Littérature scientifique sur le sujet « Oil jet lubrication »
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Articles de revues sur le sujet "Oil jet lubrication"
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Dai, Yu, Feiyue Ma, Xiang Zhu, Qiao Su et 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 (20 mai 2019) : 1935. http://dx.doi.org/10.3390/en12101935.
Texte intégralRésumé :
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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Hu, Xiaozhou, Pengfei Li, Can Quan et Jianing Wang. « CFD Investigation on Oil Injection Lubrication of Meshing Spur Gears via Lattice Boltzmann Method ». Lubricants 10, no 8 (11 août 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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Dai, Yu, Xi Chen, Duan Yang, Lanjin Xu et Xiang Zhu. « Performance of a New Aeronautic Oil-Guiding Splash Lubrication System ». Lubricants 10, no 6 (18 juin 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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Yang, Duan, He Liu, Jianfeng Zhong, Xiang Zhu et Yu Dai. « Influence of Nozzle Layouts on the Heat-Flow Coupled Characteristics for Oil-Jet Lubricated Spur Gears ». Lubricants 11, no 1 (8 janvier 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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Yin, Mei, Xi Chen, Yu Dai, Duan Yang, Lanjin Xu et Xiang Zhu. « Numerical and Experimental Investigation of Oil-Guiding Splash Lubrication in Light Helicopter’s Reducers ». Aerospace 8, no 11 (15 novembre 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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Dai, Yu, Jifu Jia, Bin Ouyang et Jianeng Bian. « Determination of an Optimal Oil Jet Nozzle Layout for Helical Gear Lubrication : Mathematical Modeling, Numerical Simulation, and Experimental Validation ». Complexity 2020 (12 mai 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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Niu, Wentao, Yanzhong Wang, Yanyan Chen et Guanhua Song. « Air barrier effect in out of mesh jet lubrication of ultra-high speed spur gears ». Industrial Lubrication and Tribology 69, no 2 (13 mars 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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Wang, Lin, Ze-kai Du, Yong Wang, Zhi-zhen Zheng et 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 (1 février 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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Wang, Jin Li, Li Quan Li et Lin Cai. « The Numerical Study of Oil Drop Jet from Oil-Air Lubrication Nozzle ». Advanced Materials Research 201-203 (février 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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Saitoh, Katsumi, Akihiro Fushimi, Koichiro Sera et Nobuyuki Takegawa. « Elemental analysis of jet engine lubrication oil and jet fuel using in-air PIXE ». International Journal of PIXE 28, no 03n04 (janvier 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.
Thèses sur le sujet "Oil jet lubrication"
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Biju, Dona. « A parametric study of oil-jet lubrication in gear wheels ». Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-150786.
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A parametric study of oil-jet lubrication in gear wheels is conducted using Computational Fluid Dynamics (CFD) to study the effect of the different design parameters on the cooling performance in a gearbox. Flow in oil jet lubrication is found to be complex with the formation of oil ligaments and droplets. Various hole radii of 1.5, 2 and 2.5 mm along with five oil velocities is analyzed and it is found that at lower volumetric rates, velocity has more effect on the cooling and at higher volumetric rates, hole size has more effect on the cooling. At higher velocities, the heat transfer is much greater than the actual heat production in the gear wheel, hence these velocity ratios are considered less suitable for jet lubrication. At low velocity ratios of below 2, the oil doesn’t fully impinge the gear bottom land and the sides leading to low cooling. Based on the cooling, impingement length and amount of oil lost to the casing surface, 2 mm hole with a velocity ratio of 2.225 is selected for a successful oil jet lubrication. Varying the inlet position in X, Y and Z directions (horizontal, vertical and lateral respectively) is found to have no improvement on the cooling. Making the oil jet hit the gear wheel surface at an angle is found to increase the cooling. Analysis with the use of a pipe to supply oil was conducted with circular and square inlet and it was found that the heat transfer decreases in both cases due to the splitting of oil jet caused by the combination of the effects of high pressure from the pipe and vorticity in the air field. A method has been developed for two gear analysis using overset meshes which can be used for further studies of jet lubrication in multi-gear systems. Single inlet is found to be better for cooling two gear wheels as it would require a reduced volumetric flow rate compared to double inlets. Oil system requirements for jet lubrication was studied and it was concluded that larger pumps have to be used to provide the high volumetric rates and highly pressurized oil required. On comparing the experimental losses from dip lubrication and the analytical losses for jet lubrication, dip lubrication is found to have lesser loses and more suitable for this case. Good quality lubrication would reduce the fuel consumption and also increase the longevity of gearboxes and hence more research into analyzing alternate lubrication systems can be carried out using the results from this thesis.
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Hehir, Ryan Thomas. « A CFD Investigation of the Two Phase Flow Regimes Inside the Bearing Chamber and De-aerator of a Jet Engine ». Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73386.
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In a jet engine air and oil are mixed during removal from the bearing chamber. Before the oil can be recycled back into the system it must be separated from the air. This is accomplished through use of a de-aerator and breather. The oil air mixture enters the de-aerator first. The de-aerator is a vertical cylinder in which the air and oil enter from the top of the system. Gravity then pulls the oil down as it circulates along the outer wall of the de-aerator. The air is forced out through a top hole and sent to the breather where any oil droplets which remain are furthered separated. A pedestal is located near the bottom of the de-aerator. The pedestal creates a gap between itself and the de-aerator wall. Ideally this gap should be large enough to allow oil to flow through the gap without pooling on the pedestal, but small enough so that air does not flow through the gap. The oil will pool up on the pedestal and reduce the efficiency of the system. In this research, a 30° conical pedestal with a gap of 10.7% was tested. The results showed that the pedestal gap of 10.7% is too large and allows air to flow through the gap. The maximum water was 8.5% and the average water thickness was 5.11%. After studying both the previous experimental data and current CFD data, it is recommended further testing be conducted on pedestal gaps between 8.5% and 9.5%.Master of Science
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MASSINI, DANIELE. « EXPERIMENTAL INVESTIGATION ON THE FLUID-DYNAMIC LOSSES IN POWER GEARBOXES FOR AEROENGINE APPLICATIONS ». Doctoral thesis, 2017. http://hdl.handle.net/2158/1085153.
Texte intégralRésumé :
Enhancing the efficiency of gearing systems is an important topic for the development of future aero-engines with low specific fuel consumption. The transmission system has indeed a direct impact on the engine overall efficiency by means of its weight contribution, internal power losses and lubrication requirements. Thus, an evaluation of its structure and performance is mandatory in order to optimize the design as well as maximize its efficiency. Gears are among the most efficient power transmission systems, whose efficiencies can exceed 99 %, nevertheless in high speed applications power losses are anything but negligible. All power dissipated through losses is converted into heat that must be dissipated by the lubrication system. More heat leads a larger cooling capacity, which results in more oil, larger heat exchangers which finally means more weight. Mechanical power losses are usually distinguished in two main categories: load-dependent and load-independent losses. The former are all those associated with the transmission of torque, while the latter are tied to the fluid-dynamics of the environment which surrounds the gears, namely windage, fluid trapping and squeezing between meshing gear teeth and inertial losses resulting by the impinging oil jets, usually adopted in high speed transmission for cooling and lubrication purposes. The relative magnitude of these phenomena is strongly dependent on the operative conditions of the transmission. While load-dependent losses are predominant at slow speeds and high torque conditions, load-independent mechanisms become prevailing in high speed applications, like in turbomachinery. Among fluid-dynamic losses, windage is extremely important and can dominate the other mechanisms. In this context, a new test rig was designed for investigating windage power losses resulting by a single spur gear rotating in a free oil environment. The test rig allows the gear to rotate at high speed within a box where pressure and temperature conditions can be set and monitored. An electric spindle, which drives the system, is connected to the gear through a high accuracy torque meter, equipped with a speedometer providing the rotating velocity. The test box is fitted with optical accesses in order to perform particle image velocimetry measurements for investigating the flow-field surrounding the rotating gear. The experiment has been computationally replicated, performing RANS simulations in the context of conventional eddy viscosity models. The numerical results were compared with experimental data in terms of resistant torque as well as PIV measurements, achieving a good agreement for all of the speed of rotations.
Time resolved PIV revealed strong instabilities in the flow field generated by the gear, highlighting the importance of performing unsteady simulations for a better modelling of this component. Results have been post-processed in terms of Fast Furier Transform (FFT) and Proper Orthogonal Decomposition (POD) in order to provide a reliable data base for future unsteady simulations.
In design phase it is important to predict the losses increase due to the lubricating oil jet impact on the spur gear varying the different geometrical and working parameters such as the jet inclination, distance and the oil mass flow rate and temperature.
For this reason the test rig was equipped with an oil control unit able to provide a controlled oil mass flow rate to a spray-bar placed within the test chamber. The oil jet can be regulated in terms of pressure and temperature, in such a way the mass flow rate can be imposed and measured by means of flow-meters. The spray-bar is equipped with a circular hole, its position can be varied as well as the inclination angle.
High speed visualizations were performed for every tested condition in order to deepen the physical understanding of the phenomena and to obtain more information on the lubrication and cooling capability. The high speed camera was placed in front of the gear exploiting an optical access while a halogen lamp was used to provide the proper lightening necessary due to the very low exposure time of the acquisitions.
In every test the power losses were also measured using the torque-meter, results were post-processed in order to insulate the torque increase due only to jet injection. The collected data were used for the validation of a simple 0D model able to well predict power losses due to jet injection under certain conditions.
Livres sur le sujet "Oil jet lubrication"
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Pinel, Stanley I. Comparison between oil-mist and oil-jet lubrication of high-speed, small-bore, angular-contact ball bearings. [Cleveland, Ohio] : National Aeronautics and Space Administration, Glenn Research Center, 2001.
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R, Signer Hans, Zaretsky Erwin V et NASA Glenn Research Center, dir. Comparison between oil-mist and oil-jet lubrication of high-speed, small-bore, angular-contact ball bearings. [Cleveland, Ohio] : National Aeronautics and Space Administration, Glenn Research Center, 2001.
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R, Signer Hans, Zaretsky Erwin V et NASA Glenn Research Center, dir. Comparison between oil-mist and oil-jet lubrication of high-speed, small-bore, angular-contact ball bearings. [Cleveland, Ohio] : National Aeronautics and Space Administration, Glenn Research Center, 2001.
Trouver le texte intégralChapitres de livres sur le sujet "Oil jet lubrication"
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Gu, Le, Liqin Wang, Zhenhuan Ye et Dezhi Zheng. « Analyses on the Splashing Parameters of High-Speed Oil Impacted a Wall in Jet Lubrications ». Dans Advanced Tribology, 120–21. Berlin, Heidelberg : Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03653-8_39.
Texte intégralActes de conférences sur le sujet "Oil jet lubrication"
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Le, Jiang, Liu Zhenxia, Lyu Yaguo et Zhu Pengfei. « Numerical Study on Flow Characteristics of Liquid Jet in Airflows ». Dans ASME Turbo Expo 2019 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91076.
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Abstract The interaction between the fuel jet, the oil jet and the airflow is involved in the afterburner (or ramjet combustion chamber) and the lubricating oil system of the aero-engine respectively. The latter mainly studies the penetration depth of the oil jet into the airflow, the oil jet breakup position and so on. In the under-race lubrication system, the oil jet is deflected due to the high-speed rotation of the oil scoop and some droplets, ligaments are separated. The deflection of the oil jet and the splash of droplets may affect the oil capture efficiency of the under-race lubrication system. At the same time, the configuration of the oil jet nozzle will also have a certain impact on the oil capture efficiency. Therefore, it is necessary to carry out research on the flow characteristics of the oil jet in the airflow, and provide reference for the oil jet nozzle configurations of the under-race lubrication system. In this paper, the calculation results show that the Couple Level-Set and Volume of Fluid (CLSVOF) method is better than the Volume of Fluid (VOF) method. The correlations between the coordinate of the oil jet breakup positions and the liquid-air momentum ratio were concluded. The equation of the trajectory curve was derived for the jet column trajectory before breakup. The difference of the oil jet flow characteristics between single jet nozzle and the twin jet nozzle and the tandem jet nozzle configuration is also studied. Finally, the design method under the tandem jet nozzle configuration is given.
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Yaguo, Lyu, Jiang Le, Liu Zhenxia et Hu Jianping. « Simulation and Analysis of Oil Scoop Capture Efficiency ». Dans ASME Turbo Expo 2018 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75989.
Texte intégralRésumé :
Under-race lubrication is the main method for the main shaft bearing of aero-engine which with higher performance. Oil scoop is an important part of the under-race lubrication structure, which plays an important role in capturing oil coming out of a stationary jet nozzle, and the efficiency of oil capture has great influence on the performance of the under-race lubrication. In this paper, a reasonable numerical simulation method is used to calculate a certain radial oil scoop. The velocity distribution of the internal air field in the lubrication structure and the oil distribution of the oil-gas two phase flow field were calculated and the scoop efficiency under different working conditions were calculated. The scoop efficiency under the three oil jet nozzles was verified by the test data. Finally, the influence of the shaft rotation speed, the oil flow rate and the number of the oil nozzles on the scoop efficiency of the radial scoop is analyzed, and the reason of these regularities is analyzed in detail. The result of this study may provide an idea or method for the optimization and improvement of oil scoop with similar structure.
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Massini, D., T. Fondelli, B. Facchini, L. Tarchi et F. Leonardi. « Experimental Investigation on Power Losses due to Oil Jet Lubrication in High Speed Gearing Systems ». Dans ASME Turbo Expo 2017 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-64703.
Texte intégralRésumé :
In order to reduce environmental and climate impact from air traffic, the main effort of aero-engine industry and research community is looking at a continuous increase in gearbox efficiency. With this kind of components every source of loss can be responsible for high heat loads; for this reason oil jet systems are used to provide proper cooling and lubrication of gears tooth surfaces. In the design phase it is important to predict the losses increase due to the lubricating oil jet impact on the spur gear, varying the different geometrical and working parameters such as the jet inclination, distance and the oil mass flow rate and temperature. An experimental investigation was carried out on a novel rotating test rig able to reproduce real engine working conditions in terms of speed, pressure and lubrication system, for a single spur gear. The rig consists of an electric spindle driving a shaft with a spur gear clamped on top. The gear is enclosed in a box where different air pressure conditions can be set and monitored. Pressure transducers and T-type thermocouples placed within the test box were used to measure the gear working conditions. The test box is also equipped with several optical accesses allowing flow field measurements or oil jet visualizations. The driving shaft is composed by two parts connected by a bearingless torquemeter equipped with a speedometer in order to perform torque losses and rotating velocity measurements. Tests were performed without the gear first, in order to separate the final value from the friction losses due to the driving shaft. Windage losses were characterized experimentally for every working condition and the results collected in a simple correlation that was used to separate the losses due to air windage from the ones due to the oil injection. An oil control unit allowed to impose the proper oil pressure and temperature conditions and to measure the mass flow rate. The oil jet was delivered by a spraybar placed within the gearbox, the jet to gear distance and relative angle were varied during the experiments. High speed visualizations were also performed for every test condition in order to deepen the physical understanding of the phenomena and to obtain more information on the lubrication capability of every jet condition. A high speed camera was placed in front of the gear exploiting an optical access while a halogen lamp was used to provide the proper lightening necessary due to the very low exposure time of the acquisitions. The wide experimental database provided, allowed the development of a simple numerical model able to well predict every losses contribution at the various working conditions.
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Fondelli, Tommaso, Antonio Andreini, Riccardo Da Soghe, Bruno Facchini et Lorenzo Cipolla. « Volume of Fluid (VOF) Analysis of Oil-Jet Lubrication for High-Speed Spur Gears Using an Adaptive Meshing Approach ». Dans ASME Turbo Expo 2015 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42461.
Texte intégralRésumé :
In high speed gearbox systems, the lubrication is generally provided using nozzles to create small oil jets that feed oil into the meshing zone. It is essential that the gear teeth are properly lubricated and that enough oil gets into the tooth spaces to permit sufficient cooling and prevent gearbox failure. A good understanding of the oil behaviour inside the gearbox is therefore desirable, to minimize lubrication losses and reduce the oil volume involved, and ensure gearbox reliability. In order to reach these objectives, a comprehensive numerical study of a single oil jet impinging radially on a single spur gear teeth has been carried out using the Volume of Fluid (VOF) method. The aims of this study are to evaluate the resistant torque produced by the oil jet lubrication, and to develop a physical understanding of the losses deriving from the oil-gear interaction, studying the droplets and ligaments formation produced by the breaking up of the jet as well as the formation of an oil film on the surface of the teeth. URANS calculations have been performed with the commercial code ANSYS FLUENT and an adaptive mesh approach has been developed as a way of significantly reducing the simulation costs. This method allows an automatic mesh refinement and/or coarsening at the air-oil interface based on the volume of fluid gradient, increasing the accuracy of the predictions of oil break-up as well as minimizing numerical diffusion of the interface. A global sensitivity analysis of adopted models has been carried out and a numerical set-up has been defined. Finally several simulations varying the oil injection angle have been performed, in order to evaluate how this parameter affects the resistant torque and the lubrication performances.
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Wu, Wei, Jibin Hu, Shihua Yuan et Xueyuan Li. « Computational Fluid Dynamics Evaluation of the Multi-Nozzle Oil-Jet Lubrication for Rolling Bearings ». Dans The 15th International Heat Transfer Conference. Connecticut : Begellhouse, 2014. http://dx.doi.org/10.1615/ihtc15.tpn.008564.
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Prabhakar, Arun, Yousif Abdalla Abakr et Kathy Simmons. « Effect of Vortex Shedding on the Performance of Scoop Based Lubrication Devices ». Dans ASME Turbo Expo 2017 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63444.
Texte intégralRésumé :
In civil aircraft aeroengine bearing chambers it is sometimes difficult to feed oil to bearings using the traditional under-race or targeted jet approaches. In such situations one proposed solution is that of a scoop delivery system. Published experimental investigations into scoop performance show that scoop collection efficiency (the percentage of oil delivered by the scoop system to its destination compared to that supplied by the feed jet) is a function of many operational and geometric parameters. However even with high speed imaging it is impossible to experimentally determine in detail the factors that most contribute to reduction in collection efficiency and it is here particularly that a computational fluid dynamics (CFD) investigation has value. In the work reported here a commercial CFD code (ANSYS Fluent) is used to investigate vortex formation at the scoop tips and the effect these structures have on scoop collection efficiency. The computational domain, a 2D slice through the chosen scoop system, is discretized utilizing ANSYS Meshing. A Volume of fluid (VOF) method is used to model the multiphase flow of oil and air in the system and the RNG k-ε turbulence model is employed. The results obtained show that the formation of vortices from the tip of the rotating scoops leads to a reduction in pressure in the region near the tip of the oil jet, subsequently causing part of the jet to divert upwards away from the scoop creating a plumed tip. The pluming effect reduces capture efficiency because the oil plume moves outwards under centrifugal effects and this oil is not captured. The frequency of vortex shedding from the scooped rotor was investigated and the Strouhal numbers obtained were around 0.132. This compares well to 0.15 for an inclined flat plate. Two potential methods to reduce the jet pluming effect are investigated one in which the sharp tip of the scoop is blunted and the other in which the jet direction is reversed. The blunt tip increased capture efficiency by almost 2%. Reversing the jet orientation reduces jet pluming but also significantly reduces capture efficiency; it was found to be 10% lower for the case investigated.
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Lee, C. W., G. R. Johnson, P. C. Palma, K. Simmons et S. J. Pickering. « Factors Affecting the Behaviour and Efficiency of a Targeted Jet Delivering Oil to a Bearing Lubrication System ». Dans ASME Turbo Expo 2004 : Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53606.
Texte intégralRésumé :
In this study oil delivery to an aero-engine bearing via a targeted jet was investigated using a bearing chamber test rig. The rig contains a high-speed rotating shaft of engine representative geometry within a stationary Perspex housing. Oil is collected from feedholes leading from scoops (scallops) on the shaft. The efficiency of this oil delivery system is dependent on jet structure and trajectory as it interacts with the rotating chamber flow. Flow visualization techniques and parametric tests are used to assess the influence of shaft speed and jet flowrate on oil collected through the feedholes. Detailed pictures of the structure of the jet in quiescent air are presented and compared with those from the rig, where there is a gas crossflow. As expected, jet break-up is accentuated in the rig. This influences jet impact behaviour at the scallop, and a consequent variation of oil distribution in the system is observed.
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Korsukova, Evgenia, Arno Kruisbrink, Hervé Morvan, Paloma Paleo Cageao et Kathy Simmons. « Oil Scoop Simulation and Analysis Using CFD and SPH ». Dans ASME Turbo Expo 2016 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57554.
Texte intégralRésumé :
The process of rotating scoops capturing oil coming out of a stationary jet nozzle was simulated with CFD (Computational Fluid Dynamics) and SPH (Smoothed Particles Hydrodynamics). The aim was to determine the efficiency of the oil capture, and the effects of varying parameters such as angular velocity of the scoops, the speed and direction of the oil jet and arrangement of the oil jets (in case of more than one jet). This configuration is found in engine cooling and/or lubricating systems: where oil scoops are used to deliver the oil to the places where direct injection is not possible. In CFD both two- and three-dimensional geometries were used; the models were then run using the Volume of Fluid method with the SST k-ω model. SPH is a meshless Lagrangian method for flow simulation, where the fluid is represented by particles. In addition to the conventional SPH formulation, three main highlights were introduced in the current work: the rotating ghost particles (representing the scoops), the particle collision model (Korzilius et al., 2014) and source and sink particles (representing the oil coming out from the nozzle and captured at the scoops respectively). The simulations allowed for the observation of the free surface of the oil jet (before, during, and after cutting of the jet by the blade), the pressure and velocity fields for the air and oil, and the efficiency of the system, defined as the ratio of oil outflow (via scoops) and inflow. This is a comparative study between CFD and SPH, where SPH is explored for a lubrication of a high-speed rotating component. The results of CFD and SPH, in particular the oil free surface and the efficiency, were then compared and validated with experimental results, demonstrating good agreement. The setup and comparison of the results obtained with the described techniques are presented in this work.
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Simmons, Kathy, Luke Harrison, Evgenia Korsukova et Paloma Paleo Cageao. « CFD Study Exploring Jet Configurations and Jet Pulsing for an Aeroengine Scoop-Based Oil Delivery System ». Dans ASME Turbo Expo 2018 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76182.
Texte intégralRésumé :
With reduction of gas turbine core size, clearances between internal components are reduced and directing oil jets for bearing lubrication becomes more difficult. If direct access to the bearings or scallops is impeded, the inclusion of oil scoops becomes highly desirable for lubricant supply. With a scoop-based system oil is targeted at a scooped rotor, collected and fed along axial passages and delivered at a different axial location thus enhancing design opportunities. The proportion of oil from the supply jet retained by the scoop system is an important design parameter that can be characterised by the concept of capture efficiency. Previous investigations have focussed on a proposed scoop device’s operating conditions and oil jet configurations; this study proposes new methods of utilising the jets to improve scoop capture efficiency. A parametric study of a 2D scoop geometry was conducted using the Computational Fluid Dynamics (CFD) software ANSYS Fluent. The simulation utilised the Volume of Fluids (VOF) approach for multiphase modelling and the k-ω SST model to account for turbulence. In the configuration studied the oil was supplied via two nozzles separated by 10 degrees circumferentially. An uneven flow rate between two oil jets in tandem allowed for the identification of jet interaction effects. A transition in capture efficiency responses was also highlighted between shallow and steep jet angles. The knowledge of individual jet behaviour may immediately improve existing tandem jet configurations. Further, the concept of pulsing the jets was investigated, the idea being initiated following observation of high speed imaging of a scoop system tested experimentally. The imaging shows that most of the uncaptured oil is deflected or splashed following interaction with the scoop. Turning the oil off for part of the cycle potentially reduces or eliminates this. By defining and implementing an optimised time scheme for the pulsation of a single jet, the capture efficiency was improved by 10%. Compensating for the associated flow rate reduction by increasing the jet velocity resulted in a further 5% increase in capture efficiency. The development of pulsed jets for practical applications has the potential to significantly improve oil scoop capture efficiency.
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Prasad, Santosh Kumar, Pradeep Sangli, Osman Buyukisik et Dave Pugh. « Prediction of Gas Turbine Oil Scoop Capture Efficiency ». Dans ASME 2014 Gas Turbine India Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gtindia2014-8329.
Texte intégralRésumé :
The lubrication system in a gas turbine engine is akin to the human blood circulatory system. Providing right quantities of oil to the right components for cooling and lubrication is the primary function of the lubrication system. In the current analysis, at the downstream end of the lube oil supply line, a stationary oil nozzle sprays a jet of oil to a high speed rotating component called an oil scoop. The function of the oil scoop which rotates at speeds usually greater than 10000 RPM is to ‘Scoop’ or capture the oil and provide an under race oil transfer mechanism to the bearings rotating especially at such high speeds. If the oil capture is less than required by the downstream bearing components, it could lead to diminished bearing lives in the gas turbine. The oil scoop consists of two or more blades that are angled with respect to the radius of the Scoop to provide an entry to the oil jet. The ‘window’ of open space between the blades is important to capture the oil. The ratio of quantity of oil captured to the total oil sprayed on to oil scoop is termed as the oil capture efficiency. Several parameters like oil nozzle distance from the blade tip, spray characteristics, jet velocity, number of blades, blade angle, window width, rotational speeds, oil temperature etc. are important factors that determine the capture efficiency of the oil scoop. Prior to the availability of efficient CFD methodologies, it was extremely difficult to develop an oil scoop capture efficiency predictive tool that involves a complex 3D fluid flow from a stationary to a rotating component. The typical Reynolds number of the jet is around 13000 and the oil scoop tip speeds of the order of Mach 0.2 to 0.4. To evaluate various scoop design configurations and enhancements, a transient CFD methodology was developed using multiphase Volume of Fluid approach available in FLUENT® software. In this paper a technique or process is described and demonstrated to simulate the right ‘periodic’ nature of the oil capture and transfer mechanism. It is shown that the CFD methodology described compares well with experimental data. This robust CFD methodology predicts the complex 3D flow with sufficient accuracy and has the potential to be used to optimize the geometry for maximum oil capture efficiency of oil scoops in gas turbine lubrication system. Significant reduction of costly experiments is also an important benefit of developing this predictive methodology.