Relevant bibliographies by topics / Air-Oil flow

Academic literature on the topic 'Air-Oil flow'

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Published: 7 July 2024

Last updated: 7 July 2024

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Journal articles on the topic "Air-Oil flow":

Li, Yang, Zhaojun Yang, Fei Chen, and Jin Zhao. "Effect of air inlet flow rate on flow uniformity under oil-air lubrication." Industrial Lubrication and Tribology 70, no. 2 (March 12, 2018): 282–89. http://dx.doi.org/10.1108/ilt-12-2016-0296.

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Purpose This paper aims to investigate the effects of air inlet flow rate on the bearing cavity and operating conditions during the oil-air lubrication. Design/methodology/approach A model of oil-air lubrication of rolling bearings is established using computational fluid dynamics numerical simulation. Moreover, temperature and vibration experiments are carried out for comparisons and validation. Findings Results suggest that the velocity and pressure distributions of the oil-air flow inside the chamber are not uniform. Moreover, the uniform decreases with increasing air inlet flow rate. The non-uniform oil distribution inside the bearing significantly influences the bearing temperature rise and lubrication effect. Furthermore, the decrease in pressure uniformity enhances the vibration intensity and increases the amplitude of the vibration acceleration by more than 40 per cent. Increasing the air inlet flow rate improves lubrication and cooling efficiency but produces intense vibrations. Originality/value A method of establishing rolling bearings model under oil-air lubrication is presented in the paper. The effect of air inlet flow rate on flow uniform under oil-air lubrication has been researched insightfully. The results provide a useful reference to improve the oil-air lubrication system and enhance the operational stability of the motorized spindle.

Sun, Qi Guo, Zheng Hui Zhou, Hong Bo Lv, and Yue Fei Wang. "Study on Distribution Performance of a New Oil-Air Distributor in Oil-Air Lubrication System." Advanced Materials Research 889-890 (February 2014): 352–57. http://dx.doi.org/10.4028/www.scientific.net/amr.889-890.352.

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The fluid domain model of a new oil-air distributor in oil-air lubrication system is built and the phase distribution of oil and air two-phase flow on distribution interface is simulated based on the CFD model in Fluent, the mass flow rate of oil and air are collected from three different cross sections when the structures of oil-air guidance slot are designed as a plane, sphere and cone shape respectively, then the influence of oil-air guidance slot structure on the performance of distributor is analyzed in the oil-air lubrication system in this paper. The results show that the spherical surface and conical surface of oil-air guidance slot can improve the uniformity and stability of the oil and air two-phase flow distribution, promote the flow pattern to form a continuous annular oil film. Among these three structures of oil-air guidance slot, we also find that the distribution performance of conical surface is the best.

Cui, Ziqiang, Chengyi Yang, Benyuan Sun, and Huaxiang Wang. "Liquid Film Thickness Estimation using Electrical Capacitance Tomography." Measurement Science Review 14, no. 1 (February 1, 2014): 8–15. http://dx.doi.org/10.2478/msr-2014-0002.

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Abstract In air/oil lubrication systems, the flow parameters, e.g., flow pattern, liquid film thickness, and air/oil flow rate, are of great importance to the transportation efficiency. In most cases, the on-going two-phase flow is annular flow with the oil moving along the tube wall and the air travelling at high speed in the center. This usually results in the formation of a thin oil film, the thickness of which is a key parameter determining the efficiency of the lubrication system. As the oil film thickness of the on-going air/oil flow varies dynamically, there is actually no applicable method for a non-intrusive test. In this paper, the use of electrical capacitance tomography (ECT) to investigate the air/oil flow has been studied. Capacitance measurements are made from an externally mounted electrode array in a non-invasive and non-intrusive manner. Both average and distributed oil film thicknesses can be calculated from the reconstructed ECT images. Simulation and experimental results show that the ECT technique can provide satisfactory results of online oil film thickness estimation

Li, Li Quan, Shao Gang Liu, Jin Li Wang, and Lin Cai. "The Research on Oil-Air Lubrication and Oil Lubrication Used in the Sliding Friction Element." Key Engineering Materials 486 (July 2011): 283–86. http://dx.doi.org/10.4028/www.scientific.net/kem.486.283.

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In order to study the effect of oil-air lubrication on sliding friction element, the experiments between oil-air lubrication and oil lubrication have been done by using friction-abrasion testing machine. By means of measuring the temperature rise, the friction coefficient of two different lubrication systems in the same conditions and studying the temperature rise and the friction coefficient of oil-air lubrication with different oil flow rate at the same load and rotating speed level, the results obtained show that when the oil flow rate of oil- air lubrication is equal to 10ml/h, the temperature rise of the element is the same as submerged lubrication caused. As the effect of oil aeration, the friction coefficient of oil-air lubrication is higher. When the load and rotating speed is at 1500N, 210rpm level, as the oil flow rate increases, the temperature rise and friction coefficient of oil-air lubrication element decreases significantly, however, they remain almost unchanged with the increasing of oil supply while the oil flow rate is increased to 15ml/h.

Woods, G. S., P. L. Spedding, J. K. Watterson, and R. S. Raghunathan. "Three-Phase Oil/Water/Air Vertical Flow." Chemical Engineering Research and Design 76, no. 5 (July 1998): 571–84. http://dx.doi.org/10.1205/026387698525252.

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Jablonská, Jana, Milada Kozubková, and Marian Bojko. "Flow of Oil and Water through the Nozzle and Cavitation." Processes 9, no. 11 (October 28, 2021): 1936. http://dx.doi.org/10.3390/pr9111936.

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Today, the correct understanding of the issue of oil and water cavitation is important due to the growing demands on working conditions in hydraulic systems (pressure and flow rate). This article deals with the measurement and subsequent mathematical modeling of cavitation in a convergent-divergent nozzle of circular cross-section. Cavitation depends on the physical properties of the flowing medium as a function of temperature. Usually, cavitation in water is defined by a two-phase flow of water and vapor, but the air contained in the water significantly affects cavitation. There is usually no vapor cavitation in the oil. Far more often, cavitation in oil is caused by the air it contains. For comparison, cavitation in water and oil was generated in experiments with an identical nozzle. The measurement was used to define boundary conditions in mathematical models and to verify simulations. The problem of cavitation was solved by three variants of multiphase flow, single-phase flow (water, oil), two-phase flow (water–vapor, oil–air) and three-phase flow (water–vapor–air, oil–vapor–air). A turbulent model with cavitation was used for all variants. The verification of simulations shows that for water cavitation it is necessary to use a three-phase model (water, vapor, air) and for oil cavitation a two-phase model (oil, air) is sufficient. The measurement results confirm the importance of the air phase in modeling cavitation in both water and oil.

Cai, Lin, Jin Li Wang, and Hong Tao Zheng. "Experiment and Numerical Study of Annular Flow Entrainment Mechanism in Oil-Air Lubrication Pipe." Advanced Materials Research 189-193 (February 2011): 1782–85. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1782.

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Annular flow is a based flow pattern of two-phase in the pipe, and oil air flow in delivery pipe of Oil-Air lubrication (OAL) system is one of them. In order to learn the entrainment mechanism of annular flow in OAL pipe, both experiment adopted observational method and numerical simulation used Computational Fluid Dynamic (CFD) were carried out. The pipe diameter is 4mm and Volume of Fluid (VOF) model was used for two phase flow in simulation. The results shows that: it is a wave-annular flow in OAL pipe, and the oil wave in pipe is affected by air, when air velocity is low, the wave is clearly and regularly, but when air velocity increases, the wave become turbulent. When oil or air flow rate increases, the shear stress of pipe wall will be increased, the wave height will be increased as air velocity increases.

Cheng, Sun-Wen, and Wen-Jei Yang. "Hysteresis in Oil Flow through a Rotating Tube with Twin Exit Branches." International Journal of Rotating Machinery 3, no. 4 (1997): 249–58. http://dx.doi.org/10.1155/s1023621x97000237.

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Oil enters a horizontal rotating tube through a radially-attached duct at one end. The tube with the other end closed is attached with radial twin exit branches permitting oil to exit into open air. Air begins to enter through one of the two branches into the tube when its rotational speed reaches certain critical values. An experimental study is performed to investigate this air-oil two-phase flow behavior. Both the tube and the branches are transparent to allow illumination and flow visualization during spin-up and spin-down processes. The branch-totube diameter ratio, rotational speed, and oil flow rate are varied. Changes in oil flow rates are measured as a function of rotational speed. A comparison is made between cases of a varying total oil flow rate due to rotation effects and a constant one under control. It is disclosed that cavitation in oil flow is induced by air entering the branches opposite to the ejecting oil flow. Subsequently air bubbles progress in the tube. The origin of this intrusion depends on the hydraulic head loss of the piping system. This study can be applied to oil lubrication analysis of rotating machinery, such as automotive transmission lines.

Guzmán, Enrique, Valente Hernández Pérez, Fernando Aragón Rivera, Jaime Klapp, and Leonardo Sigalotti. "Comparative Study of Air–Water and Air–Oil Frictional Pressure Drops in Horizontal Pipe Flow." Fluids 9, no. 3 (March 7, 2024): 67. http://dx.doi.org/10.3390/fluids9030067.

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Experimental data for frictional pressure drop using both air–water and air–oil mixtures are reported, compared and used to evaluate predictive methods. The data were gathered using the 2-inch (54.8 mm) flow loop of the multiphase flow facility at the National University of Singapore. Experiments were carried out over a wide range of flow conditions of superficial liquid and gas velocities that were varied from 0.05 to 1.5 m/s and 2 to 23 m/s, respectively. Pressure drops were measured using pressure transducers and a differential pressure (DP) cell. A hitherto unreported finding was achieved, as the pressure drop in air–oil flow can be lower than that in air–water flow for the higher range of flow conditions. Using flow visualization to explain this phenomenon, it was found that it is related to the higher liquid holdup that occurs in the case of air–oil around the annular flow transition and the resulting interfacial friction. This additional key finding can have applications in flow assurance to improve the efficiency of oil and gas transportation in pipelines. Models and correlations from the open literature were tested against the present data.

Tong, Bao Hong, Xiao Qian Sun, and Hong Su. "Numerical Simulation on Internal Flow Field of Rolling Bearing under Oil-Air Lubrication." Applied Mechanics and Materials 271-272 (December 2012): 1056–61. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.1056.

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Heat dissipation and working efficiency of transport air in rolling bearing under oil-air lubrication are closely related to the flowing state of oil-air in bearing chamber. For cylindrical roller bearing NF211, numerical simulation model of oil-air flow field in bearing chamber was established combining with the practical structure features of rolling bearing and ignoring the effect caused by roller rotation. Combining with flow field numerical simulation functions of Fluent software, simulation analysis of the flow state in bearing chamber were carried out. Based on k-ε turbulent model, three-dimensional flow field in the bearing chamber and main feature parameters of inner flow were got analyzed carefully considering the effect of twirling. Comparing with the numerical simulation of simplified flow field, it showed that energy dissipation and axial velocity of the air were influenced by the effect of twirling distinctly. Simulation results were expected to give useful references for the optimization design of the oil-air lubrication system in rolling bearing.

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Dissertations / Theses on the topic "Air-Oil flow":

Al-Aufi, Yousuf Abdullah. "Vertical annular flow characteristics for air/silicone oil system." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49216/.

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Annular flow is one of the most common two-phase flow regimes observed in industrial applications. In annular flow, the liquid flows partly as a thin film along the pipe wall and partly as droplets entrained in the turbulent gas core. Most of the previous studies about the characteristics of annular flow and the developed correlations were conducted using an air/water system. This thesis reports an investigation about the characteristics of the annular flow regime and a development of liquid film thickness measurement using an ultrasonic technique in air/water and air/silicone oil systems. Experiments were carried on an upward vertical annular flow test facility with 34.5 mm inner diameter (ID) using air/water and air/silicone oil two-phase systems. Time-varying of total pressure drop, liquid film thickness and wall shear stress were measured. The total pressure drop was measured using a remote seal differential pressure transducer and the wall shear stress was measured using a glue-on hot film sensor. An ultrasonic technique was developed to measure the liquid film thickness. It was evaluated using static and dynamic measurements. For static measurements, it was compared with the liquid film thickness calculated based on knowledge of liquid volume and area of the test rig. For dynamic measurements, it was compared with two well-known conductance measurement techniques (Multi Pin Film Sensor and concentric probe) in falling film and upward vertical annular flow test facilities respectively. The relative error between the ultrasonic technique and the other two techniques was within ±5%. A new processing method for ultrasonic measurement called Baseline removal method was developed for measuring liquid film thickness less than 0.5 mm. The influence of gas and liquid superficial velocities, viscosity and surface tension on the measured parameters was studied using both systems. Both systems showed similar trend behavior with increasing gas and liquid superficial velocities even there was a difference in fluid properties. The results were also compared with the existing correlations developed using an air/water system to predict each one of the measured parameters. Most of the tested correlations predicted the total pressure drop, liquid film thickness and wall shear stress with relative deviation of ±50% or even higher in some cases.

Phillips, Andrew. "Two phase flow in rapidly rotating porous media." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289324.

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Lee, Chan Wei. "Air and oil flow investigations in an aeroengine bearing chamber." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408637.

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Wang, Yuan S. M. Massachusetts Institute of Technology. "Air flow effects in the piston ring pack and their implications on oil transport." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76826.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012.
This thesis was scanned as part of an electronic thesis pilot project.
Cataloged from PDF version of thesis. This thesis was scanned as part of an electronic thesis pilot project.
Includes bibliographical references (p. 85).
3 different flow regimes of piston blowby air and their influences on oil transport are studied. It is found that air mainly interacts with oil close to the ring gaps and directly below the ring-liner contacts. Geometric features at the gaps to smoothen airflow and prevent flow detachments can increase blowby mass flow rate and thus drainage oil mass flow rate by up to 60%. Only oil within 1 to 2 gap widths distance from the gaps are transported through the gap by air drag and the engine pressure drop. Downstream of the ring gap, transported oil will either be caught in vortices directly below the ring gaps or pumped into the downstream ring groove due to the creation of a blowby stagnation point. Far away from the gaps, oil is mainly transported in axial direction through the grooves and the piston-liner interface. Low capillary numbers in the order of 10-5 indicate close to no oil transport into circumferential direction from blowby shear. The oil transport radially into the grooves is mainly determined by hydrostatics and capillary effects in the groove flanks whereas air in the second land only has an influence on oil transport by preventing bridging after TDC by creating a stagnation point directly below the rings on the liner.
by Yuan Wang.
S.M.

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

Farrar, B. "Hot-film anemometry in dispersed oil-water flows : Development of a hot-film anemometer based measurement technique for detailed studies of complex two-phase flows and its application.........bubbly water-kerosene and water-air flows." Thesis, University of Bradford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234685.

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Azevedo, Gabriel Romualdo de. "Estabilidade linear para intermitência severa em sistemas água-ar." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-27022018-102833/.

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Apresenta-se um modelo matemático que avalia numericamente a estabilidade do estado estacionário para escoamentos água-ar em sistemas pipeline-riser de geometria variável. Uma análise a partir da teoria de estabilidade linear é aplicada a um modelo matemático adequado ao escoamento água-ar no sistema pipeline-riser. O modelo considera equações de continuidade para a fase líquida e para a fase gasosa, admite-se escoamento unidimensional e em condição isotérmica. O líquido é considerado incompressível enquanto que a fase gasosa é considerada um gás ideal. Admite-se uma equação de momento simplificada para mistura onde despreza-se a inércia (NPW - Modelo No Pressure Wave) e o padrão de escoamento local é definido com base nas condições do escoamento e na inclinação local. Assim, a intermitência severa é controlada principalmente pela gravidade no riser e pela compressibilidade do gás no pipeline. Tanto a correlação de fluxo de deriva quanto o cálculo da queda de pressão por atrito, adotados como lei de fechamento do modelo, são determinados em função do padrão de escoamento. Injeção de gás e válvula de choke são consideradas, respectivamente, na base e no topo do riser. O modelo é aplicado à sistemas pipeline-riser com escoamento água-ar citados na literatura. Os resultados da análise de estabilidade linear numérica são comparados aos resultados experimentais e numéricos apresentando uma excelente concordância.
A mathematical model that numerically evaluates the stability of the stationary state for hilly terrain air-water flows systems is presented. Numerical linear stability analysis is performed to a suitable mathematical model for the two-phase flows in a pipeline-riser system. The mathematical model considers the continuity equations for the liquid and gas phases, one-dimensional flow and isothermal conditions. The liquid is assumed incompressible while the gas phase is considered as an ideal gas. A simplified momentum equation for the mixture, neglecting inertia (NPW - No pressure wave model) is considered and the local flow pattern is defined based on the flow conditions and the local inclination. In this way, severe slugging is controlled mainly by gravity in the riser and compressibility in the pipeline. The void fraction and friction pressure drop, utilized as closure laws, are determined based on the local flow pattern. Gas injection at the bottom of the riser and a choke valve at the top are considered. The model is applied to air-water pipeline-riser systems reported in the literature. Numerical linear stability analysis results are compared with experimental and numerical results reported in the literature with excellent agreement.

Seguinot, Lucas. "Etude et développement d'une stratégie d'analyse des performances d'un dégazeur de turbine d'hélicoptère." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAL035.

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Les exploitant aériens cherchent à réduire toujours davantage le coût d'utilisation et d'opération de maintenance des hélicoptères ainsi qu'à limiter leur impact environnemental. Par conséquent, les motoristes tels que Safran Helicopter Engines doivent constamment améliorer les performances de leurs moteurs. Cette amélioration passe notamment par la réduction des consommations de carburants et d'huile de lubrification. La consommation d'huile est liée en grande partie à la formation d'un brouillard diphasique air-huile au sein des paliers de roulements des arbres du moteur. L'air est continûment évacué en transportant des inclusions d'huile vers l'extérieur. Pour limiter ces rejets d'huile, un séparateur en rotation est utilisé pour récupérer l'huile et évacuer l'air. Afin de prédire avec davantage de précision la consommation d'huile et les pertes de charges induites par le séparateur, la présente thèse développe une stratégie d'analyse des écoulements diphasiques au sein des séparateurs. Cette stratégie s'appuie en premier lieu sur des simulations numériques du brouillard d'huile basées sur une approche Euler-Lagrange. Ces simulations permettent d'une part d'analyser l'écoulement d'air et les pertes de charges du séparateur et d'autre part d'appréhender les mécanismes de la séparation de l'huile et d'analyser la consommation en fonction des conditions de fonctionnement. Parallèlement, grâce au financement du projet européen E-Break, un banc d'essais dégazeur a été conçu dans le cadre de cette thèse et réalisé à l'Université Libre de Bruxelles. Des analyses croisées entre essais et simulations permettent de valider la méthodologie de simulation. Cependant, si les pertes de charges sont correctement prédites par le calcul, des efforts supplémentaires sont nécessaires, aussi bien sur la précision des mesures que sur la modélisation de l'écoulement diphasique, pour assurer une prédiction satisfaisante de la consommation d'huile
Air operators try to reduce ever more operation and maintenance costs of helicopters as well as to limit their environmental impact. Consequently, engine manufacturers such as Safran Helicopter Engines must constantly improve the performance level of the engines they develop. To achieve such an improvement, oil and kerosene consumption must be reduced. Oil consumption is mostly due the formation of an oil mist inside bearing chambers. As the air is continuously scavenged, it carries along oil droplets out of the engines. In order to limit the oil wastes, a separator is used which recovers oil drops carried by the owing air that is vented out. In order to predict with a better level of accuracy the oil consumption and the pressure losses induced by the separator, the present thesis develops a strategy to analyse the two-phase flow within the separator. This strategy relies in the first place on Euler-Lagrange numerical simulation of the oil mist which allow on the one hand to compute the turbulent air flow and the pressure drop induced by the separator and on the other hand to better understand the separation mechanisms and to predict the oil consumption for various operating conditions. Besides, thanks to the funding of the E-Break European project, a test bench has been designed in the framework of this PhD and set up at the Université Libre de Bruxelles. Cross comparisons between measurements and simulations allow validating the numerical methodology. However, even though pressure drops are correctly predicted by the simulation, improvements are still needed, regarding both the measurement accuracy and the two-phase numerical modelling, in order to provide a satisfactory prediction of the oil consumption

Kirov, Nikolay. "Simulation numérique de l’écoulement air-huile dans une enceinte moteur." Electronic Thesis or Diss., Toulouse, ISAE, 2024. http://www.theses.fr/2024ESAE0015.

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La tendance actuelle vers des moteurs d'avion plus puissants et plus économes en carburant crée le besoin de roulements capables de transférer des charges mécaniques plus élevées entre les composants rotatifs et fixes de la machine, à des températures extrêmes et à des régimes moteur plus élevés. Les roulements nécessitent d'être lubrifié en permanence avec une huile spécialisée afin de réduire les frottements, de dissiper la chaleur, d'éloigner les minuscules débris et ainsi d'assurer l'intégrité mécanique du moteur.Les débits massiques d'huile qui en résultent au sein du moteur sont importants et le lubrifiant doit donc être recyclé en permanence via un système de recirculation d'huile. En conséquence, les roulements sont enfermés dans des enceintes, constitués de joints étanchéités et des roulements eux-mêmes. Les enceintes à huile sont essentiellement des chambres étanches adjacentes aux roulements, ou parfois les enfermant, dans lesquelles l'huile éjectée est canalisée après la lubrification. Ils sont généralement scellés avec de l'air sous pression du côté opposé, qui passe à travers un joint labyrinthe afin d'empêcher tout écoulement sortant. En règle générale, une ouverture d'orifice de ventilation est incluse sur le dessus pour permettre à l'air de s'échapper, et une ouverture d'orifice de récupération est située près du bas pour ramener l'huile vers les pompes de récupération d'huile vers le réservoir.À l'intérieur de l'enceinte, l'huile et l'air forment un écoulement complexe à deux phases, dans lequel les effets centrifuges, le cisaillement aérodynamique et les forces de gravité provoquent la dispersion de la majorité de l'huile dans l' enceinte huile et s'accumulent sous forme de film dans les parois extérieures. Un transfert de chaleur de ces parois vers l'huile pré-refroidie à lieu, lui conférant ainsi une fonction secondaire importante : absorber une partie de la chaleur et donc refroidir l'enceinte. Il est cependant important que l'huile des roulements soit collectée et renvoyée au réservoir avant d'atteindre des températures trop élevées, afin d'éviter la cokéfaction ou, pire encore, l'inflammation, qui pourrait déclencher un incendie dans l'enceinte. La physique complexe des écoulements diphasiques conduit à un problème d'optimisation qui ne peut être résolu que via des simulations numériques.À ce jour, une quantité considérable d’incertitude demeure quant à la pratique de modélisation informatique la plus optimale pour une simulation précise, fiable et rentable des chambres de roulements dans différentes conditions de fonctionnement. L'objectif de cette thèse est donc de tester plusieurs approches de modélisation numérique pour la simulation d'un banc d'essai simplifié de enceinte, ici nommé ELUBSYS, pour lequel certaines mesures expérimentales sont disponibles et peuvent être utilisées pour fournir des moyens de validation desdites approches. Il s’agit, à savoir, d’une approche interfaciale multi-fluide à interface diffuse, d’une approche simplifiée Eulerian Integral Thin Film (EITF), d’une approche à phase dispersée Lagrangienne (Disperse Particles Model, DPM) et, enfin, d’une approche couplée EITF-DPM. Au cours de toutes ces investigations, de nouvelles connaissances ont été acquises sur les caractéristiques de l'écoulement, les paramètres d'influence et les performances globales, par rapport aux données expérimentales pour deux configurations de chambres de roulements sous une variété de débits massiques d'huile et de vitesses de rotation de l'arbre.La méthodologie couplée EITF-DPM s'est avérée obtenir une bonne précision pour les mesures de distribution d'épaisseur de film pour un coût contenu et pour une variété de régimes de fonctionnement
The current trend towards more powerful and fuel-efficient aircraft engines produces the need for bearings, capable of transferring higher mechanical loads between rotating and stationary machine components, at extreme temperatures and higher engine speeds. The bearings demand lubrication oil at all times in order to reduce friction, dissipate heat, drive tiny debris away and therefore ensure the mechanical integrity of the engine.The resulting oil mass flow rates within the engine are significant and thus the lubricant must be continuously recycled via an oil recirculation system. As a result, the bearings are encompassed within oil sumps, consisting of chambers, seals and the bearings themselves. The bearing chambers are essentially sealed chambers adjacent to, or sometimes enclosing the bearings, whereby the ejected oil is channeled into after lubrication. They are typically sealed with pressurised air on the opposite side, which is passed through a labyrinth seal in order to provide flow obstruction. Typically, a vent port opening is included on the top for the air to escape, and a scavenge port opening is located near the bottom to lead the oil to the oil scavenge pumps back to the reservoir.While still contained within the bearing chamber, the oil and the air form a complex two-phase flow, whereby centrifugal effects, aerodynamic shear and gravity forces cause the majority of the oil to disperse within the bearing chamber and accumulate as film on its outer stationary walls. Heat transfer from these walls to the pre-cooled oil takes place, therefore giving it an important secondary function - to absorb some of the heat and therefore cool the bearing chamber enclosure. It is important, however, that the oil from the bearings is collected and returned to the reservoir before reaching temperatures that are too high, in order to avoid coking or even worse - ignition, that can start a fire within the bearing chamber. The complex two-phase flow physics lead to an optimisation problem which can only be tackled via numerical simulations.To date, a considerable amount of uncertainty remains concerning the most optimal computational modelling practice for the accurate, reliable and cost-efficient simulation of bearing chambers across different operating conditions. The objective of this thesis, is therefore to test several computational modelling approaches for the simulation of a simplified bearing chamber test rig, hereby named ELUBSYS, for which some experimental measurements are available that can be used to provide means of validation of the said approaches. These are, namely, an interfacial multi-fluid diffuse-interface approach, an Eulerian Integral Thin Film (EITF) approach, a two-way coupled Discrete Parcel Method approach, and, lastly, an EITF-DPM coupled approach. During all of these investigations, new knowledge has been gained for the flow field characteristics, influencing parameters and overall predictory performance, as compared to the experimental data for two bearing chamber configurations under a variety of oil mass flow rates and shaft rotational speeds.The cost-efficient coupled EITF-DPM methodology proposed within this thesis was found to obtain good accuracy for the film thickness distribution measurements for a variety of operating conditions

Михайлова, Ірина Олександрівна. "Розвиток методів розрахунку охолодження обертових елементів газових турбін." Thesis, Національний технічний університет "Харківський політехнічний інститут", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/38782.

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Abstract:

Дисертація на здобуття наукового ступеня кандидата технічних наук (доктора філософії) за спеціальністю 05.05.16 "Турбомашини та турбоустановки", (технічні науки). – Національний технічний університету "Харківський політехнічний інститут", Міністерство освіти і науки України, Харків, 2018. Дисертацію присвячено вирішенню важливої науково-технічної задачі вдосконалення систем охолодження газових турбін шляхом подальшого розвитку методів гідравлічного і теплового розрахунку каналів системи охолодження газових турбін. Вивченню структури і властивості потоку в цих елементах, отриманню залежностей, описуючих цей потік. Виконано аналіз науково-технічної літератури, присвяченій проектуванню систем охолодження ГТД, в якому розглянуто міжнародний досвід експериментальних досліджень і обчислювальних експериментів, що до дослідження теплообміну і гідродинаміки течії в обертових елементах. В результаті аналізу літератури показано що, основним напрямом розвитку ефективних і надійних систем охолодження ГТД є підвищення точності розрахунку витратних і гідравлічних характеристик елементів системи охолодження. Показано, що на моделювання процесів впливає геометрія каналу, направлення течії (відцентрове, доцентрове), наявність супутних потоків, параметри і властивості (повітря, масло-повітря) охолоджуючого середовища. Тому від точності, з якою буде змодельований окремий елемент, залежить надійність моделювання всієї системи охолодження. Проведено адаптацію математичних моделей елементів гідравлічних мереж для розрахунку систем охолодження газових турбін, таких як: апарат закручування потоку (АЗ), теплообмінник, канали, що переміщуються. Наведено опис, теоретичні основи моделювання цих елементів гідравлічної схеми, проведені чисельні дослідження по впливу апарата закручування і теплообмінника на ефективність охолодження, складені відповідні моделі систем охолодження. Встановлено, що ефективність охолодження при застосуванні АЗ збільшується на 15%. Запропоновано підхід включення в загальну гідравлічну схему теплообмінника, при загальному наборі початкових даних, які відображають роботу теплообмінника в змінному режимі. Проведено дослідження впливу відцентрового ефекту на можливість подачі повітря в порожнини ротора турбіни. Розглянуті приклади течії повітря в порожнинах, утворених двома паралельними дисками з осьовою або радіальною подачею повітря на периферійному радіусі. Проведений CFD аналіз показав, що в залежності від напрямку подачі повітря істотно змінюється характер течії в порожнині. При радіальній подачі повітря в напрямку осі обертання має місце безвихровий характер течії, при осьовій - з'являється вихор. Проте, відмінність в характері течії майже не позначається на величині протитиску, який перешкоджає переміщенню повітря. Визначено діапазон достовірності результатів методу розрахунку насосного ефекту в придискових порожнинах роторів газових турбін, а саме: відношення ширини порожнини до зовнішнього радіуса диска не перевищує величину 0,17, що дозволяє обґрунтовано використовувати цей метод для розрахунків систем охолодження. Розроблено узагальнений підхід до методу розрахунку коефіцієнтів витрати і гідравлічного опору елементів систем охолодження газових турбін таких, як отвори, потовщені діафрагми, лабіринтові ущільнення, які регламентують витрату охолоджуючого повітря і відповідають за надійність і економічність системи охолодження. Так як розрахунок гідравлічної схеми застосовує коефіцієнти гідравлічного опору кожної ділянки схеми, а експериментальні дані часто представленні коефіцієнтами витрати, тому встановлено зв'язок між ними за допомогою припущень, які враховують різницю між стисливим і нестисливим середовищами. На основі проведених досліджень, обґрунтовано поправку на стисливість до коефіцієнту гідравлічного опору подовжених діафрагм, отворів, лабіринтових ущільнень, яка уточнює коефіцієнт гідравлічного опору до 25%. Розроблено математичну модель розрахунку підшипника, описані підходи до визначення концентрації і термодинамічних характеристик двофазного гомогенного середовища, що дозволило включити підшипник як в гідравлічну, так і теплову моделі систем охолодження газових турбін. Розроблено метод розрахунку гідравлічної мережі для маслоповітряної суміші, який істотно розширив можливості моделювання процесів охолодження роторів і підшипників газових турбін і маслозабезпечення підшипників, що дозволило провести спільний розрахунок системи охолодження ротора турбіни і підшипників. Проведено дослідження системи охолодження ротора високотемпературної газової турбіни за допомогою розроблених методів розрахунку. Встановлено, що методи розрахунку відповідають робочим даним газотурбінного двигуна Д 36.
The dissertation for the degree of Candidate of Technical Sciences (Ph. D.) in the specialty 05.05.16 "Turbomachine and turbine plants", (technical sciences). National Technical University "Kharkiv Polytechnical Institute", Ministry of Science and Science of Ukraine, Kharkiv, 2018. Dissertation is devoted to solving an important scientific and technical task of improving the cooling systems of gas turbines by further developing the methods of hydraulic and thermal calculation of the channels of the cooling system of gas turbines. To study the structure and flow properties of these elements, to obtain the dependences describing this flow. The analysis of scientific and technical literature devoted to the design of cooling systems for gas turbine engines was carried out, in which international experience of experimental studies and computational experiments was considered, to the study of heat transfer and flow hydrodynamics in rotating elements. As a result of the analysis of the literature, it is shown that the main direction of development of efficient and reliable GTE cooling systems is to improve the accuracy of the calculation of the flow and hydraulic characteristics of the elements of the cooling system. It is shown that the modeling of processes is influenced by the channel geometry, flow direction (centrifugal, centripetal), presence of associated flows, parameters and properties (air, oil-air) of the cooling medium. Therefore, the accuracy with which the simulation of the entire cooling system depends on the accuracy with which the individual element will be modeled. Mathematical models of hydraulic network elements have been adapted to calculate gas turbine cooling systems, such as: a device for swirling flow, a heat exchanger, channels that are moved. Description, theoretical bases of modeling of these elements of a hydraulic circuit, the researches carried out on the influence of the apparatus of the twist and the heat exchange apparatus on the efficiency of cooling are given, the corresponding models of cooling systems are made. Impact study conducted of the centrifugal effect on the possibility of air supply in the cavity of the rotor of the turbine has been studied. The considered examples of air flow in cavities formed by two parallel disks with axial or radial air supply at a peripheral radius. CFD analysis showed that, depending on the direction of air supply, the nature of the flow in the cavity is significantly changed. At radial air supply in the direction of the axis of rotation there is a non-vortex nature of the flow, with axial - vortex occurs. However, the difference in the nature of the flow almost does not affect the magnitude of the back pressure, which impedes the movement of air. The range of reliability of the results of the calculation method of the pump effect in the disk cavities of the rotors of the gas turbines is determined, namely: the ratio of the width of the cavity to the external radius of the disk does not exceed the value of 0.17, which allows us to use this method reasonably for calculations of the cooling systems. Developed a generalized approach to the method of calculating the flow coefficients and the hydraulic resistance of elements of the cooling systems of gas turbines such as openings, thickened diaphragms, labyrinth seals, regulating the flow of cooling air, which are responsible for the reliability and economy of the cooling system. In the calculations of the hydraulic circuit, the hydraulic resistance coefficients of each section of the circuit are used, and the experimental data are often represented by flow coefficients. Therefore, a connection is established between them using assumptions that take into account the difference between compressible and incompressible media. On the basis of the research, justified correction for compressibility to the coefficient of hydraulic resistance of elongated diaphragms, holes, labyrinth seals, which specifies the coefficient of hydraulic resistance to 25%. A mathematical model for calculating the bearing has been developed, approaches have been described for determining the concentration and thermodynamic characteristics of a two-phase homogeneous medium, which made it possible to include the bearing in both the hydraulic and thermal models of gas turbine cooling systems.A method was developed for calculating the hydraulic network for the air-oil mixture, which significantly expanded the possibilities for simulating the cooling processes of the rotors and bearings of gas turbines and providing bearings with oil, which made it possible to jointly calculate the cooling system of the turbine rotor and bearings. A study of the cooling system of the rotor of a high-temperature gas turbine was carried out using the developed calculation methods. It is established that the calculation methods correspond to the working data of the D-36 gas turbine engine.

Books on the topic "Air-Oil flow":

G, Zilliac Gregory, and Ames Research Center, eds. Computational study of surface tension and wall adhesion effects on an oil film flow underneath an air boundary layer. Moffett Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1998.

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Spedding, P. L. Data on two-phase air-water, and three-phase air-water-oil, multiphase flows transversing across a 90° horizontal bifurcating Tee-junction. Belfast: Department of Chemical Engineering, Queen's University of Belfast, 1995.

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Book chapters on the topic "Air-Oil flow":

Shahangian, Navid, Leila Sharifian, Rüdiger Beykirch, Albert Jeckel, Silja Klier, and Lothar Grupe. "Simulation of Oil Flow Behavior in the Air Gap between Rotor and Stator." In Proceedings, 68–81. Wiesbaden: Springer Fachmedien Wiesbaden, 2023. http://dx.doi.org/10.1007/978-3-658-42940-9_6.

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Li, Guangle, Guangle Zeng, Huiqing Jiang, and Haijun Shen. "Numerical Simulations on the Heat Transfer and Flow Performance of Lubricating Oil in an Air/Lubricating Oil Heat Exchanger." In Lecture Notes in Mechanical Engineering, 409–15. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-8867-9_39.

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"Front Matter." In Oil Spill Response Performance Review of Skimmers, FM1—FM12. ASTM International100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, 1998. http://dx.doi.org/10.1520/mnl10685m.

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ASTM Manual 34 provides you with all the information necessary for selecting skimmers for various applications. In assembling reports to develop this publication, government agencies were able to find and provide single copies of many test reports-copies that were available no where else but in government archives-to use for analysis. This never-before published information is now available in condensed form to the user. The data is easily accessible, meaningful, and quickly understood. Fifteen chapters cover the following skimmer types:• broom; • brush (chain and drum brush); • disc; • drum; • paddle belt; • stationary rope mop; • suspended rope mop; • ZRV rope mop; • sorbent belt; • fixed submersion plane; • submersion moving plane; • suction; • air conveyors; • weir and induced flow weir; • and advancing weir. A valuable reference for spill response professionals working in oil companies, government agencies, consulting firms, oil spill co-ops, and spill recovery contracting firms.

"Atomized Droplet Impact Kinetics Behavior of Cryogenic Air Minimum Quantity Lubrication." In Thermodynamic Mechanism of Cryogenic Air Minimum Quantity Lubrication Grinding, 106–35. IGI Global, 2024. http://dx.doi.org/10.4018/979-8-3693-3378-5.ch004.

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In this chapter, a finite element simulation analysis on dynamic behaviors of droplets when they impact onto the wall and liquid film is carried out. Firstly, the morphological evolutionary mechanism during spreading of droplets is analyzed based on the dynamic model of droplets impacting onto the wall. Secondly, the impacting dynamics of a single droplet onto the wall under different kinematic viscosities, surface tension coefficients, impact velocities, and contact angles are simulated by controlling variables based on physical parameters and atomization parameters of the lubricating oil under different CA temperatures and air pressures. Moreover, the influencing laws of different factors on droplet spreading coefficient as well as height and radius of the jet flow are analyzed. Finally, dynamic characteristics when a single droplet impacts onto the liquid film are simulated in the same way. The influencing laws of different factors on height and radius of the jet flow as well as thickness of the central liquid film are analyzed.

Zhao, Hongxia, Jiangyi Lv, Minjie Liu, and Chang Zhao. "Analysis of Automotive Thermal Management System Using One-Dimensional Simulation." In Frontiers in Artificial Intelligence and Applications. IOS Press, 2024. http://dx.doi.org/10.3233/faia231334.

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This article takes the cooling system of a certain vehicle as the model and applies simulation tools to establish its cooling system and front cabin air side model. It inputs boundary conditions such as the flow resistance characteristics of each component. Then, it completes the steady-state simulation calculation of the vehicle system under different working conditions and optimizes the design of the original cooling system model. Calculating through simulation, we obtain the flow rate, pressure distribution, and temperature rise of the system and various components. We predict and evaluate the working capacity of the cooling system and propose improvement suggestions based on the calculation and analysis results. This plays an important guiding role in the structural design and testing of the cooling system, greatly reducing research and development time and reducing research and development costs. The calculation results show that the flow rate of each component in the rated point, heating test condition, and idle condition of the original plan has decreased compared to a certain model on the same platform under the same working condition. The temperature difference between the radiator and the flow rate of the oil cooler does not meet the specification requirements. It is recommended to continue optimizing the design.

Millar, Dean L. "Wave and tidal power." In Energy... beyond oil. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780199209965.003.0006.

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This chapter reviews how electricity can be generated from waves and tides. The UK is an excellent example, as the British Isles have rich wave and tidal resources. The technologies for converting wave power into electricity are easily categorized by location type. 1. Shoreline schemes. Shoreline Wave Energy Converters (WECs) are installed permanently on shorelines, from where the electricity is easily transmitted and may even meet local demands. They operate most continuously in locations with a low tidal range. A disadvantage is that less power is available compared to nearshore resources because energy is lost as waves reach the shore. 2. Nearshore schemes. Nearshore WECs are normally floating structures needing seafloor anchoring or inertial reaction points. The advantages over shoreline WECs are that the energy resource is much larger because nearshore WECs can access long-wavelength waves with greater swell, and the tidal range can be much larger. However, the electricity must be transmitted to the shore, thus raising costs. 3. Offshore schemes. Offshore WECs are typically floating structures that usually rely on inertial reaction points. Tidal range effects are insignificant and there is full access to the incident wave energy resource. However, electricity transmission is even more costly. Tidal power technologies fall into two fundamental categories:1. Barrage schemes. In locations with high tidal range a dam is constructed that creates a basin to impound large volumes of water. Water flows in and out of the basin on flood and ebb tides respectively, passing though high efficiency turbines or sluices or both. The power derives from the potential energy difference in water levels either side of the dam. 2. Tidal current turbines. Tidal current turbines (also known as free flow turbines) harness the kinetic energy of water flowing in rivers, estuaries, and oceans. The physical principles are analogous to wind turbines, allowing for the very different density, viscosity, compressibility, and chemistry of water compared to air. Waves are caused by winds, which in the open ocean are often of gale force (speed >14 m/s).

"Lusas high as 100°C (212°F). The temperature of soybeans must 25% in the confectionery type. At an ERH of 70% and not exceed 76°C, since discoloration and protein denatura-25°C, the former contains 9.6% moisture and the latter tion will occur [47]. Seed going into storage should not be 13.6% moisture; at 60°C moisture the contents are 8.1 and heat damaged so it will not respire or germinate. 10.9%, respectively [61]. Drying is energy-intensive. Reasonably efficient com-The general practice is to dry seeds to about 75% RH mercial dryers require 830-890 cal/kg (1500-1600 Btu/lb for interim storage, but some oil mill supervisors prefer of moisture removed) [59]. 65% RH for long-term (12 months) storage, especially in The prime factor to be controlled in stabilizing seeds is colder climates. Table 9 shows the maximum moisture lev-relative humidity (%RH), which is the weight of moisture els considered safe for selected oilseeds [62]. Antimicro-per unit weight of air in the atmosphere surrounding the bial preservatives are commonly used in prepared feeds, seed compared to the maximum weight possible (satura-especially during high-humidity summer months, and tion) at that temperature expressed as a percentage. The some farmers preserve high—moisture-content cereals and term equilibrium relative humidity (ERH) simply means oilseeds with propionic acid for feed use. The oilseed RH in the adjacent air after allowing sufficient time for crushing trade does not accept treated seed. moisture in the seed to equilibrate with the air, and can be Relationships between RH and equilibrated moisture determined by analyzing the head space in a sealed equili-content are shown for soybeans in Table 10 [63]. Levels to brated container. Another allied term is water activity, Av„, which soybeans will equilibrate, in various temperatures which is ERH expressed as a decimal rather than a per-and RHs of the surrounding air, are shown in Figure 3 [64]. centage. Direct-reading instruments are available for Relationships between temperature, moisture content, and measuring RH, ERH, and A. Manual methods for deter-allowable storage time of soybeans are shown in Figure 4 mining RH include the use of a sling psychrometer to ob-[64]. tain "wet bulb" and "dry bulb" temperatures and reference to relative humidity charts. Unfortunately, many people 5. Storage still prefer to relate seed stability to percent moisture con-Designs of storage (Fig. 2C) facilities are dictated by needs tent—a far less meaningful measurement. for aeration of seed and its angle of repose—the minimum Bacteria and yeasts have much higher ERH require-angle in degrees at which a pile maintains its slope [65]. ments for growth than molds (fungi). Table 8 shows that This sometimes is reflected in the pitch of conical roofs on some fungi will grow at any of the relative humidity ranges storage bins. Similarly, downspouts and the conical bot-shown, although few toxin-producing fungi grow at below toms of bins must have pitches steeper than the angle of 75% RH [60]. repose for the respective seed or meal to flow smoothly. During equilibration, available water from the seed and Higher moisture and oil contents increase the angles of re-atmosphere is attracted to the water-absorbing seed com-pose. Angles of repose and bulk densities of some major ponents but not to the oil. Thus, high-oil-content seeds oilseeds and products are presented in Table 11. (peanut, sunflower seed, and rapeseed/canola) must be Readily flowing seeds typically are stored in vertical-dried to lower moisture levels for safe storage than lower-walled silos. In contrast, undelinted cottonseed from the gin oil-content seeds like soybeans. For example, oil-type sun-is stored on cement floors in piles whose shape is dictated flower seeds contain about 42% oil, compared to about by its angle of repose. In areas with wet falls, winters, and TABLE 8 Equilibrium Moisture Contents of Common Grains, Oilseeds, and Feed Ingredients at 65-90% Relative Humidity (25°C) and Fungi Likely to Be Encountered Equilibrium moisture contents (%) Relative Starchy cereal seeds, humidity debated oilseed Peanut, sunflower (%) meals, alfalfa pellets Soybean seed, Rapeseed/Canola Fungi 65-70 12-14 11-12 6-8 Aspergillus halophilicus 70-75 13-15 12-14 7-10 A. restrictus, A. glaucus, Wallemia sebi 75-80 14-16 14-16 8-11 A. candidus, A. ochraceus, plus the above 80-85 15-18 16-19 9-13 A. flavus, Penicillium spp., plus the above 85-90 17-20 19-23 10-16 Any of the above Ref. 60." In Handbook of Cereal Science and Technology, Revised and Expanded, 324–31. CRC Press, 2000. http://dx.doi.org/10.1201/9781420027228-30.

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Conference papers on the topic "Air-Oil flow":

Souza, Tiago Ferreira, Caio Araujo, Maurício Figueiredo, FLAVIO SILVA, and Ana Maria Frattini Fileti. "Gas Void Fraction Prediction for Air-Water and Air-Oil Two-Phase Flows via Artificial Neural Network." In 5th Multiphase Flow Journeys. ABCM, 2019. http://dx.doi.org/10.26678/abcm.jem2019.jem19-0017.

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Odozi, Utomi A., Maria A. Mendes-Tatsis, and Geoff F. Hewitt. "Three Phase Air-Oil-Water Flow Patterns." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0759.

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Abstract In this paper, the flow patterns observed during three-phase (air/oil/water) flow experiments are described. These experiments have been carried out in the Imperial College WASP High Pressure Facility with the test section (77.92 mm I.D) downwardly inclined at an angle of 1.5° to the horizontal at system pressures of 0, 5 and 10 bar(g). The results for the flow pattern have been plotted on three-phase horizontal flow pattern maps and these comparisons show that the small downward inclination angle has a pronounced effect on the flow regimes. The system pressure also has a strong effect on the flow pattern transitions. In addition to these, no complete separation was observed between the oil and water layers. The flow pattern transitions were compared with the theoretical predictions of Taitel and Dukler (1976) and this was revealed to be inadequate in predicting the three-phase flow patterns and the effect of pressure.

Glahn, A., and S. Wittig. "Two-Phase Air/Oil Flow in Aero Engine Bearing Chambers: Characterization of Oil Film Flows." In ASME 1995 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/95-gt-114.

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For the design of secondary air and lubrication oil systems a sufficient knowledge on two-phase flow and heat transfer phenomena under bearing chamber flow conditions is required. The characterization of oil film flows at the bearing chamber walls is one of the major tasks for a better understanding of these processes and, therefore, a necessity for improvements of the efficiency of aero engines. The present paper gives a contribution to this subject. Utilizing a fibre-optic LDV-setup, measurements of oil film velocity profiles have been performed in our high speed bearing chamber rig simulating real engine conditions. All data have been compared with different theoretical approaches which have been derived from a force balance at a liquid film element, including geometrical conditions and temperature dependent fluid properties, and by approaches for the eddy viscosity available in the literature.

Ho¨hn, Bernd-Robert, Klaus Michaelis, and Hans-Philipp Otto. "Minimised Gear Lubrication by a Minimum Oil/Air Flow Rate." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34119.

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The objectives of the research project were to investigate the limits concerning possible reduction of lubricant quantity in gears without detrimental influence on the load carrying capacity. The investigations covered the influence of the oil level in dip lubricated systems as well as the oil flow rate in spray lubricated systems namely oil-air supply systems on power loss, heat generation and load carrying capacity. The load carrying capacity in terms of characteristic gear failure modes was determined and was compared to the results using conventional lubricant volumes with dip lubrication. Therefore in back-to-back gear tests the parameters speed, load and oil quantity were varied for examination of the four main gear flank damages: scuffing, wear, pitting and micropitting. The investigations showed the application potential of oil/air lubrication also for heavy duty transmissions nevertheless there exists a natural limitation for lowering the oil quantity in transmissions without detrimental influence on the load carrying capacity.

Shollenberger, K. A., J. R. Torczynski, and D. L. George. "Gas Distribution in Air/Water and Air/Oil Bubble-Column Flows." In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31376.

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The effect of liquid properties on axial development of gas-volume-fraction profiles in bubble-column flows is investigated. Experiments are conducted in a cylindrical vessel with an inner diameter of 0.48 m and a height of 3 m. The liquids examined include water and two lightweight mineral oils. A cross sparger with 96 holes is used to inject air into the column with all the holes facing either upwards or downwards. The superficial gas velocity ranges from 5 to 30 cm/s, and the absolute column pressure ranges from 0.1 to 0.5 MPa. Gamma-densitometry tomography (GDT) is used to measure radial distributions of gas volume fraction at eight axial locations. The development length of the gas-volume-fraction profile is shown to increase with gas velocity and column pressure for all three liquids. The development of the cross-sectionally averaged gas-volume fraction for the air/water flow is remarkably different from that for the air/oil flows.

Zimmermann, H., A. Kammerer, R. Fischer, and D. Rebhan. "Two-Phase Flow Correlations in Air/Oil Systems of Aero Engines." In ASME 1991 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/91-gt-054.

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A strategy is outlined on how to introduce two-phase flow correlations into air/oil system calculations for aero engines. The importance of two-phase flow effects is highlighted by demonstrating their particular significance for the high altitude performance of a vent system. For air/oil mixtures very little can be obtained from the literature and correlations derived from air/water test results have to be corrected. For critical flow conditions in restrictors an improved method is developed. Some test data obtained for air/oil mixtures show, that the proposed correlations agree fairly well. Furthermore, it is shown how numerical methods for this complex field of fluid dynamics can be used in the future by the example of phase demixing by centrifugal forces.

Ahmed, W. H., C. Y. Ching, and M. Shoukri. "Characteristics of Air-Oil Two-Phase Flow Across a Sudden Expansion." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45554.

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The pressure recovery and void fraction change of air-oil two-phase flow across a sudden expansion has been investigated experimentally over a range of flow conditions. The pressure upstream and downstream of a half-inch to one-inch sudden expansion was measured using a series of pressure taps, and capacitance sensors were used to measure the void fraction along the test section. The void fraction increases as the flow approaches the sudden expansion section, with a sudden increase immediately downstream of the expansion followed by a gradual relaxation to the fully developed value further downstream. The normalized pressure recovery coefficient using the dynamic head based on the homogeneous density and two-phase velocity is found to collapse when plotted as a function of the mass quality. The experimental pressure recovery data are compared with predictions from existing models, and are found to be in good agreement with the Delhaye model with the void fraction relation of Wallis.

Xu, Rang-shu, Juan-juan Wang, Xiao-wen Chen, and Shan-shan Ju. "Numerical simulation of two-phase air/oil flow characteristic in bearing chamber." In 2011 International Conference on Electric Information and Control Engineering (ICEICE). IEEE, 2011. http://dx.doi.org/10.1109/iceice.2011.5776909.

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AbdulKareem, Lokman A., V. Hernandez-Perez, S. Sharaf, and Barry J. Azzopardi. "Characteristics of Air-Oil Slug Flow in Inclined Pipe Using Tomographic Techniques." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44546.

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The structure of gas liquid flow in horizontal and vertical pipes to some extent is well understood. However, the situation in inclined pipes is much more difficult with very little work published in literature. Changes in physical phenomena occur as the pipe inclination angle varies from the vertical through to inclined and then to horizontal. This work describes a study carried out at the University Of Nottingham on the effects of inclination on gas / liquid slug flow. Two advanced tomography techniques were applied simultaneously to the flow of a mixture of air and silicone oil in a 67 mm internal diameter pipe and the pipe was inclined at angles 0, 5, 10, 30, 45, 60, 80, 90 degrees. This paper reports on the use of twin plane electrical capacitance tomography (ECT) system developed by TomoFlow electronics Ltd to measure flow characteristics in gas-liquid flows. We report measurements over a range of liquid superficial velocities from 0.05 m/s to 0.5 m/s and gas superficial velocities from 0.06 m/s to 6 m/s at all the above angles in a pipe 6 m long. A second technique, Capacitance Wire Mesh Sensor (WMS) developed at Forschungszentrum Rossendorf-Dresden/Germany was also present in the tests, The results for the two sensors are shown to be within 1% of each other in some instances when comparing cross-sectional averaged void fraction. The data was recorded at an acquisition frequency of 1000 Hz over an interval of 60 seconds. This enabled an examination of the flow to be carried out at several levels of complexity. Both measuring sensors provide time and cross-sectionally resolved information about the spatial distribution of the phases. In present paper, the effect of inclination on the characteristics of slug flow is presented. Radial gas volume fraction profiles and bubble size distributions were also processed from the wire-mesh sensor output. The results indicate that the pipe inclination has a significant effect on the slug flow characteristics.

Sun-Seok Byeon, Youn-Jea Kim, and Jae-Young Lee. "Numerical analysis on the flow characteristics of oil-injected screw air compressor." In 2014 ISFMFE - 6th International Symposium on Fluid Machinery and Fluid Engineering. Institution of Engineering and Technology, 2014. http://dx.doi.org/10.1049/cp.2014.1172.

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Reports on the topic "Air-Oil flow":

BUTCHER, T. A. DEVELOPMENT OF A LOW PRESSURE, AIR ATOMIZED OIL BURNER WITH HIGH ATOMIZER AIR FLOW. Office of Scientific and Technical Information (OSTI), January 1998. http://dx.doi.org/10.2172/758985.

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Butcher, T. A. Development of a Low Pressure, Air Atomized Oil Burner with High Atomizer Air Flow: Progress Report FY 1997. Office of Scientific and Technical Information (OSTI), January 1998. http://dx.doi.org/10.2172/6155.

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Steenhuis, Tammo, Jean-Yves Parlange, David DiCarlo, Alon Rimmer, and Christophe Darnault. Unstable Fingered Flow in Soil-Oil-Water-Air Systems: Theoretical Predictions and Experimental Verification. Fort Belvoir, VA: Defense Technical Information Center, July 1997. http://dx.doi.org/10.21236/ada329674.

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Kiefner and Duffy. L51509 Two-Phase Flow in Horizontal and Inclined Pipes at Large Pipe Size and High Gas Density. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), February 1986. http://dx.doi.org/10.55274/r0010275.

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Knowledge of flow regime, holdup and pressure drop is needed in order to design gas and oil pipelines confidently and to minimize construction and operating costs. Previous public studies of two-phase flow in inclined pipes have used small diameter pipes two inches in diameter or less, and have primarily used air and water as the working fluids at low pressure (near one atmosphere). Present design methods are based upon the results of these experiments. In most advanced analyses available today, the flow regime transition is governed by a Froude number, the balance between inertial and buoyancy forces. The primary objective of the work has been to obtain experimental data to challenge the present two-phase flow analysis methods for large pipe size, high gas density, and pipe inclination. Present analysis and design methods for two-phase flow in pipelines are based on correlations of data from small pipes of order 2-inches diameter or less, for air-water flows at pressures near one atmosphere. To achieve this objective, Creare performed experiments in an existing test facility with a special test section assembled for this project. Pipe diameter and gas density are closer to prototypical oil and gas pipeline conditions than previous experiments reported in the literature. The key experimental results include flow regime observations, pressure drops, and holdup measurements. The instrumentation in the test facility allows detailed characteristics of the flow such as slug velocity, slug frequency, liquid film velocity, and slug length to be measured in the slug flow regime.

Weissinger, Rebecca. Status and trends of springs at Hovenweep National Monument, 1999–2021. Edited by Alice Wondrak Biel. National Park Service, August 2023. http://dx.doi.org/10.36967/2294373.

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Water is a scarce, but vital, resource at Hovenweep National Monument (NM). The National Park Service has prioritized long-term monitoring of water resources at the monument through a variety of programs and indicators since 1999. The purpose of this report is to evaluate water-quantity and water-quality data collected at long-term monitoring sites in Hovenweep NM from 1999 to 2021 for trends over time, and to summarize site-characterization data for currently monitored locations. Data are available for three active monitoring stations—Square Tower Spring, Hackberry Pool, and Goodman Point Spring—and three discontinued monitoring stations—Cajon Pool, Upper Hackberry Spring (Spring #4), and Horseshoe Spring. Water resources at Hovenweep NM have exhibited many trends over the past two decades. Pool levels at both Square Tower Spring and Hackberry Pool went up, with a step increase shown in 2016 (after no sampling in 2014–2015). In contrast, flow decreased by more than half at Goodman Point Spring and ceased at Upper Hackberry Spring (Spring #4). Flow at Horseshoe Spring also decreased, although the period of record at this site was very short. Both Upper Hackberry Spring (Spring #4) and Horseshoe Spring were removed from the monitoring rotation because flows were increasingly absent or too low to measure. Pool-level dynamics and water chemistry at Cajon Pool are characteristic of precipitation-derived water rather than groundwater; this site was removed from the monitoring rotation because it was not a good indicator of groundwater conditions. The water chemistry in both Square Tower Spring and Hackberry Pool changed significantly, but in opposite directions. Square Tower Spring had increasing total dissolved solids (TDS) and specific conductance, with all major ions showing increases over time. Hackberry Pool had decreases in TDS and most major ions through 2010, when water-chemistry lab analyses were suspended due to logistical constraints. Specific conductance continued to decrease at Hackberry Pool through 2021. The reasons for these changes are unknown. Increases in major ions at Square Tower Spring are unlikely to be related to oil and gas development in the region. Decreases in major ions at Hackberry Pool may reflect an increase in the amount of water that is entering the pool from rain and snowmelt rather than groundwater at this site. Water-quality parameters at Goodman Point Spring have remained stable. While the causes of trends in water chemistry at these sites are likely natural, the small quantities of water and harsh water-quality conditions make these sites poor habitat for aquatic life. Groundwater is naturally low in dissolved oxygen—but the dissolved-oxygen concentrations in the two pools are persistently low, sometimes falling to near zero in the summer. Water temperatures also warm in conjunction with air temperatures, with temperatures as warm as 18°C in the pools and 19°C in Goodman Point Spring. Traditionally, Puebloan cultures would have managed these small water resources to promote infiltration and retention of precipitation and to remove sediment and debris. Decreases in flow and increasing vegetation stress are likely tied to increasing air temperatures and long-term drought conditions across the region. The namesake hackberry trees at Hackberry Pool and nearby sites have shown increasing drought stress. Regionally, the underlying Dakota aquifer that feeds springs at the monument was relatively stable from 2008 to 2017, with decreasing levels from 2018 to 2021. Overall, the most concerning trends observed at springs in Hovenweep NM are likely due to climate change. Increasing air temperature threatens springflow and spring-associated vegetation through increased evapotranspiration. While pool levels have increased, recent decreases in the regional Dakota aquifer raise concerns about the stability of pools in the future. Managers could consider the potential benefits and risks of: Prioritizing protections and actions at Square Tower Spring, which has been the most resilient site at the monument in persistence of surface water and vegetation health during extreme drought. Implementing potential climate-adaptation actions that could improve groundwater infiltration upgradient of spring sites. This could include rehabilitating traditional structures to slow the flow of surface water. Implementing traditional management techniques that could increase dissolved-oxygen concentrations in the spring pools. Increasing invasive-plant removal efforts at Goodman Point Spring, which had the greatest number and cover of invasive-plant species of the three currently monitored locations. Developing interpretive stories about water-management techniques and the role of climate change in creating drought stress on iconic hackberry trees.