Purpose–This study aims to explore the formation mechanism of aerodynamic noise of a high-speed maglev train and understand the characteristics of dipole and quadrupole sound sources of the maglev train at different ...Purpose–This study aims to explore the formation mechanism of aerodynamic noise of a high-speed maglev train and understand the characteristics of dipole and quadrupole sound sources of the maglev train at different speed levels.Design/methodology/approach–Based on large eddy simulation(LES)method and Kirchhoff–Ffowcs Williams and Hawkings(K-FWH)equations,the characteristics of dipole and quadrupole sound sources of maglev trains at different speed levels were simulated and analyzed by constructing reasonable penetrable integral surface.Findings–The spatial disturbance resulting from the separation of the boundary layer in the streamlined area of the tail car is the source of aerodynamic sound of the maglev train.The dipole sources of the train are mainly distributed around the radio terminals of the head and tail cars of the maglev train,the bottom of the arms of the streamlined parts of the head and tail cars and the nose tip area of the streamlined part of the tail car,and the quadrupole sources are mainly distributed in the wake area.When the train runs at three speed levels of 400,500 and 600 km$h1,respectively,the radiated energy of quadrupole source is 62.4%,63.3%and 71.7%,respectively,which exceeds that of dipole sources.Originality/value–This study can help understand the aerodynamic noise characteristics generated by the high-speed maglev train and provide a reference for the optimization design of its aerodynamic shape.展开更多
Comparing and analyzing the difference between automatic-observed and manual-observed wind speed based on the wind speed parallel observations in two methods, we find that many elements can influence the difference be...Comparing and analyzing the difference between automatic-observed and manual-observed wind speed based on the wind speed parallel observations in two methods, we find that many elements can influence the difference between automatic-observed and manual-observed wind speed, including the levels of speed wind, observation instruments and different regions. According to these elements, correction has been conducted, and find that the correction according to the level of wind speed has the best correction effect.展开更多
为研究渠道水生植被特征对渠内水力特性影响,设计了渠道模型试验,探讨了植被生长间距、入渠流量等因素影响下渠道水位、流速变化。试验表明,入渠流量对渠内断面水位变化特征影响较小,但植被生长间距特征会改变渠内断面水位变化,在间距为...为研究渠道水生植被特征对渠内水力特性影响,设计了渠道模型试验,探讨了植被生长间距、入渠流量等因素影响下渠道水位、流速变化。试验表明,入渠流量对渠内断面水位变化特征影响较小,但植被生长间距特征会改变渠内断面水位变化,在间距为10~15、20~30、35~40 mm 3个区段具有不同的水位变化趋势。入渠流量愈大,则水位愈高;但植被生长间距愈大,则渠内水位愈低。当植被生长间距不超过25 mm时,渠内流速变化具有增、降阶段,而在间距为30~40 mm时流速较稳定。植被生长间距愈大,则流速愈高。研究认为渠内水生植被应控制其分布密度与间距,以降低水生植被对渠内动水势能的影响。展开更多
为研究县域尺度下高速交通网与旅游业间的耦合协调关系,以山东省136个县域为研究对象,建立县域高速交通网优势度与旅游业发展水平的评价指标体系,采用熵权-逼近理想解排序(technique for order preference by similarity to an ideal so...为研究县域尺度下高速交通网与旅游业间的耦合协调关系,以山东省136个县域为研究对象,建立县域高速交通网优势度与旅游业发展水平的评价指标体系,采用熵权-逼近理想解排序(technique for order preference by similarity to an ideal solution, TOPSIS)法、趋势面分析法、耦合协调模型研究二者协同发展的空间分异特性,揭示高速交通网与旅游业的相互作用特征。结果表明:2021年山东省136个县域的高速交通优势度沿齐长城快进通道、黄渤海快进通道、沿黄快进通道形成集聚态势,旅游业发展沿“千里滨海”“红色沂蒙”“鲁风运河”主题廊道中“慢游”风景道形成集聚态势;高速交通网与旅游业的耦合协调度呈南高北低、东高西低的倒U型分布,南北走向是高速交通网与旅游业耦合协调度产生空间分异特点的首要方向;高速交通网与旅游业耦合协调度存在空间集聚性和显著的空间依赖性,受距离衰减效应及虹吸效应的影响,省会经济圈和鲁南经济圈边缘地区的耦合协调程度相对薄弱。展开更多
基金The research was supported by the National Key Research and Development Program(Grant No.2020YFA0710903)the Financial Funding Project for Central Colleges and Universities(Grant No.202045014)the Science and Technology Research and Development Program of China State Railway Group Co.,Ltd.(Grant No.P2019J008).
文摘Purpose–This study aims to explore the formation mechanism of aerodynamic noise of a high-speed maglev train and understand the characteristics of dipole and quadrupole sound sources of the maglev train at different speed levels.Design/methodology/approach–Based on large eddy simulation(LES)method and Kirchhoff–Ffowcs Williams and Hawkings(K-FWH)equations,the characteristics of dipole and quadrupole sound sources of maglev trains at different speed levels were simulated and analyzed by constructing reasonable penetrable integral surface.Findings–The spatial disturbance resulting from the separation of the boundary layer in the streamlined area of the tail car is the source of aerodynamic sound of the maglev train.The dipole sources of the train are mainly distributed around the radio terminals of the head and tail cars of the maglev train,the bottom of the arms of the streamlined parts of the head and tail cars and the nose tip area of the streamlined part of the tail car,and the quadrupole sources are mainly distributed in the wake area.When the train runs at three speed levels of 400,500 and 600 km$h1,respectively,the radiated energy of quadrupole source is 62.4%,63.3%and 71.7%,respectively,which exceeds that of dipole sources.Originality/value–This study can help understand the aerodynamic noise characteristics generated by the high-speed maglev train and provide a reference for the optimization design of its aerodynamic shape.
基金Supported by Meteorological Data Sharing Center Project (2005DKA31700-01,GX07-01-01)2009 Specific Research in Non-profit Sector (200906041-053)
文摘Comparing and analyzing the difference between automatic-observed and manual-observed wind speed based on the wind speed parallel observations in two methods, we find that many elements can influence the difference between automatic-observed and manual-observed wind speed, including the levels of speed wind, observation instruments and different regions. According to these elements, correction has been conducted, and find that the correction according to the level of wind speed has the best correction effect.
文摘为研究渠道水生植被特征对渠内水力特性影响,设计了渠道模型试验,探讨了植被生长间距、入渠流量等因素影响下渠道水位、流速变化。试验表明,入渠流量对渠内断面水位变化特征影响较小,但植被生长间距特征会改变渠内断面水位变化,在间距为10~15、20~30、35~40 mm 3个区段具有不同的水位变化趋势。入渠流量愈大,则水位愈高;但植被生长间距愈大,则渠内水位愈低。当植被生长间距不超过25 mm时,渠内流速变化具有增、降阶段,而在间距为30~40 mm时流速较稳定。植被生长间距愈大,则流速愈高。研究认为渠内水生植被应控制其分布密度与间距,以降低水生植被对渠内动水势能的影响。
文摘为研究县域尺度下高速交通网与旅游业间的耦合协调关系,以山东省136个县域为研究对象,建立县域高速交通网优势度与旅游业发展水平的评价指标体系,采用熵权-逼近理想解排序(technique for order preference by similarity to an ideal solution, TOPSIS)法、趋势面分析法、耦合协调模型研究二者协同发展的空间分异特性,揭示高速交通网与旅游业的相互作用特征。结果表明:2021年山东省136个县域的高速交通优势度沿齐长城快进通道、黄渤海快进通道、沿黄快进通道形成集聚态势,旅游业发展沿“千里滨海”“红色沂蒙”“鲁风运河”主题廊道中“慢游”风景道形成集聚态势;高速交通网与旅游业的耦合协调度呈南高北低、东高西低的倒U型分布,南北走向是高速交通网与旅游业耦合协调度产生空间分异特点的首要方向;高速交通网与旅游业耦合协调度存在空间集聚性和显著的空间依赖性,受距离衰减效应及虹吸效应的影响,省会经济圈和鲁南经济圈边缘地区的耦合协调程度相对薄弱。
