基于移动边界模型的空冷阵列动态性能数值研究
|
摘要
研究动态自然风扰动下空冷阵列的热力学特性,对设计轴流风机的转速控制器具有重要意义。文中以6×5空冷阵列物理模型为数值模拟对象,基于移动边界模型和滑移网格方法,建立与求解时变风速和时变风向下的空冷阵列瞬态数学模型,并通过对比风机入口风速的实验数据和数值解,验证模型的有效性。数值结果表明,空冷阵列的风机入口平均温度和平均速度对环境风速的变化响应快速无时滞;在连续型环境风速变化下,迎风面第2行轴流风机入口空气流量可定性为风速的负系数比例对象;在脉冲型环境风速变化下,空冷阵列入口热风回流率可定性为环境风速的有差自平衡对象。空冷阵列在风向变化过程中,迎风面第1行风机的入口流量受自然风影响最大,并且迎风面位置随风向变化动态移动,移动带有2s左右的时间延迟;在风向反转下,风向边缘侧出现热风回流的轴流风机会发生位置对调。根据数值模拟结果,给出了5点关于轴流风机群分区与转速控制的建议。
It is of great significance to studying the thermodynamic characteristics of air-cooled arrays(ACA) under dynamic natural wind disturbance is of great significance for designing the speed controller of axial flow fans. Based on the moving boundary model and sliding grid method, a transient mathematical model to cooling-air flow through a 6×5 ACA under the nature wind with time-varying speed and direction was developed and calculated numerically, moreover,the predicted air velocity at the inlet of fans were compared with experimental results to verify the model. The numerical results show the following: 1) The inlet temperature and velocity of ACA response to wind speed without time delay;under the nature wind with continuous-varying velocity, the air flow of the second-row axial fans in the upwind stream can be classified to a negative proportional object to the wind velocity;the inlet hot wind reflux rate can be classified to a self-balance object with final bias to the pulse of wind velocity. 2) The inlet air flow of upwind row is most affected by the natural wind,and the dynamic movement has a time delay of about 2s;during the wind direction reverses, the hot reflux phenomenon is observed in the inlet of axial fans on the two side of wind direction, furthermore, these fans transpose in a delay of about 10s with the wind reversing. According to numerical results, 5 recommendations are proposed to the sub-grouping of fans cluster and controlling of fans rotation.
It is of great significance to studying the thermodynamic characteristics of air-cooled arrays(ACA) under dynamic natural wind disturbance is of great significance for designing the speed controller of axial flow fans. Based on the moving boundary model and sliding grid method, a transient mathematical model to cooling-air flow through a 6×5 ACA under the nature wind with time-varying speed and direction was developed and calculated numerically, moreover,the predicted air velocity at the inlet of fans were compared with experimental results to verify the model. The numerical results show the following: 1) The inlet temperature and velocity of ACA response to wind speed without time delay;under the nature wind with continuous-varying velocity, the air flow of the second-row axial fans in the upwind stream can be classified to a negative proportional object to the wind velocity;the inlet hot wind reflux rate can be classified to a self-balance object with final bias to the pulse of wind velocity. 2) The inlet air flow of upwind row is most affected by the natural wind,and the dynamic movement has a time delay of about 2s;during the wind direction reverses, the hot reflux phenomenon is observed in the inlet of axial fans on the two side of wind direction, furthermore, these fans transpose in a delay of about 10s with the wind reversing. According to numerical results, 5 recommendations are proposed to the sub-grouping of fans cluster and controlling of fans rotation.
引文
[1]陈海平,仲雅娟,付浩然,等.防风网对空冷岛换热性能影响的数值模拟[J].中国电机工程学报,2015,35(4):898-905.Chen Haiping,Zhong Yajuan,Fu Haoran,et al.Numerical simulation for the effects of windshield on heat transfer performance of air-cooled island[J].Proceedings of the CSEE,2015,35(4):898-905(in Chinese).
[2]邓慧,白焰,李小缤,等.直接空冷岛顺流基管管内冷凝的传热传质分析[J].中国电机工程学报,2015,35(24):6431-6438.Deng Hui,Bai Yan,Li Xiaobin,et al.Analysis for heat and mass transfer of condensation inside down-flow unit tube of air cooled heat exchanger[J].Proceedings of the CSEE,2015,35(24):6431-6438(in Chinese).
[3]冯澎湃,王宁玲,杨志平,等.直接空冷高背压供热机组的梯级供热特性与冷端变工况协同优化[J].中国电机工程学报,2016,36(20):5546-5554.Feng Pengpai,Wang Ningling,Yang Zhiping,et al.Cascade heating characteristics and off-design collaborative optimization of direct air-cooled high pressure heat supply power units[J].Proceedings of the CSEE,2016,36(20):5546-5554(in Chinese).
[4]杨志平,冯澎湃,王宁玲,等.质-量并行调节下直接空冷高背压供热机组弹性运行与优化[J].中国电机工程学报,2017,37(19):5655-5664.Yang Zhiping,Feng Pengpai,Wang Ningling,et al.Flexible operation and optimization of direct air-cooled high pressure heat supply power units in quality-volume regulation[J].Proceedings of the CSEE,2017,37(19):5655-5664(in Chinese).
[5]Ogata K.Modern control engineering[M].4th ed.Upper Saddle River,N.J.:Pretice Hall,Inc.,2002:146.
[6]金以慧.过程控制[M].北京:清华大学出版社,1993:10-22.Jin Yihui.Process Control[M].Beijing:Tsinghua University Press,1993(in Chinese).
[7]刘丽华,杜小泽,席新铭,等.直接空冷火电机组风机群分区调节运行实验[J].中国电机工程学报,2013,33(17):71-77.Liu Lihua,Du Xiaoze,Xi Xinming,et al.Experiments on divisional regulation of fan cluster for direct air-cooled power generating units[J].Proceedings of the CSEE,2013,33(17):71-77(in Chinese).
[8]Xiao Liehui,Ge Zhihua,Du Xiaoze,et al.Operation of air-cooling CHP generating unit under the effect of natural wind[J].Applied Thermal Engineering,2016,107:827-836.
[9]周兰欣,杨靖,杨祥良.600MW直接空冷机组变工况特性的研究[J].动力工程,2007,27(2):165-168,217.Zhou Lanxin,Yang Jing,Yang Xiangliang.Study on characteristics of 600MW directly air cooled units under variable operating conditions[J].Journal of Power Engineering,2007,27(2):165-168,217(in Chinese).
[10]张辉,耿学良,郭牧,等.直接空冷风机进口空气流动特性[J].中国电机工程学报,2013,33(5):46-53.Zhang Hui,Gen Xueliang,Guo Mu,et al.Inlet flow characteristics of fans in direct dry cooling systems[J].Proceedings of the CSEE,2013,33(5):46-53(in Chinese).
[11]季亮,谭洪卫,王亮.基于马尔可夫链的自然风风向建模[J].中南大学学报:自然科学版,2012,43(8):3274-3279.Ji Liang,Tan Hongwei,Wang Liang.Wind direction modeling using Markov chain[J].Journal of Central South University:Science and Technology,2012,43(8):3274-3279(in Chinese).
[12]张丽,李建平.风向变化特征在季风模拟评估中的应用[J].大气科学,2008,32(1):53-66.Zhang Li,Li Jianping.The application of the variation characteristics of wind direction in evaluating monsoon simulation[J].Chinese Journal of Atmospheric Sciences,2008,32(1):53-66(in Chinese).
[13]Deng L.Second order sufficient conditions for local optimal control problems evolved on manifolds[C]//201635th Chinese Control Conference(CCC).IEEE,2016:1362-1365.
[14]Liu Xin.Global solutions to compressible Navier-Stokes equations with spherical symmetry and free boundary[J].Nonlinear Analysis:Real World Applications,2018,42:220-254.
[15]Yang Lijun,Du Xiaoze,Yang Yongping.Measures against the adverse impact of natural wind on air-cooled condensers in power plant[J].Science China Technological Sciences,2010,53(5):1320-1327.
[16]ANSYS.ANSYS fluent theory guide[M].Canonsburg,USA:ANSYS Inc.,2013:1287-1289.
[17]杨立军,杜小泽,张辉,等.电站空冷凝汽器轴流风机阵列集群效应的数值研究[J].科学通报,2011,56(15):1232-1239.Yang Lijun,Du Xiaoze,Zhang Hui.Numerical investigation on the cluster effect of an array of axial flow fans for air-cooled condensers in a power plant[J].Chinese Science Bulletin,2011,56(15):1232-1239(in Chinese).
[18]杨立军,杜小泽,杨勇平.风场影响下直接空冷系统热风回流率的空间分布特性[J].工程热物理学报,2011,32(7):1181-1184.Yang Lijun,Du Xiaoze,Yang Yongping.Space characteristics of exhaust plume recirculation flow ratios for air-cooled condensers at ambient winds[J].Journal of Engineering Thermophysics,2011,32(7):1181-1184(in Chinese).
[2]邓慧,白焰,李小缤,等.直接空冷岛顺流基管管内冷凝的传热传质分析[J].中国电机工程学报,2015,35(24):6431-6438.Deng Hui,Bai Yan,Li Xiaobin,et al.Analysis for heat and mass transfer of condensation inside down-flow unit tube of air cooled heat exchanger[J].Proceedings of the CSEE,2015,35(24):6431-6438(in Chinese).
[3]冯澎湃,王宁玲,杨志平,等.直接空冷高背压供热机组的梯级供热特性与冷端变工况协同优化[J].中国电机工程学报,2016,36(20):5546-5554.Feng Pengpai,Wang Ningling,Yang Zhiping,et al.Cascade heating characteristics and off-design collaborative optimization of direct air-cooled high pressure heat supply power units[J].Proceedings of the CSEE,2016,36(20):5546-5554(in Chinese).
[4]杨志平,冯澎湃,王宁玲,等.质-量并行调节下直接空冷高背压供热机组弹性运行与优化[J].中国电机工程学报,2017,37(19):5655-5664.Yang Zhiping,Feng Pengpai,Wang Ningling,et al.Flexible operation and optimization of direct air-cooled high pressure heat supply power units in quality-volume regulation[J].Proceedings of the CSEE,2017,37(19):5655-5664(in Chinese).
[5]Ogata K.Modern control engineering[M].4th ed.Upper Saddle River,N.J.:Pretice Hall,Inc.,2002:146.
[6]金以慧.过程控制[M].北京:清华大学出版社,1993:10-22.Jin Yihui.Process Control[M].Beijing:Tsinghua University Press,1993(in Chinese).
[7]刘丽华,杜小泽,席新铭,等.直接空冷火电机组风机群分区调节运行实验[J].中国电机工程学报,2013,33(17):71-77.Liu Lihua,Du Xiaoze,Xi Xinming,et al.Experiments on divisional regulation of fan cluster for direct air-cooled power generating units[J].Proceedings of the CSEE,2013,33(17):71-77(in Chinese).
[8]Xiao Liehui,Ge Zhihua,Du Xiaoze,et al.Operation of air-cooling CHP generating unit under the effect of natural wind[J].Applied Thermal Engineering,2016,107:827-836.
[9]周兰欣,杨靖,杨祥良.600MW直接空冷机组变工况特性的研究[J].动力工程,2007,27(2):165-168,217.Zhou Lanxin,Yang Jing,Yang Xiangliang.Study on characteristics of 600MW directly air cooled units under variable operating conditions[J].Journal of Power Engineering,2007,27(2):165-168,217(in Chinese).
[10]张辉,耿学良,郭牧,等.直接空冷风机进口空气流动特性[J].中国电机工程学报,2013,33(5):46-53.Zhang Hui,Gen Xueliang,Guo Mu,et al.Inlet flow characteristics of fans in direct dry cooling systems[J].Proceedings of the CSEE,2013,33(5):46-53(in Chinese).
[11]季亮,谭洪卫,王亮.基于马尔可夫链的自然风风向建模[J].中南大学学报:自然科学版,2012,43(8):3274-3279.Ji Liang,Tan Hongwei,Wang Liang.Wind direction modeling using Markov chain[J].Journal of Central South University:Science and Technology,2012,43(8):3274-3279(in Chinese).
[12]张丽,李建平.风向变化特征在季风模拟评估中的应用[J].大气科学,2008,32(1):53-66.Zhang Li,Li Jianping.The application of the variation characteristics of wind direction in evaluating monsoon simulation[J].Chinese Journal of Atmospheric Sciences,2008,32(1):53-66(in Chinese).
[13]Deng L.Second order sufficient conditions for local optimal control problems evolved on manifolds[C]//201635th Chinese Control Conference(CCC).IEEE,2016:1362-1365.
[14]Liu Xin.Global solutions to compressible Navier-Stokes equations with spherical symmetry and free boundary[J].Nonlinear Analysis:Real World Applications,2018,42:220-254.
[15]Yang Lijun,Du Xiaoze,Yang Yongping.Measures against the adverse impact of natural wind on air-cooled condensers in power plant[J].Science China Technological Sciences,2010,53(5):1320-1327.
[16]ANSYS.ANSYS fluent theory guide[M].Canonsburg,USA:ANSYS Inc.,2013:1287-1289.
[17]杨立军,杜小泽,张辉,等.电站空冷凝汽器轴流风机阵列集群效应的数值研究[J].科学通报,2011,56(15):1232-1239.Yang Lijun,Du Xiaoze,Zhang Hui.Numerical investigation on the cluster effect of an array of axial flow fans for air-cooled condensers in a power plant[J].Chinese Science Bulletin,2011,56(15):1232-1239(in Chinese).
[18]杨立军,杜小泽,杨勇平.风场影响下直接空冷系统热风回流率的空间分布特性[J].工程热物理学报,2011,32(7):1181-1184.Yang Lijun,Du Xiaoze,Yang Yongping.Space characteristics of exhaust plume recirculation flow ratios for air-cooled condensers at ambient winds[J].Journal of Engineering Thermophysics,2011,32(7):1181-1184(in Chinese).