfaces with Consideration of the Stochastic Changes in the Lubrication Gap Height“. Journal of KONES 26, Nr. 4 (01.12.2019): 171–78. http://dx.doi.org/10.2478/kones-2019-0105.
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AbstractIn this article, the authors present the equations of the hydrodynamic theory for a slide bearing with parabolic-shaped slide surfaces. The lubricating oil is characterized by non-Newtonian properties, i.e. an oil for which, apart from the classic oil viscosity dependence on pressure and temperature, also an effect of the shear rate is taken into account. The first order constitutive equation was adopted for considerations, where the apparent viscosity was described by the Cross equation. The analytical solution uses stochastic equations of the momentum conservation law, the stream continuity and the energy conservation law. The solution takes into account the expected values of the hydrodynamic pressure EX[p(ϕ,ζ)], of the temperature EX[T(ϕ,y,ζ)], of the velocity value of lubricating oil EX[vi(ϕ,y,ζ)], of the viscosity of lubricating oil EX[ηT(ϕ,y,ζ)] and of the lubrication gap height EX[εT(ϕ,ζ)]. It was assumed, that the oil is incompressible and the changes in its density and thermal conductivity were omitted. A flow of lubricating oil was laminar and non-isothermal. The research concerned the parabolic slide bearing of finite length, with a smooth sleeve surface, with a full wrap angle. The aim of this work is to derive the stochastic equations, that allow to determine the temperature distribution, hydrodynamic pressure distribution, velocity vector components, load carrying capacity, friction force and friction coefficient, in the parabolic sliding bearing, lubricated with non-Newton (Cross) oil, including the stochastic changes in the lubrication gap height. The paper presents the results of analytical and numerical calculation of flow and operating parameters in parabolic sliding bearings, taking into account the stochastic height of the lubrication gap. Numerical calculations were performed using the method of successive approximations and finite differences, with own calculation procedures and the Mathcad 15 software.
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Lubrecht, A. A., W. E. Ten Napel und R. Bosma. „The Influence of Longitudinal and Transverse Roughness on the Elastohydrodynamic Lubrication of Circular Contacts“. Journal of Tribology 110, Nr. 3 (01.07.1988): 421–26. http://dx.doi.org/10.1115/1.3261645.
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The effect of longitudinal and transverse roughness on the elastohydrodynamic lubrication of circular contacts was investigated numerically for two different lubricating conditions. The influence of the amplitude and the wavelength of the roughness texture was also studied. The results are compared with predictions from the flow factor method.
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Yan, Ke, Tingting Yin, Jiannan Sun, Jun Hong und Yongsheng Zhu. „Flow Mechanism Characterization of Porous Oil-Containing Material Base on Micro-Scale Pore Modeling“. Materials 14, Nr. 14 (13.07.2021): 3896. http://dx.doi.org/10.3390/ma14143896.
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The self-lubricating effect of the porous oil-containing cage is realized by storing and releasing lubricants through its internal micro-scale pore structure. The internal flow and heat transfer process in the micron-submicron pore structure is crucial to the self-lubricating mechanism of the porous oil-containing cage. To this end, a new modeling method of porous cage was proposed based on random seeds theory, and the local two-dimensional models of porous cage with different micro-scale pore structure were established. The multiphysics coupling simulation analysis of lubricating oil inside the porous cage with the effect of centrifugal force and thermal expansion was carried out based on the COMSOL Multiphysics platform. In order to characterize the micro-scale pore structure, new structural parameter indicators, such as relative surface perimeter, effective porosity, tortuosity and fluid properties related to the internal flow process, were all extracted from the above models. Combing with the Hagen–Poiseuille equation, a flow resistance model of oil flow inside the porous oil-containing cage was obtained. Finally, comparison of simulation results and analytical solutions of the micro-scale resistance model was carried out to verify the correctness of the micro-scale resistance model. The work provides a new direction for the study of the lubrication mechanism of the porous oil-containing cage.
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Wang, Yingjia, Minshan Liu, Dongchen Qin und Zhenwei Yan. „Performance of high-speed hydrodynamic sliding bearings with lubricating oils combining laminar and turbulent flows“. Advances in Mechanical Engineering 12, Nr. 6 (Juni 2020): 168781402093338. http://dx.doi.org/10.1177/1687814020933389.
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High-speed hydrodynamic sliding bearings use lubricating oil that can have laminar and turbulent flow states, yet turbulent states remain relatively unstudied. This study combines theoretical analysis, numerical modeling, and experiments to analyze lubrication fluids in such bearings. It considers Reynolds equations, energy equations, and temperature-viscosity relationships under laminar and turbulent flows. The governing equations are solved by the finite difference method. Two-dimensional distributions of Reynolds number, pressure, and temperature in the bearing film, as well as the lubrication characteristics like bearing capacity and frictional force under working conditions, are analyzed. Single and mixed flow states are compared, which demonstrates the coexistence states of laminar and turbulent flows in an oil film under specific working conditions. Oil film flow distributions differ significantly according to rotational speed and eccentric conditions. Flow changes under high eccentricity are complex. The characteristics of oil films in a single flow state deviate significantly from those in mixed flow. Changes in flow state and heat should not be ignored during analysis of the lubrication performance of high-speed bearings.
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Xu, Rang Shu, Juan Juan Wang, Wei Xu und Li Bo Liu. „Numerical DPM Model for Two-Phase Flow in Aero-Engine Bearing Chamber“. Advanced Materials Research 201-203 (Februar 2011): 2267–70. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.2267.
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The main bearing chamber is a major part of the lubrication system in aero-engine, it is important to know the influence of operation parameters on air/oil two-phase flow, so as to optimize the design of aero-engine lubrication system. The air/oil two-phase flow in a simplified bearing chamber model in an aero-engine is simulated by means of discrete phase model (DPM) and wall-film model with CFD approach. The simulation results coincide with the existing experimental data. The oil film thickness and concentration of droplets in bearing chamber are presented at different rotational speeds and different lubricating oil flow rates.
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Lu, Fengxia, Meng Wang, Wenbin Pan, Heyun Bao und Wenchang Ge. „CFD-Based Investigation of Lubrication and Temperature Characteristics of an Intermediate Gearbox with Splash Lubrication“. Applied Sciences 11, Nr. 1 (31.12.2020): 352. http://dx.doi.org/10.3390/app11010352.
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In this study, we propose a computational fluid dynamics (CFD)-based method to study the lubrication and temperature characteristics of an intermediate gearbox with splash lubrication. A volume of fluid (VOF) multiphase model was used to track the interface between oil and air. A multiple reference frame (MRF) model was adopted to accurately simulate the movement characteristics of the gears, bearings, and the surrounding flow field. The thermal-fluid coupling computational model of an intermediate gearbox with splash lubrication was then established. Combined with experimental results, we verified that the lubricating oil temperature was below the limit requirement (<110 °C). The numerical results revealed that large amounts of lubricating oil were splashed onto the tooth surfaces near the gear meshing area. A large convective heat transfer coefficient corresponds to a low gear tooth surface temperature. The tooth surface temperature of the driving gear is higher than that of the driven gear. The distribution law of oil volume fraction of the bearing roller was jointly affected by the roller rotation direction and gravity. The convective heat transfer coefficient of the roller wall was largely related to the lubrication environment of the roller, including the oil distribution inside the bearing cavity and the flow rate.
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PORTER, ROGER S., und JULIAN F. JOHNSON. „FLOW PROPERTIES OF MODERN LUBRICATING OILS“. Journal of the American Society for Naval Engineers 73, Nr. 3 (18.03.2009): 511–15. http://dx.doi.org/10.1111/j.1559-3584.1961.tb02617.x.
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Koprowski, Mariusz. „An analysis of lubricating medium flow through unsymmetrical lubricating gap of conical slide bearing“. Polish Maritime Research 14, Nr. 4 (01.10.2007): 59–63. http://dx.doi.org/10.2478/v10012-007-0041-x.
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An analysis of lubricating medium flow through unsymmetrical lubricating gap of conical slide bearing This paper presents a computer analysis of lubricating medium flow through unsymmetrical lubricating gap of conical slide bearing. Numerical calculations were carried out with the use of the software Matlab 7.1 and Mathematica 5.2 for example conical slide bearings of different values of cone apex angles of pin and sleeve and set values of relative eccentricity and skewing angle as well as dimensionless bearing length equal to 1.
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Velikanov, N. L., und V. A. Naumov. „Efficiency of the pump in the lubricating and cooling fluid supply system“. Proceedings of Higher Educational Institutions. Маchine Building, Nr. 6 (759) (Juni 2023): 72–78. http://dx.doi.org/10.18698/0536-1044-2023-6-72-78.
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Cooling and lubrication are the most important processes in such operations as the metal workpiece cutting, drilling and grinding. It becomes necessary in machining a workpiece to supply the lubricating and cooling fluids to the tool operation zone in the required amount, which is provided by the pump and the connecting pipeline. Pump operation essentially depends on properties of the lubricating and cooling fluid, in particular, on its viscosity affecting the flow, pressure and energy costs. The paper propose an algorithm for determining the pump hydraulic characteristics, when supplying the lubricating and cooling fluid. As an example, the submersible vertical centrifugal pumps were considered designed for using in the machines cooling systems and systems supplying the lubricating and cooling fluid. Empirical dependences are presented of the pump head, consumed power, efficiency and indicator of the specific energy cost on the water supply. The obtained dependences were recalculated for the pump operating conditions with liquids, which viscosity was much higher than that of water. It is shown that viscosity significantly changes the pump characteristics during its operation in the network.
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Bao, Heyun, Xiaonan Hou, Xin Tang und Fengxia Lu. „Analysis of temperature field and convection heat transfer of oil-air two-phase flow for ball bearing with under-race lubrication“. Industrial Lubrication and Tribology 73, Nr. 5 (13.07.2021): 817–21. http://dx.doi.org/10.1108/ilt-03-2021-0067.
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Purpose Under-race lubrication can increase the amount of lubricating oil entering a bearing and greatly improve lubrication and cooling effects. The oil-air two-phase flow and heat transfer characteristics inside a ball bearing with under-race lubrication play a key role in lubrication and cooling performance. The purpose of this paper is to study these two characteristics, and then provide guidance for lubrication and heat dissipation of bearing with under-race lubrication. Design/methodology/approach In this paper, a simplified three-dimension heat transfer model of ball bearing with under-race lubrication is established; the coupled level set volume of fluid method is used to track the oil-air two-phase flow, and the Palmgren method is used to calculate the heat generation. The influence of rotation speed and inlet velocity on oil volume fraction, temperature and convection heat transfer is investigated. A temperature test for under-race lubrication is carried out. Findings Because of the centrifugal force, lubricating oil is located more on the outer ring raceway. As the rotation speed decreases and the inlet velocity increases, the oil volume fraction increases and the temperature decreases. Furthermore, the area with high oil volume fraction has a large convection heat transfer coefficient and low temperature. The error between the simulation temperature and the test temperature is within 10%. Originality/value The research on the temperature field and convection heat transfer characteristics of under-race lubrication ball bearings at different rotation speeds and inlet velocities is rarely involved.
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Zhang, Zheng, Fancong Meng, Feng Zhao, Kai Zheng, Bin Yang, Yongguang Cheng und Daqing Zhou. „Investigation into the Evolution of Unsteady Flow of Lubricating Oil System in Guide Bearing of a Pump Turbine Unit“. Journal of Physics: Conference Series 2285, Nr. 1 (01.06.2022): 012017. http://dx.doi.org/10.1088/1742-6596/2285/1/012017.
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Abstract The water-guide bearing lubricating oil system of pumped storage unit is prone to oil dumping and oil spillage during the start-up of the unit, which seriously threatens the safe and stable operation of the unit. In this study, a three-dimensional unsteady numerical simulation is performed to investigate the causes of oil dumping and oil spillage of a water-guide bearing lubricating oil system of a pumped storage power plant unit based on the VOF (volume of fluid) multiphase flow model and Realizable k-ε model. The unsteady flow characteristics inside the rotating oil basin and pump-type Pitot tube during the start-up process are analyzed. The results demonstrate that the change of the external characteristics of the lubricating oil system can be divided into two stages, the initial formation process of the lubricating oil flow and the stable circulation process of the lubricating oil flow. In the initial formation process, the pressure inside the rotating basin is uniformly distributed in the circumferential direction, and a high-pressure zone is generated near the inlet of the pump-type Pitot tube, driving the lubricant flow to the stationary basin above; in the stable flow cycle process, the internal lubricant flow velocity gradually decreases along the radius direction, and a large vortex zone appears behind the pump-type Pitot tube and at the inlet of it. This phenomenon leads to the lubricating oil pressure here to be lower than the saturation vaporization pressure, which may trigger lubricating oil atomization and then overflow from the seal ring. This study is committed to provide theoretical analysis and engineering reference for the investigation of the causes of oil dumping and oil spillage in the lube oil system of water guide bearings of pumped storage units.
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Zhang, Tao, Wei Zhou, Ning Zhao, Huasheng Cui und Zepeng Gao. „Heating Simulation Analysis of Lubrication System at Low Temperature“. Journal of Physics: Conference Series 2541, Nr. 1 (01.07.2023): 012017. http://dx.doi.org/10.1088/1742-6596/2541/1/012017.
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Abstract In this paper, star-ccm+ software is applied to simulate the thermal melting of engine oil under low-temperature conditions, and corresponding models are established based on the physical parameters of the fuel tank, antifreeze, lubricating oil, and heating pipe. Single-phase multi-working medium simulation and VOF (volume of fluid) multi-flow simulation were used to model and analyze the various characteristics of the lubricating oil from solidified state to liquid state under the specific box and heating pipe structure. The results showed that the simulation results of the VOF multiphase flow model under the proposed lubrication system were basically consistent with that of the single-phase multi-working medium model. The simulation efficiency could be improved by using the single-phase multi-working medium model. The simulation results of heating melting can provide a reference for the subsequent design and optimization of the heating pipeline.
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Lee, Cho-Yu, Dani Joseph Veera, Huan-Yuan Chen, Jui-Hung Chang und Kao-Ruei Hung. „Optimization of the lubrication system in a turbocharged engine“. Modern Physics Letters B 33, Nr. 14n15 (28.05.2019): 1940011. http://dx.doi.org/10.1142/s0217984919400116.
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Lubricating the engine reciprocating components effectively against various engine speeds is significant for a proper lubrication system. This paper presents the lubrication system optimization of a twin cylinder 700 c.c. turbocharged engine. A couple of modifications were tested including correction of ducts misalignment, consistence diameter of ducts and replacement of a low flow resistance oil cooler. Compared to the base engine, experimental results prove that differential pressure (DP) between the oil pump and main oil gallery has been decreased to a minimum 19% and maximum 54% at engine speed between 2000 and 7000 rpm. The lower the pressure drop, the lower the flow resistance. Thus, mechanical loss has also been improved.
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Yan, Fei, Ziyu Wang, Yuchen Du, Shijie Su, Yan Zheng und Qinfeng Li. „Research on rheological and flow behavior of lubricating grease in extremely cold weather“. Industrial Lubrication and Tribology 69, Nr. 6 (13.11.2017): 1066–73. http://dx.doi.org/10.1108/ilt-01-2017-0011.
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Purpose This paper aims to investigate the flow characteristics of lubricating grease in extremely cold weather in which it is difficult to convey the grease due to a huge pressure drop. Design/methodology/approach The rheological behavior of grease at various temperatures is studied by a rotary rheometer to determine the constitutive equation of lubricating grease. Based on the Herschel–Bulkley (H–B) model, the flow pattern of grease is then simulated by computational fluid dynamics and compared with the test results. Findings The yield stress increased dramatically when the shear rate was less than 1s−1 in the rheological experiments of continuous shear mode, and the phenomenon was more significant with the decrease in temperature. The rheological data obtained from the continuous shear mode agrees with the H–B equation after the shear thinned. In extremely cold conditions, there is a large yield stress in the lubricating grease; the numerical results show that the viscosity of lubricating grease increased with an increase in temperature, and the viscosity and velocity of lubricating grease showed uneven distribution leading to difficulty of lubricating grease delivery. Originality/value This paper focuses on the flow characteristics of lubricating grease in extremely cold area conditions which is studied rarely. In addition, the continuous shear model and oscillatory model are combined to establish the constitutive equations. Experiment and numerical simulation method are all used by establishing the H–B models.
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Cui, Peijuan, Zhanlin Hou, Luman He, Hui Zheng, Yifeng He, Yuanxun Fan, Linxue An und Yuping Huang. „Experimental Study on In Situ Storage of Grease-Lubricated Ball Screws“. Applied Sciences 14, Nr. 7 (25.03.2024): 2734. http://dx.doi.org/10.3390/app14072734.
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Lubricating grease plays an important role in the rolling screw transmission of the actuation system and is particularly concerned with the performance stability of long-term storage in aerospace applications. In this article, a batch of ball screws that were lying flat in the warehouse for about eight years were selected to extract lubricating grease from the screw raceway after being stored in situ. The oxidation performance, friction performance and rheological properties of lubricating grease were tested and compared to those of fresh grease to analyze and summarize the performance changes in lubricating grease. The transmission efficiency, friction torque, and temperature rise of ball screws without removing the original grease and those filled with fresh grease after cleaning were tested and compared. The impact of grease degradation on the transmission performance of ball screws was analyzed to provide a reference for ball screw lubrication schemes and further accelerated storage experimental design.
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Sun, Hao, und Yi Hua Feng. „The Research of Minimum Quantity Lubrication Mechanism in Grinding with Mechanical Mechanics“. Applied Mechanics and Materials 252 (Dezember 2012): 129–33. http://dx.doi.org/10.4028/www.scientific.net/amm.252.129.
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Effective cooling and lubricating is got by use a small amount of cutting fluid in MQL grinding. Compare grinding performance under various cooling lubrication, reasonable grinding temperature, lower grinding force, improved surface quality and extended wheel life is got in MQL grinding. The grinding performance of MQL grinding is also influenced by many factors, such as the nozzle shape, position, distance, and MQL flow rate.
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Kozdrach, Rafał. „The influence of base oil type on the rheological properties of ecological lubricating greases“. Nafta-Gaz 77, Nr. 2 (Februar 2021): 127–35. http://dx.doi.org/10.18668/ng.2021.02.07.
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The article presents the results of research on the influence the type of base oil in lubricating compositions has on the rheological parameters of selected lubricants. Vegetable, mineral, and synthetic dispersion phases were used to produce lubricating greases. The modified amorphous silica was used as the dispersed phase. However, as a modifying additive was used a substance containing the antioxidants, corrosion inhibitors, and EP/AW additives. The experiments on rheological properties were carried out using a Physica MCR 101 rotational rheometer (manufactured by Anton Paar), equipped with a diffusion air bearing and connected to a pneumatic supply – an oil-free Jun-Air compressor and air drying block. The device is equipped with a Peltier system for temperature control in the range of –20°C to 200°C and an external thermostatic VISCOTHERM V2 system, working in the temperature range of –20°C to 200°C. The rheometer control and measurement data analysis were performed using Rheoplus software. The tests were carried out using a cone-plate measuring system with a shear rate range of 0.01–100 s-1 at 20°C for lubricating compositions prepared on various oil bases. To evaluate the value of rheological parameters, the results of tests of the dependence between shear stress and shear rate (flow curves) were used. For the theoretical determined on the flow curves, the following rheological models were used: Bingham, Herschel–Bulkley, Casson, and Tscheuschner. The values of the shear stress (yield point) in depending on the type of dispersion phase has changed. This proves that the use of a base oil with the appropriate functional properties does not weaken, but reinforces the spatial structure of a lubricating grease. It has an important meaning when selecting construction parameters when designing a central lubrication system with grease made from a vegetable oil base (Abyssinian oil). The rheological properties of the lubricating grease are influenced by the type of base oil and thickener, any additives in the grease, the production technology of the grease, and the conditions in which it is used. The tests revealed an important influence of the base oil on the rheological parameters that describe the behaviour of lubricating compositions subjected to stresses and strains in a lubricating system.
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Raykovskiy, N. A., V. L. Yusha, A. V. Tretyakov und V. A. Zakharov. „Theoretical Estimation of Thermal Deformations of Non-Lubricated Bearings of Low-Flow Turbocharger Units“. Proceedings of Higher Educational Institutions. Маchine Building, Nr. 10 (715) (Oktober 2019): 58–69. http://dx.doi.org/10.18698/0536-1044-2019-10-58-69.
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When designing turbocharger units (microturbines) working with high-temperature flows, it is possible to completely abandon lubrication system and use self-lubricating bearings instead. At the same time, it is important to ensure the required temperature regimes and permissible temperature deformations. Currently, there are no calculation methods that could be used to determine the temperature fields and temperature deformations of the ‘rotor — self-lubrication bearings’ system. The paper proposes a numerical method for calculating bearing assemblies, which takes into account the mutual influence of the operating modes of the turbine unit and the bearing cooling system. The proposed method is tested, and the results of the analysis of temperatures and temperature deformations are presented.
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Jędrychowska, Sylwia. „Optymalizacja warunków oznaczania wody metodą miareczkowania kulometrycznego z odparowaniem dla olejów smarowych“. Nafta-Gaz 77, Nr. 7 (Juli 2021): 480–89. http://dx.doi.org/10.18668/ng.2021.07.07.
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The knowledge of the water content of various petroleum products, including lubricating oils, additives and various innovative products, is important from the point of view of manufacturing, purchasing or selling them, due to the impact on their quality and performance characteristics. In the case of lubricating oils, the presence of water can lead to premature corrosion and wear, the formation of deposits, which leads to reduced lubrication and premature clogging of filters, reduced action of additives or undesirable bacterial growth. The article presents the study on the selection of optimal conditions for the determination of water content by coulometric Karl-Fischer titration with evaporation in lubricating oils. The tests were carried out using a coulometer with a titration cell without a diaphragm by Metrohm, 917 Coulometer model with an automatic sample feeder equipped with a heating chamber 885 Compact Oven Sample Changer. Various types of lubricating oils were selected for testing, namely engine oils of different viscosity classes (5W/40, 10W/40, 15W/40, 5W/30), gear oil, hydraulic oil, turbine oil, base oil and hydraulic fluid. All selected samples of lubricating oils were tested in four different measuring conditions: 110°C and 20 ml/min; 150°C and 50 ml/min, 180°C and 50 ml/min and 150°C and 70 ml/min. It was found that for all the lubricating oils, the best results were obtained with a furnace temperature setting of 150°C and a carrier gas flow of 50 ml/min or 70 ml/min. The influence of various factors, such as the sample weight, the furnace temperature, the carrier gas flow velocity on the test course and the analysis speed, was determined. Increased carrier gas flow of up to 70 ml/min does not shorten the analysis time. In some cases, an increase in the oven temperature may speed up the analysis, but this is quite risky for some samples that decompose at given temperature. It is therefore safer to conduct the test at an oven temperature of 150°C. The speed of analysis is most influenced by an appropriate selection of the sample quantity under analysis. Depending on the water content in the tested sample, the appropriate sample weight should be selected. It should be small enough not to excessively extend the analysis, but also large enough that the amount of titrated water is at least twice as large as in the blank.
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Wang, Jian Mei, Qing Xue Huang, Zheng Yi Jiang und Kiet Tieu. „The Effects of Shear Stress on the Lubrication Performances of Oil Film of Large-Scale Mill Bearing“. Advanced Materials Research 76-78 (Juni 2009): 713–18. http://dx.doi.org/10.4028/www.scientific.net/amr.76-78.713.
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A new coupling numerical algorithm has been developed to integrate Finite Difference Method (FDM) with Boundary Element Method (BEM) to analyze shear performance of oil film by iteratively solving a series of equations such as the film flow velocity and shear stress equations for contact bodies in bearing system. With consideration of the variations of viscosity and density with pressure and temperature, the effects of shear stress of oil film layers on lubrication performance of contact surfaces under different loadcases were discussed. Moreover, Germany-made Anton Paar MRD (Magnetic Rheologic Device) was used to determine the relationship between the viscosity and shear stress of lubricating oil. The conclusions were verified to be beneficial to the further study on lubricating performance of heavy contact components and to prolong their service lives.
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Novakov, I. A., F. S. Radchenko, A. S. Ozerin, A. S. Chevtaev und O. A. Krotikova. „RESEARCH THERMODYNAMICS OF VISCOUS FLOW OF BASE OILS THAT ARE THE BASIS FOR LUBRICANT COMPOSITIONS“. IZVESTIA VOLGOGRAD STATE TECHNICAL UNIVERSITY, Nr. 12(247) (24.12.2020): 89–93. http://dx.doi.org/10.35211/1990-5297-2020-12-247-89-93.
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The thermodynamic characteristics of the process of viscous flow of mineral base lubricating oils (SGK grade AU, naphthenic T-110) and synthetic (Synfluid PAO 6 cSt) were found. It was found that the activation energy and the change in the activation entropy of the viscous flow of mineral oils, considered trade marks, are higher than that of synthetic oil. The obtained thermodynamic data made it possible to establish the mechanism of the flow of lubricating oils.
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Pardo-García, Carlos, Sofia Orjuela-Abril und Jhon Pabón-León. „Investigation of Emission Characteristics and Lubrication Oil Properties in a Dual Diesel–Hydrogen Internal Combustion Engine“. Lubricants 10, Nr. 4 (05.04.2022): 59. http://dx.doi.org/10.3390/lubricants10040059.
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Hydrogen is considered one of the main gaseous fuels due to its ability to improve thermal performance in diesel engines. However, its influence on the characteristics of lubricating oil is generally ignored. Thus, in the present investigation, an analysis of the effect on the physical and chemical properties of lubricating oil with mixtures of diesel fuel–hydrogen was carried out, and the environmental impacts of this type of mixture were assessed. The development of the research was carried out using a diesel engine under four torque conditions (80 Nm, 120 Nm, 160 Nm and 200 Nm) and three hydrogen gas flow conditions (0.75 lpm, 1.00 lpm and 1.25 lpm). From the results, it was possible to demonstrate that the presence of hydrogen caused decreases of 3.50%, 6.79% and 4.42% in the emissions of CO, HC, and smoke opacity, respectively. However, hydrogen further decreased the viscosity of the lubricating oil by 26%. Additionally, hydrogen gas produced increases of 17.7%, 29.27%, 21.95% and 27.41% in metallic components, such as Fe, Cu, Al and Cr, respectively. In general, hydrogen favors the contamination and oxidation of lubricating oil, which implies a greater wear of the engine components. Due to the significantly negative impact of hydrogen on the lubrication system, it should be considered due to its influence on the economic and environmental cost during the engine’s life cycle.
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Du, Fengming, Changduo Chen und Kaiguang Zhang. „Fluid Characteristics Analysis of the Lubricating Oil Film and the Wear Experiment Investigation of the Sliding Bearing“. Coatings 12, Nr. 1 (07.01.2022): 67. http://dx.doi.org/10.3390/coatings12010067.
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The sliding bearing is an important component in machines. The characteristics of the oil film fluid of the sliding bearing is the key factor affecting lubrication, which will affect the wear and reliability of the sliding bearing. Herein, the lubricating oil of the sliding bearing is studied, the oil film flow model considering the cavitation effect is established, the pressure and temperature distribution of the oil film under different rotational speeds is explored, and its influence on oil film pressure and temperature are analyzed. Furthermore, wear tests are carried out to measure the wear amount of the bearing bush under different rotational speeds, and the influence of the fluid characteristics of the lubricating oil film on bearing wear is explored. The simulation and experimental study in this paper can provide a reference for the design of sliding bearings.
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Chu, Li Ming, und Hsiang Chen Hsu. „A Layered-Rheology Model for Thin Film Elastohydrodynamic Lubrication of Circular Contacts“. Applied Mechanics and Materials 764-765 (Mai 2015): 160–64. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.160.
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The modified Reynolds equation for power-law fluid is derived from the viscous adsorption theory for thin film elastohydrodynamic lubrication (TFEHL) of circular contacts. The lubricating film between solid surfaces is modeled as three fixed layers, which are two adsorption layers on each surface and a middle layer. The differences between classical EHL and TFEHL with non-Newtonian lubricants are discussed. Results show that the TFEHL power law model can reasonably calculate the pressure distribution, the film thickness, and the velocity distribution. The thickness and viscosity of the adsorption layer and the flow index influence significantly the lubrication characteristics of the contact conjunction.
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Chu, Li-Ming, Hsiang-Chen Hsu und Chia-Hsiang Su. „POWER LAW FLUID MODEL INCORPORATED INTO THIN FILM ELASTOHYDRODYNAMIC LUBRICATION OF CIRCULAR CONTACTS“. Transactions of the Canadian Society for Mechanical Engineering 39, Nr. 3 (September 2015): 547–56. http://dx.doi.org/10.1139/tcsme-2015-0042.
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The modified Reynolds equation for power-law fluid is derived from the viscous adsorption theory for thin film elastohydrodynamic lubrication (TFEHL) of circular contacts. The lubricating film between solid surfaces is modeled as three fixed layers, which are two adsorption layers on each surface and a middle layer. The differences between classical EHL and TFEHL with power-law lubricants are discussed. Results show that the TFEHL power law model can reasonably calculate the pressure distribution, the film thickness, and the velocity distribution. The thickness and viscosity of the adsorption layer and the flow index significantly influence the lubrication characteristics of the contact conjunction.
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Liu, Yansheng, und Honghai Xu. „Analysis on the flow field of straddle monorail train gear box“. Journal of Physics: Conference Series 2174, Nr. 1 (01.01.2022): 012038. http://dx.doi.org/10.1088/1742-6596/2174/1/012038.
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Abstract Taking the gearbox of straddle monorail train as the research object, reasonable simplification of the geometric structure of the gearbox. Based on incompressible gas-liquid two-phase flow in gearbox, the overlapping grid technology in STAR-CCM+ software is used to solve the internal flow field of the gearbox. The effects of gear forward rotation and initial oil injection on the mass flow rate of lubricating oil in each bearing inlet/return hole in the gearbox are studied and analyzed. The results show that: with the increase of the initial oil injection rate, the mass flow rate of the oil inlet hole of each bearing increases; The positive and reverse rotation has a great influence on the mass flow rate of lubricating oil in each bearing intake hole. In the case of the same amount of oil injection, the mass flow rate of each intake hole in forward rotation is larger than that in reverse condition. The results of this research provide a theoretical basis for the detailed structure design and improvement of lubricating oil runner in gearbox.