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Finite Element Numerical Simulation and PIV Measurement of Flow Field inside Metering-in Spool Valve

Chinese Journal of Mechanical Engineering 2009年第1期22卷 102-108页

作者： gao dianrong QIAO Haijun LU Xianghui Hebei Province Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Qinhuangdao 066004 China School of Vehicle and Energy Engineering Yanshan University Qinhuangdao 066004 China Hebei Vocational ＆ Technical College of Building Materials Qinhuangdao 066004 China

The finite element method （FEM） and particle image velocimetry （PIV） technique are utilized to get the flow field along the inlet passage, the chamber, the metering port and the outlet passage of spool valve at three different valve openings. For FEM numerical simulation, the stream function ψ-vorticity ω forms of continuity and Navier-Stokes equations are employed and FEM is applied to discrete the equations. Homemade simulation codes are executed to compute the values of stream function and vorticity at each node in the flow domain, then according to the correlation between stream function and velocity components, the velocity vectors of the whole field are calculated. For PIV experiment, pulse Nd： YAG laser is exploited to generate laser beam, cylindrical and spherical lenses are combined each other to produce 1.0 mm thickness laser sheet to illuminate the object plane, Polystyrene spherical particle with diameter of 30-50 μm is seeded in the fluid as a tracing particles, Kodak ES 1.0 CCD camera is employed to capture the images of interested, the images are processed with fast Fourier transform （FFT） cross-correlation algorithm and the processing results is displayed. Both results of numerical simulation and PIV experimental show that there are three main areas in the spool valve where vortex is formed. Numerical results also indicate that the valve opening have some effects on the flow structure of the valve. The investigation is helpful for qualitatively analyzing the energy loss, noise generating, steady state flow forces and even designing the geometry structure and flow passage.

关键词： flow field spool valve finite element method (FEM) particle image velocimetry (PIV)

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Numerical Simulation of Turbulent Flow of Hydraulic Oil through 90° Circular-sectional Bend

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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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Theoretical Analysis and Numerical Simulation of the Static and Dynamic Characteristics of Hydrostatic Guides Based on Progressive Mengen Flow Controller

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Chinese Journal of Mechanical Engineering 2010年第6期23卷 709-716页

作者： gao dianrong ZHENG Dan ZHANG Zuochao Key Laboratory of Heavy Machinery Fluid Power Transmission and Control of Hebei Province Yanshan University Qinhuangdao 066004 China

The oil film thickness of oil hydrostatic guide with constant pressure supply based on capillary restrictor is greatly affected by load, and this kind of hydrostatic guide is usually applied to the machine tools with moderate load. The static and dynamic characteristics of the guide have been studied by using some theoretical, numerical and experimental approaches, and some methods and measures have been proposed to improve its performances. The hydrostatic guide based on progressive mengen（PM） flow controller is especially suitable for the heavy numerical control（NC） machine tools. However, few literatures about the research on the static and dynamic characteristics of the hydrostatic guides based on PM flow controller are reported. In this paper, the formulae are derived for analyzing the static and dynamic characteristics of hydrostatic guides with rectangle pockets and PM flow controller according to the theory of hydrostatic bearing. On the basis of the analysis of hydrostatic bearing with circular pocket, some equations are derived for solving the static pressure, volume pressure and squeezing pressure which influence the dynamic characteristics of hydrostatic guides with rectangle pocket. The function and the influencing factors of three pressures are clarified. The formulae of amplitude-frequency characteristics and dynamic stiffness of the hydrostatic guide system are derived. With the help of software MATLAB, programs are coded with C＋＋ language to simulate numerically the static and dynamic characteristics of the hydrostatic guide based on PM flow controller. The simulation results indicate that the sensitive oil volume between the outlet of the PM flow controller and the guide pocket has the greatest influence on the characteristics of the guide, and it should be reduced as small as possible when the field working condition is met. Choosing the oil with a greater viscosity is also helpful in improving the dynamic performance of hydrostatic guides. The re

关键词： PM flow controller rectangle pocket static characteristics dynamic characteristics hydrostatic guides

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Oil Pocket's Bearing Capacity Analysis of Liquid Hydrostatic Worktable in Gantry Moving Milling Center

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Chinese Journal of Mechanical Engineering 2014年第5期27卷 1008-1017页

作者： ZHAO Jianhua LIANG Yingna gao dianrong Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Liren College Yanshan University

Durning the design process of hydrostatic rotary worktable,the processing and assembly tolerance,（the offset of worktable and the gap of the oil film’s thickness）is *** it will cause that the real bearing of oil pocket deviates from the initial design value,and then the performance of rotary worktable will be reduced *** to now,no effort is found toward the research of influence of the processing and assembly tolerance on the performance of the rotary *** the hydrostatic oil film is assumed as the elastomer in this paper,and then the bearing capacity of the oil pocket is studied with and without the mass offset of the worktable by taking an expression between the bearing capacity and the oil film’s thickness of the oil pocket as the deform compatibility *** influence of the processing tolerance of the oil sealing belt’s gap on the bearing capacity of the oil pocket is *** the light of the liquid hydrostatic worktable of Gantry Moving Milling Center using on the scene,the oil pocket’s pressure of the worktable is tested using Rotary Worktable Test System under the circumstance of the mass offset of the worktable and the gap tolerance of the oil sealing belt,and then the equivalent offset of worktable,the average pressure of the oil pocket and the actual thickness of the oil film are analyzed *** test results show that the bearing capacity component of the oil pocket caused by G is consistent,and the component caused by M is relative to the position of the oil *** the oil sealing belt’s gap is larger than the theoretical value,the bearing capacity of the oil pocket is smaller than the others;whereas the bearing capacity of the oil pocket is larger than the *** maximum and minimum equivalent offsets are 0.256 4 mm and 0.047 5 mm,respectively,and the average oil pocket pressure varies from 0.345 MPa to 0.460 MPa,the maximum and minimum value of the actual oil film thickness are 109.976？m（No.7 oil

关键词： Gantry Moving Milling Center bearing capacity processing and assembly tolerance mass offset

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Combined effect of the use of carbon fiber and seawater and the molecular structure on the tribological behavior of polymer materials

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Friction 2018年第2期6卷 183-194页

作者： Zhiqiang WANG Jing NI dianrong gao School of Mechanical Engineering Hangzhou Dianzi University State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang University College of Mechanical Engineering Yanshan University

The combined effect of the use of carbon fiber and seawater and the molecular structure on the tribological behavior of various polymer materials under natural seawater lubrication was investigated. After the investigation, the wear morphology of the contact surface was observed by a laser scanning confocal microscope, and the texture of the wear scars and tracks were presented in 3 D profiles. Moreover, the mechanism of mixed lubrication and wear resistance was analyzed. The results demonstrated that the friction coefficient of carbon fiber-reinforced polyetheretherketone(CFRPEEK) is the lowest and fluctuates at approximately 0.11. Moreover, the seven polymer materials in ascending order of friction coefficients are CFRPEEK, carbon fiber-reinforced polyamide-imide, polytetrafluoroethylene, polyoxymethylene, polyetheretherketone(PEEK), acrylonitrile butadiene styrene resin, and glass fiber–epoxy resin. More critically, the simultaneous incorporation of deposition, polymeric scrap, hydrophilic groups, and seawater resulted in a decrease in the friction and wear of polymer materials under seawater lubrication. This observation implies that a synergistic friction-reducing and wear-resistant effect exists between carbon fiber, seawater, and the molecular structure of PEEK. As a result, a highly effective polymer material was discovered, CFRPEEK, which has the lowest friction coefficient of 0.11 and lowest wear rate of 2 × 10^(–5) mm^3?(N?m)^(-1) among the polymer materials; this validates the selection of dual friction pairs for seawater hydraulic components.

关键词： friction coefficient wear molecular structure polymer materials seawater lubrication

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Distribution Performance Analysis and Experimental Research on the Port Plate Pairs of Low Speed High Torque Seawater Hydraulic Motor

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Chinese Journal of Mechanical Engineering 2019年第6期32卷 206-218页

作者： Zhiqiang Wang Shaofeng Wu dianrong gao Shuncai Wang School of Mechanical Engineering Hangzhou Dianzi UniversityHangzhou 310018China Zhejiang University Hangzhou 310058China cnCATS Faculty of Engineering and the EnvironmentUniversity of SouthamptonSouthamptonUK School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China

The current research of seawater hydraulic motor mainly focused on piston motor and vane motor, but seldom regarded low speed high torque seawater hydraulic motor. Low speed high torque seawater hydraulic motor as a kind of energy conversion device and actuator plays an important role in seawater hydraulic transmission system. However, the physical and chemical properties of seawater, such as low viscosity, high causticity and poor lubrication, result in numerous problems. In this paper, the flow distribution characteristics of port plate pairs for the seawater hydraulic motor are investigated, and the leakage flow and power loss models of port plate pairs are established. Numerical simulations are carried out to examine the effects of water film, inlet pressure and rotating speed on the pressure distribution and leakage flow. And the friction and wear tests of port plate pairs are also carried out. Moreover, the test system of the seawater hydraulic motor is constructed and the performance of prototype with no-load or loading is conducted. The results indicate that the clearance of port plate pairs and inlet pressure have a significant effect on distribution characteristics, but the effect of rotating speed is not very obvious. The experimental results show that the minimum error rate can be maintained within 0.3% by the proposed flow model and the counter materials of 316 L against carbon-fiber-reinforced polyetheretherketone(CFRPEEK) are suitable for the port plate pairs of seawater hydraulic motor. Finally, based on the seawater hydraulic experiment platform, the volumetric efficiency of no-load and loading are obtained that the maximum can achieve 94.71% and 90.14%, respectively. This research work may improve the flow distribution performance, lubrication and the friction and wear properties, enhance energy converting efficiency of port plate pair and provide theoretical and technical support for the design of highperformance water hydraulic components.

关键词： Seawater hydraulic motor Port plate pairs Leakage flow Clearance Numerical simulation Friction andwear

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Friction and Wear Study on Friction Pairs with a Biomimetic Non-smooth Surface of 316L Relative to CF/PEEK under a Seawater Lubricated Condition

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Chinese Journal of Mechanical Engineering 2019年第4期32卷 47-60页

作者： Yingna Liang dianrong gao Bo Chen Jianhua Zhao School of Mechanical Engineering Yanshan University Qinhuangdao 066004China Liren College Yanshan University Qinhuangdao 066004 China Heibei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Qinhuangdao 066004 China

Current studies of a seawater axial piston pump mainly solve the problems of corrosion and wear in a slipper pair by selecting materials with corrosion resistance, self-lubrication, and wear resistance. In addition, an appropriate biomimetic non-smooth surface design for the slipper pair can further improve the tribological behavior. In this paper, 316 L stainless steel and CF/PEEK were selected to process the upper and bottom specimens, and the biomimetic non-smooth surface was introduced into the interface between the friction pair. The friction and wear tests were performed on a MMD-5 A tester at a rotation speed of 1000 r/min and load of 200 N under seawater lubricated condition. The results indicate that the main friction form of the smooth surface friction pair corresponds to abrasive wear and adhesive wear and that it exhibits a friction coe cient of 0.05–0.07, a specimen temperature of 56 ℃, a high wear rate, and surface roughness. Pits on the non-smooth surface friction pairs produced hydrodynamic lubrication and reduced abrasive wear, and thus the plowing e ect is their main friction form. The non-smooth surface friction pairs exhibit a friction coe cient of 0.03–0.04, a specimen temperature of 48 ℃, a low wear rate, and surface roughness. The study has important theoretical significance for enriching the lubrication, friction, and wear theory of a seawater axial piston pump, and economic significance and military significance for promoting the marine development and the national defense military.

关键词： Biomimetic non-smooth surface 316L CF/PEEK Seawater lubrication Friction and wear

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Numerical Simulation and Experimental Study of Heat-fluid-solid Coupling of Double Flapper-nozzle Servo Valve

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 1030-1038页

作者： ZHAO Jianhua ZHOU Songlin LU Xianghui gao dianrong Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Hebei Vocational & Technical College of Building Materials

The double flapper-nozzle servo valve is widely used to launch and guide the equipment. Due to the large instantaneous flow rate of servo valve working under specific operating conditions, the temperature of servo valve would reach 120℃ and the valve core and valve sleeve deform in a short amount of time. So the control precision of servo valve significantly decreases and the clamping stagnation phenomenon of valve core appears. In order to solve the problem of degraded control accuracy and clamping stagnation of servo valve under large temperature difference circumstance, the numerical simulation of heat-fluid-solid coupling by using finite element method is done. The simulation result shows that zero position leakage of servo valve is basically impacted by oil temperature and change of fit clearance. The clamping stagnation is caused by warpage-deformation and fit clearance reduction of the valve core and valve sleeve. The distribution roles of the temperature and thermal-deformation of shell, valve core and valve sleeve and the pressure, velocity and temperature field of flow channel are also analyzed. Zero position leakage and electromagnet＇s current when valve core moves in full-stroke are tested using Electro-hydraulic Servo-valve Characteristic Test-bed of an aerospace sciences and technology corporation. The experimental results show that the change law of experimental current at different oil temperatures is roughly identical to simulation current. The current curve of the electromagnet is smooth when oil temperature is below 80℃, but the amplitude of current significantly increases and the hairy appears when oil temperature is above 80℃. The current becomes smooth again after the warped valve core and valve sleeve are reground. It indicates that clamping stagnation is caused by warpage-deformation and fit clearance reduction of valve core and valve sleeve. This paper simulates and tests the heat-fluid-solid coupling of double flapper-nozzle servo valve, an

关键词： double flapper-nozzle servo valve heat-fluid-solid coupling numerical simulation warpage-deformation clamping stagnation zero position leakage

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Experimental Study on Influence of Dimples on Lubrication Performance of Glass Fiber-epoxy Resin Composite under Natural Seawater Lubrication

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Chinese Journal of Mechanical Engineering 2017年第1期30卷 110-117页

作者： WU Shaofeng gao dianrong LIANG Yingna CHEN Bo School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China Heibei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan UniversityQinhuangdao 066004China Liren College Yanshan UniversityQinhuangdao 066004China

Bionic non-smooth surface is widely applied in metal and ceramics materials. In order to introduce this technology to high pressure seawater pump, the influence of bionic non-smooth surface on the engineering plastics used in pump should be investigated. The comparative tests are carried out with a ring-on-disc configuration under 800, 1000, 1200 and 1400 r/min in order to research the influence of the bionic non-smooth surface on glass fiber-epoxy resin composite（GF/EPR） under natural seawater lubrication. The disc surfaces are textured with five kinds of pits, which are semi-spherical, conical, cone-cylinder combined, cylindrical pits and through holes, respectively. A smooth surface is tested as reference. The results show that the lubrication performance of dimpled GF/EPR sample is much better than that of the smooth sample under all rotational speeds. The semi-spherical pits surface has more obvious friction reduction than the others, which shows that the least reduction is approximately 43.29% of smooth surface under 1200 r/rain. However, the wear level is only marginally influenced by dimples. The surface morphology investigations disclose severe modifications caused by abrasive wear primarily. The results are helpful to vary friction properties of GF/EPR by non-smooth surface, or provide references to the design of non-smooth surfaces under certain condition.

关键词： !bionic non-smooth surface seawater lubrication friction coefficient glass fiber-epoxy resin composite stainless steel 316L

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Influence of Non-smooth Surface on Tribological Properties of Glass Fiber-epoxy Resin Composite Sliding against Stainless Steel under Natural Seawater Lubrication

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Chinese Journal of Mechanical Engineering 2015年第6期28卷 1171-1176页

作者： WU Shaofeng gao dianrong LIANG Yingna CHEN Bo School of Mechanical Engineering Yanshan University Heibei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Liren College Yanshan University

With the development of bionics, the bionic non-smooth surfaces are introduced to the field of tribology. Although non-smooth surface has been studied widely, the studies of non-smooth surface under the natural seawater lubrication are still very fewer, especially experimental research. The influences of smooth and non-smooth surface on the frictional properties of the glass fiber-epoxy resin composite（GF/EPR） coupled with stainless steel 316 L are investigated under natural seawater lubrication in this paper. The tested non-smooth surfaces include the surfaces with semi-spherical pits, the conical pits, the cone-cylinder combined pits, the cylindrical pits and through holes. The friction and wear tests are performed using a ring-on-disc test rig under 60 N load and 1000 r/min rotational speed. The tests results show that GF/EPR with bionic non-smooth surface has quite lower friction coefficient and better wear resistance than GF/EPR with smooth surface without pits. The average friction coefficient of GF/EPR with semi-spherical pits is 0.088, which shows the largest reduction is approximately 63.18% of GF/EPR with smooth surface. In addition, the wear debris on the worn surfaces of GF/EPR are observed by a confocal scanning laser microscope. It is shown that the primary wear mechanism is the abrasive wear. The research results provide some design parameters for non-smooth surface, and the experiment results can serve as a beneficial supplement to non-smooth surface study.

关键词： non-smooth surface friction coefficient wear resistance glass fiber-epoxy resin composite seawater lubrication stainless steel 316L

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