旋风分离器内涡核摆动的特性研究
|
摘要
涡核摆动是旋风分离器流体运动的一种非稳定现象,会对流场造成扰动,导致颗粒返混进而影响分离效率.为了探究涡核摆动的规律和机理,本文对单入口蜗壳式旋风分离器内的流场进行研究,运用PDPA测量流场的基本数据,采用Reynolds应力输运模型对其流动进行数值模拟,并定义旋流不稳定性指数TⅡ来分析流动的不稳定性.结果表明,截面Z/D=0.71上瞬时切向速度波动经Fourier变换后,存在一个集中分布的频率,此频率由涡核摆动导致,而且数值模拟结果与实验测量数据吻合较好。通过对涡核中心的运动轨迹分析,发现在整个旋风分离器空间内部都存在涡核摆动现象;在同一时刻,各个截面的涡核中心偏离几何中心的情况并不相同,涡核区域也不一致;各个截面的涡核中心的连线并不在一个平面或者直线上,而是摆动的。此外,分析TⅡ曲线发现气流从不对称的入口结构进入旋风分离器内部,涡核中心开始偏离几何中心,不稳定性逐渐扩大;随着旋流运动向下,入口结构不对称对旋流的影响变小,不稳定性又逐渐减小;流动最终在Z/D=8之后趋于稳定.
Vortex core oscillation is a kind of unstable phenomenon in cyclone separator. Which can cause the backmixing of particles and affect the separation efficiency. To explore its mechanism, an experimental investigation was conducted for a volute cyclone with single inlet. The basic data of flow field would be measured by Phase Doppler Particle Analyzer(PDPA). Secondly, the numerical simulation data should be carried by Reynolds Stress model(RSM). Finally, an index(Time instability index) was defined to analyze the instability of flow. The results showed that tangential velocity of Z/D = 0.71 could obtain an obvious fundamental frequency by Fourier transform technique, which was caused by vortex core oscillation. The calculation results of frequency of Z/D = 0.71 were in good agreement with the experimental measurement data. Through the analysis of vortex core center, the vortex core oscillation phenomenon was found to exist in the whole space within cyclone separator.At the same time, cases of the vortex core center deviating from the geometric center in different section were not the same. The curve of vortex core centers in each section was not in a plane or a straight line, but swing. Furthermore, the flow fluctuation was large in the upper region of cyclone because of the non-axisymmetry of entrance while the flow tended to stable afterZ/D = 8.
Vortex core oscillation is a kind of unstable phenomenon in cyclone separator. Which can cause the backmixing of particles and affect the separation efficiency. To explore its mechanism, an experimental investigation was conducted for a volute cyclone with single inlet. The basic data of flow field would be measured by Phase Doppler Particle Analyzer(PDPA). Secondly, the numerical simulation data should be carried by Reynolds Stress model(RSM). Finally, an index(Time instability index) was defined to analyze the instability of flow. The results showed that tangential velocity of Z/D = 0.71 could obtain an obvious fundamental frequency by Fourier transform technique, which was caused by vortex core oscillation. The calculation results of frequency of Z/D = 0.71 were in good agreement with the experimental measurement data. Through the analysis of vortex core center, the vortex core oscillation phenomenon was found to exist in the whole space within cyclone separator.At the same time, cases of the vortex core center deviating from the geometric center in different section were not the same. The curve of vortex core centers in each section was not in a plane or a straight line, but swing. Furthermore, the flow fluctuation was large in the upper region of cyclone because of the non-axisymmetry of entrance while the flow tended to stable afterZ/D = 8.
引文
[1]Elsayed K.Design of a Novel Gas Cyclone Vortex Finder Using the Adjoint Method[J].Separation and Purification Technology,2015,142(2):274-286
[2]吴小林,熊至宜,姬忠礼,等.旋风分离器旋进涡核的数值模拟[J].化工学报,2007,58(2):383-390WU X L,XIONG Z Y,JI Z L,et al.Numerical Simulation of Precessing Vortex Core in Cyclone Separator[J].Journal of Chemical Industry and Engineering(China),2007,58(2):383-390
[3]Haig C W,Hursthouse A.An Empirical Investigation Into Influence of Pressure Drop on Particle Behavior in Small Scale Reverse-Flow Cyclones[J].Powder Technol?ogy,2015,275:172-181
[4]Ter Linden A J.Investigations Into Cyclone Dust Collectors[J].Proceedings of the Institution of Mechanial Engineers,1949,160(1):233-251
[5]Boysan F,Ayers W H,Swithenbank J,et al.A Fundamental Mathematical Modeling Approach to Cyclone Design[J].Transactions of the Institution of Chemical Engineers,1982,60:222-230
[6]Boysan F,Ewan BCR,Swithenbank J,et al.Experimental and Theoretical Studies of Cyclone Separator Aerodynamics[M].Powtech 83 Particle Technology,1983:305-306
[7]Hoekstra A J,Israel A T,Derksen J J,et al.The Application of Laser Diagnostics to Cyclonic Flow With Vortex Precession[C]//Proceedings of the 9th International Symposium on Applications of Laser Techniques to Fluid Mechanics,Lisbon,1998:431-435
[8]Derksen J J,vanden Akker H E A.Simulation of Vortex Core Precession in a Reverse-Flow Cyclone[J].AIChE Journal,2000,46(7):1317-1331
[9]Yazdabadi P A,Griffiths A J.Alternate Eddy Shedding Set up by the Non-Axisymmetric Recirculation Zone at the Exhaust of a Cyclone Dust Separator[J].Trans I Chem E,1996,74A:363-368
[10]Stefen Obermair,Jakob Woisetschlager,Gemot Staudinger.Investigation of the Flow Pattern in Different Dust Outlet Geometries of a Gas Cyclone byLaser Doppler Anemometry[J].Powder Technology,2003,138(2/3):239-251
[11]魏耀东,燕辉,时铭显.蜗壳式旋风分离器环形空间流场的研究[J].石油炼制与化工,2000,31(11):46-50WEI Y D,YAN H,SHI M X.Study on Flow in the Annular Space of a Cyclone Separator with a Volute Inlet[J].Petroleum Processing and Petrochemical,2000,31(11):46-50
[12]姬忠礼,时铭显_旋风分离器内流场的测试技术[J].中国石油大学学报(自然科学版),1991,15(6):52-58JI Z L,SHI M X.Flow Fiuld Measurement in Cyclone Separator[J].Journal of the University of Petrolem(China),1991,15(6):52-58
[13]王江云,毛羽,王娟,等.FCC沉降器内粗旋与顶旋分离器连接结构的优化[J].石油学报(石油加工),2008,24(3):251-255WANG J Y,MAO Y,WANG J,et al.Optimization of Linkage Structure Between Primary and Secondary Separator in FCC Disengagers[J].Acta Petrolei Sinica(Petroleum Processing Section),2008,24(3):251-255
[14]王娟,毛羽,钟安海,等.FCC沉降器全部空间三维流场的数值模拟[J].石油学报(石油加工),2007,23(5):15-21WANG J,MAO Y,ZHONG A H,et al.Numerical Simulation of 3D Turbulent Flow in a FCC Disengage[J].Acta Petrolei Sinica(Petroleum Processing Section),2007,23(5):15-21
[15]吴小林,姬忠礼.PV型旋风分离器的内流场的试验研究[J].石油学报(石油加工),1997,13(3):93-99WXU X L,JI Z L.Experimental Study on Flow Field of PV Type Cyclone Separator[J].Acta Petrolei Sinica(Petroleum Processing Section),1997,13(3):93-99
[16]严超宇,吴小林,时铭显.旋风分离器非稳态流场的简化分析[J].流体机械,2002,30(3):18-21YAN C Y,WU X L,SHI M X.Simplified Analysis of the Unsteady Flow Field in a Cyclone Separator[J].Flow Machinery,2002,30(3):18-21
[17]王江云,毛羽,孟文,等.旋风分离器内非轴对称旋转流场的测量[J].石油学报(石油加工),2015,31(4):920-928WANG J Y,MAO Y,MENG W,et al.Experimental Measurement of Non-Axisymmetric Rotating Flow Field in Cyclone Separator[J].Acta Petrolei Sinica(Petroleum Processing Section),2015,31(4):920-928
[18]毛羽,庞磊,王小伟,等.旋风分离器内三维紊流场的数值模拟[J].石油炼制与化工,2002,33(2):1-6MAO Y,PANG L,WANG X W,et al.Numerical Modeling of Three-Dimension Turbulent Field in Cyclone Separator[J].Petroleum Processing and Petrochemical,2002,33(2):1-6
[19]刘淑艳,张雅,王保国.用RSM模拟旋风分离器内的三维湍流流场[J].北京理工大学学报,2005,25(5):377-380LIU S Y,ZHANG Y,WANG B G.Cyclone Separator Three-Dimensional Turbulent Flow-Field Simulation Using the Reynolds Stress Model[J].Transactions of Beijing Institute of Technology,2005,25(5):377-380
[20]周力行.湍流气粒两相流动和燃烧的理论与数值模拟[M].北京:科学出版社,1994:153-157ZHOU L X.Theoretical and Numerical Simulation of Turbulent Gas-Particle Two Phase Flow and Combustion[J].Beijing:Science Press,1994:153-157
[2]吴小林,熊至宜,姬忠礼,等.旋风分离器旋进涡核的数值模拟[J].化工学报,2007,58(2):383-390WU X L,XIONG Z Y,JI Z L,et al.Numerical Simulation of Precessing Vortex Core in Cyclone Separator[J].Journal of Chemical Industry and Engineering(China),2007,58(2):383-390
[3]Haig C W,Hursthouse A.An Empirical Investigation Into Influence of Pressure Drop on Particle Behavior in Small Scale Reverse-Flow Cyclones[J].Powder Technol?ogy,2015,275:172-181
[4]Ter Linden A J.Investigations Into Cyclone Dust Collectors[J].Proceedings of the Institution of Mechanial Engineers,1949,160(1):233-251
[5]Boysan F,Ayers W H,Swithenbank J,et al.A Fundamental Mathematical Modeling Approach to Cyclone Design[J].Transactions of the Institution of Chemical Engineers,1982,60:222-230
[6]Boysan F,Ewan BCR,Swithenbank J,et al.Experimental and Theoretical Studies of Cyclone Separator Aerodynamics[M].Powtech 83 Particle Technology,1983:305-306
[7]Hoekstra A J,Israel A T,Derksen J J,et al.The Application of Laser Diagnostics to Cyclonic Flow With Vortex Precession[C]//Proceedings of the 9th International Symposium on Applications of Laser Techniques to Fluid Mechanics,Lisbon,1998:431-435
[8]Derksen J J,vanden Akker H E A.Simulation of Vortex Core Precession in a Reverse-Flow Cyclone[J].AIChE Journal,2000,46(7):1317-1331
[9]Yazdabadi P A,Griffiths A J.Alternate Eddy Shedding Set up by the Non-Axisymmetric Recirculation Zone at the Exhaust of a Cyclone Dust Separator[J].Trans I Chem E,1996,74A:363-368
[10]Stefen Obermair,Jakob Woisetschlager,Gemot Staudinger.Investigation of the Flow Pattern in Different Dust Outlet Geometries of a Gas Cyclone byLaser Doppler Anemometry[J].Powder Technology,2003,138(2/3):239-251
[11]魏耀东,燕辉,时铭显.蜗壳式旋风分离器环形空间流场的研究[J].石油炼制与化工,2000,31(11):46-50WEI Y D,YAN H,SHI M X.Study on Flow in the Annular Space of a Cyclone Separator with a Volute Inlet[J].Petroleum Processing and Petrochemical,2000,31(11):46-50
[12]姬忠礼,时铭显_旋风分离器内流场的测试技术[J].中国石油大学学报(自然科学版),1991,15(6):52-58JI Z L,SHI M X.Flow Fiuld Measurement in Cyclone Separator[J].Journal of the University of Petrolem(China),1991,15(6):52-58
[13]王江云,毛羽,王娟,等.FCC沉降器内粗旋与顶旋分离器连接结构的优化[J].石油学报(石油加工),2008,24(3):251-255WANG J Y,MAO Y,WANG J,et al.Optimization of Linkage Structure Between Primary and Secondary Separator in FCC Disengagers[J].Acta Petrolei Sinica(Petroleum Processing Section),2008,24(3):251-255
[14]王娟,毛羽,钟安海,等.FCC沉降器全部空间三维流场的数值模拟[J].石油学报(石油加工),2007,23(5):15-21WANG J,MAO Y,ZHONG A H,et al.Numerical Simulation of 3D Turbulent Flow in a FCC Disengage[J].Acta Petrolei Sinica(Petroleum Processing Section),2007,23(5):15-21
[15]吴小林,姬忠礼.PV型旋风分离器的内流场的试验研究[J].石油学报(石油加工),1997,13(3):93-99WXU X L,JI Z L.Experimental Study on Flow Field of PV Type Cyclone Separator[J].Acta Petrolei Sinica(Petroleum Processing Section),1997,13(3):93-99
[16]严超宇,吴小林,时铭显.旋风分离器非稳态流场的简化分析[J].流体机械,2002,30(3):18-21YAN C Y,WU X L,SHI M X.Simplified Analysis of the Unsteady Flow Field in a Cyclone Separator[J].Flow Machinery,2002,30(3):18-21
[17]王江云,毛羽,孟文,等.旋风分离器内非轴对称旋转流场的测量[J].石油学报(石油加工),2015,31(4):920-928WANG J Y,MAO Y,MENG W,et al.Experimental Measurement of Non-Axisymmetric Rotating Flow Field in Cyclone Separator[J].Acta Petrolei Sinica(Petroleum Processing Section),2015,31(4):920-928
[18]毛羽,庞磊,王小伟,等.旋风分离器内三维紊流场的数值模拟[J].石油炼制与化工,2002,33(2):1-6MAO Y,PANG L,WANG X W,et al.Numerical Modeling of Three-Dimension Turbulent Field in Cyclone Separator[J].Petroleum Processing and Petrochemical,2002,33(2):1-6
[19]刘淑艳,张雅,王保国.用RSM模拟旋风分离器内的三维湍流流场[J].北京理工大学学报,2005,25(5):377-380LIU S Y,ZHANG Y,WANG B G.Cyclone Separator Three-Dimensional Turbulent Flow-Field Simulation Using the Reynolds Stress Model[J].Transactions of Beijing Institute of Technology,2005,25(5):377-380
[20]周力行.湍流气粒两相流动和燃烧的理论与数值模拟[M].北京:科学出版社,1994:153-157ZHOU L X.Theoretical and Numerical Simulation of Turbulent Gas-Particle Two Phase Flow and Combustion[J].Beijing:Science Press,1994:153-157