下击暴流作用下坡地风场特性研究
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摘要
下击暴流多发生于山地丘陵地区,而目前对于下击暴流的研究多集中在平地地形的稳态风场。为研究坡地地形对下击暴流风场特性的影响,采用冲击射流物理试验与大涡模拟(LES)方法对平地以及三个不同坡度的坡地风场进行了试验测试与数值模拟。结果表明:大涡模拟捕捉到了风场的瞬态变化特征,环涡结构在首次越过山坡时,在坡顶檐口位置产生下击暴流风场整个生命周期中的最大风速;坡地地形除檐口位置具有显著加速效应外,其他位置未发现风速增大效应;与平地风场相比,檐口位置水平风速与竖向风速都有所增大,且近地面水平风速加速因子M_t达到约1.3。近地面湍流度增大较为明显的区域为起坡位置及坡后位置,坡中及檐口位置加速效应较小,檐口位置湍流度加速因子随坡度的增大而略有增加。
Downburst often occurs in the mountainous and hilly areas. At present, the research of downburst mainly concentrates on the steady wind field in flat terrain. To investigate the effects of slope terrain on downburst wind field, an impinging jet physical experiment and the large eddy simulation(LES) were used to test and simulate the wind field in flat and three different gradient slopes. The results indicate that the large eddy simulation capture the transient characteristics of wind field, and the maximum wind speed of the wind field during the whole life cycle of downburst appears when the vortex structure first arriving the crest of the slope. Except the crest of the slope has significant speed-up effect, other positions were not found this effect. Compared with the wind field on flat terrain, both horizontal and vertical wind speed have increased, and the wind speed-up factor, M_t, near the ground reached about 1.3. The position where turbulence intensity increases obviously including the foot of the slope and the area behind the crest, and other positions do not have the obvious increasing effect. With the increasing of the gradients, the amplification factor of turbulence intensity at the crest increases slightly.
Downburst often occurs in the mountainous and hilly areas. At present, the research of downburst mainly concentrates on the steady wind field in flat terrain. To investigate the effects of slope terrain on downburst wind field, an impinging jet physical experiment and the large eddy simulation(LES) were used to test and simulate the wind field in flat and three different gradient slopes. The results indicate that the large eddy simulation capture the transient characteristics of wind field, and the maximum wind speed of the wind field during the whole life cycle of downburst appears when the vortex structure first arriving the crest of the slope. Except the crest of the slope has significant speed-up effect, other positions were not found this effect. Compared with the wind field on flat terrain, both horizontal and vertical wind speed have increased, and the wind speed-up factor, M_t, near the ground reached about 1.3. The position where turbulence intensity increases obviously including the foot of the slope and the area behind the crest, and other positions do not have the obvious increasing effect. With the increasing of the gradients, the amplification factor of turbulence intensity at the crest increases slightly.
引文
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[18]MASON M S,WOOD G S,FLETCHER D F.Impinging jet simulation of stationary downburst flow over topography[J].Wind and Structures,2007,10(5):437-462.
[19]MASON M S,WOOD G S,FLETCHER D F.Numerical simulation of downburst winds[J].Journal of Wind Engineering and Industrial Aerodynamics,2009,97(11/12):523-539.
[20]MASON M S.Numerical investigation of the influence of topography on simulated downburst wind fields[J].Journal of Wind Engineering and Industrial Aerodynamics,2010,98(1):21-33.
[21]MASON M S,FLETCHER D F,WOOD G S.Numerical simulation of idealized three-dimensional downburst wind fields[J].Engineering Structures,2010,32:3558-3570.
[22]汪之松,左其刚,唐伟峰,等.稳态冲击射流作用下平地及坡地高层建筑的风荷载特性[J].建筑结构学报,2017,38(3):103-110.WANG Zhisong,ZUO Qigang,TANG Weifeng,et al.Wind load characteristics for high-rise building on flat terrain and slope under steady-state impinging jet[J].Journal of Building Structures,2017,38(3):103-110.
[23]ABD-ELAAL E S,MILLS J E,MA X.Empirical models for predicting unsteady-state downburst wind speeds[J].Journal of Wind Engineering and Industrial Aerodynamics,2014,129(6):49-63.
[2]JACKSON P S,HUNT J C R.Turbulent wind flow over a low hill[J].Quarterly Journal of the Royal Meteorological Society,1975,101:929-955.
[3]JACKSON P S.The influence of local terrain features on the site selection for wind energy generating systems BLWT-1-1979[R].Boundary Layer Wind Tunnel Laboratory Internal Report.Ontario:University of Western Ontario,1979.
[4]HUNTJCR,LEIBOVICHS,RICHARDS K J.Turbulent shear flow over low hill[J].Quarterly Journal of the Royal Meteorological Society,1988,114:1435-1470.
[5]MASON P,SYKES R.Flow over an isolated hill of moderateslope[J].Quarterly Journal of the Royal Meteorological Society,1979,105:383-395.
[6]魏奇科,李正良,孙毅.山地风加速效应的计算模型[J].华南理工大学学报(自然科学版),2010(11):54-58.WEI Qike,LI Zhengliang,SUN Yi.Calculation model of speed-up effect of wind velocity in hilly terrain[J].Journal of South China University of Technology(Natural Science),2010(11):54-58.
[7]孙毅,李正良,黄汉杰,等.山地风场平均及脉动风速特性试验研究[J].空气动力学学报,2011,29(5):593-599.SUN Yi,LI Zhengliang,HUANG Hanjie,et al.Experiment research on mean and fluctuating wind velocity in hilly terrain wind field[J].Acta Aerodynamica Sinica,2011,29(5):593-599.
[8]李正良,魏奇科,孙毅.复杂山地风场幅值特性试验研究[J].工程力学,2012(3):184-191.LI Zhengliang,WEI Qike,SUN Yi.Experimental research on amplitude characteristics of complex hilly terrain wind field[J].Engineering Mechanics,2012(3):184-191.
[9]李正良,徐姝亚,肖正直,等.山地风速地形修正系数沿山坡的详细插值分布[J].湖南大学学报(自然科学版),2016(3):23-31.LI Zhengliang,XU Shuya,XIAO Zhengzhi,et al.Detailed interpolation distribution of hilly wind topographic factor along hillside[J].Journal of Hunan University(Natural Sciences),2016(3):23-31.
[10]中华人民共和国建设部.建筑结构荷载规范:GB50009-2012[S].北京:中国建筑工业出版社,2012.
[11]OSEGUERA R M,BOWLES R L.A simple analytic 3-dimensional downburst model based on boundary layer stagnation inflow:100632[R].Washington D.C.:NASATechnical Memorandum,1988.
[12]VICROY D D.A simple,analytical,asymmetric microburst model for downdraft estimation:104053[R].Washington D.C.:NASA Technical Memorandum,1991.
[13]WOOD G S,KWOK K C S.An empicically derived estimate for the mean velocity profile of a thunderstorm downbursts[C]//Proceedings of 7th AWES Workshop.Auckland:AWES,1988.
[14]HOLMES J D,OLIVER S E.An emprical model of a downburst[J].Engineering Structures,2000,22:1167-1172.
[15]邹鑫,汪之松,李正良.稳态下击暴流风速剖面模型研究[J].振动与冲击,2016,35(15):74-79.ZOU Xin,WANG Zhisong,LI Zhengliang.Wind velocity profile model of steady thunderstorm downburst[J].Journal of Vibration and Shock,2016,35(15):74-79.
[16]李朝.近地湍流风场的CFD模拟研究[D].哈尔滨:哈尔滨工业大学,2010.
[17]WOOD G S,KWOK K C S,MOTTERAM N A,et al.Physical and numerical modeling of thunderstorm downbursts[J].Journal of Wind Engineering and Industrial Aerodynamics,2001,89(6):535-552.
[18]MASON M S,WOOD G S,FLETCHER D F.Impinging jet simulation of stationary downburst flow over topography[J].Wind and Structures,2007,10(5):437-462.
[19]MASON M S,WOOD G S,FLETCHER D F.Numerical simulation of downburst winds[J].Journal of Wind Engineering and Industrial Aerodynamics,2009,97(11/12):523-539.
[20]MASON M S.Numerical investigation of the influence of topography on simulated downburst wind fields[J].Journal of Wind Engineering and Industrial Aerodynamics,2010,98(1):21-33.
[21]MASON M S,FLETCHER D F,WOOD G S.Numerical simulation of idealized three-dimensional downburst wind fields[J].Engineering Structures,2010,32:3558-3570.
[22]汪之松,左其刚,唐伟峰,等.稳态冲击射流作用下平地及坡地高层建筑的风荷载特性[J].建筑结构学报,2017,38(3):103-110.WANG Zhisong,ZUO Qigang,TANG Weifeng,et al.Wind load characteristics for high-rise building on flat terrain and slope under steady-state impinging jet[J].Journal of Building Structures,2017,38(3):103-110.
[23]ABD-ELAAL E S,MILLS J E,MA X.Empirical models for predicting unsteady-state downburst wind speeds[J].Journal of Wind Engineering and Industrial Aerodynamics,2014,129(6):49-63.