割草机流道内流场数值模拟及实验研究
|
摘要
本文对割草机的国内外研究进展进行了大量调研,介绍了PIV技术和叶轮机械内部流场研究的国内外进展;对各种单相气体流动的数学模型进行对比,建立了适合割草机流道气体流动的数值模型;介绍了网格生成技术和不同网格的特点,运用GAMBIT建立流道模型并对其进行非结构网格划分;选用标准κ—ε模型作为流动的数值模型,并作相关假设,采用SIMPLE算法进行方程的求解计算,得到流道内流场的速度、静压强以及湍动能分布规律,分析了刀绳长度、电机转速对流场特性的影响机理;设计并搭建了实验台,完成PIV流场测试实验,并将实验结果与数值计算结果进行了比较分析。
数值模拟的结果表明割草机流道内部流动相对于基准面呈基本对称的分布。刀绳长度、电机转速的变化共同影响内部流场。刀绳越长,电机转速越大,割草机切割杂草的能力越强;在速度一定时,应尽量选用长刀绳,这样可获得流场内部尽量大的压差,加强机具抛撒碎草的能力;电机转速一定时长刀绳所引起的速度脉动更强,由速度的脉动产生空气动力噪声更大。
试验的结果表明流场的速度分布相对基面呈近似对称分布。实验结果和数值计算比较吻合。数值计算和实验结果比较吻合。由于边缝中的流体除了做回转运动外还可被吸向中心区域的低压区,因而短刀绳时的流道内部流场比长刀绳时更紊乱。
In this dissertation, giving a brief research progress of the grass trimmer and a survey of PIV and turbo machine internal flow field technology at home and abroad; comparing all kinds of simulation models of single-phase air flow, establishing the model fitted to grass trimmer's flow channel; introducing the grid generation and their features, establishing the flow passage's model and generating unstructured grid by GAMBIT; choosing the k-s model to enclose the rotating flow field, and adopting some hypothesis to the model, using the SIMPLE method to simulate the flow field, giving some results such as velocity, pressure and kinetic energy distribution, analyzing the length of blade and rotating speed velocity of motor how to effect the flow field's distribution; designing and making a fixable experiment table, completing PIV flow field testing experiment.
The result of simulation indicates that the internal flowing in flow field is a symmetric distribution comparing to the basic surface. The length of blade and velocity of motor effect the flow field and grass trimmer's cutting ability, noise control and the ability of dripping grass. A longer blade and higher motor rotating speed can get a better cutting ability. a longer blade when the rotating speed is fixed can get a bigger pressure drop which can make grass dripping out of the flow field in time. longer blade when the rotating speed is fixed can make a bigger velocity pulse which will make the noise more higher.
The experiment indicates that the velocity in flow field is a symmetric distribution comparing to the basic surface. The results anastromose between experiment and numerical simulation. The length of blade effects the flow field's features. The main reason is that the fluid in the gap may be absorbed to the low pressure area inside in addition to rotating movement, which makes the flow field disorderly.
数值模拟的结果表明割草机流道内部流动相对于基准面呈基本对称的分布。刀绳长度、电机转速的变化共同影响内部流场。刀绳越长,电机转速越大,割草机切割杂草的能力越强;在速度一定时,应尽量选用长刀绳,这样可获得流场内部尽量大的压差,加强机具抛撒碎草的能力;电机转速一定时长刀绳所引起的速度脉动更强,由速度的脉动产生空气动力噪声更大。
试验的结果表明流场的速度分布相对基面呈近似对称分布。实验结果和数值计算比较吻合。数值计算和实验结果比较吻合。由于边缝中的流体除了做回转运动外还可被吸向中心区域的低压区,因而短刀绳时的流道内部流场比长刀绳时更紊乱。
In this dissertation, giving a brief research progress of the grass trimmer and a survey of PIV and turbo machine internal flow field technology at home and abroad; comparing all kinds of simulation models of single-phase air flow, establishing the model fitted to grass trimmer's flow channel; introducing the grid generation and their features, establishing the flow passage's model and generating unstructured grid by GAMBIT; choosing the k-s model to enclose the rotating flow field, and adopting some hypothesis to the model, using the SIMPLE method to simulate the flow field, giving some results such as velocity, pressure and kinetic energy distribution, analyzing the length of blade and rotating speed velocity of motor how to effect the flow field's distribution; designing and making a fixable experiment table, completing PIV flow field testing experiment.
The result of simulation indicates that the internal flowing in flow field is a symmetric distribution comparing to the basic surface. The length of blade and velocity of motor effect the flow field and grass trimmer's cutting ability, noise control and the ability of dripping grass. A longer blade and higher motor rotating speed can get a better cutting ability. a longer blade when the rotating speed is fixed can get a bigger pressure drop which can make grass dripping out of the flow field in time. longer blade when the rotating speed is fixed can make a bigger velocity pulse which will make the noise more higher.
The experiment indicates that the velocity in flow field is a symmetric distribution comparing to the basic surface. The results anastromose between experiment and numerical simulation. The length of blade effects the flow field's features. The main reason is that the fluid in the gap may be absorbed to the low pressure area inside in addition to rotating movement, which makes the flow field disorderly.
引文
[1]中华人民共和国国家质量监督检验检疫总局、中国国家标准化管理委员会.林业机械,便携式割灌机和割草机安全要求(GB 19725-2005/ISO 11806:1997)[S].北京:中国标准出版社,2005.
[2]李凯捷,朴奇焕.草坪割草机的检测分析和技术参数的设计与选择[J].林业机械与木工设备,2002,30(4):24-33.
[3]赵大伟,石淑英.浅析旋刀式草坪割草机产品质量状况[J].林业劳动安全,2001,14(2):27-28.
[4]孙鹤泉.二维流场测量技术PIV[J].研究与开发,2002,6:43-45.
[5]刘栋.离心泵内部液固两相流场的数值模拟和实验研究[D].江苏大学硕士论文,2006.
[6]王晓文.贯流风机流场的实验和数值研究[J].实验力学,2002,17(1):35-41.
[7](日)村田暹.贯流风机的实验研究[J].暖通空调,1997,27(2):32-34.
[8]王林翔,陈鹰,章明川.阀腔内速度场的PIV测量[J].机床与液压,2002,5:32-33.
[9]徐舒,王煜.PIV测试技术在反应器流场研究中的应用[J].山西化工,2004,24(3):18-21.
[10]胡如夫.离心式通风机设计与改造中的降噪方法[J].流体机械,2000,28(10):32-34.
[11]Whale J,Anderson C.G.,Bareiss R,etal.An experimental and numerical study of the vortex structure in the wake of a wind turbine[J].In:Journal of Wind Engineering and Industrial Aerodynamics[C].2000,84(1),1-21.
[12]Willert C,Raffel Markus,Kompenhans Jurgen,etal.Recent applications of particle image velocimetry in aerodynamic research[J].Flow Measurement and Instrumentation.1996,7(4),247-256.
[13]Vogel Alfred,Lauterborn Werner.Time resolved particle image velocimetry[J].In:Optics and Lasers in Engineering[C].1998,9(3-4),277-294.
[14]Grant I,Smith G.Modern developments in particle image velocimetry[J].In:Optics and Lasers in Engineering[C].1998,9(3-4),245-264
[15]闻苏平,宫武旗,王学军.旋转离心叶轮内部非定常流动的PIV测量[J].流体机械,2004,32(4):1-4.
[16]刘振全.涡旋压缩机涡旋齿线休整的图解法和修正角的研究[J].甘肃工业大学报,1999,10:22-25.
[17]竺晓程.PDA和PIV在旋转叶轮测量中的周向定位[J].流体机械,2003,31(4):1-3,17.
[18]杨延相.内燃机缸内流场PIV测试技术中获取数据的方法[J].天津大学学报,2000,33(3):275-279.
[19]陈景仁.流体力学及传热学[M].北京:国防工业出版社,1984.
[20]章本照.流体力学中的有限元法[M].北京:机械工业出版社,1986.
[21]刘超群.多重网格法及其在计算流体力学中的应用[M].北京:清华大学出版社,1995.
[22]Wtabakoff.Turbomachinery perform Deterioration Exposed toparticulates Environment[J].In:Fluid Eng.1984,51(106):227-250.
[23]洪若瑜.内循环和外循环硫化床中超细粉流态化的研究[D].中科院化工冶金研究所博士论文,1996.
[24]戴江.离心泵叶轮中固液两相流计算[J].工程热物理学报,1996,(2).
[25]C J Chen,S Y Jaw.Fundamentals of Turbulence Modeling[J].Taylor&Francis,Washington,1998.
[26]陶文铨.数值传热学(第二版)[M].西安:西安交通大学出版社,2001.
[27]B E Launder,D B Spalding.Lectures in Mathematical Models of Turbulence[J].Academic Press,London,1972.
[28]郭鸿志.传输过程数值模拟[M].北京:冶金工业出版社,1998.
[29]V.Yakhot,S.A.Orzag.Renormalization group analysis of turbulence:basic theory[J].Scient Computer.1986,(1)3-11.
[30]T.H.Shih,W.W.Liou,A.Shabbir,etal.A new k- ε eddy viscosity model for high Reynolds number turbulent flows[J].Computer Fluids.1995,24(3):227-238.
[31]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.
[32]周力行.湍流两相流动与燃烧的数值模拟[M].北京:清华大学出版社,1991.
[33]周力行.多相湍流反应流体力学[M].北京:国防工业出版社,2002.
[34]Crowe C.Heat transfer an fluid mesh[J].Inst Stanf Univ,1976.
[35]韩占忠,王敬,兰小平.FLUENT流体工程仿真计算实例与应用IM].北京理工大学出版社,2004.
[36]朱自强.应用计算流体力学[M].北京:北京航空航天大学出版社,1999.
[37]谢明亮.离心风机叶轮内两相流数值模拟与粘灰机理分析[D].武汉科技大学硕士论文,2004.
[38]唐辉.离心泵内流场的数值模拟[J].水泵技术,2003,3:3-8,14.
[39]Markus Rattel,Christian E Willert,Jugen Kompenhans.Particle Image Velocimetry:A Practical Guide[M].Germany:Springer-Verlag Berlin Heidelberg,1998.
[40]许宏庆,袁格.应用PIV技术测量二维瞬时流场[J].空气动力学学报,1993,11(4):409-414.
[41]杨祖清.流动显示技术[M].北京:国防工业出版社.2002.
[2]李凯捷,朴奇焕.草坪割草机的检测分析和技术参数的设计与选择[J].林业机械与木工设备,2002,30(4):24-33.
[3]赵大伟,石淑英.浅析旋刀式草坪割草机产品质量状况[J].林业劳动安全,2001,14(2):27-28.
[4]孙鹤泉.二维流场测量技术PIV[J].研究与开发,2002,6:43-45.
[5]刘栋.离心泵内部液固两相流场的数值模拟和实验研究[D].江苏大学硕士论文,2006.
[6]王晓文.贯流风机流场的实验和数值研究[J].实验力学,2002,17(1):35-41.
[7](日)村田暹.贯流风机的实验研究[J].暖通空调,1997,27(2):32-34.
[8]王林翔,陈鹰,章明川.阀腔内速度场的PIV测量[J].机床与液压,2002,5:32-33.
[9]徐舒,王煜.PIV测试技术在反应器流场研究中的应用[J].山西化工,2004,24(3):18-21.
[10]胡如夫.离心式通风机设计与改造中的降噪方法[J].流体机械,2000,28(10):32-34.
[11]Whale J,Anderson C.G.,Bareiss R,etal.An experimental and numerical study of the vortex structure in the wake of a wind turbine[J].In:Journal of Wind Engineering and Industrial Aerodynamics[C].2000,84(1),1-21.
[12]Willert C,Raffel Markus,Kompenhans Jurgen,etal.Recent applications of particle image velocimetry in aerodynamic research[J].Flow Measurement and Instrumentation.1996,7(4),247-256.
[13]Vogel Alfred,Lauterborn Werner.Time resolved particle image velocimetry[J].In:Optics and Lasers in Engineering[C].1998,9(3-4),277-294.
[14]Grant I,Smith G.Modern developments in particle image velocimetry[J].In:Optics and Lasers in Engineering[C].1998,9(3-4),245-264
[15]闻苏平,宫武旗,王学军.旋转离心叶轮内部非定常流动的PIV测量[J].流体机械,2004,32(4):1-4.
[16]刘振全.涡旋压缩机涡旋齿线休整的图解法和修正角的研究[J].甘肃工业大学报,1999,10:22-25.
[17]竺晓程.PDA和PIV在旋转叶轮测量中的周向定位[J].流体机械,2003,31(4):1-3,17.
[18]杨延相.内燃机缸内流场PIV测试技术中获取数据的方法[J].天津大学学报,2000,33(3):275-279.
[19]陈景仁.流体力学及传热学[M].北京:国防工业出版社,1984.
[20]章本照.流体力学中的有限元法[M].北京:机械工业出版社,1986.
[21]刘超群.多重网格法及其在计算流体力学中的应用[M].北京:清华大学出版社,1995.
[22]Wtabakoff.Turbomachinery perform Deterioration Exposed toparticulates Environment[J].In:Fluid Eng.1984,51(106):227-250.
[23]洪若瑜.内循环和外循环硫化床中超细粉流态化的研究[D].中科院化工冶金研究所博士论文,1996.
[24]戴江.离心泵叶轮中固液两相流计算[J].工程热物理学报,1996,(2).
[25]C J Chen,S Y Jaw.Fundamentals of Turbulence Modeling[J].Taylor&Francis,Washington,1998.
[26]陶文铨.数值传热学(第二版)[M].西安:西安交通大学出版社,2001.
[27]B E Launder,D B Spalding.Lectures in Mathematical Models of Turbulence[J].Academic Press,London,1972.
[28]郭鸿志.传输过程数值模拟[M].北京:冶金工业出版社,1998.
[29]V.Yakhot,S.A.Orzag.Renormalization group analysis of turbulence:basic theory[J].Scient Computer.1986,(1)3-11.
[30]T.H.Shih,W.W.Liou,A.Shabbir,etal.A new k- ε eddy viscosity model for high Reynolds number turbulent flows[J].Computer Fluids.1995,24(3):227-238.
[31]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.
[32]周力行.湍流两相流动与燃烧的数值模拟[M].北京:清华大学出版社,1991.
[33]周力行.多相湍流反应流体力学[M].北京:国防工业出版社,2002.
[34]Crowe C.Heat transfer an fluid mesh[J].Inst Stanf Univ,1976.
[35]韩占忠,王敬,兰小平.FLUENT流体工程仿真计算实例与应用IM].北京理工大学出版社,2004.
[36]朱自强.应用计算流体力学[M].北京:北京航空航天大学出版社,1999.
[37]谢明亮.离心风机叶轮内两相流数值模拟与粘灰机理分析[D].武汉科技大学硕士论文,2004.
[38]唐辉.离心泵内流场的数值模拟[J].水泵技术,2003,3:3-8,14.
[39]Markus Rattel,Christian E Willert,Jugen Kompenhans.Particle Image Velocimetry:A Practical Guide[M].Germany:Springer-Verlag Berlin Heidelberg,1998.
[40]许宏庆,袁格.应用PIV技术测量二维瞬时流场[J].空气动力学学报,1993,11(4):409-414.
[41]杨祖清.流动显示技术[M].北京:国防工业出版社.2002.