摘要
目前,国际和国内的射频功率基准,主要利用射频功率的热效应,测量吸收高频或微波功率后的温度变化,根据温度变化得出被测功率的量值。由于吸收高频或微波功率后基准装置的温度场变化,将直接关系到整个基准的工作。因此,有必要根据传热学的相关理论,研究装置及其各部分的热特性和各种干扰或其它外界条件对装置的影响。
本文在研究国家宽带功率基准的过程中,首先利用有限元分析软件对负载和基准装置进行建模,通过设置不同的边界条件和热源等条件,分析装置的热特性。然后通过理论分析,对装置进行数学建模,利用传热学中钓集总参数分析法,对环境温度变化的影响和两个方向上热流的分配进行了详细的分析填补了功率基准中热分析的空白,为基准的设计提供了理论依据。根据研究结果,对装置进行了改善,最终得到受外界条件影响较小的稳定系统。其次,针对功率基准电热转化的原理,用多物理场耦合理论,对负载和隔热段部分由电磁能转化为热能的过程进行了分析,并对温度场进行了仿真。更好的仿真了功率基准的实际工作情况。
At present, the thermal effect of the RF power is used mainly to measure the temperature change of the load after absorbing the RF power or the microwave power in the RF power standard. Then, use the temperature change to get the measured power. With the development of contemporary science, heat transfer becomes more and more useful for almost every domain. Because the temperature change of the power standard after absorbing RF power or the microwave power will affect the work of the power standard, it is necessary to use the theories of heat transfer to analyze the thermal characteristics. Then, a steady system will be formed.
At first, the computational model of power standard and load are formed by ANSYS software and different examinations are simulated using different boundary condition and heat source. Then, the mathematical model of the power standard is formed in this thesis. The influence of the environmental temperature change and the distribution of the heat flow in two directions are analyzed using the lumped parameter method. These will provide the theoretical basis to design the power standard. At last, the process of multi-field simulation is studied. And the examinations of the load and heat insulation are simulated using the method of multi-field simulation. The electromagnetic field is combined with the temperature field during these analyses and it is much closer to the actual situation and improves the simulation accuracy.
引文
[1]冯新善等.高频、微波功率的计量测试.第一版.北京:中国计量出版社,1987年.25-30.
[2]A.E.Fantom,Power and Energy:National Standards,Proc.IEEE,74,1,pp.94-101,Jan.1986.
[3]汤世贤.微波测量.北京:国防:工业出版社,1991.33-40.
[4]B.Vowinkei,Broad Band Calorimeter for Precision Measurement of Millimeter and Submillimeter Wave Power,IEEE Trans.IM-29,183-189,1980
[5]M.L.Crowford:A New RF-dc Substitution Calorimeter with Automatically Controlled Reference Power,IEEE Trans.IM-17,No.4 Dec,1968.
[6]杨世铭等.《传热学》.北京:高等教育出版社,1998.1-50.
[7]陈晓霞.ANSYS 7.0高级分析.北京:机械工业出版社,2004.78-80.
[8]张志涌等.精通MATLAB 6.5版.北京:北京航空航天大学出版社,2003.54-55.
[9]Ansys Corporation.《ANSYS热分析指南》.2000.
[10]唐兴伦.ANSYS工程应用教程热与电磁学篇.北京:中国铁道出版社,2003.196-199.
[11]张朝晖.ANSYS8.0热分析教程与实例解析.北京:中国铁道出版社,2005.241-247.
[12]Han Zhiyu,Reitz R D.A Temperature Wall Function Formulation for Variable-Density Turbulent Flows with Application to Engine Convective Heat Transfer Modeling.Heat Mass Transfer,1997.
[13]李瀚荪.电路分析基础.北京:高等教育出版社,2002.65-68.
[14]张榴晨.有限元法在电磁计算中的应用.北京:中国铁道出版社,1996.187-188.
[15]N.Hartman,R.A.Rimmer.Electromagnetic,thermal,and structural analysis of RF cavities using ANSYS.Proceedings of the 2001 Particle Accelerator Conference.Chicago:IEEE,2001.
[16]Ansys Corporation.Ansys 10.0 online help:http://www.ansys.com,2003-5-1
[17]Ansys Corporation.《ANSYS耦合场分析指南》.2002.
[18]Ansys Corporation.《ANSYS电磁场分析培训手册》.2002.
[19]Ansys Corporation.《ANSYS电磁场分析指南》.2000.
[20]马信山.电磁场基础.北京:清华大学出版社,1995.56-69.
[21]杨宪章.电磁场原理.北京:高等教育出版社,1985.256-362.
[22]周跃庆.感应淬火电磁-热耦合场的有限元分析.金属热处理.第2期,2007.
[23]Tudbury C.Electromagnetics in induction heating.IEEE Transactions on Magnetics,1974.
[24]储乐平.钢板感应加热机理及电磁-热耦合场的数值模拟.中国造船.第1期,2005.