附面层位移厚度对沙障防风效益评价的适用性研究——以聚乳酸(PLA)沙障为例  

Applicability study of the boundary layer displacement thickness to the evaluation of sand barrier windbreak benefits:A case of polylactic acid sand barrier

作　　者：张帅[1] 原伟杰 刘卉 王海霞[1] 官昊慧 王鹿振 ZHANG Shuai;YUAN Weijie;LIU Hui;WANG Haixia;GUAN Haohui;WANG Luzhen(Experimental Center of Forestry in North China,Chinese Academy of Forestry/National Permanent Scientific Research Base for Warm Temperate Zone Forestry of Jiulong Mountain in Beijing,Beijing 102300,China;Water&Land Eco-Environment Technology Institute of Beijing Co.Ltd,Beijing 100080,China;Qinghai Provincial Investigation,Design&Research Institute of Water Conservancy&Hydropower Co.,Ltd,Xining 810000,Qinghai,China)

机构地区：[1]中国林业科学研究院华北林业实验中心/北京九龙山暖温带国家森林长期科研基地,北京102300 [2]沃德兰特(北京)生态环境技术研究院有限公司,北京100080 [3]青海省水利水电勘测规划设计研究院有限公司,青海西宁810000

出　　处：《干旱区地理》2023年第12期1973-1983,共11页Arid Land Geography

基　　金：国家自然科学基金青年基金项目(32001375);国家林业和草原局科技创新青年拔尖人才项目(2019132604);林业科学技术推广项目([2019]34)资助。

摘　　要：地表粗糙度作为风蚀防护中常用的传统指标,在防护林、沙障等工程措施的防护效益评价中发挥了重要作用。但在实际应用中发现,地表粗糙度存在不完全准确的现象。针对这一问题,引入新的参考指标附面层位移厚度,借助风洞模拟实验的方法,通过测定不同边长聚乳酸沙袋沙障中的风速频数、拟合风速流场、计算防风效能等来验证地表粗糙度和附面层位移厚度这2个指标的准确性。结果表明:随着聚乳酸沙袋沙障障格边长的增大,平均风速呈现出上升的趋势,其中障格边长为1.5 m和2.0 m沙障内的平均风速分别是1.0 m沙障的1.13和1.24倍;防风效能则呈现出下降的趋势,其中障格边长为1.0 m沙障内各处均大于0.6,1.5 m沙障内各处均大于0.5,2.0 m沙障内各处均大于0.4;风速流场高速区的面积呈现出增大的趋势。这表明随着沙障障格边长的增大,沙障的防护作用逐渐下降。与此同时,随着沙障障格边长的增大,附面层位移厚度呈现出减小的趋势,而地表粗糙度则呈现出先减小后增大的趋势。综上,附面层位移厚度在评价沙障防护作用时的准确性更高,可作为新的补充参考指标。Surface roughness,a conventional index widely applied in wind erosion protection,plays a crucial role in evaluating the effectiveness of engineering measures such as forest and sand barriers.Despite its prevalent use,practical applications reveal its limited accuracy.Consequently,we introduce a novel index termed“boundary layer displacement thickness”.Through wind tunnel simulations,we assessed the wind speed frequency distribution of various sandbag barriers.We computed the mean wind speed,wind prevention efficiency,and also scrutinized the wind speed flow field to validate the precision of both roughness and boundary layer displacement thickness measurements.The findings indicate that an increase in the length of the polylactic acid sandbag barrier corresponds to an upward trend in average wind speed.Specifically,the average wind speed within the 1.5-m and 2.0-m barriers is 1.13 and 1.24 times that of the 1.0-m barrier,respectively.Concurrently,wind prevention efficiency experiences a decline,with values exceeding 0.6 for the 1.0-m barrier,0.5 for the 1.5-m barrier,and 0.4 for the 2.0-m barrier.Analysis of the wind velocity field data reveal that the high-speed zone expands as the barrier grid size increases,signifying a weakened protective effect with large sand barriers.Notably,the boundary layer displacement thickness demonstrates a consistent decreasing trend with increasing barrier size,aligning with the aforementioned pattern.However,surface roughness exhibits an anomalous pattern,initially decreasing and then increasing.In summary,the boundary layer displacement thickness proved to be more accurate and emerged as a promising supplementary reference indicator for evaluating the efficacy of wind erosion protection measures.

关 键 词：附面层位移厚度 风蚀评价 风洞模拟 聚乳酸沙障 

分 类 号：S775[农业科学—森林工程]