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Numerical Simulation of Turbulent Flow of hydraulic oil through 90° Circular-sectional Bend

Chinese Journal of Mechanical Engineering 2012年第5期25卷 905-910页

作者： WANG Liwei GAO Dianrong ZHANG Yigong 1 Technology Center Taiyuan Heavy Industry Co. Ltd. Taiyuan 030024 China College of Mechanical Engineering Yanshan University Qinhuangdao 066004 China

oil flow through pipe bends is found in many engineering applications. However, up to now, the studies of oil flow field in the pipe bend appear to be relatively sparse, although the oil flow field and the associated losses of pipe bend are very important in practice. In this paper, the relationships between the turbulent flow of hydraulic oil in a bend and the Reynolds number Re and the curvature ratio δare studied by using computational fluid dynamics （CFD）. A particular emphasis is put on hydraulic oil, which differs from air or water, flowing through 90° circular-sectional bend, with the purpose of determining the turbulent flow characteristics as well as losses. Three turbulence models, namely, RNG κ-ε model, realizable k-ε model, and Reynolds stress model （RSM）, are used respectively. The simulation results in the form of contour and vector plots for all the three turbulence models for pipe bends having curvature ratio of δ=0.5, and the detailed pressure fields and total pressure losses for different Re and δ for RSM are presented. The RSM can predict the stronger secondary flow in the bend better than other models. As Re increases, the pressure gradient changes rapidly, and the pressure magnitude increases at inner and outer wall of the bend. When δ decreases, two transition points or transition zones of pressure gradient arise at inner wall, meanwhile, the transition point moves towards the inlet at outer wall of the bend. Owing to secondary flow, the total pressure loss factor k increases as the bend tightens, on the contrary, as Re increases, factor k decreases due to higher velocity heads, and the rapid change of pressure gradient on the surface of the bend leads to increasing of friction and separation effects, and magnified swirl intensity of secondary flow. A new mathematical model is proposed for predicting pressure loss in terms of Re and δ in order to provide support to the one-dimensional simulation software. The proposed research provides referenc

关键词： hydraulic oil 90° bend turbulent flow pressure loss computational fluid dynamics (CFD)

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Resistance Characteristics of hydraulic oil through Isodiametric T-type Duct with Sharp Corners

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Chinese Journal of Mechanical Engineering 2009年第2期22卷 250-255页

作者： TANG Jinglin WANG Liwei LI Xia College of Mechanical Engineering Yanshan University Qinhuangdao 066004 China Taiyuan Heavy Mechinery Group Taiyuan 030024 China

Rational determination and reduction of local energy loss of oil flow at pipe junctions are of important significance to improve hydraulic pipeline＇s work efficiency, especially for complex hydraulic pipeline connected by isodiametric T-type ducts with sharp comers to get combined and divided flow. From this point of view, the formulae of resistance loss for combined flow and divided flow through isodiametric T-type duct with sharp comers as well as the correlations of resistance loss coefficients in the branches of the duct are derived using energy method. On this basis, resistance characteristics of hydraulic oil in the duct are obtained by numerical simulation of different flow modes, which are commonly applied in hydraulic pipelines, using computational fluid dynamics （CFD） method, and the reasons for the resistance loss are analyzed based on the pressure change mechanism in the flow field. A part of simulation results was validated with the reference data. The research shows that for combined flows the resistance loss of symmetrical is lower than that of unsymmetrical to obtain low speed in common branch, but to gain high speed is quite the contrary, for divided flows, the symmetrical is always a reasonable choice to reduce resistance loss. These conclusions can be applied to optimize the design of hydraulic pipeline.

关键词： hydraulic oil T-type duct energy method computational fluid dynamics (CFD) resistance characteristic

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Measurement of Diffusion Coefficients of Air in Silicone oil and in hydraulic oil

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Chinese Journal of Chemical Engineering 2011年第2期19卷 205-211页

作者：丁川范毓润 State Key Lab of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

A piston-cylinder apparatus was established to measure the solubility and diffusivity of air in dimethyl silicone oils and in hydraulic oils based on the PVT state equation of air and the solution of unsteady one-dimensional diffusion *** measured diffusivity-temperature relation can be well fitted by the Arrhenius equation for engineering *** correlation between the solute diffusivity D and solvent viscosity μ is *** terms of Eyring＇s activation theory,the activation in the air-silicone-oil diffusion process is quite different from that in the momentum transport of the silicone oil：the activation entropy of the former is positive while that of latter is ***,the activation enthalpies of the two processes are in the same order of magnitude,which leads to the observation that Dμ/T is roughly constant.

关键词： air silicone oil hydraulic oil diffusion coefficient viscosity

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Theory analysis and experimental research on on-line contamination detecting technology in hydraulic oil

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Journal of Coal Science & Engineering(China) 2006年第1期12卷 115-118页

作者：姚成玉赵静一张齐生 Institute of Electrical Engineering Yanshan University Qinhuangdao 066004 China College of Mechanical Engineering Yanshan University Qinhuangdao 066004 China

A system of on-line contamination detecting in hydraulic oil based on silting principle is accomplished, where, metal filter membrane as detector, solenoid as active force to propel piston to blotter and gain differential pressure, step motor drives the membrane to filtrate and counter-flush, LabVIEW as detecting software platform, oil's contamination detecting indirectly by gauging differential pressure. Based on theory analysis, accomplished is relation between contamination level and differential pressure, realizing polynomial curve fitting, and calibration experiment. Field experiment is simulated in the condition of experimental laboratory, has credible precision and real-time performance, which can popularize to the field of production.

关键词： hydraulic oil on-line detecting silting principle

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STUDY ON CARRIER PURIFICATION TECHNOLOGY FOR hydraulic oil

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Journal of China University of Mining and Technology 1996年第2期6卷 69-73页

作者：张晞

The surface feature of contaminative oil is analysed and the theory of carrier purification technology for hydraulic oil is put forward. Experiments have been done in laboratory. The main performance of the purified o... 详细信息

关键词： hydraulic oil are getting carrier purification

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Diagnosis and management of the polluted hydraulic oil

Diagnosis and management of the polluted hydraulic oil

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第一届液压技术与矿山装备国际学术会议

作者： KANG Wen-long WANG Yang Liaoning Technical University

hydraulic technology is widely applied in various fields of national economy,so the performance of hydraulic system directly influences all aspects of the economic *** status of hydraulic oil is very important for the working performance of hydraulic *** pollution of hydraulic oil is one of the important causes which cause the fault of hydraulic system And it will cause the failure of system and loss of *** it is very important that the fault of hydraulic system be diagnosed and *** paper introduces hydraulic oil pollution and the method of diagnosing and treating it.

关键词： hydraulic oil pollution diagnosis treatment

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STUDY ON DYNAMIC PERFORMANCE OF THE hydraulic oil

STUDY ON DYNAMIC PERFORMANCE OF THE HYDRAULIC OIL

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第五届振动工程及其机械技术国际会议

作者： X.G.Liu~a C.B.Chu~b a College of Energy and Power Engineering.Huazhong University of Science and Technology, Wuhan,430074,P.R.China b Nanchang Institute of Technology,Nanchang 330099 P.R China

＜正＞The hydraulic system performance is influenced by dynamic performance of hydraulic oil under working conditions *** this paper,for the non-linear properties of the mixture of pure hydraulic oil and air,the authors constructed the interrelationship of the various parameters of the fluid using state equation form and constructed the mixture effective density as a function of the pressure,temperature and the air content in fluid,created a mathematical analysis model,calculated the fluid bulk modulus with different air *** graphical compute results show the main factors which affect the fluid effective density and bulk modulus change,which also provide the engineers and technicians a more direct-viewing reference,thus for them designing accurate hydraulic systems model and carrying on dynamic analysis lay the foundation.

关键词： hydraulic oil non-linear dynamic performance

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Influence of oil and water media on fretting behaviour of AISI 52100 steel rubbing against AISI 1045 steel

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中国有色金属学会会刊:英文版 2004年第z1期14卷 364-369页

作者： REN Ping-di CHEN Guang-xiong ZHU Min-hao ZHOU Zhong-rong The Key Laboratory of Education Ministry of China on Advanced Material Technology Southwest Jiaotong University Chengdu 610031 China

A series of fretting test were carried out using a DELTA PLINT testing system to study the influence of hydraulic oil and water on fretting behaviour of AISI 52100 steel rubbing against AISI 1045 steel. The test result shows that media hydraulic oil and water have a distinct influence on fretting behaviour of the tested materials. Medium water can lead to shifting of the partial slip regime in the fretting map from a larger displacement amplitude toward a smaller one and enlargement of the mixed slip regime, in comparison with that in ambient atmosphere. While medium hydraulic oil can result in shifting of the partial slip regime from a smaller displacement amplitude toward a larger one. In the gross slip regime, hydraulic oil and water play a positive role as lubrication media. They can clearly decrease the fretting friction coefficient between AISI 52100 and AISI 1045. The test result also demonstrates that this lubrication effect will get better with increasing displacement amplitude and that hydraulic oil is better than water for lubrication. SEM observation of the wear scars displays that the fretting wear mainly results from abrasive wear and delamination of the fretted materials when using these two kinds of substances as lubrication media.

关键词： fretting hydraulic oil water lubrication

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