Journal articles: 'Air-Oil flow'

1

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.

2

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.

3

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

4

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.

5

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.

7

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.

8

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.

9

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.

10

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.

11

Hanks, James E., and Chester G. McWhorter. "Spray Droplet Size for Water and Paraffinic Oil Applied at Ultralow Volume." Weed Technology 7, no. 4 (December 1993): 799–807. http://dx.doi.org/10.1017/s0890037x00037787.

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Spray droplet size of water and paraffinic oil was affected by air pressure, nozzle type, and liquid flow rate when applied with an ultralow volume (ULV), air-assist sprayer. Volume median diameters of water were generally larger than oil at constant air pressure and liquid flow rate. Droplet size decreased as air pressure increased, but increased as liquid flow rate increased. Volume median diameters of water droplets ranged from 41 to 838μm and from 16 to 457μm with oil when atomized at air pressures ranging from 14 to 84 kPa. Relative spans ranged from 1.2 to 18.0 and 2.0 to 7.2 for water and oil, respectively.

12

Brandt, Agata, Krystian Czernek, Małgorzata Płaczek, and Stanisław Witczak. "Downward Annular Flow of Air–Oil–Water Mixture in a Vertical Pipe." Energies 14, no. 1 (December 23, 2020): 30. http://dx.doi.org/10.3390/en14010030.

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The paper presents the results of a study concerned with the hydrodynamics of an annular downward multiphase flow of gas and two mutually non-mixing liquids through a vertical pipe with a diameter of 12.5 mm. The air, oil and water were used as working media in this study with changes in superficial velocities in the ranges of jg = 0.34–52.5 m/s for air, jo = 0.000165–0.75 m/s for oil, and jw = 0.02–2.5 m/s for water, respectively. The oil density and viscosity were varied within the ranges of ρo = 859–881 kg/m3 and ηo = 29–2190 mPas, respectively. The research involved the identification of multiphase flow patterns and determination of the void fraction of the individual phases. New flow patterns have been identified and described for the gravitational flow conditions of a two-phase water–oil liquid and a three-phase air–water–oil flow. New flow regime maps and equations for the calculation of air, oil and water void fractions have been developed. A good conformity between the calculated and measured values of void fraction were obtained. The map for the oil–water–air three-phase flow is valid for the following conditions: j3P = 0.35–53.4 m/s (velocity of three-phase mixture) and oil in liquid concentration βo* = 0.48–94% (oil in liquid concentration). In the case of a downward annular oil–water two-phase flow, this map is valid for liquid mixture velocity jl = 0.052–2.14 m/s and βo* = 0.48–94%.

13

Liu, Cong, Baohong Tong, Guotao Zhang, Wei Wang, Kun Liu, and Peimin Xu. "Effect of behavior of oil–air lubrication flow on characteristic of point contact sliding wear." Industrial Lubrication and Tribology 71, no. 3 (April 8, 2019): 381–89. http://dx.doi.org/10.1108/ilt-08-2018-0305.

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Purpose This paper aims to investigate the influence of oil–air lubrication flow behavior on point contact sliding wear characteristics. Design/methodology/approach Oil–air lubrication equations between point contact counterparts were established on the basis of volume of fluid model. The effects of oil supply and injection azimuth on oil-phase volume fraction and its pressure distribution were simulated with commercial software Fluent. Characteristics of point contact sliding wear were then tested with an MFT-3000 friction tester under oil–air lubrication condition. The influence of flow behavior on wear characteristic was investigated combined with numerical and experimental results. The wear mechanism was revealed using SEM, EDS and ferrography. Findings When air supply speed is constant, the oil-phase volume fraction increases with the increase in oil supply, which helps form continuous oil film and decrease the sliding wear evidently. The injection angle and distance considerably influence the oil–air flow behavior. When injecting at a certain distance and angle, the oil-phase volume fraction reaches its maximum, and the abrasion loss is minimal. Under the test conditions in this study, abrasive particles are mainly debris and a few spiral cuttings. The wear mechanism is abrasive wear. Originality/value The influence of the behavior of oil–air lubrication flow on the characteristic of point contact sliding wear is analyzed. This work provides guidance for the application of oil–air lubrication technology in point contact friction pairs.

14

Pietrzak, Marcin. "Flow patterns and gas fractions of air–oil and air–water flow in pipe bends." Chemical Engineering Research and Design 92, no. 9 (September 2014): 1647–58. http://dx.doi.org/10.1016/j.cherd.2013.12.008.

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15

Yang, Xiao Ming, Jian Wen Chen, Lei Li, Jin Jin Liu, and Yu Long Zhao. "Flow Field Simulation and Atomization Characteristic of Pneumatic Oil Mist Swirler." Advanced Materials Research 339 (September 2011): 400–405. http://dx.doi.org/10.4028/www.scientific.net/amr.339.400.

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Based on the theory of Fluid Dynamics CFD and Fluid analysis software Fluent，we accomplished the flow field simulation of internal speed and internal pressure of pneumatic oil mist atomizer. Both the flow field simulation and the results of experiment are in good agreement，particle size and density of oil mist change very little when the pressure of compressed air is kept constant while the distance of nozzle and baffle is varied. When the distance from nozzle to baffle is fixed, and the pressure of compressed air is increased gradually, the density of oil mist will increase and the particle size of oil mist will decrease along with the increasing pressure of compressed air. This decreasing trend of particle size of oil mist will slow down when the pressure of compressed air increases to 0.35Mpa. The particle size of oil mist can reach 2μm.

16

Zeng, Qunfeng, Jinhua Zhang, Jun Hong, and Cheng Liu. "A comparative study on simulation and experiment of oil-air lubrication unit for high speed bearing." Industrial Lubrication and Tribology 68, no. 3 (April 11, 2016): 325–35. http://dx.doi.org/10.1108/ilt-05-2015-0066.

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Purpose The purpose of this paper is to design an oil-air lubrication system with low temperature rise, vibration and noise simplifies the spindle configuration. The oil-air lubrication unit is a key component for high-speed grinding machine tools. The development of oil-air lubrication unit suitable for high/ultrahigh rotational speed is a daunting task owing to the lubrication challenges. Design/methodology/approach This paper emphasizes three main issues: the analysis of oil-air two-phase flow for tradition oil-air lubrication unit with the simulation method; the design of new oil-air lubrication unit for the high/ultrahigh-speed grinding machine tools and the comparative experiment research of tradition and new oil-air lubrication unit. The optimum structure parameters that create the optimum flow pattern and operating conditions resulting in low temperature increase, vibration and noise of oil-air lubricated spindle can be achieved by the simulation method and experiments. Findings The simulation and experimental results show that new oil-air lubrication unit lubricating a high speed electric spindle has a better performance with a small temperature increase and vibration, which means that our proposed method is an effective design method for oil-air lubrication system. Originality/value A design method suitable for high-speed oil-air lubrication unit is proposed. New oil-air lubrication unit is expected to apply for high/ultrahigh rotational speed grinding machine tools.

17

Zhang, Wenliang, Xiaopeng Xie, and Guogang Gao. "Transient formation theory of air-microbubble oil and testing its oil-spraying mechanism." AIP Advances 13, no. 3 (March 1, 2023): 035321. http://dx.doi.org/10.1063/5.0134933.

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In oil–air lubrication systems, large numbers of air microbubbles are often included in the oil phase. However, the principles of microbubble formation in oil–air annular flow and their influencing factors remain uncertain, and previous conclusions regarding the effects of microbubbles on the viscosity properties of the lubricant oil are inconsistent. Thus, there is an urgent need for experimental verification. In this paper, a transient force balance model is established and used to ascertain the formation of air microbubbles in oil (AB-oil) for an oil–air annular flow. The stability of these microbubbles is analyzed using the Rayleigh–Plesset equation. Theoretical analysis shows that the microbubble radius is the key factor affecting the force balance and stability of microbubbles in oil. Experiments are conducted based on this theoretical analysis, and the void fraction of AB-oil is determined through image analysis to verify the principles and influencing factors of AB-oil formation in oil–air lubrication systems. The viscosity properties of AB-oil are then tested using a rheometer. The experimental results indicate that the formation of AB-oil is affected by oil viscosity, pipe range, oil feeding rate, and air pressure. AB-oil exhibit different viscosity properties at different shear rates and void fractions. Finally, the relationship between the void fraction and viscosity at different shear rates is determined from the experimental data. The outcomes of this research provide insights into the characteristics of oil–air lubrication systems for high-speed machine tool spindles.

18

Sun, Qi Guo, Xiong Shi Wang, Ying Wang, and Zhi Hong Li. "The Characteristics of the Annular Flow through the Sudden-Expansion Pipe of the Oil-Air Lubrication System." Advanced Materials Research 889-890 (February 2014): 358–62. http://dx.doi.org/10.4028/www.scientific.net/amr.889-890.358.

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The characteristics of the sudden-expansion pipe in oil-air lubrication system have been analyzed based on Fluent. The results show that the pressure and oil film mutate when the annular flow through the sudden-expansion pipe and the suddenly change of position of pressure and film is not affected by the inlet air velocity, however, the strength of pressure and film is in direct ratio with the inlet air velocity. The film of oil-air annular flow in the pipeline before the suddenly expanding part is well-distributed, but the distribution after that is widely affected by the air velocity and the pipe diameter, and furthermore the larger air velocity and pipe diameter increase the degree of dispersion of the annular flow film.

19

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

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

20

Dutra, Guilherme, Cicero Martelli, Marco Da Silva, Rodolfo Patyk, and Rigoberto Morales. "Air Flow Detection in Crude Oil by Infrared Light." Sensors 17, no. 6 (June 3, 2017): 1278. http://dx.doi.org/10.3390/s17061278.

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OKAZAKI, Tadao. "Measuring of Oil & Air Flow with Standing Microwave." Transactions of the Japan Society of Mechanical Engineers Series C 73, no. 731 (2007): 2161–66. http://dx.doi.org/10.1299/kikaic.73.2161.

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Farsetti, Silvia, Stefano Farisè, and Pietro Poesio. "Experimental investigation of high viscosity oil–air intermittent flow." Experimental Thermal and Fluid Science 57 (September 2014): 285–92. http://dx.doi.org/10.1016/j.expthermflusci.2013.12.004.

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Xu, G. P., K. W. Tou, and C. P. Tso. "Two-Phase Void Fraction and Pressure Drop in Horizontal Crossflow Across a Tube Bundle." Journal of Fluids Engineering 120, no. 1 (March 1, 1998): 140–45. http://dx.doi.org/10.1115/1.2819638.

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Void fraction and friction pressure drop measurements were made for an adiabatic, horizontal two-phase flow of air-water, air-oil across a horizontal in-line, 5 × 20 tube bundle with pitch-to-diameter ratio, P/D, of 1.28. For both air-water and air-oil flow, the experimental results showed that the average void fraction were less than the values predicted by a homogenous flow model, but were well correlated with the Martinelli parameter Xtt and liquid-only Froude number FrLO. The two-phase friction multiplier data exhibited an effect of flow pattern and mass velocity, and they could be well-correlated with the Martinelli parameter.

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Zheng, Xudong, Fangwei Xie, Diancheng Wu, Xinjian Guo, Bing Zhang, Van Xo Nguyen, and Yun Wang. "CFD simulation of air effect on flow field characteristics of hydro-viscous clutch with constant speed difference." Mechanics & Industry 19, no. 2 (2018): 208. http://dx.doi.org/10.1051/meca/2018032.

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The purpose of this paper is to study the air effects on transmission characteristics of hydro-viscous clutch and reveal the distribution law of the flow field of the oil film. The computational-fluid-dynamics (CFD) simulation model of oil film with radial oil grooves between friction pairs is taken as the study object. Considering the air effects, the pressure field, two-phase distribution, transmission torque and temperature field of the oil film are analyzed comparatively by using the CFD technology. The results show that the presence of air changes the pressure and temperature distributions of the oil film. With increase of the absolute rotational speed, the air volume fraction increases and the radius value of the air-liquid boundary decreases under condition of constant speed difference, which makes the coverage rate of the oil film on the surface of the friction disks reduce and the transmission torque of the oil film decrease. These simulation results are attributed to the study of hydro-viscous-drive and its applications. This paper also can provide a theoretical basis for the mechanism of power transmission through oil film in the presence of air effects.

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Cheng, Sun-Wen, and Wen-Jei Yang. "Modeling of Two-Phase Flow through a Rotating Tube with Twin Exit Branches." International Journal of Rotating Machinery 6, no. 3 (2000): 159–66. http://dx.doi.org/10.1155/s1023621x00000154.

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A numerical model is proposed to determine the dynamic behavior of single-phase and twophase, two-component flows through a horizontal rotating tube with identical twin exit branches. The working fluid, oil, enters the tube through a radial duct attached at one end and exits into open air through the twin radial branches, one located at midway and the other at the end of the tube. The branch-to-tube diameter ratio, rotational speed, and total oil flow rate are varied. It is experimentally revealed in previous study that the air cavitation occurs at lower speeds, leading to a two-phase flow with the air-oil ratio (void fraction) varying with the rotating speed. A unique characteristic in two-phase flow, i.e., hysteresis, is found to exist in both oil flow rates and inlet pressure. In theoretical modeling, the governing flow equations are incorporated by empirical equations for hydraulic head losses. The predicted and measured exit oil flow rates are compared with good agreement in both the single-phase and annular flow regimes. Only qualitative agreement is achieved in the bubbly and bubbly-slug flow regimes. The model can be applied to improve the design and thus enhance the performance of automatic transmission lines, and the cooling efficiency of rotating machines and petroleum drilling process.

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Sun, Qi Guo, Dong Xu Chen, Xiong Shi Wang, and Zheng Hui Zhou. "Coanda Effect on the Impact of Distribution Characteristics of Oil-Air Annular Flow." Applied Mechanics and Materials 620 (August 2014): 166–70. http://dx.doi.org/10.4028/www.scientific.net/amm.620.166.

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The T-junction model is simulated in Fluent by changing the curvature of branch pipe, and then the distribution characteristics of the annular flow was studied in T-junction distributor. The mass flow and pressure of the annular flow in this T-junction are studied, and the impact of Coanda Effect on the annular flow distribution characteristic is analyzed in oil-air two phases flow. The results show that, Coanda Effect affects the distribution of oil-air annular flow unevenly. The mass flow rate of air phase and the air velocity of outlet increase with decreasing the curvature, while the mass flow rate of liquid decrease with decreasing the curvature of the branch pipe connection; T-shaped junction inlet pressure is high, but the pressure gradient is small, the pressure gradient in the small curvature manifold is larger than that in the large curvature manifold.

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Wu, Hao Tian, and Guo Ding Chen. "The Calculation of Two-Phase Gas/Liquid Homogenous Flow in Bearing Chambers." Materials Science Forum 532-533 (December 2006): 717–20. http://dx.doi.org/10.4028/www.scientific.net/msf.532-533.717.

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The research of lubrication oil flow on gas/liquid two-phase flow is necessary in the designing process of engine bearing. It influences the consequent design and the whole engine’s reliability. This paper proposes the two-phase homogenous flow model considering lubrication oil and air. Based on the homogenous flow model, the Navier-Stokes equations is solved by the methods of the turbulent model and Finite Differential Method (FDM) to obtain the flow field and the influence of conditional and structural parameters on the flow. With the results, the results from single flow model and two-phase homogenous flow are compared. And the effects of air volume fraction, rotor speed and lubrication oil speed at entrance on exit pressure and speed are discussed.

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Sun, Qi Guo, Zheng Hui Zhou, and Yue Fei Wang. "Experiment of Effects of Oil Volume-Per-Cycle on Oil Film’s Thickness under Oil-Air Lubrication." Applied Mechanics and Materials 620 (August 2014): 476–80. http://dx.doi.org/10.4028/www.scientific.net/amm.620.476.

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Abstract: Thickness of oil film, a parameter of an oil-air lubrication system, is an important evaluation criterion for two-phase annular flow flowed in the system. Experiment of the effects of oil volume-per-cycle on oil film’s thickness is done on a special test rig using ECT technology, and then the changing rule of oil film’s thickness is analyzed in this paper. The results show that, at the first the thickness of oil film is thinness and weakness, and then it changes to thickness and stabilization, at the last the oil focusing on the bottom of tube. The break of annular flow and the blocking of oil at elbow tube have been studied experimentally and theoretically.

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Zi, Xintian, Kai Chen, Qinghua Bai, Xinming Li, Xuyang Jin, Xu Wang, and Feng Guo. "The Enhancement of Oil Delivery and Bearing Performance via A Guiding-Structured Nozzle under Oil–Air Lubrication." Lubricants 12, no. 2 (February 16, 2024): 60. http://dx.doi.org/10.3390/lubricants12020060.

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The oil–air lubrication method is specifically employed for high or ultra-high-speed spindle rolling bearings. Under high-speed conditions, the air curtain formed inside the bearing cavity obstructs oil delivery, thereby limiting further increases in spindle rotation speed. To enhance oil delivery capability, a guiding-structured nozzle has been developed to concentrate the jet flow and improve penetration through the air curtain. Tests were conducted on an oil–air lubricated bearing test bench to investigate the impact of nozzle structures and oil types on torque and temperature rise. The results demonstrate that compared to conventional nozzles, the guiding-structured nozzle requires smaller optimal amounts of oil supply, indicating its superior ability to deliver oil. Further examination of oil jet patterns and droplet distributions confirms that the guiding-structured nozzle provides a more concentrated jet flow with uniform distribution and smaller droplet sizes in diameter. These characteristics contribute to highly efficient oil delivery. Additionally, synthetic oils reduce droplet size, torque, and temperature rise in mixed lubrication regimes due to their formation of an anti-friction absorption layer on rubbing surfaces.

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Jablonská, Jana, Milada Kozubková, and Patrik Marcalík. "Experimental circuit for the generation of cavitation in oil flow." EPJ Web of Conferences 269 (2022): 01022. http://dx.doi.org/10.1051/epjconf/202226901022.

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The paper deals with the flow of oil through an experimental hydraulic circuit with a convergent divergent nozzle with a circular cross-section. Under different physical conditions, i.e. changes in pressure, flow and temperature, the formation and development of cavitation is monitored. As it is a highly dynamic flow in a transparent nozzle, cavitation is monitored using a high-speed camera and the frequency of formation and dissolution of the cavitation bubble and the movement of the cavitation cloud is then determined. The authors deal with the issue of the amount of dissolved or undissolved air in the hydraulic oil. Both variants of air influence the formation, development and size of the cavitation area. This cavitation is in this case called air cavitation. In technical practice, the issue of air cavitation is relevant, especially in the pump suction, where vacuum, leaks and hence air intake may occur.

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Sun, Qi Guo, Ali Cai, Zheng Hui Zhou, Zhi Hong Li, and Xiong Shi Wang. "Analysis for the Fluctuation Characteristics of Annular Flow in the Oil-Air Lubrication System." Applied Mechanics and Materials 487 (January 2014): 408–12. http://dx.doi.org/10.4028/www.scientific.net/amm.487.408.

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Fluctuation characteristics of the pressure drop distribution and liquid film distribution along a pipe of the oil-air annular flow in oil-air lubrication system are calculated respectively introducing Chisholm constant c base on the Chisholm theory and simulated by Fluent in this paper. The results show that the theoretical calculation results of the pressure drop and liquid film agree qualitatively with the simulation results, and the fluctuation characteristics of the pressure drop and liquid film thickness are augmented respectively when the air velocity increases. These conclusions will do favors for predicting and controlling the lubricant in the oil-air lubrication system.

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Xu, Rang Shu, Juan Juan Wang, Wei Xu, and Li Bo Liu. "Numerical DPM Model for Two-Phase Flow in Aero-Engine Bearing Chamber." Advanced Materials Research 201-203 (February 2011): 2267–70. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.2267.

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The main bearing chamber is a major part of the lubrication system in aero-engine, it is important to know the influence of operation parameters on air/oil two-phase flow, so as to optimize the design of aero-engine lubrication system. The air/oil two-phase flow in a simplified bearing chamber model in an aero-engine is simulated by means of discrete phase model (DPM) and wall-film model with CFD approach. The simulation results coincide with the existing experimental data. The oil film thickness and concentration of droplets in bearing chamber are presented at different rotational speeds and different lubricating oil flow rates.

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Li, Miaomiao, Yu Wang, Weifang Chen, and Rupeng Zhu. "Temperature rise characteristics for angular-contact ball bearings with oil-air lubrication based on fluid-solid conjugate heat transfer." Advances in Mechanical Engineering 13, no. 1 (January 2021): 168781402199092. http://dx.doi.org/10.1177/1687814021990927.

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At present, the thermal analysis of oil-air-lubricated angular-contact ball bearings uses empirical heat transfer coefficients to calculate heat transfer. This approach presents problems such as simulating the actual lubrication flow field and ignoring the internal heat conduction in the bearing ring. This paper proposes a CFD steady-state analysis model of oil-air-lubricated angular-contact ball bearings based on fluid-solid conjugate heat transfer to analyze the flow field and temperature field. A temperature rise test of oil-air-lubricated angular-contact ball bearings was carried out to verify the positive determination of the simulation analysis results. Based on a fluid-solid conjugate heat transfer steady-state analysis model, the effects of lubrication parameters, operating conditions, and rolling element materials on the temperature rise characteristics of oil-air-lubricated angular-contact ball bearings were studied. The research results provide a method for analyzing the temperature rise characteristics of oil-lubricated bearings and provide a basis for the analysis of oil-lubricated bearing life.

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Sun, Qi Guo, Ying Wang, and Xiong Shi Wang. "Research on Coanda Effect Appeared in Oil-Air Annular Flow through the Conical Diffuser." Applied Mechanics and Materials 668-669 (October 2014): 331–35. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.331.

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Physical model and numerical simulation model for oil-air annular flow through conical diffusers are built by Fluent, and Coanda Effect, a commonly phenomenon, appeared in this kind of oil-air annular flow field is studied, especially influences of Coanda Effect on the attachment of the liquid phase of annular flow trended to the curved wall are analyzed in detail by changing expansion angles to calculate the radial pressure distribution and pressure drop, employed numerical simulation method, in this paper. The simulation results show that the expansion angle has a great influence on the attachment of liquid phase in annular flow to the curved wall, the radial pressure gradient is an important factor of the Coanda Effect which make the liquid phase of annular flow convey near the wall, and the radial pressure gradient will decrease but the pressure drop increase when the expansion angle becomes larger. These conclusions will provide useful reference in designing pipelines conveying the two-phase annular flow in oil-air lubrication system.

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B, Guo. "Effect of Fluid Contact Angle of Oil-wet Ceramic Fracture Proppant on the Water Flow from Sandstones to Proppant Packs." Petroleum & Petrochemical Engineering Journal 6, no. 1 (2022): 1–9. http://dx.doi.org/10.23880/ppej-16000295.

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Ceramic fracture proppants are extensively used for enhancing oil and gas well productivity in low-permeability reservoirs. Previous work reported attracting-oil-repelling-water (AORW) property of oil-wet proppants at the faces of fractures. Because of lack of method for measuring contact angle of proppant packs, the terms water-wet proppant and oil-wet proppant were defined on the basis of observations of liquid droplets on the surfaces of proppant packs without quantitative measurement. An innovative method was developed in this study to determine the contact angles of fracture proppant packs. The effect of oil contact angle of oil-wet fracture proppant pack on the competing water/oil flow from sandstone cores to the packs was investigated. It was found that, for a given fracture proppant pack, the sum of the water contact angle and oil contact angle measured in the liquid-air-solid systems is less than 180 degrees, i.e., the two angles are not supplementary. This is believed due to the weak wetting capacity of air to the solid surfaces in the liquid-air-solid systems. Both water and oil contact angles should be considered in the classification of wettability of proppant packs. Fracture proppant packs with water contact angles greater than 90 degrees and oil contact angles significantly less than 90 degrees can be considered as oil-wet proppants. Reducing oil contact angles of oil-wet proppants can increase capillary force, promote oil imbibition into the proppant packs, and thus improve the AORW performance of proppants. Fracture proppant packs with water contact angles less than 90 degrees and oil contact angles less than 90 degrees may be considered as mixed-wet proppants. Their AORW performance should be tested in laboratories before they are considered for well fracturing operations.

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Sun, Hengchao, Guoding Chen, Li’na Wang, and Fei Wang. "Ligament and Droplet Generation by Oil Film on a Rotating Disk." International Journal of Aerospace Engineering 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/769862.

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The lubrication and heat transfer designs of bearing chamber depend on an understanding of oil/air two-phase flow. As initial and boundary conditions, the characteristics of ligament and droplet generation by oil film on rotating parts have significant influence on the feasibility of oil/air two-phase flow analysis. An integrated model to predict the oil film flow, ligament number, and droplet Sauter mean diameter (SMD) of a rotating disk, which is an abstraction of the droplet generation sources in a bearing chamber, is developed based on the oil film force balance analysis and wave theory. The oil film thickness and velocity, ligaments number, and droplet SMD are calculated as functions of the rotating disk radius, rotational speed and oil volume flow rate and oil properties. The theoretical results show that the oil film thickness and SMD are decreased with an increasing rotational speed, while the radial, transverse velocities, and ligament number are increased. The oil film thickness, radial velocity, and SMD are increased with an increasing oil flow rate, but the transverse velocity and ligament number are decreased. A test facility is built for the investigation into the ligament number of a rotating disk, and the measurement of ligament number is carried out by means of a high speed photography.

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Ding, Wei Ya, Xue Wu Hu, and Xiao Ming Sheng. "Double-Acting Air-Oil Intensifier Driven by Twin Roller Piston Air Cylinder." Applied Mechanics and Materials 220-223 (November 2012): 580–84. http://dx.doi.org/10.4028/www.scientific.net/amm.220-223.580.

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The double-acting air-oil intensifier designed in this paper can continuously output high pressure oil which meets the requirements of equipment that is high-pressure and with recirculation motion and it is driven by pneumatic substituting the independent hydraulic power source driven by electric motor. It consists of twin roller piston air cylinder, force amplifier, hydraulic cylinder and oil supercharger. The piston of air cylinder propelled by pressure gas makes cyclic motion and the driving force of piston increased by force amplifier pushes the piston of hydraulic cylinder and forces out hydraulic oil, then oil is input to the system after the second time when pressure amplification by oil superchargers. It has many advantages such as higher pressure ratio, compact structure, high efficiency, low cost and easy access to regulate pressure and flow rate.

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Chait, Arnon, and Seppo A. Korpela. "The secondary flow and its stability for natural convection in a tall vertical enclosure." Journal of Fluid Mechanics 200 (March 1989): 189–216. http://dx.doi.org/10.1017/s0022112089000625.

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The multicellular flow between two vertical parallel plates is numerically simulated using a time-splitting pseudospectral method. The steady flow of air, and the time-periodic flow of oil (Prandtl numbers of 0.71 and 1000, respectively) are investigated and descriptions of these flows using both physical and spectral approaches are presented. The details of the time dependency of the flow and temperature fields of oil are shown, and the dynamics of the process is discussed. The spectral transfer of energy among the axial modes comprising the flow is explored. The spectra of kinetic energy and thermal variance for air are found to be smooth and viscously dominated. Similar spectra for oil are bumpier, and the dynamics of the time-dependent flow are determined to be confined to the lower end of the spectrum alone.The three-dimensional linear stability of the multicellular flow of air is parametrically studied. The domain of stable two-dimensional cellular motion was found to be constrained by the Eckhaus instability and by two types of monotone instability. The two-dimensional multicellular flow is unstable above a Grashof number of about 8550 (with the critical Grashof number for the base flow being 8037). Therefore the flow of air in a sufficiently tall vertical enclosure should be considered to be three-dimensional for most practical applications.

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Hikmah, Nurhikmah. "PENGOLAHAN MINYAK JELANTAH SEBAGAI PENGGANTI BAHAN BAKAR MINYAK PADA KOMPOR MINYAK BERTEKANAN." EduMatSains : Jurnal Pendidikan, Matematika dan Sains 7, no. 1 (July 5, 2022): 65–76. http://dx.doi.org/10.33541/edumatsains.v7i1.3869.

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Used cooking oil (Jelantah's oil) is a frying rest oil which can't be used again to fry because it contains compounds that are quite dangerous for human health, which can be destructive for humans healthy. Beside to reduce an ambient contamination, used cooking oil can be recycled as an alternative fuel, in this case as to replace kerosene. The purpose of this study was to determine the effect of the primary Air Fuel Ratio on the combustion process in pressurized stove oil and knowing whether or not the direct combustion process of used cooking oil as an alternative fuel. The filth on used cooking oil must be removed to avoid a streaming gagging on koil. Analyzing used cooking oil water rate. Fuel tank loaded with used cooking oil. Fill the compressor with an air to pressurize the fuel tank. Used cooking oil streamed inside the tank by manages flow rate then stream air with regulatory crane so up to scale which particular on flowmeter gases. Ruled air flow rate with scales regulatory crane flowmeter until up to stable state on appreciative given. Measuring temperature on burn tool with positioning different one (Spuyer, burner, burner's tip, kindled tip). The larger the primary Air Fuel Ratio, the better the mixing so that the total conversion of triglycerides into CO2 and CO products is greater. Used cooking oil may be directly used as an alternative fuel into an oil stove, especially pressured oil stove.

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Suzuki, Isao, Ryo Tasaki, Kkenjiro Miki, Etsuji Kajita, and Takanobu Yagi. "OIL LAYER FLOW AROUND SKIMMING VESSELS." International Oil Spill Conference Proceedings 1989, no. 1 (February 1, 1989): 167–73. http://dx.doi.org/10.7901/2169-3358-1989-1-167.

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ABSTRACT The flow of an oil layer around an advancing skimming vessel was investigated theoretically on the following assumptions: (1) the oil layer is so thin that the velocity distribution is uniform over the depth; (2) there is no shear and tension at the oil-water interface; and (3) the density difference between oil and water is so small that the elevation of the air-oil interface is negligible. The investigation showed that the oil layer flow is replaced by a supercritical flow in a shallow open water channel which is characterized by the densimetric Froude number in the ideal case of inviscid fluids with no interfacial tension. Tank tests have been carried out to verify the theoretical model and its simulation of an oil layer flow, using scale models of a mono-hull vessel. Similar models with different entrance angles have been tested, at varying ship speeds and oil layer thicknesses. The test results show that the theoretical model and the similitude are valid at lower densimetric Froude numbers, and the effect of the Froude number appears at higher densimetric Froude numbers.

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Zhou, Hailun, Liang Fang, Ming Zhang, Gangyi Cao, and Jianyang Su. "Study of the Effect of Static Eccentricity on Vibration Damping Properties of Squeeze Film Dampers Considering the Two-Phase Flow Case." Lubricants 12, no. 3 (February 27, 2024): 75. http://dx.doi.org/10.3390/lubricants12030075.

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To analyze the effect of static eccentricity on the air ingestion distribution and vibration damping properties of the SFD, a numerical simulation study of SFDs considering two-phase flow was carried out based on CFD using a transient solution method and dynamic mesh technique. The results show that the angle between the static eccentricity direction and the circumferential direction of the oil supply hole increases and the air ingestion area in the oil film expands. In contrast, the oil film damping decreases, and the larger the static eccentricity distance, the greater its effect on the air ingestion area in the oil film. When the circumferential angle is small, the oil film damping increases with the increase of static eccentricity distance, and when the circumferential angle is large, the oil film damping decreases with the increase of static eccentricity distance and then increases. With the increase of static eccentricity distance, the air ingestion area at both ends of the oil film increases. At the same time, studying the effect of dynamic eccentricity shows that as the dynamic eccentricity increases, the oil film damping first decreases and then increases, and the air ingestion area increases. Comparing the 1 hole, the 2 hole, and the 3 hole oil supplies, the air ingestion area is significantly larger in the 1 hole oil supply than in the 2 hole or the 3 hole oil supplies, and the oil film damping of the 1 hole oil supply is smaller than the oil film damping of the 2 hole or the 3 hole oil supplies. It can be seen from the present study that in the actual installation of the SFD, when the circumferential angle is less than 60°, the static eccentricity can be increased appropriately. When the circumferential angle is greater than 60°, the static eccentricity can be appropriately reduced.

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Galkin, A. F., I. V. Kurta, V. Yu Pankov, and M. D. Ilinov. "Oil flow influence on accuracy of forecasting mine air temperatures." Neftyanoe khozyaystvo - Oil Industry 4 (2020): 98–100. http://dx.doi.org/10.24887/0028-2448-2020-4-98-100.

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FUJII, Senju, Ryosuke AMAYA, and Masaharu KAMEDA. "Numerical simulation of oil-air flow in disengaged wet clutches." Proceedings of Conference of Kanto Branch 2021.27 (2021): 10E06. http://dx.doi.org/10.1299/jsmekanto.2021.27.10e06.

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Höhn, B. R., K. Michaelis, and H. P. Otto. "Minimised gear lubrication by a minimum oil/air flow rate." Wear 266, no. 3-4 (February 2009): 461–67. http://dx.doi.org/10.1016/j.wear.2008.04.037.

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Pietrzak, Marcin, Małgorzata Płaczek, and Stanisław Witczak. "Upward flow of air-oil-water mixture in vertical pipe." Experimental Thermal and Fluid Science 81 (February 2017): 175–86. http://dx.doi.org/10.1016/j.expthermflusci.2016.10.021.

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Jiang, Le, Yaguo Lyu, Yanjun Li, Yewei Liu, Yankun Hou, and Zhenxia Liu. "Numerical and Experimental Investigations to Assess the Impact of an Oil Jet Nozzle with Double Orifices on the Oil Capture Performance of a Radial Oil Scoop." Aerospace 10, no. 12 (December 5, 2023): 1015. http://dx.doi.org/10.3390/aerospace10121015.

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To study the influence of orifice spacing on the oil–air two-phase flow and the oil capture efficiency of an oil scoop in an under-race lubrication system, an experimental platform for under-race lubrication was built, and a calculation model for the oil–air two-phase flow field was established. The rationality of the experiment and the validity of the numerical model were verified by comparing the experimental and numerical results. The results showed that under the same oil supply pressure, the captured oil mass flow rate of the double-orifice structure was much higher than that of the single-orifice structure, though it was still less than twice that of the single-orifice structure. When applying a tandem layout structure of double orifices to an under-race lubrication system, the orifice spacing of the tandem layout structure should be determined based on a full evaluation of the influence of the orifice spacing and working condition parameters on the oil capture performance. Otherwise, it may lead to a decrease in oil capture efficiency, with the maximum reduction even reaching 12%.

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Naufal Annafi, Muhammad, Asman Ala, and Jarot Delta Susanto. "Optimizing Air Compressor Productivity in Supporting Operational Activities on The Mt Ship. Gamalam." International Journal of Advanced Multidisciplinary 2, no. 2 (September 14, 2023): 608–11. http://dx.doi.org/10.38035/ijam.v2i2.304.

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Air compressors are auxiliary machines on board that can produce high pressure air. This research was conducted because the productivity of the air compressor was less than optimal, causing air production and the performance of the air compressor to be less than optimal and disrupting operational activities on the ship. The impact that occurs when air production is reduced in the air compressor, the ship cannot operate according to the contract specified by the company, because the initial start of the main engine or main engine on board requires compressed air. Many factors can cause reduced production of air produced by air compressors, including the lack of performance of the suction valve and exhaust valve on the high pressure section which causes less maximum or longer time for filling air into the air bottle, low flow of the lubrication system on the piston which causes no compression to produce air. This research was carried out with the aim of identifying and analyzing the causes of the lack of performance of the suction and exhaust valves on high pressure sections and low flow of the piston lubrication system which results in less optimal performance of the air compressor when filling into air bottles. The method used in this study uses a qualitative descriptive method using primary and secondary data collection approaches and techniques. The lack of performance of the inlet and exhaust valves can be corrected by cleaning the carbon deposits on the valves and leveling the valve surfaces. The low flow of the lubrication system on the piston can be done by checking the lubricating oil pump, cleaning the lubricating oil filter, changing the lubricating oil periodically according to the instruction manual book, and adding lubricating oil according to the specifications of the air compressor.

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Mykhailenko, Taras, Oleksandr Goridko, and Illia Petukhov. "Особливості теплогідравлічних процесів у маслорадіаторі авіаційного газотурбінного двигуна." Aerospace Technic and Technology, no. 5 (October 3, 2023): 50–56. http://dx.doi.org/10.32620/aktt.2023.5.03.

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The modern gas turbine engines (GTEs) development is associated with an increase in the compressor pressure ratio and the gas temperature at the turbine inlet with a simultaneous reduction in the size and weight of the engine. The reliable operation of the GTE largely depends on the oil system excellence. In circulating oil systems, to ensure the lubrication and cooling of engine friction units, a high multiplicity of oil circulation is necessary. The preparation of oil for the next lubrication cycle is related to its cooling, cleaning of mechanical impurities formed during operation, and air separation. Oil coolers are used to cool the oil in GTEs. Air or fuel can be used as the cooling medium. Regardless of the cooling medium choice, a two-phase mixture (oil-air) and not a single-phase oil, as is considered when designing oil coolers, affects the course of thermo-hydraulic processes. Therefore, the subject of this paper is thermohydraulic processes in two-phase media. The goal of this study is to determine the specific aspects of thermohydraulic processes during the oil-air mixture cooling in an aviation gas turbine engine to further improve oil cooler design approaches. This paper aims to show the differences in the course of thermohydraulic processes in two-phase media from single-phase media and to emphasize the importance of considering them when designing oil coolers. The main results are as follows. For a two-phase flow, changes in temperature and pressure change not only the thermophysical properties of the phases but also the gas content, density, and speed of the mixture, which affects the course of thermohydraulic processes in the oil cooler. Under certain combinations of parameters, the structure of the two-phase flow may change. A low value of the equilibrium speed of sound can lead to unpredictable operation of the oil cooler and the oil system as a whole. In addition, the presence of an oil-air mixture reduces the heat transfer capacity of the oil cooler compared with the results of calculations using standard methods. In conclusion, it can be stated that to increase the efficiency of the oil system, it is extremely important to establish the regularities of thermo-hydraulic processes for the two-phase flow of the oil-air mixture and consider this during the design of oil coolers.

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Al-Ruhaimani, F., E. Pereyra, C. Sarica, E. M. Al-Safran, and C. F. Torres. "Experimental Analysis and Model Evaluation of High-Liquid-Viscosity Two-Phase Upward Vertical Pipe Flow." SPE Journal 22, no. 03 (November 18, 2016): 712–35. http://dx.doi.org/10.2118/184401-pa.

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Summary Understanding the behavior of two-phase flow is a key parameter for a proper oil/gas-production-system design. Mechanistic models have been developed and tuned to model the entire production system. Most existing two-phase-flow models are derived from experimental data with low-viscosity liquids (μL < 20 mPa·s). However, behavior of two-phase flow is expected to be significantly different for high-viscosity oil. The effect of high liquid viscosity on two-phase flow is still not well-studied in vertical pipes. In this study, the effect of high oil viscosity on upward two-phase gas/oil-flow behavior in vertical pipes was studied experimentally and theoretically. A total of 149 air/high-viscosity-oil and 21 air/water experiments were conducted in a vertical pipe with an inner diameter (ID) of 50.8 mm. Six different oil viscosities—586, 401, 287, 213, 162, and 127 mPa·s—were considered. The superficial-liquid and -gas velocities were varied from 0.05 to 0.7 m/s and from 0.5 to 5 m/s, respectively. Flow pattern, pressure gradient, and average liquid holdup were measured and analyzed in this study. The experimental results were used to evaluate different flow-pattern maps, mechanistic models, and correlations for two-phase flow. Significant discrepancies between experimental and predicted results for pressure gradient were observed.

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Liu, He, Huiyun Cheng, Yu Dai, and Xiang Zhu. "Atomization Characteristics of Special-Design Pneumatic Two-Fluid Nozzles for Helicopter Main Reducers: A Numerical and Experimental Investigation." Aerospace 9, no. 12 (December 15, 2022): 834. http://dx.doi.org/10.3390/aerospace9120834.

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Oil mist lubrication can be utilized as an emergency lubrication system in the main reducer of a helicopter. A special-design pneumatic two-fluid nozzle is the crucial system component for atomizing lubricant oil, so exploring the atomization characteristics of the nozzle has a significance on effectively improving oil mist lubrication performance. A CFD (computational fluid dynamics) model with a DPM (discrete phase model) technique and a specialized atomization test system were set up to both numerically and experimentally investigate the nozzle’s atomization characteristics. For the atomization properties of the nozzle, the impacts of air pressure, gas–liquid pressure ratio, lubricant oil flow rate, and lubricant oil property factors, including viscosity and surface tension, were investigated. Combining the experimental and the numerical findings reveals that an increasing air pressure and gas–liquid pressure ratio contribute to the atomization effect of the nozzle, especially the air pressure. In addition, a higher lubricant oil flow rate is slightly unfavorable for atomization, but a rise in viscosity and surface tension prevents the atomization of the lubrication oil.

Journal articles on the topic 'Air-Oil flow'

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