弯管流量计水流特性的数值模拟及流量系数的试验研究
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摘要
本文分别对4种不同管径、3种不同弯径比的90°圆形弯管流量计进行试验研究。根据自由涡旋理论、强制涡旋理论和实测结果,研究了流量系数随弯径比和弯管直径的变化规律,得出了流量与压差的关系。试验表明,在弯径比一定的情况下,流量系数随管径而变,并非常数。
本文研究了雷诺数对流量系数的影响。研究表明,雷诺数和流量系数的关系是比较复杂的,受到弯径比、管径大小和来流量影响。当管径较大,雷诺数大于2×10~5时,流量系数随雷诺数几乎不变化;当雷诺数小于2×10~5时,流量系数随着雷诺数的减小而减小。当管径较小、雷诺数较小时,尚未发现流量系数随雷诺数减小而减小的规律。因此,在小雷诺数时,流量系数的变化规律仍需要进一步研究。
本文采用国际大型通用软件FLUENT软件为计算平台,利用RNGκ-ε湍流模型,研究了弯管径向的压强分布、弯管内外壁压强沿程分布和弯径比对压强的影响,求得了不同管径、不同弯径比情况下流量与压差的关系。计算结果表明,除个别断面计算值与实测值有较大差别外,其余大部分断面计算结果与实测结果基本一致。求得了流量与流量系数的关系。计算结果表明,对于一定的管径和弯径比,流量系数基本为一常数,这和试验结果是一致的。根据计算结果和试验结果对比,得出了不同管径、不同弯径比情况下测流的最佳断面。
研究表明,弯管内流速变化沿径向有一极大点。极大点位置始终在弯管内侧与中心轴线之间。三维数值模拟表明,速度最大值逐渐向外侧偏移。最终在θ=65°断面,速度最大值等值线分离,形成两条独立的最大值等值线,并且随着角度的增大,向弯管的顶端和底部发展。
计算结果表明,在θ=8°断面,开始出现二次流。随后二次流越来越明显,二次流一直延续到弯管出口。正是由于二次流的存在,使得弯管水流沿程呈螺旋状流动。
In this paper,four kinds of different diameter、three kinds of different bend diameter ratio of 90°circular pipe flowmeter are carried out pilot studies. According to forced vortex theory and experimental results,the laws of flow coefficient changing with the bending radius ratio and diameter and the relations of flow rate and pressure are studied.Test shows that in the certain bending radius ratio,flow coefficient varying with diameter is not constant.
In this paper,the impacts of Reynolds number on flow coefficient are investigated.Researches show that the relations between flow coefficient and Reynolds number are more complex and affected by bending radius ratio、diameter and flow rate.When the diameter is large and Reynolds number is larger than 2×10~5,flow coefficient hardly varies with Reynolds number;when Reynolds number is smaller than 2×10~5,flow coefficient decreases with Reynolds number.When the diameter is small and Reynolds number is smaller than 2×10~5,the law of flow coefficient decreasing with Reynolds is not found. Therefore,when Reynolds number is small,the changes of flow coefficient still need further study.
In this paper,using international current software FLUENT software as computing platforms and RNG k-εmodel as turbulence model,the pressure distribution along the Diameter、pressure distribution along the inside and outside wall and the impacts of bending radius ratio on pressure and the relations between flow rate and pressure of different diameter and bending radius ratio are studied.The results show that calculated and the measured values are very different for some sections and calculated results are consistent with the experimental results for the most sections,the relations between flow rate and flow coefficient are obtained.The results show that the flow coefficient is a constant which is accorded with the test results.According to the calculated results and test results,best flow measurement section is gained for different diameter,bending radius.
Research shows that it existes a max velocity point along the diameter which is between the inboard and central axis.Three-dimensional numerical simulation shows that the max speed gradually migrates to lateral.Finally,in the sectionθ= 65°,the max speed contours separate which forms two independent max contours and develop to to the top and bottom with the angle increasing.
Calculated results shows that in the sectionθ= 65°secondary flow appears. Subsequently,it becomes obviously which extends to the export.Because of existence of secondary flow,it forms a spiral flow along the elbow flowmeter.
本文研究了雷诺数对流量系数的影响。研究表明,雷诺数和流量系数的关系是比较复杂的,受到弯径比、管径大小和来流量影响。当管径较大,雷诺数大于2×10~5时,流量系数随雷诺数几乎不变化;当雷诺数小于2×10~5时,流量系数随着雷诺数的减小而减小。当管径较小、雷诺数较小时,尚未发现流量系数随雷诺数减小而减小的规律。因此,在小雷诺数时,流量系数的变化规律仍需要进一步研究。
本文采用国际大型通用软件FLUENT软件为计算平台,利用RNGκ-ε湍流模型,研究了弯管径向的压强分布、弯管内外壁压强沿程分布和弯径比对压强的影响,求得了不同管径、不同弯径比情况下流量与压差的关系。计算结果表明,除个别断面计算值与实测值有较大差别外,其余大部分断面计算结果与实测结果基本一致。求得了流量与流量系数的关系。计算结果表明,对于一定的管径和弯径比,流量系数基本为一常数,这和试验结果是一致的。根据计算结果和试验结果对比,得出了不同管径、不同弯径比情况下测流的最佳断面。
研究表明,弯管内流速变化沿径向有一极大点。极大点位置始终在弯管内侧与中心轴线之间。三维数值模拟表明,速度最大值逐渐向外侧偏移。最终在θ=65°断面,速度最大值等值线分离,形成两条独立的最大值等值线,并且随着角度的增大,向弯管的顶端和底部发展。
计算结果表明,在θ=8°断面,开始出现二次流。随后二次流越来越明显,二次流一直延续到弯管出口。正是由于二次流的存在,使得弯管水流沿程呈螺旋状流动。
In this paper,four kinds of different diameter、three kinds of different bend diameter ratio of 90°circular pipe flowmeter are carried out pilot studies. According to forced vortex theory and experimental results,the laws of flow coefficient changing with the bending radius ratio and diameter and the relations of flow rate and pressure are studied.Test shows that in the certain bending radius ratio,flow coefficient varying with diameter is not constant.
In this paper,the impacts of Reynolds number on flow coefficient are investigated.Researches show that the relations between flow coefficient and Reynolds number are more complex and affected by bending radius ratio、diameter and flow rate.When the diameter is large and Reynolds number is larger than 2×10~5,flow coefficient hardly varies with Reynolds number;when Reynolds number is smaller than 2×10~5,flow coefficient decreases with Reynolds number.When the diameter is small and Reynolds number is smaller than 2×10~5,the law of flow coefficient decreasing with Reynolds is not found. Therefore,when Reynolds number is small,the changes of flow coefficient still need further study.
In this paper,using international current software FLUENT software as computing platforms and RNG k-εmodel as turbulence model,the pressure distribution along the Diameter、pressure distribution along the inside and outside wall and the impacts of bending radius ratio on pressure and the relations between flow rate and pressure of different diameter and bending radius ratio are studied.The results show that calculated and the measured values are very different for some sections and calculated results are consistent with the experimental results for the most sections,the relations between flow rate and flow coefficient are obtained.The results show that the flow coefficient is a constant which is accorded with the test results.According to the calculated results and test results,best flow measurement section is gained for different diameter,bending radius.
Research shows that it existes a max velocity point along the diameter which is between the inboard and central axis.Three-dimensional numerical simulation shows that the max speed gradually migrates to lateral.Finally,in the sectionθ= 65°,the max speed contours separate which forms two independent max contours and develop to to the top and bottom with the angle increasing.
Calculated results shows that in the sectionθ= 65°secondary flow appears. Subsequently,it becomes obviously which extends to the export.Because of existence of secondary flow,it forms a spiral flow along the elbow flowmeter.
引文
[1]秦绪斌.弯管流量计国内外发展概述[J].自动化仪表,1992,6:1-5.
[2]W.M.Lansford.The Use of an Eblow in a Pipe Line for Determining the Rate of Flow in the Pipe.University of Illionis.Engineering Experiment Station Bulletin No.289.Dec.1936.
[3]H.Addison.The use of Pipe Bends as Flow Meter.Engineering,1938,145:227-229.
[4]D.C.Taylor and M.B.Mcpherson.Elbow Meter Performance.Journal of the American Water Works Association,1954,1(46):123-134.
[5]L.K.Spink.Principles and Practice of Flow Meter Engineering.Eighth edition,The Foxboro Company,1958.
[6]Murdock J.W.and Geogory C.Elbow Flow Meter Investigation.NBTL Research Project,1962.
[7]Murdock J.M.Performance Charactertistic of Elbow Flow Meters.Trans.of ASME,1964,D86.
[8]Taylor A M K P,Whitelaw J H and Yianneskis M.Curved ducts with strong secondary motion:velocity measurements of developing laminar and turbulent flow[J].Journal of Fluids Engineering,1982,104:350-359.
[9]史桦.弯管流量计的流量计算[J].核动力工程,1981,2(2)。
[10]陆祖祥.弯管流量计[J].工业仪表与自动化装置,1981(6).
[11]宗秉惠.弯头流量计的理论与设计[J].工业仪表与自动化装置,1982(5).
[12]陆祖祥.45°方向取压弯管流量计[J].化工自动化及仪表,1984(4).
[13]姚文华.弯管流量计的原理和应用[J].自动化仪表,1986,17(8).
[14]何卓烈.弯管流量计的试验研究及其在工业上的应用前景.工业仪表与自动化装置.1987(4).
[15]马材芬,史峰,徐忠.90°弯道内紊流的试验研究[J].工程热物理学报,1990,11(1):37-40.
[16]史峰,徐忠,马材芬.大曲率弯道内湍流数值计算与测量[J].空气动力学学报,1990,8(4):423-429.
[17]钱承耀,钱玉.弯管流量计流量系统的试验研究[J].西安交通大学报,1994,(9):120-125.
[18]许承,郭荣伟.三维弯管内分离流场的试验研究[J].航空学报,1994,15(9):1095-1099.
[19]尚虹,王尚锦,席光,袁民建,孔庆利.90°圆截面弯管内三维紊流场实验研究[J].航空动力学报,1994,9(3):263-266.
[20]李郁侠,吴周虎.利用弯管测量弯道流量的理论分析与实验研究[J].灌溉排水.1995,14(1):6-11.
[21]廖明燕,罗万象.弯管流量计流量系数的研究[J].自动化仪表,1999,(11):5-8.
[22]胡志伟,李勤凌,苗永淼.三维强弯管内湍流场的数值分析[J].西安交通大学学报.1998,32(1):49-52.
[23]梁德旺,王国庆,吕兵.低速高湍流度90°弯管流动数值模拟[J].南京航空航天大学学报,2000,32(4):381-387.
[24]樊洪明,何钟怡,王小华.弯曲管道内流动的大涡模拟[J].水动力学研究与进展,2001,16(1):78-83.
[25]樊洪明,李先庭,何钟怡,江亿.方形截面弯管二次流数值模拟[J].热能动力工程,2002,17(5):510-513.
[26]丁珏,翁培奋.三种湍流模式数值模拟直角弯管内三维分离流动的比较[J].计算物理,2003,20(5):386-390.
[27]罗永虹,杨俊,潘卫明.90°方截面弯管的湍流计算[J].武汉大学学报(工学版),2003,36(2):62-65.
[28]温良英,张正荣,白晨光.管道流量与弯管压差的关系及流量系数的实验研究.管道设计与设备.2003.1:1-2.
[29]丁珏,翁培奋.90°弯管内流动的理论模型及流动特性的数值研究[J].计算力学学报,2004,21(3):314-321.
[30]胡艳华,时铭显.90°方弯管内气相流场的数值模拟与分析[J].石油机械.2007,35(8):9-12.
[31]孙志强,周孑民,张宏建.弯管流量计测量特性的数值模拟与试验研究[J].传感技术学报.2007,20(6):1412-1415.
[32]梁国伟,蔡武昌.流量测量技术及仪表[J].北京:机械工业出版社,2002:39-120.
[33]W.Lim,Ki,K.C.,Myung.Numeriacal Investigation on the Installation Effects of Electromagnetic Flowmeter Downstream of a 90°Elbow-laminar Flow Case.Flow Measurement and Instrumentation,1999.10(3):167-174.
[34]温良英.弯管特性及其在流量检测中的应用[J].工业加热,2000,(4):39-41.
[35]叶权昌.已系列化的90°弯管流量计[J].石油化工自动化,1998,(4):43-59.
[36]于雪松.基于CAN总线的弯管流量计测量系统的研究与设计.燕山大学硕士论文.2004年.
[37]李郁侠.弯管水流流量压差关系公式推导与验证[J].武汉水利电力大学学报,1995,(4):225-229.
[38]郑建光,梁国伟.弯管流量计的特性实验研究[J].中国计量学院学报,1999,(12):39-44.
[39]宋建华.弯管流量计基本特点及其在供热系统中的应用[J].仪表技术与传感器,1997:27-29.
[40]宋建华,李志.弯管流量计与孔板流量计的性能比较[J].自动化仪表,1998,(3):17-19.
[41]周雪漪.计算水力学[M].清华大学出版社,1995.
[42]陶文铨.数值传热学(第二版)[M].西安交通大学出版社,2001.
[43]郭鸿志.传输过程数值模拟[M].冶金工业出版社,1998.
[44]J.D.Anderson,Computational Fluid Dynamics:The Basics with Applications.McGrawHill[M].1995.清华大学出版社,2002.
[45]S.V.Patanker,Numerical Heat Transfer and Fluid Flow.Hemisphere[M],Washington,1980.
[46]P.chow,M.Cross,K.Pericleous,A natuial extension of the conventional finite volume method into polygonal unstructured meshes for CFD application.App.Math.Modlling,20:170-183,1996.
[47]H.K.Versteeg,W.Malalasekera,An Introduction to Computational Fluid Dynamics:The Finite Volumn Method.Wiley,New York,1995.
[48]H.Schlichting,Boundary Layer Theory,8th ed.McGrawHill,New York,1979.
[49]王福军.计算流体动力学分析-CFD软件原理与应用[M].清华大学出版社,2004.
[50]Preston.Shell Flow Meter Engineering Handbook.1968,132-133.
[51]朱磊,张志昌,李郁侠.弯管流量计试验研究.电网与水力发电进展,2007(8).
[2]W.M.Lansford.The Use of an Eblow in a Pipe Line for Determining the Rate of Flow in the Pipe.University of Illionis.Engineering Experiment Station Bulletin No.289.Dec.1936.
[3]H.Addison.The use of Pipe Bends as Flow Meter.Engineering,1938,145:227-229.
[4]D.C.Taylor and M.B.Mcpherson.Elbow Meter Performance.Journal of the American Water Works Association,1954,1(46):123-134.
[5]L.K.Spink.Principles and Practice of Flow Meter Engineering.Eighth edition,The Foxboro Company,1958.
[6]Murdock J.W.and Geogory C.Elbow Flow Meter Investigation.NBTL Research Project,1962.
[7]Murdock J.M.Performance Charactertistic of Elbow Flow Meters.Trans.of ASME,1964,D86.
[8]Taylor A M K P,Whitelaw J H and Yianneskis M.Curved ducts with strong secondary motion:velocity measurements of developing laminar and turbulent flow[J].Journal of Fluids Engineering,1982,104:350-359.
[9]史桦.弯管流量计的流量计算[J].核动力工程,1981,2(2)。
[10]陆祖祥.弯管流量计[J].工业仪表与自动化装置,1981(6).
[11]宗秉惠.弯头流量计的理论与设计[J].工业仪表与自动化装置,1982(5).
[12]陆祖祥.45°方向取压弯管流量计[J].化工自动化及仪表,1984(4).
[13]姚文华.弯管流量计的原理和应用[J].自动化仪表,1986,17(8).
[14]何卓烈.弯管流量计的试验研究及其在工业上的应用前景.工业仪表与自动化装置.1987(4).
[15]马材芬,史峰,徐忠.90°弯道内紊流的试验研究[J].工程热物理学报,1990,11(1):37-40.
[16]史峰,徐忠,马材芬.大曲率弯道内湍流数值计算与测量[J].空气动力学学报,1990,8(4):423-429.
[17]钱承耀,钱玉.弯管流量计流量系统的试验研究[J].西安交通大学报,1994,(9):120-125.
[18]许承,郭荣伟.三维弯管内分离流场的试验研究[J].航空学报,1994,15(9):1095-1099.
[19]尚虹,王尚锦,席光,袁民建,孔庆利.90°圆截面弯管内三维紊流场实验研究[J].航空动力学报,1994,9(3):263-266.
[20]李郁侠,吴周虎.利用弯管测量弯道流量的理论分析与实验研究[J].灌溉排水.1995,14(1):6-11.
[21]廖明燕,罗万象.弯管流量计流量系数的研究[J].自动化仪表,1999,(11):5-8.
[22]胡志伟,李勤凌,苗永淼.三维强弯管内湍流场的数值分析[J].西安交通大学学报.1998,32(1):49-52.
[23]梁德旺,王国庆,吕兵.低速高湍流度90°弯管流动数值模拟[J].南京航空航天大学学报,2000,32(4):381-387.
[24]樊洪明,何钟怡,王小华.弯曲管道内流动的大涡模拟[J].水动力学研究与进展,2001,16(1):78-83.
[25]樊洪明,李先庭,何钟怡,江亿.方形截面弯管二次流数值模拟[J].热能动力工程,2002,17(5):510-513.
[26]丁珏,翁培奋.三种湍流模式数值模拟直角弯管内三维分离流动的比较[J].计算物理,2003,20(5):386-390.
[27]罗永虹,杨俊,潘卫明.90°方截面弯管的湍流计算[J].武汉大学学报(工学版),2003,36(2):62-65.
[28]温良英,张正荣,白晨光.管道流量与弯管压差的关系及流量系数的实验研究.管道设计与设备.2003.1:1-2.
[29]丁珏,翁培奋.90°弯管内流动的理论模型及流动特性的数值研究[J].计算力学学报,2004,21(3):314-321.
[30]胡艳华,时铭显.90°方弯管内气相流场的数值模拟与分析[J].石油机械.2007,35(8):9-12.
[31]孙志强,周孑民,张宏建.弯管流量计测量特性的数值模拟与试验研究[J].传感技术学报.2007,20(6):1412-1415.
[32]梁国伟,蔡武昌.流量测量技术及仪表[J].北京:机械工业出版社,2002:39-120.
[33]W.Lim,Ki,K.C.,Myung.Numeriacal Investigation on the Installation Effects of Electromagnetic Flowmeter Downstream of a 90°Elbow-laminar Flow Case.Flow Measurement and Instrumentation,1999.10(3):167-174.
[34]温良英.弯管特性及其在流量检测中的应用[J].工业加热,2000,(4):39-41.
[35]叶权昌.已系列化的90°弯管流量计[J].石油化工自动化,1998,(4):43-59.
[36]于雪松.基于CAN总线的弯管流量计测量系统的研究与设计.燕山大学硕士论文.2004年.
[37]李郁侠.弯管水流流量压差关系公式推导与验证[J].武汉水利电力大学学报,1995,(4):225-229.
[38]郑建光,梁国伟.弯管流量计的特性实验研究[J].中国计量学院学报,1999,(12):39-44.
[39]宋建华.弯管流量计基本特点及其在供热系统中的应用[J].仪表技术与传感器,1997:27-29.
[40]宋建华,李志.弯管流量计与孔板流量计的性能比较[J].自动化仪表,1998,(3):17-19.
[41]周雪漪.计算水力学[M].清华大学出版社,1995.
[42]陶文铨.数值传热学(第二版)[M].西安交通大学出版社,2001.
[43]郭鸿志.传输过程数值模拟[M].冶金工业出版社,1998.
[44]J.D.Anderson,Computational Fluid Dynamics:The Basics with Applications.McGrawHill[M].1995.清华大学出版社,2002.
[45]S.V.Patanker,Numerical Heat Transfer and Fluid Flow.Hemisphere[M],Washington,1980.
[46]P.chow,M.Cross,K.Pericleous,A natuial extension of the conventional finite volume method into polygonal unstructured meshes for CFD application.App.Math.Modlling,20:170-183,1996.
[47]H.K.Versteeg,W.Malalasekera,An Introduction to Computational Fluid Dynamics:The Finite Volumn Method.Wiley,New York,1995.
[48]H.Schlichting,Boundary Layer Theory,8th ed.McGrawHill,New York,1979.
[49]王福军.计算流体动力学分析-CFD软件原理与应用[M].清华大学出版社,2004.
[50]Preston.Shell Flow Meter Engineering Handbook.1968,132-133.
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