滑阀节流棱边圆角对流量特性影响的三维模型仿真

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Jun.2013机 床 与 液 压Hydromechatronics Engineering Vo1.41 No.12DOI：10.3969/j.issn.1001-3881.2013.12.002Numerical Simulation Study on the Influence of Arris-edgeFillet of Spool Valve on Flow CharacteristicsWANG Dongwei，YE ZhengmaoSchool of Mechatronics Enginering，Harbin Institute of Technology，Harbin 150001，China1.IntroductionAbstract：The flow characteristic of the spool valve afects the performance of the servo valve.U·sing Fluent，this paper discusses the folowing four cases：the ideal spool valve，the spool valveswith arris-edge filets of 5，8 and 10 tam.The efects of diferent filets 0n the valves flow charac-teristics are discussed and a correction formula for the flow coeficient of ideal spool valve is pro-posed by polynomial approximation of the simulation results。

Key words：flow characteristics，Fluent，the working arris-edge filetA three-stage electro-hydraulic selwo valve is thekey component of high power electro-hydraulic servocontrol systems. Because of its outstanding featuressuch as large capacity， high-frequency response，high resolution and high reliability，etc，three-stageelectro.hydraulic servo valves have been widely usedin many high-performance apparatus including 6-DOFmotion simulators.vibrating tables and load simula-tors，etc1-2].Generaly，the main valve of athree-stage electro.hydraulic servo valve is a spoolvalve.and its fluid flow rate is controlled by chan。

ging the flow area of the valve port by the relative mo-tion of the valve spool and sleeve3]。

The flow characteristic of the spool valve affectsthe perform ance of the servo valve.Actually， theworking arris-edge fillet is unavoidable in practicalmanufacture.The presence of the fillet has great in。

Therefore，this study provides insightful guidance forthe manufacture and testing of servo valve J 4 1。

Received：2013-03-17National Natural Science Foundation for young(51205077)YE Zhengmao.Associate professor.E-mail：yezhm### hit.educaThe research on the flow characteristics of spoolvalve is quite dificult for the folowing two reasons：① It is dificult to detect a opening of only a few mi-crons in the experiment.( The theoretical formulais derived from the simplified model and thus the for。

mula is not effective in certain circumstances l 5 f。

ings，and it is relatively easy to apply，so this paperstudies the effect of the working arris-edge fillet ofvalve spool on the flow characteristics using Fluent。

2.Theoretical formula of the slide valveflow characteristicsThe ideal model of the spool valve is shown inFig.1，it shows that，aside from the two left and fightcontrol channels，the valve has four channels con-necting the outside hydraulic circuits，namely port P，port T，port A and port B.Port P connects to thepressure oil source，port A and port B connect to thetwo load cavities of actuator respectively，and port Tconnects to the tank.It is often assumed that the pos-itive direction of the spool valve is moving to theright，thus，port 1 and port 4 are open，port 2 andport 3 are closed.In this assumption，port 1 and port4 are working valve ports。

ideal spool valve，the valve port model is shownin Fig.2。

WANG Dongwei，et al：Numerical Simulation Study on the Influence of Arris-edgeFillet of Spool Valve on Flow Characteristics 7Fig.1 Structure of the ideal spool valveFig.2 The valve port model of ideal cylindrical spool valveAccording to the Fluid mechanics，the flow for-mula is：W here：area ofQ。

Q。CzA (1)is flow，Cd is flow coeficient，A is the flowthrottling(kg/m )，Ploutlet(Pa)。

port，P is density of hydraulic oilpresure inlet(Pa)，P2 is pressureIn this paper，the spool valve is made up of fourthrottling ports，so the flow formula of spool valve is：Q4Q04CdA (P -P2)/V (2)However，the radius of the arris-edge filet for areal spool can not be zero.An actual spool model isshown in Fig.3。

Fig.3 The actual spool valve modelNow the flow formula of the spool valve is：Q4c B 丽 -r)(3)where B is the width of the throttling port。

The flow characteristics can be analyzed by theformula(2)and(3).Ifthe change ofthe flow coef-ficient is ignored，for ideal spool valve，the flow wilchange with the opening of the valve linearly。

And for the actual spool valve，its flow charac-teristic curve should be the asymptote based on theflow characteristic curve of the ideal spool valve.Theflow characteristic curve is shown in Fig.4。

Q l/minJ- / O xJtjmalveFig.4 Flow characteristic curve3.The geometry model and the simula-tion methodThe simulation model in this paper is shown inFig.1.The following four spool valve models are es-tablished：the ideal spool valve，the spool valves withworking arris-edge filets of 5p，m，8p.m and lOpm。

From Fig.1.the conclusions can be drawn that thevalve has two symmetrical valve chambers and bothvalve chambers are axisymmetrica1. To reduce thecalculation.only 1/4 model of a single valve cham-ber needs to be established。

Th e main purpose of the simulation is to obtainthe flow through the throttling port of the valve.Theoverall length of the model is up to 30 mm.Howev。

er，the size of the opening is just tens of or even sev-eral microns.the proportion of the two sizes is solarge that it brings great dificulties to give the modela proper mesh.To ensure the accuracy of the calcu。

1ation and improve computational eficiency.the localmesh refinement method should be adopted[6].Themeshed model is shown in Fig.5。

Fig.5 The meshed modelTh e meshed models are imported into Fluent，aseries of parameters should be set[7].After runningthe simulation，the flows in different openings can be8 Hydromechatronics Engineeringobtained and the flow coeficients in different openingcan be calculated accordingly。

4.Simulation results and analysisThis paper mainly discusses the situation whenthe opening is less than 100 m，and 17 points areselected for research.The three.dimensional modelsin these different openings are established。then themodels are meshed and simulated，and a series of theflow values can be obtained.From the simulation re。

suits，the flow characteristic curves can be drawn asshown in Fig.6 and Fig.7。

50o0O400o0暑 300o0200001O00o00 20 40 6O 8O 100OpeninghmFig.6 The flow characteristic curve0 20 40 60 80 10OOpening. mFig.7 The flow coeficient curveAccording to Fig.6，the following conclusionscan be drawn：1)The flow characteristic curve of the idealspool valve is approximately linear。

2)With the same opening，the flow increaseswith the arris-edge fillet。

3)If the aris-edge filet is held constant，withthe increase of opening，the influence of the fillet onthe flow becomes smaller and smaller. When the 0-pening is large enough，theactual spool valve get closeof the ideal spool valve。

flow characteristics of theto the flow eharacteristics4)Because of the aris-edge filet，there is flowleakage at the zero position.And larger fillet radiuswill lead to greater flow leakage.The larger the filetradius is，the greater the flow leakage will be。

5.Efects on the flow coefficientThe folowing conclusions can be drawn fromFig.7：1)For an ideal spool valve，it is generaly be-lieved that the flow coefficient is constant.However，the flow coefficient changesand this change is particularlyalong with the openingobvious in the micro-o。

pening.Then with the opening increasing，the flowcoeficient is substantially a constant。

2、 If there is a arris-edge fillet on the spoolvalve.its flow coeficient will be larger than that ofthe ideal spool valve and wil1 increase with the fillets size. This can be explained by the fact that thepresence of the filet lcads to the increase of the flowarea。

Apply a polynomial approximation to the flowcoeficient of the ideal spool valve(when the openingis less than 40 m)and the formula can be ex。

pressed as：Cd-8.315 7×10- 8.539×10-5 ：-0.003 2x：0.054 5x.，0.374 6this is the correction form ula for the flow coemcientand it can be used directly to calculate the flow inlater applications without any complex simulations。

6.ConclusionsIn this paper，the influence of the arris-edge fil-let on the flow characteristics of spool valve is stud。

ied.First this paper uses the theory of fluid dynamicsto analyze the effect ofthe arris.edge fillet on the flowcharacteristics.Th en based on Fluent。numerical sim。

ulation of the above.mentioned effect is carried out。

The result of simulation indicated that the exist-ence of the arris-edge fillet will increase the flow areaof the spool valve，1flow curve linearity。

eading to the deterioration of theLarger fillet will result in worselinearity and greater leakage at zero position，and thiswill seriously afect the perform ance of the servovalve.Therefore，a more reasonable processing tech-nology should be adopted to minimize the arris-edgefillet。

Finally，based on the simulation results，thispaper gives the flow coefficient correction form ula at8 6 4 2 0 8 6 4 2 O 8 6 4 2 2 2 2 2 1 l l 1 l O O O ) WANG Dongwei，et al：Numerical Simulation Study on the Influence of Arris.edgeFilet of Spool Valve on Flow Characteristics 9the micro·opening to avoid the complicated simula-·tions.The flow can be directly obtained by the f0r-u a，which pr。Vides guidance r sp。 Va Ves es。 [4]tln g·References：[2][3]HAN Junwei，LI Hongren.Application of Fluid ControlTechnology in the Environment Analogue and SimulationTest FacilitiesJ].nuid Power Transmission and Con-tro1.2005，3(2)：34-38。

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PAN Xudong. Study on ser ovalve spool valve overlap[5][6][7]value hydraulic measuring system and the key technics ofthe systeml J 1.Dissertation for the doctoral degree in en。

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滑阀节流棱边圆角对流量特性影响的三维模型仿真王东魏，叶正茂哈尔滨工业大学 机电工程学院，哈尔滨 150001摘要 ：滑阀的流量特性直接影响伺服阀的性能。使用 Fluent软件对滑阀在不存在棱边圆角(理想滑阀)，棱边圆角分别为5 m、8 m和10 m等4种情况进行数值仿真研究，得出棱边圆角对滑阀流量特性的影响规律 ，并对理想滑阀的流量系数进行了修正。

关键词：流量特性；Fluent；节流棱边圆角中图分类号：TH12