Artículos de revistas: "Oil jet lubrication"

1

Dai, Yu, Feiyue Ma, Xiang Zhu, Qiao Su, and Xiaozhou Hu. "Evaluation and Optimization of the Oil Jet Lubrication Performance for Orthogonal Face Gear Drive: Modelling, Simulation and Experimental Validation." Energies 12, no. 10 (2019): 1935. http://dx.doi.org/10.3390/en12101935.

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The oil jet lubrication performance of a high-speed and heavy-load gear drive is significantly influenced and determined by the oil jet nozzle layout, as there is extremely limited meshing clearance for the impinging oil stream and an inevitable blocking effect by the rotating gears. A novel mathematical model for calculating the impingement depth of lubrication oil jetting on an orthogonal face gear surface has been developed based on meshing face gear theory and the oil jet lubrication process, and this model contains comprehensive design parameters for the jet nozzle layout and face gear pair. Computational fluid dynamic (CFD) numerical simulations for the oil jet lubrication of an orthogonal face gear pair under different nozzle layout parameters show that a greater mathematically calculated jet impingement depth results in a greater oil volume fraction and oil pressure distribution. The influences of the jet nozzle layout parameters on the lubrication performance have been analyzed and optimized. The relationship between the measured tooth surface temperature from the experiments and the corresponding calculated impingement depth shows that a lower temperature appears in a situation with a greater impingement depth. Good agreement between the mathematical model with the numerical simulation and the experiment validates the effectiveness and accuracy of the method for evaluating the face gear oil jet lubrication performance when using the impingement depth mathematical model.

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2

Hu, Xiaozhou, Pengfei Li, Can Quan, and Jianing Wang. "CFD Investigation on Oil Injection Lubrication of Meshing Spur Gears via Lattice Boltzmann Method." Lubricants 10, no. 8 (2022): 184. http://dx.doi.org/10.3390/lubricants10080184.

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The meshless Lattice Boltzmann Method (LBM) is introduced and employed to solve the complex two-phase flow problem of jet lubrication of meshing spur gears. Computational fluid dynamics (CFD) simulations based on LBM are carried out using the model of an oil jet impacting rotating gear presented by available experiments, which reveals how the liquid column is broken throughout the tooth tip cutting off the oil jet. Typical oil flow phenomena obtained by simulations are compared with experiments, demonstrating good qualitative agreement, which validates the feasibility of LBM to simulate the air–oil–structure interaction problems involved in the jet lubrication of spur gears. A three-dimensional (3D) simulation model of a spur gear pair lubricated by an oil jet is established, and simulations with different operating conditions are conducted. The evolution process of the oil jet while injecting into the meshing zone is captured, and the effects of jet velocities, jet heights and jet angles on the lubrication performance are investigated.

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3

Dai, Yu, Xi Chen, Duan Yang, Lanjin Xu, and Xiang Zhu. "Performance of a New Aeronautic Oil-Guiding Splash Lubrication System." Lubricants 10, no. 6 (2022): 130. http://dx.doi.org/10.3390/lubricants10060130.

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Among ever-increasing demands for low power consumption, low weight, and compact reducer systems, an oil-guiding splash lubrication method integrating the oil-guiding cylinder and pipes is suggested to be more suitable for light helicopters, instead of conventional splash or oil jet lubrication. Aiming at improving the lubrication and cooling performance of this special lubrication method, this paper introduces an oil-guiding channel to increase oil quantity reaching the driving gear, bearings, and spline. Firstly, the lubrication and cooling effect of the oil-guiding channel in the main gearbox is investigated at various speeds and oil depths by leveraging with a computational fluid dynamics (CFD) technique. Then, a specialized test bench is set up and utilized for experiments to verify the CFD study. These results show that the numerical results are very satisfactory with the data of experimentation, and the maximum value of relative errors is no more than 15%. What is more, the oil flow rate passing through the monitoring plane with the oil-guiding channel is much greater than that without the channel by about three orders of magnitude. It also suggests that the oil-guiding channel could dramatically increase the lubricating oil in the meshing gear pair, and significantly improve the lubrication and cooling effect.

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4

Yang, Duan, He Liu, Jianfeng Zhong, Xiang Zhu, and Yu Dai. "Influence of Nozzle Layouts on the Heat-Flow Coupled Characteristics for Oil-Jet Lubricated Spur Gears." Lubricants 11, no. 1 (2023): 25. http://dx.doi.org/10.3390/lubricants11010025.

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Aiming to explore the influence of nozzle layouts on the lubrication and cooling performance of spur gears under oil jet lubrication conditions, this paper introduces a heat-flow coupled analysis method to predict the temperature field of the tooth surface with different nozzle layouts. Firstly, the friction heat formulas integrating the coefficient of friction and average contact stress are presented for calculating heat generation. We also present the impingement depth model, which considers the nozzle orientation parameters, jet velocity, and gear structure of the given spur gear pair for laying out the nozzle. Then, a heat-flow coupled finite element analysis method is exploited to resemble the jet lubrication process and gain the gear temperature characteristics. Finally, the numerical results of this model compare well with those of the experiments, showing that this heat-flow coupled model provides accurate temperature prediction, indicating that the nozzle layouts determined as a function of the oil jet height, deviation distance, and oil injection angle significantly influence the lubrication and cooling performance. Further, this study also reveals that the lubrication performance in cases where the nozzle approaches the side of the pinion is relatively superior.

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5

Yin, Mei, Xi Chen, Yu Dai, Duan Yang, Lanjin Xu, and Xiang Zhu. "Numerical and Experimental Investigation of Oil-Guiding Splash Lubrication in Light Helicopter’s Reducers." Aerospace 8, no. 11 (2021): 345. http://dx.doi.org/10.3390/aerospace8110345.

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Limited by the space and weight of the reducer, it is difficult to use traditional oil-jet lubrication and splash lubrication for a light helicopter, so an oil-guiding splash lubrication method is adopted as a research object in this paper. Firstly, the lubrication performance of the oil-guiding cylinder in the main reducer under different rotating speeds, oil levels, and flight attitudes is investigated based on the computational fluid dynamics (CFD) method. Then, a specific test rig is developed, and lubrication tests are carried out to verify the feasibility and correctness of the simulation. These results show that oil level, rotating speed, and flight attitude have a great influence on splash lubrication performance.

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6

Dai, Yu, Jifu Jia, Bin Ouyang, and Jianeng Bian. "Determination of an Optimal Oil Jet Nozzle Layout for Helical Gear Lubrication: Mathematical Modeling, Numerical Simulation, and Experimental Validation." Complexity 2020 (May 12, 2020): 1–18. http://dx.doi.org/10.1155/2020/2187027.

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To provide a basic guidance for the selection of nozzle layout, a mathematical model of the impingement depth for helical gears under oil jet lubrication is established. Furthermore, computational fluid dynamics (CFD) methods are adopted to validate the effectiveness and accuracy of the derived impingement model. Firstly, the distribution characteristics of the oil volume fraction and oil-gas pressure in meshing area were obtained in flow field simulation. Meanwhile, the influence of spray angle, jet velocity, and gear ratio on lubrication effect was obtained. Then, the transient temperature field of the tooth surface was simulated by the method of thermal-fluid coupling analysis, and the lowest temperature distribution and the corresponding oil jet velocity were determined. Finally, experiments on the temperature characteristics measured by an infrared thermal imager of helical gears with different nozzle parameters were carried out in a gear test rig. The simulation results of transient temperature field are in good agreement with those obtained by experiments, and it indicates that the thermal-fluid coupling analysis method is correct and feasible to predict the temperature field of the helical gear pair under oil injection jet lubrication.

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7

Niu, Wentao, Yanzhong Wang, Yanyan Chen, and Guanhua Song. "Air barrier effect in out of mesh jet lubrication of ultra-high speed spur gears." Industrial Lubrication and Tribology 69, no. 2 (2017): 81–87. http://dx.doi.org/10.1108/ilt-12-2015-0208.

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Purpose This paper aims to reveal the mechanism of air barrier effect in jet lubrication and to figure out the influence of gear parameters and conditions on air barrier, thus providing guidance to the design of jet lubrication in ultra-high speed gear cooling system. Design/methodology/approach The computational fluid dynamics method is used to calculate the flow and pressure of ultra-high speed gears. The flow and pressure distributions are obtained under different gear parameters and working conditions, so their variations are obtained. A multiphase flow model is established to simulate the flow regime of oil jet to ultra-high speed gears. Simple experiments are carried out to observe the air barrier effect of high-speed gears. Findings Air barrier effect exists in the jet lubrication of ultra-high speed spur gears, which could prevent oil jet to reach on the gear surfaces. The results show that the generated pressure has positive relations with gear speed, module and width; however, as the increasing of gear width, their marginal contribution to pressure is decreasing. The computational results coincide well with the experimental results. Originality/value The research presented here proposed the air barrier effect of ultra-high speed gears for the first time. It also leads to a design reference guideline that could be used in jet lubrication of ultra-high speed gears, thus preventing lubrication and cooling failures.

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8

Wang, Lin, Ze-kai Du, Yong Wang, Zhi-zhen Zheng, and Guo-ding Chen. "Temperature measurement and error analysis of the transverse plane of oil-jet-lubrication herringbone gear with infrared pyrometers." Review of Scientific Instruments 94, no. 2 (2023): 024902. http://dx.doi.org/10.1063/5.0098729.

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Frictional power losses of high-speed and heavy-load herringbone gearboxes increase the temperature of the gearbox. Thus, real-time surface temperature measurement is significant for evaluating the gearbox lubrication design. A rotating gear test rig with an infrared pyrometer is developed in this paper to conduct real-time and accurate temperature measurements of the transverse plane of the oil-jet-lubrication herringbone gear. First, the influencing factors and measuring errors of surface temperature are analyzed using the infrared pyrometer. The emissivity of the measured surface of a gear tooth painted with matte black is experimentally calibrated. Second, the temperature measurement tests of the oil-jet-lubrication herringbone gear under different conditions are carried out. Measurement errors resulting from purge air pressure, purge air temperature, and oil-jet temperature are also experimentally studied. The results indicate that the purge gas flow can reduce the measurement errors of the infrared pyrometer resulting from oil mist with an appropriate purge air pressure and purge air temperature. Finally, a mathematical curve-fitting of the measurement results between the infrared pyrometer and thermocouple is carried out. The calculated temperatures by the curve-fitting formula are compared with the measured thermocouple temperature, with the relative differences being less than 1 °C. Thus, the curve-fitting formula is credible for the real-time measurement of surface temperature, while the relevant measuring method is also valuable for engineering applications of high-speed gear systems under oil-jet-lubrication conditions.

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9

Wang, Jin Li, Li Quan Li, and Lin Cai. "The Numerical Study of Oil Drop Jet from Oil-Air Lubrication Nozzle." Advanced Materials Research 201-203 (February 2011): 361–64. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.361.

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Nozzle is an important part of oil-air lubrication system. This paper uses Computational Fluid Dynamics (CFD) software FLUENT to study the flow field of oil air, and different air pressure and nozzle throat size are discussed. The results show that: When air pressure is increased from 0.05Mpa to 0.1Mpa, the maximum diameter (2mm) percentage reduces, but the diameters distribution is almost unchanged as the air pressure is increased to 0.3MPa. The throat diameter is decreased, the mean Sauter diameter of oil drop reduces. This paper will provide a theoretical basis for oil-air lubrication nozzle design and selection.

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10

Saitoh, Katsumi, Akihiro Fushimi, Koichiro Sera, and Nobuyuki Takegawa. "Elemental analysis of jet engine lubrication oil and jet fuel using in-air PIXE." International Journal of PIXE 28, no. 03n04 (2018): 85–92. http://dx.doi.org/10.1142/s0129083518500171.

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To understand the elemental characteristics of the exhaust particles from a jet aircraft, we performed an element analysis using an in-air PIXE system of the different lubrication oils of a jet engine (Mobil Jet Oil II, Mobil Jet Oil 254 and Eastman Turbo Oil 2380) and the jet fuel (JET A-1) to determine the effects on the exhaust particles. A high concentration (1,400–2,500 wt.-ppm) of P was detected from the analyzed three oil samples. The high concentration of P is probably due to the tricresyl phosphate (TCP: C[Formula: see text]H[Formula: see text]O4P) contained in the oil samples. The S concentrations of the JET A-1 fuel samples with different collection dates were in the range of [Formula: see text]10 to 530 wt.-ppm. These results aid in determining the component features of nanoparticles emitted from an aircraft.

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11

Fushimi, Akihiro, Katsumi Saitoh, Yuji Fujitani, and Nobuyuki Takegawa. "Identification of jet lubrication oil as a major component of aircraft exhaust nanoparticles." Atmospheric Chemistry and Physics 19, no. 9 (2019): 6389–99. http://dx.doi.org/10.5194/acp-19-6389-2019.

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Abstract. Jet engine aircraft are ubiquitous and significant sources of atmospheric nanoparticles. Using size-resolved particulate samples collected near a runway of the Narita International Airport, Japan, we clearly demonstrate that organic compounds in the ambient nanoparticles (diameters: < 30 nm) were dominated by nearly intact forms of jet engine lubrication oil. This finding provides direct evidence for the importance of unburned lubrication oil as a source of aircraft exhaust nanoparticles and also has an implication for their environmental impacts near airports and in the upper troposphere.

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12

Li, Linlin, Sanmin Wang, Xuyang Zhang, Zhibin Li, Fei Li, and Haoran Zou. "Numerical Calculation Analysis and Characteristic Research on Windage Loss of Oil-Jet Lubricated Aviation Gear Pair." International Journal of Aerospace Engineering 2022 (February 8, 2022): 1–15. http://dx.doi.org/10.1155/2022/7499587.

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The VOF (volume of fluid) multiphase transient simulation model of the windage loss of the gear pair under oil-jet lubrication was carried out by using the dynamic mesh technology with the powerful parallel computing capabilities of the Super Cloud Computing Center. Firstly, a two-phase (oil-gas) turbulence numerical model was established in the process of oil-jet lubrication. The numerical simulation test was designed by orthogonal experiment. The influence of the oil-jet lubrication parameters and their interaction on the windage power loss was studied by means of variance analysis. The results showed that the influence of injection speed on the windage power loss was the largest and proportional, followed by injection temperature and injection pressure, and the latter two factors were inversely proportional. Then, the fitting calculation formula of windage loss related to each influencing factor is obtained based on the numerical simulation results. Furthermore, by observing the velocity vector distribution of the internal flow field of the gearbox with different time, the formation mechanism of windage loss is understood intuitively, and the measures to reduce windage loss are put forward. Finally, the mechanical and energy characteristics of the windage loss under different oil injection parameters are proposed, by analyzing and calculating the differential pressure force, viscous force, turbulent kinetic energy, and turbulent dissipation rate around the gear pair. This paper provides a method guidance for the calculation of windage power loss and efficiency of aviation gear pair under elastohydrodynamic lubrication in engineering application.

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13

Stanković, Miloš, Nenad Kolarević, Nikola Davidovic, and Marko Miloš. "Influence of the air pressure and oil amount to the temperature of the high-speed bearings lubricated by oil mist." Industrial Lubrication and Tribology 74, no. 3 (2021): 335–41. http://dx.doi.org/10.1108/ilt-06-2021-0222.

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Purpose The purpose of this paper is to improve the lubrication and remove as much as possible of the heat generated in the bearing assembly, embedded in the jet engine. Design/methodology/approach To determine the necessary values of the air pressure and oil amount, an experimental approach is used. For that purpose, a custom made test rig is developed. Findings Less amount of oil makes better lubrication conditions, reflected in the smaller temperature of the bearings. Concerning the air pressure, too high and too low air pressure deteriorates the lubrication parameters. An optimum value should be determined experimentally. The influence of oil amount is remarkably bigger than the influence of air pressure. Originality/value This experimental investigation provides an easy and fast way to improve the high-speed bearings lubrication parameters.

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14

Fondelli, Tommaso, Antonio Andreini, Riccardo Da Soghe, Bruno Facchini, and Lorenzo Cipolla. "Numerical Simulation of Oil Jet Lubrication for High Speed Gears." International Journal of Aerospace Engineering 2015 (2015): 1–13. http://dx.doi.org/10.1155/2015/752457.

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The Geared Turbofan technology is one of the most promising engine configurations to significantly reduce the specific fuel consumption. In this architecture, a power epicyclical gearbox is interposed between the fan and the low pressure spool. Thanks to the gearbox, fan and low pressure spool can turn at different speed, leading to higher engine bypass ratio. Therefore the gearbox efficiency becomes a key parameter for such technology. Further improvement of efficiency can be achieved developing a physical understanding of fluid dynamic losses within the transmission system. These losses are mainly related to viscous effects and they are directly connected to the lubrication method. In this work, the oil injection losses have been studied by means of CFD simulations. A numerical study of a single oil jet impinging on a single high speed gear has been carried out using the VOF method. The aim of this analysis is to evaluate the resistant torque due to the oil jet lubrication, correlating the torque data with the oil-gear interaction phases. URANS calculations have been performed using an adaptive meshing approach, as a way of significantly reducing the simulation costs. A global sensitivity analysis of adopted models has been carried out and a numerical setup has been defined.

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15

Dai, Yu, Chongyu Liang, Xi Chen, and Xiang Zhu. "Numerical Analysis for Wetting Behaviors of an Oil Jet Lubricated Spur Gear." Lubricants 10, no. 2 (2022): 17. http://dx.doi.org/10.3390/lubricants10020017.

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As it is widely employed in the aeronautical transmission system, a better understanding of the oil jet lubrication behavior is vital to determine the total system energy consumption. Firstly, this study presents related theoretical models such as the sum of oil jet resistance torque, impingement depth, and wetted area of the oil film for calibrating the physical characteristics of the impact of the oil jet on the gear flank. Then, in terms of the flow phenomenology of the liquid column for the oil jet impact on an isolated spur gear, a detailed transient and spatial flow field analysis becomes available, benefiting from an overset mesh method integrating with a volume-of-fluid (VOF) method. Furthermore, not only the oil jet resistance torque, but also the impingement depth as well as the spatial and temporal evolution of wetted surface by the oil film on the gear tooth given by numerical investigations were compared well with the theoretical calculations.

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16

Putintsev, S. V., S. S. Strelnikova, and S. A. Anikin. "Calculation and identification of the coordinate of oil jet ejection from the gap of a rotating connecting rod bearing." Traktory i sel'hozmashiny 1, no. 5 (2020): 25–32. http://dx.doi.org/10.31992/0321-4443-2020-5-25-32.

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The development of a modern high-speed, energy-efficient and reliable diesel engine requires high-quality lubrication of all friction parts in general and parts of the cylinder-piston group (CPG) in particular. The relevance of this research is due to the insufficient study of the process of oil jet supply of CPG parts, implemented in combined lubrication systems of modern high-speed four-stroke engines and significantly affecting the processes of friction, wear and scuffing of parts of this group. The analysis of previously performed works in this area has shown the feasibility of not only setting up an experiment, but also using computational modeling in order to increase the informa-tivity of the results obtained. The aim of the study was to determine the coordinates of the point of ejection of the oil jet from the gap of the rotating connecting rod bearing. According to the accepted working hypothesis, the point of ejection of the oil jet was the geometric place of the maximum gap in the connecting rod bearing. To calculate the angular coordinate of this point, authors used the method of composing and solving equations of plane motion of a solid body. As a result of the re-search, an analytical expression of the desired coordinate was obtained and its value was calculated during the working cycle for the conditions of the nominal operating mode of the research object – a high-speed universal air-cooled diesel engine 1CH 8.5/8.0 (TMZ-450D). Ensuring the reliability and increasing the accuracy of the results of the study is confirmed by comparison with the calculated data obtained by the method of classical dynamics of piston engines. The array of calculated values of the coordinate of the oil jet ejection point from the gap of the rotating connecting rod bearing of the diesel engine, defined in this paper, will be used for debugging the developed tool for calculating modeling of the oil jet feed process and subsequent optimization of the conditions of lubrication, friction and wear of CPG parts on this basis.

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17

Ozasa, Toshihiro, Takashi Noda, and Toshiaki Konomi. "Elastohydrodynamic Lubrication Model of Connecting Rod Big-End Bearings: Application to Real Engines." Journal of Tribology 119, no. 3 (1997): 568–78. http://dx.doi.org/10.1115/1.2833538.

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This study presents an elastohydrodynamic (EHD) lubrication model of connecting rod big-end bearings developed taking into consideration the effects of inertia and oil holes. In this model, the effect of inertia, namely the body force, on load and deformation is practically and rationally expressed based on engine dynamics and a structural model of a connecting rod. A method of defining the deformation of bearings has been proposed to simplify numerical analysis. The effect of oil holes, namely an oil feed hole in a journal and an oil jet hole in a bearing, is considered as a boundary condition in the EHD lubrication theory. Calculations of oil flow rate and power loss are also included.

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18

Bianchi, Eduardo C., Rafael L. Rodriguez, Rodolfo A. Hildebrandt, et al. "Application of the auxiliary wheel cleaning jet in the plunge cylindrical grinding with Minimum Quantity Lubrication technique under various flow rates." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 233, no. 4 (2018): 1144–56. http://dx.doi.org/10.1177/0954405418774599.

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Minimum Quantity Lubrication is an alternative technique to conventional techniques that are related to environmental sustainability and economic benefits. This technique promotes the substantial reduction of the amount of coolant employed in machining processes, representing a mitigation of risks to people’s health that are involved with the process. On the other hand, it has been reported in the literature that some problems of using the Minimum Quantity Lubrication technique can impair the grinding efficiency. One of these problems is associated with wheel clogging phenomenon, which is caused by inefficient chip removal from the cutting zone as well as from mixture of metal dust and oil accumulated on the wheel surface during grinding. If chips lodge inside the pores of the grinding wheel as machining progresses, they will adversely affect dimensional and geometric quality of final product. Also, this will require more frequent dressing. A solution for this problem can be an effective cleaning system of the abrasive wheel during grinding with the traditional Minimum Quantity Lubrication technique Assisted with Wheel Cleaning Jet. In this context and aiming to explore the various potential health, environmental and economic benefits that have been widely reported in the literature about the use of Minimum Quantity Lubrication technique in grinding, this study presents an application of the Minimum Quantity Lubrication technique at flow rates (30, 60 and 120 mL/h) and assisted with wheel cleaning jet (Minimum Quantity Lubrication + Assisted with Wheel Cleaning Jet) in plunge grinding of a hardened steel with an aluminum oxide wheel. Experiments were also carried out with traditional Minimum Quantity Lubrication (without wheel cleaning) and with the conventional coolant techniques for comparison. The output variables were geometrical errors (surface roughness and roundness) of the workpiece, diametric wheel wear, acoustic emission, vibration and tangential cutting force. Results showed that Minimum Quantity Lubrication + Assisted with Wheel Cleaning Jet (with wheel cleaning jet) not only outperformed the traditional Minimum Quantity Lubrication technique in all the parameters analyzed, but in some cases it proved to be compatible with the conventional coolant technique under the conditions investigated. Also, most of values of the output parameters tested decreased with increase in flow rate.

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19

Massini, Daniele, Tommaso Fondelli, Bruno Facchini, Lorenzo Tarchi, and Federico Leonardi. "High Speed Visualizations of oil Jet Lubrication for Aero-engine Gearboxes." Energy Procedia 101 (November 2016): 1248–55. http://dx.doi.org/10.1016/j.egypro.2016.11.140.

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Sahoo, Sarthak Prasad, and Saurav Datta. "Machining response of Ti64 alloy under Nanofluid Minimum Quantity Lubrication (NFMQL)." E3S Web of Conferences 309 (2021): 01087. http://dx.doi.org/10.1051/e3sconf/202130901087.

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Rapid wear progression of cutting insert associated with attainment of excessive tool-tip temperature are indispensable causes which limit operational domain of cutting velocity during dry turning of Ti64 alloy. Again, to counteract demerits of flood cooling, jet of air-oil mist (MQL technology) is employed in which water-based coolants or vegetable oils are highly preferable. On the other hand, inclusion of nano-additives within base fluid, and supply the same through MQL system (NFMQL) is also a trendy area of research. Application potential of NFMQL is understood over conventional MQL in terms of better cooling, and lubrication effects due to improved thermo-physical, and tribological properties of the resultant cutting fluid. In this context, present study aims to assess performance of MQL jet containing biodegradable Jatropha oil (carried by pressurized air) when applied during longitudinal turning of Ti64 work alloy. In addition, advantages of 2D layered-structured graphene nanoplatelets (when dispersed into Jatropha oil), in purview of machining performance on difficult-to-cut Ti64 alloy under NFMQL, are studied in this work. Experimental data are compared on the basis of different lubrication conditions (dry, conventional MQL, and NFMQL). Morphology of tool wear is studied in detail. The work extends towards studying chip morphology and machined surface finish of the end product, as influenced by variation in lubrication conditions.

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21

Wen, Baogang, Yemin Li, Meiling Wang, and Yang Yang. "Measurement for Lubricant Distribution in an Angular Contact Ball Bearing and Its Influence Investigation." Lubricants 11, no. 2 (2023): 63. http://dx.doi.org/10.3390/lubricants11020063.

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Oil lubrication is widely adopted in rolling bearings, the characteristics of which affect the oil film formation and friction state, and also the heat generation and dissipation characteristics. However, it is difficult to measure the internal lubrication of rolling bearings in practice, which is of great importance for lubrication and structure design. In this work, one measurement system for lubricant distribution was built and installed on a test rig to obtain original pictures of the lubricant in bearings. Grayscale images were obtained by picture processing to characterize the lubricant distribution, and the image pixels were evaluated for the characterization of lubricant volume. Finally, the measurement of the lubricant distribution in the angular ball bearing was carried out under different lubrication and cage groove conditions, and their influences were investigated. The results show that the lubricant distribution is affected by the oil jet nozzle angle, operating speed, and cage structure. The lubricant capacity among balls and the cage pocket in bearings gradually increased with the increase in the nozzle angle and the depth of the cage grooves, but decreased with the increasing operating speed. The experimental results are helpful to provide a basis for the structure and lubrication design of ball bearings.

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22

Liu, Xiaochu, Xiujie Chen, Zhongwei Liang, et al. "The Tribological Properties of 30CrMnSiA Bearing Steels Treated by the Strengthening Grinding Process under Lubrication Wear." Materials 15, no. 20 (2022): 7380. http://dx.doi.org/10.3390/ma15207380.

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This study used the strengthening grinding process (SGP) to treat the surface of 30CrMnSiA bearing steels. The effect of the jet angle of SGP on the tribological properties of 30CrMnSiA bearing steels under lubrication was investigated. The principle of enhancing wear resistance of 30CrMnSiA bearing steel ascribed to SGP was discussed in detail. The results showed that the lubrication properties and surface hardness of the 30CrMnSiA steels were enhanced due to the formation of numerous microscale microscope oil pockets on the surface layer and the grain refinement of the surface microstructures, resulting in a significant improvement in wear resistance. With the jet angle of SGP increased from 0° to 90°, the friction coefficient, the wear volume, and the specific wear rate were exhibited to reduce rapidly first, then reduce slowly, and then rise slowly. With the optimal parameters at the jet angle of 60°, compared with the control sample, the average friction coefficient was reduced from 0.2235 to 0.1609, and the wear volume and specific wear rate were reduced from 9.04 × 10−3 mm3 to 3.82 × 10−3 mm3 and from 15.13 × 10−3 mm2/N to 6.36 × 10−3 mm2/N, respectively. When the jet angle was 90°, the reduced wear resistance was mainly attributed to the excessive roughness that caused the oil coating on the surface to be severely damaged.

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23

Dai, Y., W. Wu, H. B. Zhou, J. Zhang, and F. Y. Ma. "Numerical Simulation and Optimization of Oil Jet Lubrication for Rotorcraft Meshing Gears." International Journal of Simulation Modelling 17, no. 2 (2018): 318–26. http://dx.doi.org/10.2507/ijsimm17(2)co6.

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24

Babic, D. M., Andrew Torrance, and D. B. Murray. "Soap Mist Jet Cooling of Grinding Processes." Key Engineering Materials 291-292 (August 2005): 239–44. http://dx.doi.org/10.4028/www.scientific.net/kem.291-292.239.

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Grinding, like other abrasive processes, may generate high local temperatures along the arc of cut. These can cause various forms of surface damage in the most sensitive finishing phase of the manufacturing cycle. Traditional cooling methods based on large amounts of water-oil emulsions can be both ineffective and environmentally unacceptable. A new approach to this problem has been devised utilizing the high penetrative power of fast air jets combined with a water/soap mist to greatly improve convective cooling and lubrication along the arc of cut. The results obtained offer striking improvements compared to traditional liquid coolants especially if the relative simplicity of the method is considered.

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25

Keller, M. C., C. Kromer, L. Cordes, C. Schwitzke, and H. J. Bauer. "CFD study of oil-jet gear interaction flow phenomena in spur gears." Aeronautical Journal 124, no. 1279 (2020): 1301–17. http://dx.doi.org/10.1017/aer.2020.44.

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ABSTRACTOil-jet lubrication and cooling of high-speed gears is frequently employed in aeronautical systems, such as novel high-bypass civil aero engines based on the geared turbofan technology. Using such oil-jet system, practitioners aim to achieve high cooling rates on the flanks of the highly thermally loaded gears with minimum oil usage. Thus, for an optimal design, detailed knowledge about the flow processes is desired. These involve the oil exiting the nozzle, the oil impacting on the gear teeth, the oil spreading on the flanks, the subsequent oil fling-off, as well as the effect of the design parameters on the oil flow. Better understanding of these processes will improve the nozzle design phase, e.g. regarding the nozzle positioning and orientation, as well as the nozzle sizing and operation.Most related studies focus on the impingement depth to characterize the two-phase flow. However, the level of information of this scalar value is rather low for a complete description of the highly dynamic three-dimensional flow. Motivated by the advancements in numerical methods and the computational resources available nowadays, the investigation of the oil-jet gear interaction by means of computational fluid dynamics (CFD) has come into focus lately.In this work, a numerical setup based on the volume-of-fluid method is presented and employed to investigate the two-phase flow phenomena occurring in the vicinity of the gear teeth. The setup consists of a single oil-jet impinging on a single rotating spur gear. By introducing new metrics for characterizing the flow phenomena, extensive use of the possibilities of modern CFD is made, allowing a detailed transient and spatially resolved flow analysis. Thus, not only the impingement depth, but also the temporal and spatial evolution of wetted areas on the gear flanks, as well as the evolution of the oil volume in contact with the gear flanks are extracted from the simulation data and compared in a CFD study.The study consists of 21 different simulation cases, whereby the effect of varying the jet velocity, the jet inclination angle, the jet diameter, and the gear speed are examined. Consistent results compared to a simplified analytical approach for the impinging depth are obtained and the results for the newly introduced metrics are presented.

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Pinel, Stanley I., Hans R. Signer, and Erwin V. Zaretsky. "Comparison Between Oil-Mist and Oil-Jet Lubrication of High-Speed, Small-Bore, Angular-Contact Ball Bearings." Tribology Transactions 44, no. 3 (2001): 327–38. http://dx.doi.org/10.1080/10402000108982465.

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27

Van Treuren, K. W., D. N. Barlow, W. H. Heiser, M. J. Wagner, and N. H. Forster. "Investigation of Vapor-Phase Lubrication in a Gas Turbine Engine." Journal of Engineering for Gas Turbines and Power 120, no. 2 (1998): 257–62. http://dx.doi.org/10.1115/1.2818113.

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The liquid oil lubrication system of current aircraft jet engines accounts for approximately 10–15 percent of the total weight of the engine. It has long been a goal of the aircraft gas turbine industry to reduce this weight. Vapor-Phase Lubrication (VPL) is a promising technology to eliminate liquid oil lubrication. The current investigation resulted in the first gas turbine to operate in the absence of conventional liquid lubrication. A phosphate ester, commercially known as DURAD 620B, was chosen for the test. Extensive research at Wright Laboratory demonstrated that this lubricant could reliably lubricate rolling element bearings in the gas turbine engine environment. The Allison T63 engine was selected as the test vehicle because of its small size and bearing configuration. Specifically, VPL was evaluated in the number eight bearing because it is located in a relatively hot environment, in line with the combustor discharge, and it can be isolated from the other bearings and the liquid lubrication system. The bearing was fully instrumented and its performance with standard oil lubrication was documented. Results of this baseline study were used to develop a thermodynamic model to predict the bearing temperature with VPL. The engine was then operated at a ground idle condition with VPL with the lubricant misted into the #8 bearing at 13 ml/h. The bearing temperature stabilized at 283°C within 10 minutes. Engine operation was continued successfully for a total of one hour. No abnormal wear of the rolling contact surfaces was found when the bearing was later examined. Bearing temperatures after engine shutdown indicated the bearing had reached thermodynamic equilibrium with its surroundings during the test. After shutdown bearing temperatures steadily decreased without the soakback effect seen after shutdown in standard lubricated bearings. In contrast, the oil-lubricated bearing ran at a considerably lower operating temperature (83°C) and was significantly heated by its surroundings after engine shutdown. In the baseline tests, the final bearing temperatures never reached that of the operating VPL system.

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28

Ungeheuer, Florian, Dominik van Pinxteren, and Alexander L. Vogel. "Identification and source attribution of organic compounds in ultrafine particles near Frankfurt International Airport." Atmospheric Chemistry and Physics 21, no. 5 (2021): 3763–75. http://dx.doi.org/10.5194/acp-21-3763-2021.

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Abstract. Analysing the composition of ambient ultrafine particles (UFPs) is a challenging task due to the low mass and chemical complexity of small particles, yet it is a prerequisite for the identification of particle sources and the assessment of potential health risks. Here, we show the molecular characterization of UFPs, based on cascade impactor (Nano-MOUDI) samples that were collected at an air quality monitoring station near one of Europe's largest airports, in Frankfurt, Germany. At this station, particle-size-distribution measurements show an enhanced number concentration of particles smaller than 50 nm during airport operating hours. We sampled the lower UFP fraction (0.010–0.018, 0.018–0.032, 0.032–0.056 µm) when the air masses arrived from the airport. We developed an optimized filter extraction procedure using ultra-high-performance liquid chromatography (UHPLC) for compound separation and a heated electrospray ionization (HESI) source with an Orbitrap high-resolution mass spectrometer (HRMS) as a detector for organic compounds. A non-target screening detected ∼200 organic compounds in the UFP fraction with sample-to-blank ratios larger than 5. We identified the largest signals as homologous series of pentaerythritol esters (PEEs) and trimethylolpropane esters (TMPEs), which are base stocks of aircraft lubrication oils. We unambiguously attribute the majority of detected compounds to jet engine lubrication oils by matching retention times, high-resolution and accurate mass measurements, and comparing tandem mass spectrometry (MS2) fragmentation patterns between both ambient samples and commercially available jet oils. For each UFP stage, we created molecular fingerprints to visualize the complex chemical composition of the organic fraction and their average carbon oxidation state. These graphs underline the presence of the homologous series of PEEs and TMPEs and the appearance of jet oil additives (e.g. tricresyl phosphate, TCP). Targeted screening of TCP confirmed the absence of the harmful tri-ortho isomer, while we identified a thermal transformation product of TMPE-based lubrication oil (trimethylolpropane phosphate, TMP-P). Even though a quantitative determination of the identified compounds is limited, the presented method enables the qualitative detection of molecular markers for jet engine lubricants in UFPs and thus strongly improves the source apportionment of UFPs near airports.

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Obata, Fumio, Hisayuki Yamaura, Hisataka Tanaka, Kazuo Morioka, and Hideo Mitsudo. "Centrifugal Lubrication of Spur Gears. (1st Report, Behavior and Flow Rate of Oil Jet)." Transactions of the Japan Society of Mechanical Engineers Series C 60, no. 573 (1994): 1783–90. http://dx.doi.org/10.1299/kikaic.60.1783.

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30

Meier, T., D. Gross, and N. Hanenkamp. "COMPARISON OF SPRAYABILITY AND SOLUBILITY OF BIO-BASED LUBRICANTS WITH LIQUID CARBON DIOXIDE." MM Science Journal 2021, no. 5 (2021): 5077–84. http://dx.doi.org/10.17973/mmsj.2021_11_2021155.

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In recent years, cryogenic minimum quantity lubrication (CMQL) has been established in comparison to pure cryogenic cooling. The used oil has a crucial influence on the success of the technology. The aim of this study is to investigate the influence of oils from renewable resources with regard to their miscibility with carbon dioxide (CO2) and their spraying behavior. Ten different bio-based oils (synthetic ester, natural ester and fatty alcohol) have been examined regarding their suitability for CMQL compared to a conventional mineral hydrocrack oil. A validation based on sprayability and solubility properties with liquid CO2 has been performed. The sprayability and the resulting oil droplet size have an impact on the amount of oil entering the process zone and thus on the lubrication performance of the coolant concept. For this reason, a high-speed camera has been used to capture shadow images of the jet from an external cooling nozzle. In addition the width, intensity and uniformity of the oil application were evaluated. The solubility of the bio-based oils in CO2 is investigated in a static mixing chamber with varied mixing ratio. The miscibility of the bio-based oils in a single channel supply system was investigated with high-speed recordings of a dynamic mixing chamber. The results of the various experimental setups have been compared.

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31

da Silva, E. J., E. C. Bianchi, J. F. G. de Oliveira, and P. R. de Aguiar. "Evaluation of grinding fluids in the grinding of a martensitic valve steel with CBN and alumina abrasives." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 217, no. 8 (2003): 1047–55. http://dx.doi.org/10.1177/095440540321700802.

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In this paper the performances of different cutting fluids and grinding wheel types were analysed in the grinding of SAE HVN-3 workpieces. The resulting residual stress, wheel wear and roughness were evaluated. The influence of the cutting fluid jet velocity vj was also analysed. As a conclusion, the lubrication ability seems to be the governing factor in the cutting fluid performance. The use of CBN wheels can significantly reduce the thermal damage in grinding, leading to compressive residual stresses. The CBN wheel and the cutting oil give an optimum combination for performing this grinding operation.

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32

Ouyang, Bin, Feiyue Ma, Yu Dai, and Yanyang Zhang. "Numerical analysis on heat-flow-coupled temperature field for orthogonal face gears with oil–jet lubrication." Engineering Applications of Computational Fluid Mechanics 15, no. 1 (2021): 762–80. http://dx.doi.org/10.1080/19942060.2021.1918259.

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Wang, A. L., Y. Q. Wei, X. J. Zhu, et al. "Mechanism Analysis of Improving Grinding Quality with Machining Fluids of Oil Filmed Water Droplets." Key Engineering Materials 304-305 (February 2006): 266–70. http://dx.doi.org/10.4028/www.scientific.net/kem.304-305.266.

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Green machining fluids of oil-filmed water-droplets (OW) can be produced by means of combined mist-jet with cooled air, minimum naturally dissoluble oils (botanic or ester oils) and little water, which are beneficial to realize zero-emission machining and thoroughly eliminate the influences of the conventional water-miscible machining fluids on the operators’ health and the eco-environments as well as save energy consumption and lower in production costs. In this study, grinding performances and mechanism analyses of green machining fluids are investigated by comparison to the conventional ones such as emulsion flood coolant on the plane NC grinder. The investigations have further shown that green machining fluids can improve grinding quality in comparison with emulsion flood coolant due to good lubrication and cooling effects, which are applicable to many situations of machining processes.

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34

Niel, D., C. Changenet, F. Ville, and M. Octrue. "Thermomecanical study of high speed rolling element bearing: A simplified approach." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 233, no. 4 (2017): 541–52. http://dx.doi.org/10.1177/1350650117750806.

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Rolling element bearing is an essential component in mechanical transmission because it reduces friction between two rotating parts. Two main approaches to evaluate power losses are proposed in literature: (i) global engineering models using few input data; (ii) local models which are more accurate but need much more information on rolling element bearing geometry. Based on thermal network approach, an intermediate model is developed in this study. This new model allows obtaining lumped information (temperature of rings) with a minimum of input data (external geometry only) and by using global power loss models. This intermediate model is developed for angular contact ball bearing under oil jet lubrication for high speed application. Thermal network results are compared with experimental findings.

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35

Yuan, Song Mei, Si Liu, Lu Tao Yan, and Qing Chun Xiong. "Experimental Evaluation on the Effect of the Position of the Nozzle in End Milling under Minimum Quantity Lubrication Condition." Applied Mechanics and Materials 155-156 (February 2012): 42–46. http://dx.doi.org/10.4028/www.scientific.net/amm.155-156.42.

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Stricter environmental regulations are making the use of an ample amount of conventional coolant impossible because of its negative impact on the environment. Consequently, the use of minimum quantity lubrication (MQL) has been regarded as an promising alternative to conventional fluid coolant applications. Despite several studies, there have been a few investigations about the influence of the MQL nozzle position, such as distance from tool-workpiece contact zone, elevation angles, the included angle between jet direction and feed direction. The current study presents experimental investigations on influences of the above parameters on performance in end milling. Tool wear and surface roughness are experimentally studied to compare the effects of different positions. The results show that the setting location of the nozzle is an important factor regarding the effective application of MQL oil mist.

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36

Qiao, Chenfeng, Jing Yu, Shuai Zhang, Zhengda Liu, and Jinlong Wang. "Combined Effect of a Laser Cladded Coating and Surface Texture on Tribological Performance Under Dry Sliding and Starved Lubrication." Metals and Materials International 28, no. 3 (2022): 666–78. http://dx.doi.org/10.1007/s12540-021-01138-9.

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AbstractFe-based alloy coating was laser cladded on gray cast iron using Ni-Cu alloy as an intermediate layer. The cross section of the laser cladded coating was characterized by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and a Vickers hardness tester. A microdimple texture was created by reciprocating an electrolyte jet with prefabricated mask (REJP) machining on an Fe-based alloy coating. The tribological performances of untextured and textured coatings were examined through interrupted wear tests using an in-house developed reciprocating ball-on-plate tribotester under dry sliding and starved lubricated conditions. The results show that the presence of microdimple edges in the nonconformal contact region has a detrimental effect on the friction performance under dry sliding. However, the microdimples can be beneficial for trapping debris to preserve a smoother contacting surface and thus a lower volume wear track compared to untextured coatings. Due to its role in oil reservoirs and debris entrapment, the microdimple textured coating can maintain a low friction coefficient for a long time period after lubricant oil cutoff and results in a lower volume wear track under starved lubrication. Graphical abstract

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37

Zhang, Jun, Jing-ru Mao, Shun-sen Wang, Jun-jie Zhang, and Peng Sun. "Influence of noncondensible gas on flowing characteristics of multiple nozzle oil jet pump for lubrication system in steam turbine." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 229, no. 8 (2015): 876–88. http://dx.doi.org/10.1177/0957650915593025.

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38

Anastopoulos, George, Petros Schinas, Ypatia Zannikou, Maria Komiotou, Fanourios Zannikos, and Dimitrios Karonis. "Impact of N,N-Bis(2-ethoxyethyl) Fatty Acid Amides on the Lubrication Performance of Kerosene Fuel F-34 for Use in CI Engines." Fuels 4, no. 1 (2023): 19–32. http://dx.doi.org/10.3390/fuels4010002.

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In an attempt to avoid serious problems that can affect the efficiency of refueling ground-operated vehicles and aircraft during military operations, the Armed Forces of the North Atlantic Treaty Organization (NATO) are introducing the use of a unique fuel for both air and land use. The fuel that has been selected is the F-34, similar to Jet A-1, which is used in civil aviation, in order to replace diesel fuel in many applications. It has to be mentioned that tests performed with this fuel, which is kerosene type on the high frequency reciprocating rig (HFRR) have shown that such fuel is responsible for severe wear. This very high wear is related to the very low lubricity of aviation fuel. Having the idea to improve the lubricity of aviation fuel to the level of fuels used in compression ignition engines (diesel fuel), seven N,N-Bis(2-ethoxyethyl) fatty acid amides were formulated from various vegetable oils (sunflower oil, soybean oil, cottonseed oil, olive oil, tobacco seed oil, coconut oil, used frying oil), and they were evaluated as lubricity improvers of the aviation fuel. The required tribological measurements for lubricity rating were carried out by employing ISO 12156-1 test method on an HFRR instrument. The test conditions during the measurements were in the range of 55% to 58% for the relative humidity and 24 °C for the temperature. The results from the tribological measurements showed that all N,N-Bis(2-ethoxyethyl) fatty acid amides used were rated as efficient in order to provide an acceptable mean wear scar diameter (below 460 μm) at concentrations from 150 to 300 ppm. Additive concentrations below 150 ppm did not improve the lubricity at the required level. The increase of N,N-Bis(2-ethoxyethyl) fatty acid amides at concentrations over 300 ppm did not have any significant decrease in the wear scar diameter. A comparison between the N,N-Bis(2-ethoxyethyl) fatty acid amides showed that those formulated by non-polyunsaturated oils like olive oil and coconut oil seem to have better lubricity improver characteristics.

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Cican, Grigore, Daniel Eugeniu Crunteanu, Radu Mirea, Laurentiu Constantin Ceatra, and Constantin Leventiu. "Biodiesel from Recycled Sunflower and Palm Oil—A Sustainable Fuel for Microturbo-Engines Used in Airside Applications." Sustainability 15, no. 3 (2023): 2079. http://dx.doi.org/10.3390/su15032079.

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An experimental assessment of burning behavior of some aviation fuel and biodiesel obtained from waste oil mixture has been performed within this paper. The biodiesel was obtained from sunflower and palm waste oil (SFP) and the mixtures consisted of 10, 30 and 50% biodiesel in regular aviation fuel. The aviation fuel is a mixture of Jet A fuel + 5% Aeroshell 500 oil (called Ke) with the oil being added for turbo-engine’s lubrication. So, the used fuels were: Ke, Ke + 10% SFP, Ke + 30% SFP, Ke + 50% SFP. In first step, SFP was characterized in terms of: density, kinematic viscosity, flash and freezing points and calorific power. Also a deeper analysis was made by using FTIR for all the fuels involved in the experiments. The second step consisted of assessing the chemical reactions that occur during the burning process. Thus starting from the known elemental analysis, the air needed for a stoichiometric reaction has been calculated for each fuel mixtures. Also the resulting CO2 and water has been calculated from the reactions. The third step consisted of experimental testing the burning behavior of the above mentioned fuels on a micro turbo-engine. The used engine was Jet Cat P80® provided by Gunt Hamburg, Barsbüttel, Germany. The variation of: rpm vs. time, burning temperature vs. time and fuel debit vs. rpm are presented for starting and yield procedures. The tests have been conducted at 8 different working regimes of the engine. For each regime, an 1 min testing period was chose, during which burning temperature vs. rpm, fuel debit vs. rpm and thrust force vs. rpm were monitored. For maximum regime, only calculus for burning, thermal efficiencies and specific consumption have been made. As a main conclusion, the engine working behavior was steady throughout the entire range of rpm and for all the blends fed, thus the studied fuel blends may be considered as sustainable fuel for applications that are using micro turbo-engines with main advantages related to pollution and raw materials allowing the production of this type of fuel.

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40

Tonkonogov, Boris P., Leonid N. Bagdasarov, Kseniya A. Popova, and Sergey S. Agabekov. "INVESTIGATION OF INFLUENCE OF ESTER STRUCTURE ON THERMAL-OXIDATIVE OILS STABILITY." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 61, no. 2 (2018): 73. http://dx.doi.org/10.6060/tcct.20186102.5598.

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This work aims are analysis the influence of the structure of esters on their thermo-oxidative stability. Then we select the composition of additives to improve the oxidation properties of aviation turbine engines. As the main method we used the following study: Standard Test Method for Corrosiveness and Oxidation and Stability of hydraulic oils, aircraft turbine engine lubricants and other highly refined oils ASTM 4636-99. It has been found that the esters of dicarboxylic acids and aliphatic alcohols have a low thermal oxidative stability, which may result in frequent change in the oil lubrication system and washing with gasoline or jet fuel. Thus, compositions based on esters of dibasic acids and aliphatic alcohol are good plasticizers having abrasion resistance and frost resistance. Thought they have low pour points and high viscosity index. As a basis for aviation oil hindered esters are recommended, which have high thermal oxidative stability. In the industry esters obtained by etherification of the mixture of acids and a polyhydric alcohol are used. Esters are optimal on its viscosity-temperature properties which were obtained in the reaction of etherification of pentaerythrit and trimetilolpran alcohols, and mixtures of hexane, heptane, nonanoic, octanoic acids. Physico-chemical parameters of esters are improved with increasing in number of functional groups in the molecule. The reason for this is that the esters were obtained by the reaction of etherification of n-C9 acids with pentaerythritol alcohols which forms a sterically hindered ester. This structure has no hydrogen atom in the molecule in β-position, which prevents the formation of cyclic hydrocarbons. However, to get oils with high performance require it is necessary to add additives. Therefore, domestic and foreign literatures and requirements for oxidation stability were analyzed. Based on these data the main requirements were formulated for oil composition of aircraft gas turbine engines. As the results of the oxidative stability testing it were found that to obtain oil which satisfies to all modern requirements for thermal oxidative stability, it requires the use of complex of antioxidants of phenolic and amine types. Forcitation:Tonkonogov B.P., Bagdasarov L.N., Popova K.A., Agabekov S.S. Investigation of influence of ester structure on thermal-oxidative oils stability. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 2. P. 73-79

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41

Stoicescu, Maria, and Eugen Mihail Ionescu. "ROMANIAN ACHIEVEMENTS IN PETROLEUM INDUSTRY." CBU International Conference Proceedings 2 (July 1, 2014): 134–41. http://dx.doi.org/10.12955/cbup.v2.456.

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Petroleum has been and still remains, in equal measure, a friend and an enemy to humanity: a friend for its use in numerous applications over the years, from the lubrication of cart axles to jet fuel; an enemy for creating permanent conflicts between countries, leading to a global conflagration. This layout has perpetuated for over two millennia, until today.The problem of petroleum has a multitude of aspects: economic, political, financial, social, military, legislative and, last but not least, scientific and technical. It has taken a share of sacrifices, which may not be overlooked, to be rightfully called “black gold.” Subject to continuous development, petroleum is still indispensable to our quotidian life, although attempts have been made to replace it with alternative energy sources due to its negative effects on the planet, which are increasingly visible.The present state of petroleum industry is the result of a continuous labor of many generations of researchers, professors, engineers, technicians, foremen, and workers, especially from petroleum producing countries. Romania is one of the first petroleum producers and ranked first in Europe and among the first nations worldwide until the end of the 19th century. During the 20th century, a large number of oil and gas reservoirs were discovered in many countries on all continents; even today Romania still remains an important producer with encouraging perspectives.Romanian contributions to the progress of petroleum industry are noticeable, being appreciated and implemented by the major companies worldwide. This work intends to present just several of these contributions, some of which are highlighted and highly regarded.

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42

Trofimov, I. L., M. M. Svirid, S. V. Boichenko, A. V. Yakovlieva, S. V. Ternovenko, and M. Bartosh. "STUDY OF ANTI-WEAR PROPERTIES OF BLENDED JET FUELS BASED ON CAMELINA OIL ETHYL ESTERS." Energy Technologies & Resource Saving, no. 4 (December 20, 2019): 18–24. http://dx.doi.org/10.33070/etars.4.2019.03.

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Presented studies are related to the spheres of aviation and machine-building. Anti-wear properties of conventional jet fuel, fatty acids ethyl esters bio-additives derived from camelina oil and their blends were investigated experimentally. It was found that lubricity of bio-additive is significantly higher comparing to conventional oil-derived jet fuel. It was found that addition of bio-additive into the composition of jet fuel leads to strengthening of boundary film, decreasing of friction coefficient and improvement of anti-wear properties of fuel blends. The mechanism of fatty acids esters influence on improvement of anti-wear properties of jet fuel was substantiated. It was shown that camelina oil fatty acids esters positively influence on lubricating ability of oil-derived jet fuels and may be used in order to improve anti-wear properties of conventional jet fuels. Ref. 15, Fig. 2, Tabl. 1.

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43

Putintsev, S. V., S. S. Pilatskaya, Alexey S. Ratnikov, and Alexander S. Ratnikov. "Visualization of piston engine cylinder oil-jet lubricating process." Journal of Physics: Conference Series 1177 (February 2019): 012006. http://dx.doi.org/10.1088/1742-6596/1177/1/012006.

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Boichenko, Sergii, Kazimierz Lejda, Anna Iakovlieva, Hubert Kuszewski, and Oksana Vovk. "EXPERIMENTAL STUDY ON ANTIWEAR PROPERTIES FOR BLENDS OF JET FUEL WITH BIO-COMPONENTS DERIVED FROM RAPESEED OIL." Transactions of the Institute of Aviation 245, no. 4 (2016): 352–65. http://dx.doi.org/10.5604/05096669.1230970.

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Antiwear properties of jet fuel, two kinds of biocomponents derived from rapeseed oil and their mixtures were investigated experimentally. Antiwear properties were estimated by the value of the scuffing load and the limiting load of scuffing applied to the friction pair working in a fuel medium. Biocomponents, mainly rapeseed oil FAME and rapeseed oil FAME modified via vacuum distillation were used during the study. It is found that lubricity of biocomponents is significantly higher comparing to conventional jet fuel. It is explained by the chemical composition of FAME: highly polarity of molecules stipulate their good adsorption at the surface of friction pair. High viscosity of biocomponents due to chemical structure positively influence on their lubricity. Adding biocomponents into jet fuel results in strengthening boundary film and thus improves antiwear properties of fuel blends. It is determined that FAME modified via vacuum distillation possess better lubricating ability comparing to standard FAME derived from rapeseed oil. Correlation between viscosity and lubricity of fuel is shown

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45

Gore, D. B., A. T. Revill, and D. Guille. "Petroleum hydrocarbons ten years after spillage at a helipad in Bunger Hills, East Antarctica." Antarctic Science 11, no. 4 (1999): 427–29. http://dx.doi.org/10.1017/s0954102099000541.

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Surface and subsurface sediments from a helipad in Bunger Hills were collected ten years after accidental contamination with a small quantity (probably < 10 litres) of petroleum products. The contaminants are dominated by Jet A2 synthetic lubricating oil which exhibits no evidence of degradation or environmental mobility. In contrast, Jet A1 turbine kerosene is less abundant at the surface than at 20 cm depth. There is no evidence for biodegradation of the Jet A1 in the subsurface sample, suggesting that kerosene is environmentally mobile in the surface sediments.

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46

An, Qing Long, Yu Can Fu, and Jiu Hua Xu. "Research on Cryogenic Pneumatic Mist Jet Impinging Cooling and Lubricating of Grinding Processes." Key Engineering Materials 359-360 (November 2007): 460–64. http://dx.doi.org/10.4028/www.scientific.net/kem.359-360.460.

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Grinding, characterized by its high specific energy consumption, may generate high grinding zone temperature. These can cause thermal damage to the ground surface and poor surface integrity, especially in the grinding of difficult-to-machine materials. Conventional cooling methods based on large amounts of water-oil emulsions can be both ineffective and environmentally unacceptable. Here a new high efficiency cooling technology—cryogenic pneumatic mist jet impinging cooling technology is offered. It utilizes the high penetrative power of fast cryogenic air jet combined with a little quantity of 0°C water to greatly improve heat transfer effects in the machining zone. The experimental results indicated that CPMJI could offer better machining effects compared to cold air jet and traditional flood cooling method in the grinding of titanium alloy.

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Binjua, Decelyne Elly, Seock-Sam Kim, Young-Jun Jang, and Jong-Kuk Kim. "Friction and Wear Mechanisms of Cu/ta-C Coatings Under PAO-4 and PAO-4 with MoDTC Lubrication." Journal of Engineering Advancements 01, no. 04 (2020): 183–87. http://dx.doi.org/10.38032/jea.2020.04.009.

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The tribological behavior of various types of DLC coatings in formulated and non-formulated lubricants are needed for proper usage of these coatings. In this research, the friction and wear mechanism of four different DLC coatings in poly-alpha-olefin type 4 (PAO-4) with and without MoDTC were investigated using ball-on-disc tribometer. One ta-C (tetrahedral amorphous carbon) and three Cu/ta-C (copper doped ta-C) with different sputter power of 50 W, 150 W, and 200 W coatings were deposited on silicon wafers by using FCVA (filtered cathodic vacuum arc) technique for this research. The results indicate that ta-C coating on silicon wafer has the lowest average friction coefficient (CoF) and better wear resistance than Cu/ta-C coating when lubricated under PAO-4 oil with MoDTC. Cu/ta-C with sputter powers of 150 W and 200 W exhibited the highest average friction coefficient under PAO-4 oil with MoDTC. Meanwhile, the average CoF for all samples were similar under PAO-4 base oil. In terms of wear, ta-C coating showed the highest wear rate under PAO-4 base oil then followed by Cu/ta-C with sputter power of 50 W. Nonetheless, Cu/ta-C with sputter powers of 150 W and 200 W exhibited significantly low wear rate under PAO-4 base oil compared to PAO-4 oil with MoDTC.

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48

Liu, Jing, Hengtai Ni, Zidan Xu, and Guang Pan. "A simulation analysis for lubricating characteristics of an oil-jet lubricated ball bearing." Simulation Modelling Practice and Theory 113 (December 2021): 102371. http://dx.doi.org/10.1016/j.simpat.2021.102371.

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Wang, Yanzhong, Wentao Niu, Song Wei, and Guanhua Song. "Influence of spin flow on lubricating oil jet—Design method of oil spray parameters to high speed spur gears." Tribology International 92 (December 2015): 290–300. http://dx.doi.org/10.1016/j.triboint.2015.07.017.

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50

Leland, J. E., and M. R. Pais. "Free Jet Impingement Heat Transfer of a High Prandtl Number Fluid Under Conditions of Highly Varying Properties." Journal of Heat Transfer 121, no. 3 (1999): 592–97. http://dx.doi.org/10.1115/1.2826020.

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Resumen

An experimental investigation was performed to determine the heat transfer rates for an impinging free-surface axisymmetric jet of lubricating oil for a wide range of Prandtl numbers (48 to 445) and for conditions of highly varying properties (viscosity ratios up to 14) in the flowing film. Heat transfer coefficients were obtained for jet Reynolds numbers from 109 to 8592, nozzle orifice diameters of 0.51, 0.84 and 1.70 mm and a heated surface diameter of 12.95 mm. The effect of nozzle to surface spacing (1 to 8.5 mm), was also investigated. Viscous dissipation was found to have an effect at low heat fluxes. Distinct heat transfer regimes were identified for initially laminar and turbulent jets. The data show that existing constant property correlations underestimate the heat transfer coefficient by more than 100 percent as the wall to fluid temperature difference increases. Over 700 data points were used to generate Nusselt number correlations which satisfactorily account for the highly varying properties with a mean absolute error of less than ten percent.

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