Journal articles on the topic 'Bearing chamber'
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1
Nazin, Vladimir. "Identifying the influence of design parameters of single-chamber hydrostatic bearing of fuel pump on its main characteristics." Eastern-European Journal of Enterprise Technologies 1, no. 7 (127) (February 28, 2024): 30–36. http://dx.doi.org/10.15587/1729-4061.2024.298646.
Abstract:
The object of this study is hydrostatic processes in the fluid friction bearings of gear-type aviation fuel pumps. The problem of the influence of the design parameters of a single-chamber hydrostatic bearing on its main characteristics was solved. The main characteristics were considered to be the load-bearing capacity and the flow rate of the working fluid. When determining the main characteristics of a single-chamber hydrostatic bearing, the Reynolds and flow balance equations were solved jointly. The resulting diagram of pressure distribution over the working surface of the bearing was used to determine the main characteristics. The influence of the clearance, nozzle diameter, and chamber width on the load-bearing capacity and working fluid flow of a single-chamber hydrostatic bearing was studied. It has been established that as the gap increases, the load-bearing capacity of a single-chamber bearing decreases, and the flow rate of the working fluid increases. As the nozzle diameter increases, the bearing's load-bearing capacity increases. Increasing the width of the chambers leads to an increase in the load-bearing capacity and flow of working fluid through the bearing. When the gap increases from 0.0125 mm to 0.0425 mm, the bearing capacity decreases by 1.156 times. The flow rate of working fluid through the bearing increases by 1.4 times. With an increase in the nozzle diameter from 1.5 mm to 3 mm, the bearing capacity increases slightly by approximately 1.02 times. Increasing the width of the chambers from 4 mm to 8 mm increases the load-bearing capacity by 1.29 times and increases the flow rate of working fluid by 1.4 times. The results show that a single-chamber hydrostatic bearing can provide the required load-bearing capacity by selecting design parameters. The given mathematical dependences could be used for practical calculations of single-chamber hydrostatic bearings
2
Flouros, Michael. "The Impact of Oil and Sealing Air Flow, Chamber Pressure, Rotor Speed, and Axial Load on the Power Consumption in an Aeroengine Bearing Chamber." Journal of Engineering for Gas Turbines and Power 127, no. 1 (January 1, 2005): 182–86. http://dx.doi.org/10.1115/1.1805009.
Abstract:
Trends in aircraft engines have dictated high speed rolling element bearings up to 3 million DN or more with the consequence of having high amounts of heat rejection in the bearing chambers and high oil scavenge temperatures. A parametric study on the bearing power consumption has been performed with a 124 mm pitch circle diameter (PCD) ball bearing in a bearing chamber that has been adapted from the RB199 turbofan engine DN∼2×106. The operating parameters such as oil flow, oil temperature, sealing air flow, bearing chamber pressure, and shaft speed have been varied in order to assess the impact on the power consumption. This work is the first part of a survey aiming to reduce power losses in bearing chambers. In the first part, the parameters affecting the power losses are identified and evaluated.
3
Flouros, Michael. "Reduction of Power Losses in Bearing Chambers Using Porous Screens Surrounding a Ball Bearing." Journal of Engineering for Gas Turbines and Power 128, no. 1 (May 1, 2005): 178–82. http://dx.doi.org/10.1115/1.1995769.
Abstract:
Trends in aircraft engine design have caused an increase in mechanical stress requirements for rolling bearings. Consequently, a high amount of heat is rejected, which results in high oil scavenge temperatures. An RB199 turbofan bearing and its associated chamber were modified to carry out a survey aiming to reduce power losses in bearing chambers. The test bearing was a 124 mm PCD ball bearing with a split inner ring employing under-race lubrication by two individual jets. The survey was carried out in two parts. In the first part, the investigations were focused on the impact on the power losses in the bearing chamber of the operating parameters, such as oil flow, oil temperature, sealing air flow, bearing chamber pressure, and shaft speed. In the second part, the investigations focused on the reduction of the dwell time of the air and oil mixture in the bearing compartment and its impact on the power losses. In this part, porous screens were introduced around the bearing. These screens would aid the oil to flow out of the compartment and reduce droplet-droplet interactions as well as droplet-bearing chamber wall interactions. The performance of the screens was evaluated by torque measurements. A high-speed camera was used to visualize the flow in the chamber. Considerable reduction in power loss was achieved. This work is part of the European Research programme GROWTH ATOS (Advanced Transmission and Oil Systems).
4
Gorse, P., S. Busam, and K. Dullenkopf. "Influence of Operating Condition and Geometry on the Oil Film Thickness in Aeroengine Bearing Chambers." Journal of Engineering for Gas Turbines and Power 128, no. 1 (March 1, 2004): 103–10. http://dx.doi.org/10.1115/1.1924485.
Abstract:
Increasing the efficiency of modern jet engines does not only imply to the mainstream but also to the secondary air and oil system. Within the oil system the bearing chamber is one of the most challenging components. Oil films on the chamber walls are generated from oil droplets, ligaments, or film fragments, which emerge from bearings, seal plates and shafts, and enter the bearing chamber with an angular momentum. Furthermore, shear forces at its surface, gravity forces, and the design of scavenge and vent ports strongly impact the behavior of the liquid film. The present paper focuses on the experimental determination of the film thickness in various geometries of bearing chambers for a wide range of engine relevant conditions. Therefore, each configuration was equipped with five capacitive probes positioned at different circumferential locations. Two analytical approaches are used for a comprehensive discussion of the complex film flow.
5
Назин, Владимир Иосифович. "ВЛИЯНИЕ УГЛОВ ПОЛОЖЕНИЯ КАМЕР НА НАРУЖНЫХ И ВНУТРЕННИХ ЧАСТЯХ ГИДРОСТАТОДИНАМИЧЕСКОГО ПОДШИПНИКА СДВОЕННОГО ТИПА НА ЕГО НЕСУЩУЮ СПОСОБНОСТЬ." Aerospace technic and technology, no. 4 (August 31, 2019): 50–56. http://dx.doi.org/10.32620/aktt.2019.4.09.
Abstract:
The task is to study the bearing capacity of the double type bearing at different angular positions of the chambers on the outer and inner working surfaces. It is given a mathematical model of a double type hydrostatodynamic bearing in a stationary formulation, which makes it possible to determine its bearing capacity. It is considered the cases of laminar and turbulent flow of the working fluid in the slit path of the double type bearing. Both gradient and portable flows of the working fluid are considered in recording the flow of working fluid along the contour of the 1st chamber. The expression for the flow rate of the working fluid at the entrance to the chambers is written for the case of using the jet as a pressure compensator. The cost balance equations and the Reynolds equations, written for both the outer and inner working surfaces of the double type bearing, were solved jointly. Applied assumptions are usually taken in the hydrodynamic theory of lubrication in writing the Reynolds equations. The most common V.N. Constantinescu method was applied for turbulence coefficients. The expression for the balance of expenditure equations and the Reynolds equations are expanded to the dimensionless type. The most effective numerical methods for the numerical implementation of the expenditure balance equations and Reynolds equations are analyzed and applied. The most economical finite-difference method in combination with the longitudinal-transverse sweep method was applied to solve the Reynolds equation. The accuracy of the solution was assigned when determining the pressures in the chambers and on the inter-chamber jumpers. Geometric and operating parameters of the double type bearing were assigned based on currently existing recommendations for the design of fluid-friction bearings. The results of the calculation of the bearing capacity of the double type bearing for different camera angles on the external and internal parts of this bearing are obtained. The results of the calculation of the bearing capacity of the double type bearing in the form of graphs are given. The analysis of the obtained results was made and conclusions were made on the obtained results, allowing designers to more efficiently design bearings of this type.
6
Fang, Long, and Guoding Chen. "The study of droplet deformation and droplet volume fraction in an aero-engine bearing chamber." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 6 (May 24, 2018): 2264–77. http://dx.doi.org/10.1177/0954410018777595.
Abstract:
Inside an aero-engine bearing chamber, the shape, velocity, and temperature of each droplet shed from roller elements keep changing under the actions of the rotating airflow. Research on droplet deformation, droplet motion, and droplet volume fraction is fundamental to the understanding of the complex two-phase flow in an aero-engine bearing chamber. In this paper, the modified Taylor analogy breakup model, equations of temperature and motion are established to obtain the size, temperature, and velocity of a deformed droplet. Subsequently, a method is presented to solve for the droplet volume fraction in a bearing chamber based on the size and motion parameters of deformed droplets. In the end, a simplified bearing chamber experimental setup has been constructed. Comparisons between the experimental results and theoretical calculations show a good match based upon the research analogy used. The research work in this paper can provide theoretical foundations for the analyses of heat exchange and lubrication in bearing chambers. This also has great significance in realizing the rigorous design required for the lubrication system of an aero-engine.
7
Wittig, S., A. Glahn, and J. Himmelsbach. "Influence of High Rotational Speeds on Heat Transfer and Oil Film Thickness in Aero-Engine Bearing Chambers." Journal of Engineering for Gas Turbines and Power 116, no. 2 (April 1, 1994): 395–401. http://dx.doi.org/10.1115/1.2906833.
Abstract:
Increasing the thermal loading of bearing chambers in modern aero-engines requires advanced techniques for the determination of heat transfer characteristics. In the present study, film thickness and heat transfer measurements have been carried out for the complex two-phase oil/air flow in bearing chambers. In order to ensure real engine conditions, a new test facility has been built up, designed for rotational speeds up to n = 16,000 rpm and maximum flow temperatures of Tmax = 473 K. Sealing air and lubrication oil flow can be varied nearly in the whole range of aero-engine applications. Special interest is directed toward the development of an ultrasonic oil film thickness measuring technique, which can be used without any reaction on the flow inside the chamber. The determination of local heat transfer at the bearing chamber housing is based on a well-known temperature gradient method using surface temperature measurements and a finite element code to determine temperature distributions within the bearing chamber housing. The influence of high rotational speed on the local heat transfer and the oil film thickness is discussed.
8
Zhu, Hong Xia, Yingxiao Lin, and Jing Yi Zhao. "Research on the Micro Self-Vibration of Aerostatic Bearing with Pocketed Orifice Type Restrictor." Applied Mechanics and Materials 333-335 (July 2013): 2076–79. http://dx.doi.org/10.4028/www.scientific.net/amm.333-335.2076.
Abstract:
In this paper, Computational Fluid Dynamics (CFD) is used to analyze the micro self-vibration of aerostatic bearing with pocketed orifice type restrictor as the bearings performance is stable and it is widely used ultra-precision equipments. By using Large Eddy Simulation (LES), time-variation flow field inside the bearing is obtained. Then the pressure fluctuation characteristics is discussed because it influences the micro self-vibration of the bearing directly. Moreover, the relationship between bearing diameter, orifice diameter, air chamber diameter, air chamber depth and the micro self-vibration is researched. The results can be considered for the designing of ultra-precision aerostatic bearing with pocketed orifice type restrictor.
9
Nazin, Vladimir. "Identifying the influence of design parameters of a hydrostatic bearing in an aircraft fuel pump on its static characteristics." Eastern-European Journal of Enterprise Technologies 5, no. 1 (125) (October 31, 2023): 28–34. http://dx.doi.org/10.15587/1729-4061.2023.289426.
Abstract:
The object of this study is hydrostatic processes in the sliding bearings of gear-type aviation fuel pumps. The problem of the influence of the design parameters of the fuel pump bearing on its static characteristics was solved. Load-bearing capacity, lubricant consumption, and operating temperature conditions were considered as static characteristics. The determination of these characteristics was based on the pressure distribution function in the working fluid layer. An option was adopted with two load-bearing chambers located on the working surface of the hydrostatic bearing. Three options for the circumferential arrangement of chambers relative to the line of action of the external load were studied. A quantitative assessment of the effect of increasing the temperature of the working fluid on the consumption of lubricant and bearing capacity is given. It has been established that with an increase in the angle of position of chambers relative to the line of action of the external load, the flow rate of the working fluid in the bearing increases, and its load-bearing capacity decreases. With a clearance in the bearing of 0.0225 mm, with an increase in the angle of the chambers from 30° to 40°, the flow of working fluid through the bearing increases by approximately 1.64 times. When the gap increases to 0.0425 mm and the angle of the chambers changes from 30° to 40°, the flow rate of the working fluid increases by approximately 1.2 times. The load-bearing capacity of the bearing with an increase in the chamber position angle from 30° to 40° decreases with a gap of 0.0225 mm by approximately 1.6 times, and with a gap of 0.0425 mm by approximately 1.93 times. An increase in the temperature of the working fluid leads to a decrease in the load-bearing capacity of the bearing by 2.5 % and an increase in the flow rate of the working fluid in the bearing by 4.6 %. The results allow for more rational design of hydrostatic bearings for fuel gear pumps.
10
Yuan, Xi Chuan, Hui Guo, and Liang Yun Wang. "Experiment Study of Heat Transfer in Aeroengine Bearing Chambers." Applied Mechanics and Materials 86 (August 2011): 448–53. http://dx.doi.org/10.4028/www.scientific.net/amm.86.448.
Abstract:
In this paper, a method of heat transfer test research in aeroengine bearing chamber has been introduced. The method attains the law of heat transfer in bearing chamber and the influence of heat transfer coefficient on bearing dn value, oil flow, supply oil temperature, sealing air flow by simulating the oil work condition in turboshaft engine typical high temperature bearing chamber.
11
Zhou, Hui, Jun Zheng, Ji Xing Hu, Rui Peng Sang, and Zhi Hua Wan. "Study of MoS2-Ti Composite Coatings Applied in Precision Ball Bearings." Advanced Materials Research 538-541 (June 2012): 281–85. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.281.
Abstract:
708C Ball bearings were made of 9Cr18 steel which had precision of class 4, MoS2-Ti composite coatings were deposited on inner and outer races of ball bearings by unbalanced magnetron sputtering system, and bearing cages were made of PTFE-based self-lubricating polymers. Bearing’s tribological torques as a function of storage time in high humidity environment were studied by using LHU-2 thermal & humidity test chamber and Bearing 2000 torque measurement device. Developing bearing vacuum performance test rig to research bearing’s torque as a function of running time, bearings were dismantled after test and using XPS to analyze the surfaces of bearing’s races and balls. The results show that storied in the environment of 30°C, 85% RH, bearing’s running torques increased proportionally as the storage time went on. When run-in the bearings which were storied for 440 days, the start and average running torques of bearings could come back to the level which was the same as the test start, but the fluctuation of bearing’s average running torque increased. Running in one direction at the speed of 650 r/min, in vacuum environment (~10-4Pa) and ambient temperature, tested bearings showed good running performance with low friction torque varied only between 1g·cm~2 g·cm until to the test ended at 1.872×108 revolutions. XPS analysis showed that a stable and sustainable solid lubrication system was established among bearing’s races, balls and cages.
12
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.
Abstract:
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.
13
Busam, Stefan, Axel Glahn, and Sigmar Wittig. "Internal Bearing Chamber Wall Heat Transfer as a Function of Operating Conditions and Chamber Geometry." Journal of Engineering for Gas Turbines and Power 122, no. 2 (January 3, 2000): 314–20. http://dx.doi.org/10.1115/1.483209.
Abstract:
Increasing efficiencies of modern aero-engines are accompanied by rising turbine inlet temperatures, pressure levels and rotational speeds. These operating conditions require a detailed knowledge of two-phase flow phenomena in secondary air and lubrication oil systems in order to predict correctly the heat transfer to the oil. It has been found in earlier investigations that especially at high rotational speeds the heat transfer rate within the bearing chambers is significantly increased with negative effects on the heat to oil management. Furthermore, operating conditions are reached where oil coking and oil fires are more likely to occur. Therefore, besides heat sources like bearing friction and churning, the heat transfer along the housing wall has to be considered in order to meet safety and reliability criteria. Based on our recent publications as well as new measurements of local and mean heat transfer coefficients, which were obtained at our test facility for engine relevant operating conditions, an equation for the internal bearing chamber wall heat transfer is proposed. Nusselt numbers are expressed as a function of non-dimensional parameter groups covering influences of chamber geometry, flow rates and shaft speed. [S0742-4795(00)02202-X]
14
Jintao, Mo, Gu Chaohua, Pan Xiaohong, Zheng Shuiying, and Ying Guangyao. "Experimental and numerical analysis of a self-circulating oil bearing system for gear pumps." Industrial Lubrication and Tribology 70, no. 1 (January 8, 2018): 115–25. http://dx.doi.org/10.1108/ilt-07-2016-0143.
Abstract:
Purpose For moderate pressure and high pressure gear pumps, the temperature failure problem of bearings is now of considerable concern because of their heavy loads. However, the compact structure and the efficiency consideration make it extremely difficult to improve the bearing cooling. A self-circulating oil bearing system is developed for gear pumps with self-lubricating bearings to solve this problem. The oil is aspirated in from the low pressure chamber of the gear pump and discharged to the same chamber by using the pressure difference in the journal bearing, thus achieving the self-circulation. Design/methodology/approach An experiment test rig has been built for the feasibility study. The oil flow rate under different speeds has been recorded. Furthermore, the temperatures of the bearings with or without the oil circulation have been compared. Additionally, the oil flow in the test rig has been simulated using computational fluid dynamics codes. Findings The experimental and numerical results agree well. The experimental results indicate that the oil flow rate increases approximately linearly with the speed and the bearing temperature can be lowered successfully. The calculation results indicate that the bearing load capacity is nearly the same. Both the experimental and numerical studies establish that the self-circulating oil bearing system works successfully. Originality value As far as the authors know, it is the first time to find that the self-circulation can be built using the pressure difference in the bearing oil film, and this principle can be applied in the cooling and lubrication of the gear pumps to solve the temperature failure problem.
15
Chen, Bo, Guo Ding Chen, and Xiao Long Shen. "Oil Droplet Motion Considering Breakup in an Aeroengine Bearing Chamber." Advanced Materials Research 199-200 (February 2011): 638–45. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.638.
Abstract:
Oil droplets can break up during flight and form many secondary droplets in an aero-engine bearing chamber due to aerodynamic drag forces. The motion properties of secondary droplets have significant influence on the two-phase oil/air flow phenomena in bearing chambers. In this work, oil droplet trajectories and velocities are developed by accounting for in-flight breakup. The droplet motion is modelled using a Lagrangian tracking method, and the trajectories and velocities are calculated by numerical integration of the oil particle momentum equation with forth-order Runge-Kutta scheme. The trajectories and velocities change abruptly at the breakup location, compared with unconsidering breakup. Subsequently, the effects of operating conditions on oil droplet motions are discussed. The numerical results show that the influence of breakup on oil droplet trajectory and velocity are considered necessarily when simulating two-phase oil/air flows in bearing chambers.
16
Shaw, Dein, Hui An Hsieh, and Chi Yu Lo. "Analysis of Hydrodynamic Porous Bearing with External Pressure Supply." Key Engineering Materials 642 (April 2015): 328–32. http://dx.doi.org/10.4028/www.scientific.net/kem.642.328.
Abstract:
For the need of high speed and load capacity of precision industry, a bearing used in a high speed spindle is studied. The hydrodynamic bearing composed a hydrodynamic bearing made of porous material and several hydrostatic chambers with an external oil system. The hydrodynamic bearing is pressurized with oil chamber and supports the spindle shaft both at rest and at rotation state. Because of the external pressure and the property of porous material, the load capacity of hydraulic bearing can be promoted without decreasing precision. To consider the relationship of parameters, we applied the Reynolds equation and Darcy’s law to describe the flow of the oil film between bearing and spindle shaft.
17
Mykhailenko, T. P., A. Yu Lysytsia, I. I. Petukhov, and A. V. Kovalov. "Specific Aspects in Numerical Simulation of Complex Processes in Gas Turbine Engine Bearing Chamber." IOP Conference Series: Materials Science and Engineering 1226, no. 1 (February 1, 2022): 012038. http://dx.doi.org/10.1088/1757-899x/1226/1/012038.
Abstract:
Abstract The complex interrelation of thermal and hydraulic processes in a gas turbine engine bearing chamber requires modelling methods based on the multiphase flow mechanics and Computational Fluid Dynamics (CFD) to predict the fluid distribution and heat transfer phenomena. This paper presents a study of different approaches to CFD modelling of multiphase oil-air flow in the bearing chamber. The Volume of Fluid and Eulerian multiphase models, Steady and Transient solvers, “Realizable k-ε” and “k-ω SST” turbulence models were analysed. The Eulerian Wall Film Model implemented in ANSYS Fluent was applied to model an oil film formation on the bearing chamber walls. The CFD results were compared with available experimental data to formulate practical recommendations for precise modelling of processes in the bearing chamber.
18
Zhou, Yang, Bowen Che, and Ci Yuan. "The design and analysis of a high-speed circular arc gear pump journal bearing." Advances in Mechanical Engineering 10, no. 12 (December 2018): 168781401881928. http://dx.doi.org/10.1177/1687814018819288.
Abstract:
A series of problems arise when a gear pump operates at high speed, including instability of the rotor, deformation of the chamber, and wear of the journal bearing. Among all failure modes, journal bearing wear is the most serious. The wear of journal bearings of a circular arc gear pump that operates at high speed is thus presented in this article. A journal bearing that offsets the unbalanced radial force is designed by analysis of the fluid and determination of eccentricity of the gear shaft. Experiments show that the wear of the new journal bearing is effectively reduced.
19
Ren, Guozhe, Yanpeng Li, Huan Zhao, Yang Yan, Wenfeng Xu, and Dan Sun. "Research on Oil–Gas Two-Phase Flow Characteristics and Improvement of Aero-Engine Bearing Chamber." Lubricants 11, no. 9 (August 23, 2023): 360. http://dx.doi.org/10.3390/lubricants11090360.
Abstract:
In order to study the oil–gas two-phase flow characteristics of an aero-engine bearing chamber and improve the scavenge effect of lubricating oil, the two-phase flow solution model of a bearing chamber based on the Euler–Euler method was established. Three improvement schemes were proposed for the ventilation structure and scavenge structure of the bearing chamber. The flow characteristics and scavenge characteristics of a conventional bearing chamber and three improvement schemes under different working conditions were analyzed in depth. The results show that after the conventional bearing chamber ventilation structure is embedded (Embed) and improved, with the increase in the embedding depth, the oil in the cavity is further blocked in the cavity, the amount of oil flowing out from the vent is further reduced, and the scavenge efficiency is further improved. After the slope improvement of the scavenge structure of the conventional bearing chamber, due to the increase in the depth of the oil return groove, the drag effect of the air shear force in the cavity on the oil in the oil return groove is further weakened, and the oil accumulation area on the right side of the scavenge port is further suppressed. The volume fraction of the oil in the cavity is further reduced, and the scavenge efficiency is further improved. The combined improvement scheme (ES) can take into account the advantages of embedding and slope improvement schemes, and further improve the scavenge efficiency. Compared to the conventional bearing chamber, when the oil flow rate is 200 L/h and the speed is 15,000 r/min, the oil return efficiency of the embedded (h = 12 mm), slope (l = 56 mm) and combined improvement schemes are increased by 20.19%, 13.43%, and 37.94%, respectively.
20
Glahn, A., M. Kurreck, M. Willmann, and S. Wittig. "Feasibility Study on Oil Droplet Flow Investigations Inside Aero Engine Bearing Chambers—PDPA Techniques in Combination With Numerical Approaches." Journal of Engineering for Gas Turbines and Power 118, no. 4 (October 1, 1996): 749–55. http://dx.doi.org/10.1115/1.2816990.
Abstract:
The present paper deals with oil droplet flow phenomena in aero engine bearing chambers. An experimental investigation of droplet sizes and velocities utilizing a Phase Doppler Particle Analyzer (PDPA) has been performed for the first time in bearing chamber atmospheres under real engine conditions. Influences of high rotational speeds are discussed for individual droplet size classes. Although this is an important contribution to a better understanding of the droplet flow impact on secondary air/oil system performance, an analysis of the droplet flow behavior requires an incorporation of numerical methods because detailed measurements as performed here suffer from both strong spatial limitations with respect to the optical accessibility in real engine applications and constraints due to the extremely time-consuming nature of an experimental flow field analysis. Therefore, further analysis is based on numerical methods. Droplets characterized within the experiments are exposed to the flow field of the gaseous phase predicted by use of our well-known CFD code EPOS. The droplet trajectories and velocities are calculated within a Lagrangian frame of reference by forward numerical integration of the particle momentum equation. This paper has been initiated rather to show a successful method of bearing chamber droplet flow analysis by a combination of droplet sizing techniques and numerical approaches than to present field values as a function of all operating parameters. However, a first insight into the complex droplet flow phenomena is given and specific problems in bearing chamber heat transfer are related to the droplet flow.
21
Аисса, Дуаиссиа Омар Хадж. "ЧИСЛЕННОЕ ИССЛЕДОВАНИЕ ТЕПЛООТДАЧИ В КАМЕРЕ ПОДШИПНИКА ГТД." Open Information and Computer Integrated Technologies, no. 81 (November 16, 2018): 92–103. http://dx.doi.org/10.32620/oikit.2018.81.10.
Abstract:
To determine the required oil pumping through the GTE rotor support, an accurate calculation of the heat flow from the engine to the GTE bearing chamber is necessary. The complexity of the mathematical description of thermo-hydraulic processes is associated with the presence of a multiphase mixture in the bearing chamber, consisting of oil, going for lubrication and cooling of the support elements, and air, used for seals pressurization. The work is devoted to the issues of numerical study of the effect of regime parameters on the heat transfer coefficient in the bearing chamber of the GTE. For these purposes, the methodology based on conservation laws and CFD modeling methods is applied. The change in the heat transfer coefficient in the characteristic sections of the chamber is considered. The influence of the oil film distribution around the circumference of the chamber is shown.
22
Huang, Ming, Hailong Cui, Pinkuan Liu, Mengyang Li, Yueqing Zheng, and Zhengyi Jiang. "A theoretical and experimental study on the stiffness of aerostatic thrust bearings with vacuum preloading." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 233, no. 2 (March 25, 2018): 256–70. http://dx.doi.org/10.1177/1350650118764149.
Abstract:
In this paper, the pressure distribution of aerostatic thrust bearings with vacuum pre-loading was investigated by solving the full Navier–Stokes equations based on the computational fluid dynamics method. The influences of the supply pressure, vacuum pressure, orifice diameter, and gas film thickness on the absolute pressure ratio were investigated. The finite difference method was used to study the effects of the vacuum chamber area, orifice diameter, orifice number, supply pressure, and vacuum pressure on the bearing stiffness. It is confirmed that the orifice diameter and film thickness had a great influence on the absolute pressure ratio, which increased with the reduction in the gas film thickness and the rise in the orifice diameter. The bearing stiffness can be improved by increasing the supply pressure, orifice number or vacuum chamber area or decreasing the orifice diameter or vacuum pressure, which provides useful guidance for the optimization design of aerostatic thrust bearings with vacuum preloading.
23
Wang, Yanzhong, and E. Shiyuan. "Design and Research of Bearing Reliability Test Bed Based on Multi-Dimensional Vibration Loading." Journal of Physics: Conference Series 2101, no. 1 (November 1, 2021): 012045. http://dx.doi.org/10.1088/1742-6596/2101/1/012045.
Abstract:
Abstract Rolling bearings are widely used in aviation, aerospace and other important fields, and their reliability is greatly affected by external vibration excitation during service. Due to the large volume and high cost of the combined structure of shaking table and test chamber, this paper designed a dynamic reliability test bed specially for rolling bearings to study the influence of external vibration excitation with different directions, frequencies and amplitudes on vibration signals and service life of rolling bearings. The test bed is loaded with external excitation by means of electromagnetic shakers in two directions, and the flexible material is used to realize the displacement of the test chamber under two external excitation directions at the same time. The bearing vibration loading life test carried out by this test bed has important guiding significance for the design of rolling bearing. The experimental results show that the test bed can apply axial and radial vibration loads of 1-800Hz sinusoidal waveform, and the vibration acceleration can reach 1g, which can simulate the effect of actual working conditions.
24
Lee, C. W., P. C. Palma, K. Simmons, and S. J. Pickering. "Comparison of Computational Fluid Dynamics and Particle Image Velocimetry Data for the Airflow in an Aeroengine Bearing Chamber." Journal of Engineering for Gas Turbines and Power 127, no. 4 (March 1, 2004): 697–703. http://dx.doi.org/10.1115/1.1924635.
Abstract:
Investigations into the single-phase velocity field of a model aeroengine bearing chamber are presented. Adequately resolving the airflow field is important to subsequent computational modeling of two-phase fluid transport and heat transfer characteristics. A specially designed test rig, representing the features of a Rolls Royce Trent series aeroengine bearing chamber, was constructed. Experimental data for the airflow field was obtained using particle image velocimetry (PIV). The results show a strong influence of shaft rotation and chamber geometry on the flow features within the bearing chamber. A computational fluid dynamics (CFD) simulation was carried out using the commercial CFD code FLUENT 6. Flow features were adequately modeled, showing the features of secondary velocities. Turbulence modeling using the differential Reynolds stress (RSM) model shows good agreement with the experimental data.
25
Fang, Long, Guoding Chen, and Deng Liu. "A determination criterion for predicting the outcome of oblique collision between an oil droplet and solid surface." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 11 (January 28, 2016): 2066–74. http://dx.doi.org/10.1177/0954406215627840.
Abstract:
In a bearing chamber, oil droplets shed from the bearing impinge on the outer chamber housing with different angles. The outcome of oblique collision between an oil droplet and the outer chamber housing determines the flow characteristic of wall oil film which has an important meaning to realize the rigorous lubrication design in the bearing chamber. However, the study of predicting the outcome of oblique collision between an oil droplet and solid surface is relatively rare. In this paper, an experimental setup about oil droplet–solid surface oblique collision and a numeric calculation model using Volume of Fluid (VOF) method have been built. And a lot of experimental work and numerical calculations have been done in a wide range of conditions. Based on that, a determination criterion is ultimately established for predicting the outcome of oblique collision between an oil droplet and solid surface. With the experimental data from literatures and this paper, the determination criterion is verified. The research work in this paper is not only a foundation work for better understanding the conditions of lubrication in bearing chamber but also an important reference for the study of droplet–solid surface collision.
26
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.
Abstract:
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.
27
Michaelis, Susan. "An update on aircraft oil bearing chamber sealing." Sealing Technology 2018, no. 3 (March 2018): 6–8. http://dx.doi.org/10.1016/s1350-4789(18)30144-2.
28
Farrall, Mark, Kathy Simmons, Stephen Hibberd, and Philippe Gorse. "A Numerical Model for Oil Film Flow in an Aeroengine Bearing Chamber and Comparison to Experimental Data." Journal of Engineering for Gas Turbines and Power 128, no. 1 (March 1, 2004): 111–17. http://dx.doi.org/10.1115/1.1924719.
Abstract:
The work presented forms part of an ongoing investigation, focusing on modeling the motion of a wall oil film present in a bearing chamber and comparison to existing experimental data. The film is generated through the impingement of oil droplets shed from a roller bearing. Momentum resulting from the impact of oil droplets, interfacial shear from the airflow, and gravity cause the film to migrate around the chamber. Oil and air exit the chamber at scavenge and vent ports. A previously reported numerical approach to the simulation of steady-state two-phase flow in a bearing chamber, which includes in-house submodels for droplet-film interaction and oil film motion, has been extended. This paper includes the addition of boundary conditions for the vent and scavenge together with a comparison to experimental results obtained from ITS, University of Karlsruhe. The solution is found to be sensitive to the choice of boundary conditions applied to the vent and scavenge.
29
Qian, Yuming, Jingkui Li, Binjie Qu, and Zhibin Liu. "Parameter optimization design of an aero-engine bearing chamber based on active learning Kriging." Journal of Physics: Conference Series 2691, no. 1 (January 1, 2024): 012047. http://dx.doi.org/10.1088/1742-6596/2691/1/012047.
Abstract:
Abstract The air-oil two-phase flow in the aero-engine bearing chamber is highly complex and unsteady. To obtain the mapping relationship between the oil volume fraction in the chamber and the oil inlet flow rate and rotational speed for further design optimization, the air-oil two-phase flows are simulated using the level set method in COMSOL Multiphysics software. To avoid frequent calls to the simulation model during the optimization process, which consumes huge computational costs, the Kriging model is applied to approximate the true response of the computational fluid dynamics (CFD) simulations. The point addition process is assisted by introducing the active learning function EI to enhance the efficiency of constructing the Kriging model. Particle swarm optimization (PSO) is applied to optimize the Kriging-based optimization objective function. With the optimal parameters’ combination, the performance of the oil return in the aero-engine bearing chamber is improved. This study has guiding significance for the lubrication design of the aero-engine bearing chamber.
30
Czolczyñski, K., T. Kapitaniak, and K. Marynowski. "Stiffness and damping coefficients of air rings with a chamber feeding system." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 212, no. 2 (February 1, 1998): 131–43. http://dx.doi.org/10.1243/1350650981541958.
Abstract:
When, during the operation of rotors supported in gas bearings, their rotational velocity reaches a sufficiently high value, loss of steady state stability occurs. This instability is caused by the loss of damping properties of the gas film, which leads to self-excited vibrations. These vibrations are the basic obstacle to a widespread application of gas bearings. The phenomenon of self-excited vibrations can be avoided by introducing an elastic supporting structure between the bearing bushes and the casing, characterized by properly selected stiffness and damping coefficients. In practice, such a structure can have the form of an externally pressurized gas ring. In this paper, on the basis of selected examples, those ranges of the values of stiffness and damping coefficients of the gas ring that make it possible to retain steady state stability at practically any rotational velocity of the rotor are demonstrated. A design of the ring structure, especially of its feeding system, is also shown, which ensures the required values of stiffness and damping coefficients (with regard to the stability). These investigations have been carried out by means of a numerical simulation method with the use of a mathematical model of the gas bearing, which has already been verified many times.
31
Zhang, Yan-qin, Jin-jun Hou, Wei-cheng Gao, Zhi-wei Zhao, De-fan Zhou, and Hai-kuo Cheng. "Prediction model of the clearance oil film for static vertical rail considering the ram deformation." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234, no. 1 (June 18, 2019): 42–49. http://dx.doi.org/10.1177/1350650119855489.
Abstract:
In order to improve the cutting rigidity of hydrostatic oil pad on large vertical lathes’ vertical rail of hydrostatic ram, on the basis of a single-chamber oil pad, this paper proposed a new type of the double-chamber oil pad. Pressure field distribution law of the single-chamber and the double-chamber oil pad was obtained by the finite element volume method. Then, using the fluid–structure coupling method and Workbench software the deformation law of ram was obtained under different working conditions. Finally, oil film’s prediction model of the single-chamber and the double-chamber oil pad was solved under different working conditions. Oil film’s prediction model of the single-chamber oil pad and the double-chamber oil pad was obtained under various working conditions. The results show that the maximum deformation of the single-chamber of upper oil pad ranges from 0.079 to 0.92 µm, while the double-chamber oil pad ranges from 0.07 to 0.68 µm. The maximum deformation of the single chamber of lower oil pad ranges from 0.91 to 9.21 µm, while the double-chamber oil pad ranges from 0.74 to 9.14 µm, and the maximum deformation of the double-chamber oil pad is less than that of the single chamber, which shows that the rigidity of the double-chamber oil pad is better than that of the single chamber. The results are helpful to improve the bearing performance and service life of bearings.
32
Moczulak, Bartosz, Grzegorz Żywica, Wojciech Miąskowski, Wojciech Kiński, and Paweł Bagiński. "Experimental Study of the Thermal and Wear Characteristics of a Foil Bearing Lubricated with a Low-Boiling Liquid." Applied Sciences 13, no. 11 (June 2, 2023): 6766. http://dx.doi.org/10.3390/app13116766.
Abstract:
Developing high-speed rotating machines, such as microturbines, requires new solutions for bearing systems. Foil bearings are one of the fastest-growing high-speed bearing technologies. This article presents the results of experimental studies on foil bearings conducted on a test rig reflecting the operating conditions of the target machine. The tested bearings were therefore placed in a chamber filled with a low-boiling medium used as a working fluid in vapour microturbines. The experiments were carried out for several test cycles following a repeatable procedure. To carry out the tests under specific environmental conditions, a measurement cycle according to the developed test procedure and a temperature stabilization system for long-term measurements were proposed. The research involved determining the thermal characteristics of four foil bearing variants and assessing the impact of operating conditions on their wear. Additional research has shown that the operating characteristics are highly dependent not only on the materials and geometry of the bearing but also on the surface roughness of the mating parts. This study is part of ongoing work to select appropriate designs and material packages for foil bearings operating under conditions involving lubricating film formation and heat dissipation.
33
Wu, Feng He, Shu Zhi Li, Chong Min Jiang, and Dong Dong Gao. "Design of the B-Axis of the Water Chamber Special Turn-Milling Center." Key Engineering Materials 621 (August 2014): 294–303. http://dx.doi.org/10.4028/www.scientific.net/kem.621.294.
Abstract:
As the key part of nuclear pressure vessels, the water chamber head has the features of large size, complex shape and difficult processability. The processes of conventional machining method are too decentralized, the cumulative error is large, and the processing cycle is long. In order to meet the efficiency and high-precision machining requirements of the nuclear power water chamber head, a design scheme of special turn-milling machining center and B-axis components is proposed. The part characteristics and machining difficulties of the water chamber head are analyzed in the paper. The machining areas and processes are subdivided, the numerical control technological process is presented. In order to complete the finish machining of the water chamber's inner and outer surfaces and its inclined holes and sloping faces, the movable gantry milling machining center with pendulant ram is designed. According to the head processing requirements, three design schemes of B-axis components assembly, single row cylindrical roller bearing type, double row tapered roller bearing type and the central axis unloading type, are proposed. Through the theory analysis and statics and modal comparative analysis, the central axis unloading type is adopted as the optimal proposal in B-axis component design. Simulation and experimental results show that the turn-milling machining center based on the unloading B-axis assembly can satisfy the precision requirement of the water chamber head.
34
Adeniyi, A. A., H. P. Morvan, and K. A. Simmons. "A coupled Euler-Lagrange CFD modelling of droplets-to-film." Aeronautical Journal 121, no. 1246 (October 13, 2017): 1897–918. http://dx.doi.org/10.1017/aer.2017.107.
Abstract:
ABSTRACTIn this paper, a droplet to film interaction model technique is presented. In the proposed approach, the liquid and gas continua are modelled using an enhanced Volume-of-Fluid (VoF) technique while the droplets are tracked using a Lagrangian framework and are coupled to the Eulerian phases using source terms. The eventual target application is an aeroengine bearing chamber in which oil is found as droplets, shed from the bearings, splashing on impact, separated from wall surfaces at obstacles or simply re-entrained, and as a continuum oil film coating the bearing chamber outer walls which it also cools. In finite volume Computational Fluid Dynamics (CFD) techniques, a prohibitively large number of cells would be required to describe the details of the droplet impact phenomenon. Based on published correlations, the splashing droplets are created and tracked as Lagrangian particles. The flowing film and the gas continua are handled with an enhanced VoF technique.
35
Glahn, A., and S. Wittig. "Two-Phase Air/Oil Flow in Aero Engine Bearing Chambers: Characterization of Oil Film Flows." Journal of Engineering for Gas Turbines and Power 118, no. 3 (July 1, 1996): 578–83. http://dx.doi.org/10.1115/1.2816687.
Abstract:
For the design of secondary air and lubrication oil systems, a sufficient knowledge of 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 fiber-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 geometric conditions and temperature dependent fluid properties, and by approaches for the eddy viscosity available in the literature.
36
Дуаиссиа, Омар Хадж Аисcа, and Тарас Петрович Михайленко. "ОСОБЕННОСТИ ТЕПЛООБМЕНА В КАМЕРЕ ПОДШИПНИКА ГАЗОТУРБИННОГО ДВИГАТЕЛЯ." Aerospace technic and technology, no. 6 (December 20, 2018): 19–28. http://dx.doi.org/10.32620/aktt.2018.6.03.
Abstract:
The issue of ensuring the thermal regime of the rotor support, which guarantees reliable operation of the power plant, is particularly important in designing oil systems of aviation gas turbine engines, as well as ground-based GTEs. The exact calculation of the heat flux from the engine to the GTE bearing chamber is necessary to determine the required oil pumping through the GTE rotor support. The complexity of the mathematical description of thermo-hydraulic processes is associated with the presence of a multiphase mixture in the bearing chamber, consisting of oil, which is applied to lubricate and cool the support elements, and the air applied to pressurize the seals. The current practice of designing oil systems is based on the experimental data and technology that has been established more than 20 years ago. The development trends of aircraft engines, aimed at reducing specific fuel consumption and harmful emissions, suggest higher loads and temperatures in the engine while reducing power take-off for reliable operation of its main systems. This adds demands for oil systems and leads to the need to improve their circuits and elements using modern methods of modeling and design, accumulated knowledge of work-flows. The article deals with the features of the heat exchange process between the walls of the bearing chamber and the multi-phase oil-air flow applying the developed three-dimensional CFD-model of the oil-air flow in the cavity of the rotor support of a gas turbine engine. The developed CFD model is verified and the results of a numerical study of thermal-hydraulic processes are presented by the example of a bearing chamber with simplified geometry applying experimental open access data. It is presented the effect of gravity and shear forces (shear stress) on the distribution of the flow and heat transfer in the bearing chamber, which is reflected in the nonuniform distribution of the oil film and the heat transfer coefficient around the circumference of the cavity. It is determined the influence of the size on oil droplets moving in the oil-air flow on the distribution of the oil film and the heat transfer coefficient in the bearing chamber
37
Knuever, Marco, Daniela Mele, and Roberto Sulpizio. "Mineralization and Skarn Formation Associated with Alkaline Magma Chambers Emplaced in a Limestone Basement: A Review." Minerals 13, no. 9 (September 9, 2023): 1184. http://dx.doi.org/10.3390/min13091184.
Abstract:
The emplacement of shallow magma chambers within a carbonate basement is a typical feature of many volcanic systems around the world. The accompanying formation of exoskarns, endoskarns, cumulates, exsolved fluids and differentiated melts at the interface between the magma chamber and carbonate host-rock is well documented through mineralogical and geochemical studies of ejected skarns and cumulates and through fluid and melt inclusion studies. This review presents the current knowledge on the interaction of alkaline magma chambers with carbonate-bearing host-rocks, with a focus on the geochemical evolution and mineralization at the outer margins of the magma chamber and the accessory mineral phases at Somma-Vesuvius, Colli Albani and Merapi volcanic systems. Furthermore, we discuss how this interaction and its products, especially the CO2 released during the thermometamorphic decarbonation of the carbonate host-rock, impacts the eruptive behavior in all three systems.
38
Moczulak, Bartosz, and Wojciech Miąskowski. "Methods of Research of Foil Bearings in START-STOP Cycle in the Presence of Working Medium." Agricultural Engineering 23, no. 4 (December 1, 2019): 41–51. http://dx.doi.org/10.1515/agriceng-2019-0035.
Abstract:
AbstractA method for testing sliding bearings with an elastic bearing liner was presented in the paper with a focus on the issue of selection of particular time intervals of the START-STOP test cycle. Then, results of the tests carried out according to the selected material combinations were presented. The working cycle of foil bearings tested on the test stand was performed in an automatic mode at the set number of sequences start-work-rundown-stop. Due to the highest use of sliding bearings during start and rundown of a machine, this type of tests is essential for selection of relevant sets of material for bearing elements. The article also presents the use of a thermo-visual camera for identification of additional thermal loads and manners of temperature stabilization in the test chamber.
39
Петухов, Илья Иванович, Тарас Петрович Михайленко, Андрей Александрович Брунак, Сергей Валерьевич Епифанов, Артём Викторович Ковалёв, Олег Владимирович Шевчук, and Василий Викторович Тихомиров. "ОСОБЕННОСТИ ОБРАБОТКИ ЭКСПЕРИМЕНТАЛЬНЫХ ДАННЫХ ПРИ ОПРЕДЕЛЕНИИ КОЭФФИЦИЕНТА ТЕПЛООТДАЧИ В МАСЛЯНОЙ ПОЛОСТИ ОПОРЫ ГТД." Aerospace technic and technology, no. 8 (August 31, 2020): 73–81. http://dx.doi.org/10.32620/aktt.2020.8.10.
Abstract:
The development of gas turbine technology is accompanied by an increase in temperatures, pressures, and airflow velocity in the gas path. Increasing operating cycle parameters for gas turbine engine complicates the tasks of ensuring the permissible temperature state of engine parts, requires improving the methods of their calculation and design. This fact fully applies bearing assemblies, especially those operating in a hot environment, and causes interest in the study of thermohydraulic processes in the bearing chamber, which determines the temperature state of the rotor parts. The necessity of pressurizing the seals leads to the presence of the oil-air mixture in the bearing chamber. A wide range of operating parameters, flow inhomogeneity, phase disequilibrium, and phase separation significantly complicate the mathematical description of processes in the bearing chamber, including the use of CFD-modeling. Therefore, considerable attention is paid to experimental research. The experimental results are used not only to verify mathematical models but also to obtain generalizing dependencies. Most often, the desired value is the heat transfer coefficient in the oil cavity of the support. The article deals with the heat transfer features in the near-wall zone of the gas-turbine engine bearing chamber which were associated with the presence of oil-air flow. Also, approaches to the experimental determination of the heat transfer coefficient were analyzed and an appropriate system for measuring the local temperatures of the media was formed. The values of the error of the experimental heat transfer coefficient and the degree of influence of the determining factors were estimated. The contribution of the non-uniformity of the temperature field in the walls of the chamber and the uncertainty in the value of the temperature of the flow core was determined. The advantages of using the averaged heat transfer coefficient for engineering calculations and the significant influence of the averaging method on its value were also shown. Averaging over the heat flux density corresponds most accurately to the tasks of such calculations, at which the total heat flux through the chamber walls does not change.
40
Sun, Hengchao, Guoding Chen, Yonghong Zhang, and Li’na Wang. "Theoretical and experimental studies on the motion and thermal states of oil droplet in a bearing chamber." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 230, no. 14 (February 24, 2016): 2596–614. http://dx.doi.org/10.1177/0954410016629690.
Abstract:
Study on the motion and thermal states of oil droplet is an important part of research on the oil/air two-phase flow and heat transfer in an aero engine bearing chamber. In this paper, dimensional analysis is applied to the airflow analysis of bearing chamber. That makes the analysis model suitable for a wide range of geometric and operating conditions. Moreover, the temperature solution is added to the oil droplet motion analysis. That could promote the calculation accuracy of the droplet trajectory, velocity, and temperature. Firstly, the similarity criteria of the airflow in a bearing chamber are determined based on the dimensional analysis. The airflow distribution general formulas are proposed based on the numerical results of airflow velocity and temperature. The general formulas include 14 similarity criteria and are suitable for various geometric and operating conditions. The reliability of the general formulas is verified by some available experimental results. Secondly, the difference equations of the oil droplet velocity and temperature are listed by the difference method. The velocity and temperature of the droplet are obtained using a step-by-step method. The influence of droplet diameter, shaft rotational speed, air flow rate, and temperature on the oil droplet trajectory, velocity, and temperature are discussed. Thirdly, a test facility is built in order to investigate into the oil droplet motion and thermal states in a bearing chamber. The trajectory and velocity of the oil droplet are measured by the high-speed photography. Lastly, the proposed theoretical method about the oil droplet motion and thermal states is verified by above measurement results. The work in this paper may have a certain significance for perfecting the research system and improving the research level on the oil/air two-phase flow and heat transfer in an aero engine bearing chamber.
41
Yoshimoto, S., Y. Yoshida, and K. Yagi. "The Seal System in Aerostatic Journal Bearings for High Vacuum Chambers." Journal of Tribology 126, no. 2 (April 1, 2004): 310–15. http://dx.doi.org/10.1115/1.1611498.
Abstract:
This paper investigates the performance of a seal system for an aerostatic journal bearing used in a high vacuum chamber. The seal system consists of axially spaced viscous seals and annular exhaust grooves that are located between the viscous seals. Each exhaust groove is coupled to a separate vacuum pump in order to achieve a vacuum chamber pressure of less than 10−3 Pa. The vacuum chamber pressure is affected by design parameters such as the number of viscous seal stages, seal length, seal gap, and exhaust tube conductance. The influence of these design parameters on the pressure distribution across seal regions and the vacuum chamber pressure are discussed theoretically. It is subsequently shown that an aerostatic journal bearing with three-stage seal system installed can obtain a reduction in the vacuum chamber pressure almost to the ultimate pressure of a vacuum pump, providing there is no leak or outgassing from materials.
42
Peng, Xi Gao, Jia Lin Sun, Gan Shi, and Shao Ping Huang. "A New Technique for Testing Abrasion Resistance of Refractories at Elevated Temperatures." Advanced Materials Research 105-106 (April 2010): 230–33. http://dx.doi.org/10.4028/www.scientific.net/amr.105-106.230.
Abstract:
Based on an extensive comparison of test methods for abrasion resistance from home and abroad, a new technique for abrasion resistance at elevated temperature has been developed with some improvements. Two connected airtight chambers are designed to prevent compressed air from entering the sample chamber, so that heat loss of the sample chamber can be reduced and the chamber temperature is less disturbed. The sample surface temperature can reach stable within 5 min and the temperature fluctuation on sample surface can be less than 20°C in the course of inleting the compressed air at working temperatures up to1400°C. The repeatability was tested using float-glass plate as reference sample at ambient temperature and using high alumina bricks for elevated temperature. A variation coefficient under 7% at ambient temperature has been achieved. Comparison of abrasion resistance at elevated temperature was tested respectively on a high alumina brick and on a silicon nitride bonded silicon carbide brick and the results could be significantly distinguished. Nitrogen can be blown into sample chamber during heating the furnace to prevent nonoxide bearing samples from being oxidized.
43
Li, Lu Jun, Ming Zhang, Yu Zhu, and Jin Chun Hu. "Analysis of Vacuum-Degree Limit of Plane Circular High-Vacuum Gas-Bearing." Key Engineering Materials 467-469 (February 2011): 940–49. http://dx.doi.org/10.4028/www.scientific.net/kem.467-469.940.
Abstract:
This paper studied a one-dimensional model of high-vacuum plane circular gas-bearing with a three-stage sealing system, and analyzed the performances of the high-vacuum gas-bearing by combining the finite element method and the flow rate principle of the vacuum technology. For an expected pressure in the vacuum chamber, the zero load-capacity accident could take place. The reasons for the zero load-capacity accident were given through analyzing the flow rate of each sealing stage while the relationship between the pressure in the vacuum chamber and the inlet pressure was obtained. Besides, the influences of many parameters on the vacuum degree limit of the vacuum chamber were examined carefully. The analysis in this paper showed that for a given multi-stage seal system, the vacuum degree limit of the vacuum-chamber was inherent at the nonzero load-capacity condition.
44
BABA, HAYRİ, FATMA GÜNDOĞDU, and MUSTAFA SEVİNDİK. "Myxomycetes biodiversity in Gaziantep Province (Turkey) with four new records." Phytotaxa 478, no. 1 (January 5, 2021): 105–18. http://dx.doi.org/10.11646/phytotaxa.478.1.7.
Abstract:
Myxomycetes were cultured in moist chambers using substrate material collected in Gaziantep province, Turkey, during 2017–2019. Fruit bodies of wild myxomycetes were collected at ten locations. Rotten or live tree bark, leaves, debris, vegetable, and animal material, which were considered likely to contain spores, were also collected. Natural samples were immediately dried, and potential spore-bearing material was kept in a warm and humid environment with the moist chamber technique. A total of 537 samples were studied and 203 myxomycetes isolates were obtained, 33 of which were natural samples, 76 were obtained with the moist chamber technique and 94 were obtained both naturally and with the moist chamber technique in the laboratory. Six orders, 9 families, 16 genera and 42 species were identified in 3 subclasses. All species were new in Gaziantep province and four myxomycetes were identified as new records in Turkey; Didymium atrichum Henney & Alexop., Didymium serpula Fr., Craterium obovatum Peck and Physarum bivalve Pers. were added to the Turkish mycota.
45
Галиев, Ильгиз, Ilgiz Galiev, Камиль Хафизов, Kamil Khafizov, Фарит Халиуллин, and Farit Khaliullin. "MODERNIZATION THE SYSTEM OF BEARING UNITS LUBRICATION OF A TURBO COMPRESSOR OF THE TRACTOR ENGINE." Vestnik of Kazan State Agrarian University 14, no. 1 (March 30, 2019): 71–76. http://dx.doi.org/10.12737/article_5cceddb77ac7e0.09639673.
Abstract:
A technically acceptable solution to the problem of increasing power is the use of a supercharger (compressor). This means that the air entering the engine is compressed before it enters the combustion chamber, i.e. the compressor provides the necessary amount of air, sufficient for complete combustion of the increased dose of fuel. Consequently, with the previous working volume of the engine combustion chamber and the same revolutions, we get more power, and the use of a turbocharger is a constructive solution to achieve this goal. However, due to the intensity of the operating mode of the turbochargers with a sharp change in the crankshaft rotation speed and load parameters during operation of the equipment (the rotor speed varies from 30,000 min-1 to 120,000 min-1, the exhaust gas temperature reaches 7500C) it requires effective lubrication of its bearings rotor. In this regard, in the lubrication system of the bearing assembly, a hydroaccumulator of membrane type was structurally provided. The article presents a constructive scheme of the connection of the hydroaccumulator in the lubrication system of the bearing pin of the turbocharger, presents photographs of the experimental setup to confirm the effectiveness of this design solution. The experiment was carried out after the engine stopped, operating at maximum, average and minimum crankshaft speeds, and the rundown time of the turbocharger rotor and pressure drop in the lubrication system of the turbocharger bearing assembly were measured from the moment the engine stopped. It was revealed that the installation of a hydroaccumulator in the lubrication system of the bearing assembly of the turbocharger will ensure the oil feed of the bearings with a sharp reduction in crankshaft rotation during engine overloads, which is confirmed by an increase in the overrun of the turbocharger rotor by 30 ... 40%, while the standard flow and oil pressure remain.
46
Fulignati, P., P. Marianelli, and A. Sbrana. "Glass-bearing felsic nodules from the crystallizing sidewalls of the 1944 Vesuvius magma chamber." Mineralogical Magazine 64, no. 3 (June 2000): 481–96. http://dx.doi.org/10.1180/002646100549373.
Abstract:
AbstractIn the 1944 Vesuvius eruption, the shallow magma chamber was disrupted during the highly energetic explosive phases. Abundant cognate xenoliths such as subvolcanic fergusites and cumulates, hornfels, skarns and rare marbles occur in tephra deposits.Mineral chemistry, melt inclusions in minerals and glassy matrix compositions show that fergusites (highly crystalline rocks made of leucite, clinopyroxene, plagioclase, olivine, apatite, oxides and glass) do not correspond to melt compositions but result from combined sidewall accumulation of crystals, formed from K-tephriphonolitic magma resident in the chamber, and in situ crystallization of the intercumulus melt. Very low H2O contents in the intercumulus glass are revealed by FTIR and apatite composition. Whole rock compositions are essentially determined by the bulk mineral assemblages.Glass–bearing fergusites constitute the outer shell of the magma chamber consisting of a highly viscous crystal mush with a melt content in the range 20–50 wt.%. The leucite/(clinopyroxene+olivine) modal ratio, varies with the extraction order of magmas from the chamber, decreasing upwards in the stratigraphic sequence. This reflects a vertical mineralogical zonation of the crystal mush. These data contribute to the interpretation of the subvolcanic low–pressure crystallization processes at the magma chamber sidewalls affecting alkaline potassic magmas.
47
Babin, Alexander, Leonid Savin, and Sergey Majorov. "Dynamic Characteristics of Rotors on Passive and Active Thrust Fluid-film Bearings with Fixed Pads." MATEC Web of Conferences 148 (2018): 11003. http://dx.doi.org/10.1051/matecconf/201814811003.
Abstract:
Application of fluid-film bearings in rotor machines in many cases could have no alternative due to obvious advantages when compared to roller element bearings. Integration of information technology in mechanical engineering resulting in emergence of a new field of research – mechatronic bearings which allowed tracking condition of the most important parts of a machine and adjusting operational parameters of the system. Application of servo valves to control the flow rate through a fluid-film bearing is the most universal and simple way of rotor’s position control due to relative simplicity of modelling and absence of need to radically change the design of conventional hydrodynamic bearings. In the present paper numerical simulations of passive (conventional as opposed to mechatronic) and active hybrid thrust fluid-film bearings with a central feeding chamber are presented, that are parts of a mechatronic rotor-bearing node. Numerical model of an active thrust bearing is based on solution of equations of hydrodynamics, rotor dynamics and an additional model of a servo valve. Various types of control have been investigated: P, PI and PID control, and the dynamic behaviour of a system has been estimated under various loads, namely static, periodic and impulse. A design of a test rig has been proposed to study passive and active thrust fluid-film bearings aimed at, among other, validation of numerical results of active bearings simulation.
48
Li, Shaobai, Caixia Li, and Wei Wang. "Simulation of Unsteady Flows of Oil/Gas in the Ventless Bearing Chamber of an Aero-Engine." Aerospace 9, no. 4 (April 12, 2022): 211. http://dx.doi.org/10.3390/aerospace9040211.
Abstract:
The unsteady motion behavior of oil/gas two-phase flow in a novel ventless bearing chamber has significant impacts on the lubrication and heat transfer efficiency of bearings due to the various advantages of lower pressure levels and weaker rotating airflow effects. In this paper, the unsteady motion behavior of oil/gas two-phase flow in a ventless aero-engine bearing chamber is investigated by three-dimensional numerical simulation through the volume of fluid (VOF) method, and the numerical method is verified using published experimental data. The flow characteristics of oil/gas two-phase in the secondary flow and three-dimensional flow are investigated. The results show the evolution of vortices and the transition of the driving mode in the unsteady motion of oil/gas two-phase flow, and a criterion for the shift of the driving mode at different rotor speeds is proposed. As the rotation speed increases, the variation trend of the velocity field and pressure field of oil/gas two-phase flow is consistent, and the accumulation region of oil becomes inconspicuous. The results indicate a reference for enhancing the performance of lubrication systems for aero-engines.
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Liu, Jing, Wenzhuo Yu, Yawei Fang, Zimao Pan, and Guohui Cao. "Finite Element Analysis on the Seismic Performance of Concrete-Filled Steel Tube Columns with a Multiple-Chamber Round-Ended Cross-Section." Buildings 14, no. 4 (April 19, 2024): 1154. http://dx.doi.org/10.3390/buildings14041154.
Abstract:
This study proposes a form of concrete-filled steel tube column with a multiple-chamber round-ended cross-section (M-CFST). Longitudinal and transverse stiffening ribs divide the circular-ended section into different chambers, strengthening the steel tube’s confinement effect on the core concrete and improving the component’s seismic performance. A three-dimensional finite element (FE) solid model of the M-CFST is created by employing the FE software ABAQUS. Quasi-static analysis is conducted to investigate the influence of parameters, such as chamber arrangement, aspect ratio, and axial compression ratio, on flexural hysteresis performance. Moreover, the failure modes, hysteresis curves, skeleton curves, strain development, and energy dissipation of the components are analyzed. The results show the following: (1) The FE model presented in this study can simulate the quasi-static behavior of CFST columns accurately, and the calculated results are in good agreement with the measured values. (2) The seismic performance of the composite column is excellent, with a large number of chambers leading to a robust hysteresis curve for the composite columns, resulting in increased bearing capacity and energy dissipation capacity. However, the energy dissipation performance of the specimen with a two-chamber arrangement is slightly lower than that with a single-chamber arrangement. (3) The results of the finite element analysis suggest that the long and short sides of the CFST columns with a large length–width ratio should be arranged to be relatively close in length.
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CHEN, Guoding. "Oil Droplet Size Distribution and Deposition Properties in Bearing Chamber." Journal of Mechanical Engineering 47, no. 10 (2011): 139. http://dx.doi.org/10.3901/jme.2011.10.139.