表面圆柱形突体水力特性的试验研究与数值模拟
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摘要
在高坝泄水建筑物中会遇到常见的高速水流问题,如空化空蚀、掺气、脉动振动、消能防冲等。尤其在溢流坝、泄洪洞、陡槽等泄洪建筑物中,当水流速度达到一定程度时,水流压强低于相应的饱和蒸汽压强,产生空化现象。空穴流由低压区流到压力升高区便会产生空蚀破坏。当空化现象不可避免时,为了减免高速水流空化产生的空蚀破坏,经济而有效的措施是在低压空化区或在易发生空蚀部位上游设置掺气设施强迫掺气。在泄水建筑物施工中,过流壁面常会形成圆柱形突体、升坎、跌坎、凹槽、三角形突体及蜂窝等不平整突体。泄水建筑物的运行实践表明,即使过流壁面上仅残留几毫米的不平整突体,亦会引起砼表面大范围的空蚀破坏。首先,本文针对突体引发空化现象的国内外研究现状和发展动态作了比较全面的回顾;其次,本文重点对由圆柱形突体引发空化的水力特性进行探讨,在直流式水洞中利用三维粒子图像测速仪(PIV)对其进行了初步试验研究,通过测量两种不同高度不锈钢试件在不同掺气浓度条件下空化区的流速分布,探讨掺气量与速度场分布的关系;最后,本文针对泄水建筑物过流壁面中的圆柱形突体周围流场进行数值模拟,模拟不同高度圆柱形突体以及不同掺气浓度对空化区域内流动特性的影响,给出瞬时流速场和压力场,并与PIV实测结果进行了比较,结果表明,数值模拟与实测值总体上吻合较好,能较好地模拟因表面圆柱形突体引发的空化现象。
Some problems of high-velocity flow are often encountered when released from these high dams, such as cavitation, aeration, fluctuation, vibration, energy dissipation etc. Especially in spillway dams, spillway tunnels and chute spillways of high-head discharge structures, cavitation phenomena will occur while flow velocity reaches a certain value and flow pressure is lower than the relevant saturated vapor pressure. Cavitation erosion arises from the cavity flow from underpressure to higher pressure. As cavitation phenomenon is inevitable, in order to prevent the erosion due to the cavitation in high-velocity flow, an economic and effective measure is to set up aerators for generating forced aeration in underpressure cavitation regions or upper locations liable to cavitation erosion. Surface irregularities such as offset into flow, offset away from flow, cylindrical protrusion, and triangular protrusion on the surface usually exist under the construction of outlet works. The operation practice of outlet works showed that large-scale cavitation damage would occur even if there existed a slight surface irregularity of only a few millimeters on the overflow surface. Firstly, a comprehensive review and a progress in cavitation characteristics of high velocity flow over a surface cylindrical protrusion; Secondly, Three-dimensional Particle Image Velocimetry has been used to study the flow field of high-velocity flows over surface irregularity—cylindrical protrusions. By measuring the flow velocity distribution over two different heights of stainless steel specimens in cavitation region with different air concentrations, the relation between entrained air rate and flow velocity was investigated. Finally, this thesis presents numerical simulation of both horizontal and vertical two-dimensional flow fields around cylindrical protrusions on overflow surface of flood release structures. Effects of cylindrical protrusions with different heights and different air concentrations on flow characteristics in cavitation region were considered. Velocity and pressure profiles in horizontal and vertical two-dimensional flows were obtained, and a comparison with the PIV measured data was made. The results showed that numerical simulation reasonably agree well with experimental data.
Some problems of high-velocity flow are often encountered when released from these high dams, such as cavitation, aeration, fluctuation, vibration, energy dissipation etc. Especially in spillway dams, spillway tunnels and chute spillways of high-head discharge structures, cavitation phenomena will occur while flow velocity reaches a certain value and flow pressure is lower than the relevant saturated vapor pressure. Cavitation erosion arises from the cavity flow from underpressure to higher pressure. As cavitation phenomenon is inevitable, in order to prevent the erosion due to the cavitation in high-velocity flow, an economic and effective measure is to set up aerators for generating forced aeration in underpressure cavitation regions or upper locations liable to cavitation erosion. Surface irregularities such as offset into flow, offset away from flow, cylindrical protrusion, and triangular protrusion on the surface usually exist under the construction of outlet works. The operation practice of outlet works showed that large-scale cavitation damage would occur even if there existed a slight surface irregularity of only a few millimeters on the overflow surface. Firstly, a comprehensive review and a progress in cavitation characteristics of high velocity flow over a surface cylindrical protrusion; Secondly, Three-dimensional Particle Image Velocimetry has been used to study the flow field of high-velocity flows over surface irregularity—cylindrical protrusions. By measuring the flow velocity distribution over two different heights of stainless steel specimens in cavitation region with different air concentrations, the relation between entrained air rate and flow velocity was investigated. Finally, this thesis presents numerical simulation of both horizontal and vertical two-dimensional flow fields around cylindrical protrusions on overflow surface of flood release structures. Effects of cylindrical protrusions with different heights and different air concentrations on flow characteristics in cavitation region were considered. Velocity and pressure profiles in horizontal and vertical two-dimensional flows were obtained, and a comparison with the PIV measured data was made. The results showed that numerical simulation reasonably agree well with experimental data.
引文
[1]梁川,倪汉根.三角形突体初生空化与空蚀的试验研究.成都科技大学学报,1996(2):32-40.
[2]李建中,宁利中.高速水力学[M].西安:西北工业大学出版社,1994.
[3]黄继汤.空化与空蚀的原理及应用[M].北京:清华大学出版社,1991.
[4]李谋恒,黄玉灵.空化与空蚀[M].武汉:武汉水利电力学院教材,1984.
[5]尹洪昌.泄水建筑物空蚀破坏及防治.泄水工程与高速水流,1995(4):1-53.
[6]高速水流论文译丛.第一辑,第一册,北京,科学出版社,1958年.
[7]P.C.加尔彼凌登.水工建筑物的空蚀[M].水利出版社,1981.
[8]刘家峡水电厂.刘家峡水电站泄水道空蚀、磨损破坏与修补[G].第三届水工混凝土建筑物修补技术交流会论文集.丰满发电厂,1992.
[9]赵秀文译.中译本“水工建筑物的空蚀”[M].水利出版社,1981年.
[10]Warnock J E.Experiences of the Bureau of Relamation:Cavitation in hydraulic Structures[J].Transactions ASCE,1947,112:43-58.
[11]高季章,潘家铮,何摄主.高坝泄洪消能及高速水流.中国大坝50年[C].北京:中国水利水电出版社,2000,734-785.
[12]梁川.过流壁面不平整度控制标准的拟定[J].四川水力发电,1996,9,(3):102-106.
[13]刘长庚.泄水建筑物局部突体初生空化数试验研究[A].水利水电科学研究院科学研究论文集[C].北京:水利电力出版社,1983,13:36-56.[
14]董志勇,居文杰等.减免空蚀掺气浓度的试验研究.水力发电学报,2006,25(3):106-115.
[15]DONG Zhi-yong,CAI Xin-ming and DING Chun-sheng.Pressure behaviors corresponding to least air concentration to prevent cavitation erosion[C].Proc.of the 31th IAHR Congress,Seoul,Korea,2005,2815-2823.
[16]DONG Zhi-yong,LU Yang-quan and JU Wen-jie et al.Pressure characteristics of cavitation control by aeration[J].Journal of Hydrodynamics,Ser.B,2005,17(6):764-769.
[17]DONG Zhi-yong,SU Pei-lan.Cavitation control by aeration and its compressible characteristics[J].Journal of Hydrodynamics,Ser.B,2006,18(4):499-504.
[18]Dong Zhi-yong,Liu Zhi-ping,Wu Yi-hong and Zhang Dong(2008):An experimental investigation of pressure and cavitation characteristics of high velocity flow over a cylindrical protrusion in the presence and absence of aeration,Journal of Hydrodynamics,20(1):60-66.
[19]Knapp,R.T."Recent Investigations of the Mechanics of Cavitation and Cavitation Damage." Trans.ASME,77,1045-1054,1955.
[20]Self,M.,and Ripken,J.F.:"Steady-state Cavity Studies in a Free-jet Water Tunnel," St.Anthony Falls Hydr.Lab.Rep.47.July,1955.
[21]Knapp,R.T.:"Investigation of the Mechanics of Cavitation and Cavitation Damage-Final Report," Calif.Inst.of.Tech.Hydrodyn.Lab.Rep.,June,1957.
[22]Gilbare,D.,and Serrin,J.:"Free Boundaries and Jets in the Theory of Cavitation,"Jr.Math,and Physics,29,1-12,April,1950.
[23]Rouse,H.,and McNown,H.S.:"Cavitation and Pressure Distribution-Head Forms at Zero Angle of Yaw,"State University of Iowa Studies in Engineering,Bull,32,noA20,1948.
[24]Young,J.O.,and Holl,J.W.:"Effects of Cavitation on Periodic Wakes Behind Symmetric Wedges," Trans.ASME,88,Ser.D,Jr.Basic Engineering,163-176,1966.
[25]Peterka A J.The effect of entrained air on cavitation pitting[J].Proc.IAHR Minnesota Conference.1953,507-518.
[26]Russell S O,Sheehan GJ.Effect of entrained air on cavitation damage[J].Canadian Journal of Civil Engineering.
[27]时启燧.高速水气两相流[M].北京.中国水利水电出版社,2007.
[28]王希锐,徐秉衡,周林泰等.丰满溢流坝水流底层掺气减蚀原型试验报告.水利学报.1982(2).
[29]刘士和.高速水流[M].北京,科学出版社,2005,111-113.
[30]邓正湖,哈换文.溢流面掺气不平整度控制及临界空驶掺气浓度的原型研究[J].水利学报.1982.12(12).
[31]李炜,谢齐.管道中沿任意不平整体的压力分布[J].武汉水利电力学院学报.1984(4),30-41.
[32]周胜,孙晓霞,高霈生.管道中圆化突体的压力分布和初生空化数[J].水利学报1984,6(2):36-44.
[33]柯文助,任建勋,宋耀祖.低Re数圆柱绕流的场协同分析.中国工程热物理学 会2003年学术会议传热传质学,216-219.
[34]张宏伟,刘之平,张东.挑坎下游高速掺气水流的数值模拟[J].水利学报2008,39(12):1302-1307.
[35]C.Vortmann,G.H.Schnerr,S.Seelecke.Thermodynamic modeling and simulation of cavitating nozzle flow.International Journal of Heat and Fluid Flow 24(2003):774-783.
[36]杜斯特F,梅林F,怀特洛JH著.激光多普勒测速技术的原理和实践[M].沈熊,许宏庆,周作元译.北京:科学出版社,1992.
[37]Adrian R J.Particle2imaging techniques for experimental fluid me2chanics[J].Annual Review Fluid Mechanics,1991,23:261-304.
[38]Broder,Sommer feld M.A PIV /PTV system for analyzing turbulent bubbly flow[J].Experiments in Fluids,2000,(18):20-26.
[39]Deen N G.Two2phase PIV bubbly flows:status and trend[J].Experiments in Fluids,2002,(15):226.
[40]Hassan Y A,Villafuerte J O.Multiphase flow studies using particle image velocimetry[C].Germany:4 th International Symposium on Particle Image Velocimetry G ttingen,2001.17-19.
[41]孙鹤泉,康海贵,李广伟.PIV的原理与应用[J].水道港口,2002,23,(1):42-45.
[42]孙鹤泉,康海贵.DPIV流场测试技术中的数据处理[J].大连理工大学学报,2000,40(3):364-367.
[43]Grunefeld G,Finke H.Probing the velocity fields of gas and liquid phase simultaneously in a two2phase flow[J].Experiments in Fluids,2000,29(11):322-330.
[44]CHENGWen,YuichiMurai.An algorithm for estimating liquidflow from PIV measurement data of bubble motion[J].V S J,2004,23(11):107-114.
[45]lindken R,MerzkirchW.Velocity measurement of liquid and gaseous phase for a system of bubbles rising in water[J].Experiments in Fluids,2000,26:194-201.
[46]J Westerweel.Fundamentals of digital particle image velccimetry[J].Measurement Science and Technology,1997,8(12):1379-1392.
[47]朱家鲲.计算流体力学[M].北京:科学出版社,1985
[48]苑明顺.掺气槽挟气区流动数值模拟[J].水利学报.1990(8).
[49]谭立新.水气二相流数值模拟研究.四川大学博士学位论文,1999,4.
[50]李建中.二相流基本方程的封闭问题及水气二相流数学模型[J].陕西水力发电.2000,16(4):1-4.
[51]许唯临.水工水气两相流的数值模拟[J].水动力学研究与进展,2001,16(2):226-230.
[52]杨永全,魏文礼.明渠气水二相流的双流体模型[J].应用力学学报,2001,18(4):28-31.
[53]张宏伟,谭立新,陈刚等.水气二相流双流体模型研究现状[J].陕西水力发电,2001,17(4):15-18.
[54]杨纹,周力行,李荣先.气液两相湍流流动的拉式大涡模拟研究.FLUENT第一届中国用户大会文集.北京.2001,11.
[55]张晓东.泄洪洞高速水流三维数值模拟.中国水利水电科学研究院博士学位论文.2004,8.
[56]Zhiyong Dong,Yihong Wu and Dong Zhang(2008):Effect of aeration on cavitation characteristics of cylindrical protrusions with different heights,Proc.of 16~(th)IAHR-APD Congress and 3~(rd) Symp.of IAHR-ISHS,Nanjing,Vol.6,2157-2162.
[2]李建中,宁利中.高速水力学[M].西安:西北工业大学出版社,1994.
[3]黄继汤.空化与空蚀的原理及应用[M].北京:清华大学出版社,1991.
[4]李谋恒,黄玉灵.空化与空蚀[M].武汉:武汉水利电力学院教材,1984.
[5]尹洪昌.泄水建筑物空蚀破坏及防治.泄水工程与高速水流,1995(4):1-53.
[6]高速水流论文译丛.第一辑,第一册,北京,科学出版社,1958年.
[7]P.C.加尔彼凌登.水工建筑物的空蚀[M].水利出版社,1981.
[8]刘家峡水电厂.刘家峡水电站泄水道空蚀、磨损破坏与修补[G].第三届水工混凝土建筑物修补技术交流会论文集.丰满发电厂,1992.
[9]赵秀文译.中译本“水工建筑物的空蚀”[M].水利出版社,1981年.
[10]Warnock J E.Experiences of the Bureau of Relamation:Cavitation in hydraulic Structures[J].Transactions ASCE,1947,112:43-58.
[11]高季章,潘家铮,何摄主.高坝泄洪消能及高速水流.中国大坝50年[C].北京:中国水利水电出版社,2000,734-785.
[12]梁川.过流壁面不平整度控制标准的拟定[J].四川水力发电,1996,9,(3):102-106.
[13]刘长庚.泄水建筑物局部突体初生空化数试验研究[A].水利水电科学研究院科学研究论文集[C].北京:水利电力出版社,1983,13:36-56.[
14]董志勇,居文杰等.减免空蚀掺气浓度的试验研究.水力发电学报,2006,25(3):106-115.
[15]DONG Zhi-yong,CAI Xin-ming and DING Chun-sheng.Pressure behaviors corresponding to least air concentration to prevent cavitation erosion[C].Proc.of the 31th IAHR Congress,Seoul,Korea,2005,2815-2823.
[16]DONG Zhi-yong,LU Yang-quan and JU Wen-jie et al.Pressure characteristics of cavitation control by aeration[J].Journal of Hydrodynamics,Ser.B,2005,17(6):764-769.
[17]DONG Zhi-yong,SU Pei-lan.Cavitation control by aeration and its compressible characteristics[J].Journal of Hydrodynamics,Ser.B,2006,18(4):499-504.
[18]Dong Zhi-yong,Liu Zhi-ping,Wu Yi-hong and Zhang Dong(2008):An experimental investigation of pressure and cavitation characteristics of high velocity flow over a cylindrical protrusion in the presence and absence of aeration,Journal of Hydrodynamics,20(1):60-66.
[19]Knapp,R.T."Recent Investigations of the Mechanics of Cavitation and Cavitation Damage." Trans.ASME,77,1045-1054,1955.
[20]Self,M.,and Ripken,J.F.:"Steady-state Cavity Studies in a Free-jet Water Tunnel," St.Anthony Falls Hydr.Lab.Rep.47.July,1955.
[21]Knapp,R.T.:"Investigation of the Mechanics of Cavitation and Cavitation Damage-Final Report," Calif.Inst.of.Tech.Hydrodyn.Lab.Rep.,June,1957.
[22]Gilbare,D.,and Serrin,J.:"Free Boundaries and Jets in the Theory of Cavitation,"Jr.Math,and Physics,29,1-12,April,1950.
[23]Rouse,H.,and McNown,H.S.:"Cavitation and Pressure Distribution-Head Forms at Zero Angle of Yaw,"State University of Iowa Studies in Engineering,Bull,32,noA20,1948.
[24]Young,J.O.,and Holl,J.W.:"Effects of Cavitation on Periodic Wakes Behind Symmetric Wedges," Trans.ASME,88,Ser.D,Jr.Basic Engineering,163-176,1966.
[25]Peterka A J.The effect of entrained air on cavitation pitting[J].Proc.IAHR Minnesota Conference.1953,507-518.
[26]Russell S O,Sheehan GJ.Effect of entrained air on cavitation damage[J].Canadian Journal of Civil Engineering.
[27]时启燧.高速水气两相流[M].北京.中国水利水电出版社,2007.
[28]王希锐,徐秉衡,周林泰等.丰满溢流坝水流底层掺气减蚀原型试验报告.水利学报.1982(2).
[29]刘士和.高速水流[M].北京,科学出版社,2005,111-113.
[30]邓正湖,哈换文.溢流面掺气不平整度控制及临界空驶掺气浓度的原型研究[J].水利学报.1982.12(12).
[31]李炜,谢齐.管道中沿任意不平整体的压力分布[J].武汉水利电力学院学报.1984(4),30-41.
[32]周胜,孙晓霞,高霈生.管道中圆化突体的压力分布和初生空化数[J].水利学报1984,6(2):36-44.
[33]柯文助,任建勋,宋耀祖.低Re数圆柱绕流的场协同分析.中国工程热物理学 会2003年学术会议传热传质学,216-219.
[34]张宏伟,刘之平,张东.挑坎下游高速掺气水流的数值模拟[J].水利学报2008,39(12):1302-1307.
[35]C.Vortmann,G.H.Schnerr,S.Seelecke.Thermodynamic modeling and simulation of cavitating nozzle flow.International Journal of Heat and Fluid Flow 24(2003):774-783.
[36]杜斯特F,梅林F,怀特洛JH著.激光多普勒测速技术的原理和实践[M].沈熊,许宏庆,周作元译.北京:科学出版社,1992.
[37]Adrian R J.Particle2imaging techniques for experimental fluid me2chanics[J].Annual Review Fluid Mechanics,1991,23:261-304.
[38]Broder,Sommer feld M.A PIV /PTV system for analyzing turbulent bubbly flow[J].Experiments in Fluids,2000,(18):20-26.
[39]Deen N G.Two2phase PIV bubbly flows:status and trend[J].Experiments in Fluids,2002,(15):226.
[40]Hassan Y A,Villafuerte J O.Multiphase flow studies using particle image velocimetry[C].Germany:4 th International Symposium on Particle Image Velocimetry G ttingen,2001.17-19.
[41]孙鹤泉,康海贵,李广伟.PIV的原理与应用[J].水道港口,2002,23,(1):42-45.
[42]孙鹤泉,康海贵.DPIV流场测试技术中的数据处理[J].大连理工大学学报,2000,40(3):364-367.
[43]Grunefeld G,Finke H.Probing the velocity fields of gas and liquid phase simultaneously in a two2phase flow[J].Experiments in Fluids,2000,29(11):322-330.
[44]CHENGWen,YuichiMurai.An algorithm for estimating liquidflow from PIV measurement data of bubble motion[J].V S J,2004,23(11):107-114.
[45]lindken R,MerzkirchW.Velocity measurement of liquid and gaseous phase for a system of bubbles rising in water[J].Experiments in Fluids,2000,26:194-201.
[46]J Westerweel.Fundamentals of digital particle image velccimetry[J].Measurement Science and Technology,1997,8(12):1379-1392.
[47]朱家鲲.计算流体力学[M].北京:科学出版社,1985
[48]苑明顺.掺气槽挟气区流动数值模拟[J].水利学报.1990(8).
[49]谭立新.水气二相流数值模拟研究.四川大学博士学位论文,1999,4.
[50]李建中.二相流基本方程的封闭问题及水气二相流数学模型[J].陕西水力发电.2000,16(4):1-4.
[51]许唯临.水工水气两相流的数值模拟[J].水动力学研究与进展,2001,16(2):226-230.
[52]杨永全,魏文礼.明渠气水二相流的双流体模型[J].应用力学学报,2001,18(4):28-31.
[53]张宏伟,谭立新,陈刚等.水气二相流双流体模型研究现状[J].陕西水力发电,2001,17(4):15-18.
[54]杨纹,周力行,李荣先.气液两相湍流流动的拉式大涡模拟研究.FLUENT第一届中国用户大会文集.北京.2001,11.
[55]张晓东.泄洪洞高速水流三维数值模拟.中国水利水电科学研究院博士学位论文.2004,8.
[56]Zhiyong Dong,Yihong Wu and Dong Zhang(2008):Effect of aeration on cavitation characteristics of cylindrical protrusions with different heights,Proc.of 16~(th)IAHR-APD Congress and 3~(rd) Symp.of IAHR-ISHS,Nanjing,Vol.6,2157-2162.