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Flutter control effect and mechanism of central-slotting for long-span bridges

YANG Yongxin, GE Yaojun, XIANG Haifan

《结构与土木工程前沿(英文)》 2007年 第1卷 第3期   页码 298-304 doi: 10.1007/s11709-007-0039-6

摘要: The flutter control effect and mechanism of central-slotting, which have gradually been adopted in the design and construction of long-span bridges as an effective flutter controlling measure, were investigated with theoretical analysis and wind tunnel test. Five basic girder cross-sections representing five typical aerodynamic configurations were selected and central-slotted with two different slot widths. Then, a series of sectional model tests and theoretical analyses based on the two-dimensional three-degrees-of-freedom coupling flutter analysis method (2 dimension-3 degrees of freedom method, 2d-3DOF method) were carried out to investigate the aerodynamic performance, flutter mechanism and flutter modality of the five basic sections and their corresponding central-slotted sections. The results show that central-slotting can not always improve the aerodynamic stability of bridge structure. The control effect of central-slotting depends on the aerodynamic configuration of the original girder section and the corresponding central-slotting width. If the original section is inappropriate or the slot width is unsuitable, central-slotting will even deteriorate the structural flutter performance. Theoretical investigations indicated that the differences in flutter control effects come from the different formation and evolution of aerodynamic damping, and flutter modality especially the participation level of heaving motion also has a significant influence on the control effect of central-slotting.

关键词: aerodynamic configuration     aerodynamic performance     flutter mechanism     aerodynamic stability     theoretical analysis    

Aerodynamic stability evolution tendency of suspension bridges with spans from 1000 to 5000 m

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0980-z

摘要: Aerodynamic instability owing to aerostatic and flutter-related failures is a significant concern in the wind-resistant design of long-span suspension bridges. Based on the dynamic characteristics of suspension bridges with spans ranging from 888 to 1991 m, we proposed fitted equations for increasing spans and base frequencies. Finite element models of suspension bridges with increasing span from 1000 to 5000 m were constructed. The structural parameters were optimized to follow the fitted tendencies. To analyze the aerodynamic instability, streamlined single-box section (SBS), lattice truss section (LTS), narrow slotted section (NSS), and wide slotted section (WSS) were considered. We performed three-dimensional (3-D) full-mode flutter analysis and nonlinear aerostatic instability analysis. The flutter critical wind speed continuously decreases with span growth, showing an unlimited approaching phenomenon. Regarding aerostatic instability, the instability wind speed decreases with span to approximately 3000 m, and increases when the span is in the range of 3000 to 5000 m. Minimum aerostatic instability wind speed with SBS or LTS girder would be lower than observed maximal gust wind speed, indicating the probability of aerostatic instability. This study proposes that suspension bridge with span approximately 3000 m should be focused on both aerostatic instability and flutter, and more aerodynamic configuration optimistic optimizations for flutter are essential for super long-span suspension bridges with spans longer than 3000 m.

关键词: suspension bridge     super long-span     finite element model     aerodynamic instability     aerodynamic configuration    

一种小展弦比高升力飞机的气动布局研究

宋文骢,谢品,郑遂,李玉璞

《中国工程科学》 2001年 第3卷 第8期   页码 70-75

摘要:

针对未来歼击机隐身、高机动和超声速巡航的特点,分析了主要的设计矛盾,并且就亚跨声速升阻特性、低速大迎角特性和超声速阻力特性等若干设计问题提出了具体的解决方案。作者认为,深入研究流动机理,挖掘现有气动力措施的应用潜力,发展新的设计概念,采用相应的总体与控制措施,在众多的设计点之间权衡折衷取舍,有可能全面达到设计目标。

关键词: 气动布局     超声速巡航     隐身     过失速机动    

Numerical analysis of aerodynamic noise radiated from cross flow fan

CHEN Anbang, LI Song, HUANG Dongtao

《能源前沿(英文)》 2008年 第2卷 第4期   页码 443-447 doi: 10.1007/s11708-008-0063-9

摘要: The flow field in a cross flow fan was simulated by solving the 2-D unsteady Reynolds-averaged Navier-Stokes equations. The calculated pressure fluctuations of the blades, the vortex wall, and the rear wall were then used as noise sources to calculate the sound field. The Ffowcs Williams-Hawkings (FW-H) equation was employed to predict the noise field caused by these sources. The predictions show that the rear wall and the vortex wall sources contribute significantly to the total noise and that both the predicted aerodynamic performance and noise agree well with the experimental results.

关键词: predicted aerodynamic     Williams-Hawkings     calculated pressure     aerodynamic performance     unsteady Reynolds-averaged    

Effects of green roof damping and configuration on structural seismic response

《结构与土木工程前沿(英文)》   页码 1133-1144 doi: 10.1007/s11709-023-0959-9

摘要: Sustainable structures are critical for addressing global climate change. Hence, their structural resilience or ability to recover from natural events must be considered comprehensively. Green roofs are a widely used sustainable feature that improve the environment while providing excellent occupant amenity. To expand their usage, their inherent damping and layout sensitivity to seismic performance are investigated in this study. The soil of a green roof can serve as a damper to dissipate the energy generated by earthquakes or other dynamic events. Results of preliminary analysis show that a green roof soil can increase localized damping by 2.5% under both dry and saturated conditions. Based on these findings, nonlinear time-history analyses are conducted on a three-story building in SAP2000 to monitor the structural behavior with and without a green roof. The increased damping in the green roof soil is beneficial to the structural performance, i.e., it reduces the building displacement and acceleration by 10% and 12%, respectively. Additionally, certain configurations are more effective and beneficial to the structural response than others, which suggests the possibility of design optimization. Based on the findings of this study, new methods of modeling and considering green roofs in structural design are established.

关键词: green infrastructure     green roof     structural resilience     seismic design    

Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

《结构与土木工程前沿(英文)》 2023年 第17卷 第4期   页码 522-532 doi: 10.1007/s11709-023-0930-9

摘要: Owing to long-distance advancement or obstacles, shield tunneling machines are typically shut down for maintenance. Engineering safety during maintenance outages is determined by the stability of the tunnel face. Pressure maintenance openings are typically used under complicated hydrogeological conditions. The tunnel face is supported by a medium at the bottom of the excavation chamber and compressed air at the top. Owing to the high risk of face failure, the necessity of support pressure when cutterhead support is implemented and a method for determining the value of compressed air pressure using different support ratios must to be determined. In this study, a non-fully chamber supported rotational failure model considering cutterhead support is developed based on the upper-bound theorem of limit analysis. Numerical simulation is conducted to verify the accuracy of the proposed model. The results indicate that appropriately increasing the specific gravity of the supporting medium can reduce the risk of collapse. The required compressed air pressure increases significantly as the support ratio decreases. Disregarding the supporting effect of the cutterhead will result in a tunnel face with underestimated stability. To satisfy the requirement of chamber openings at atmospheric pressure, the stratum reinforcement strength and range at the shield end are provided based on different cutterhead aperture ratios.

关键词: tunnel face stability     cutterhead configuration     aperture ratio     pressure gradient     support ratio    

Experimental study of aerodynamic interference effects on aerostatic coefficients of twin deck bridges

Zhiwen LIU , Zhengqing CHEN , Gao LIU , Xinpeng SHAO ,

《结构与土木工程前沿(英文)》 2009年 第3卷 第3期   页码 292-298 doi: 10.1007/s11709-009-0048-8

摘要: The aerodynamic interference effects on aerostatic coefficients of twin deck bridges with large span were investigated in detail by means of wind tunnel test. The distances between the twin decks and wind attack angles were changed during the wind tunnel test to study the effects on aerodynamic interferences of aerostatic coefficients of twin decks. The research results have shown that the drag coefficients of the leeward deck are much smaller than that of a single leeward deck. The drag coefficients of a windward deck decrease slightly compared with that of a single deck. The lift and torque coefficients of windward and leeward decks are also affected slightly by the aerodynamic interference of twin decks. And the aerodynamic interference effects on lift and torque coefficients of twin decks can be neglected.

关键词: twin decks     aerodynamic interference effects     aerostatic coefficients     wind tunnel test    

Optimizing the configuration of a clearwell by integrating pilot and full-scale tracer testing

LIU Wenjun, DU Zhipeng, JIN Junwei

《环境科学与工程前沿(英文)》 2007年 第1卷 第3期   页码 270-275 doi: 10.1007/s11783-007-0045-x

摘要: In this paper, the main factors impacting the plug flow pattern of a clearwell were investigated by integrating pilot-scale, full-scale clearwell tracer testing and computational fluid dynamics (CFD) simulation. It was found that pilot tracer testing, full-scale tracer testing and CFD simulation all demonstrated that the correlation between the ratio of / and can be approximately expressed by: / = 0.189 4ln()-0.049 4. This study confirmed that the installation of baffles within clearwells is an efficient way to optimize their configuration. In addition, the inlet velocity has a minimal contribution to the ratio of /. However, the ratio of turning channel width to channel width () significantly contributes to the ratio of/. The optimal ratio of is 0.8–1.2 for maintaining better plug flow pattern. The number of turning channels is one of the main factors that impact the ratio of /. When increasing the number of turning channels, a lower ratio of / is obtained.

New response surface model and its applications in aerodynamic optimization of axial compressor blade

LIU Xiaojia, NING Fangfei

《能源前沿(英文)》 2008年 第2卷 第4期   页码 541-549 doi: 10.1007/s11708-008-0077-3

摘要: A parametric method for the axial compressor 2D blade profiles is proposed in which the blade geometries are defined with the parameters commonly used for blade definition, which ensures that the geometric significance is clear and an unreasonable blade profile is not generated. Several illustrations are presented to show the fitting precision of the method. A novel response surface model is proposed which regards the objective distribution function in the vicinity of a sample as normal school, and then generates the response surface function in the whole design space by a linear combination of distribution functions of all the samples. Based on this model, a numerical aerodynamic optimization platform for the axial compressor 2D blade profiles is developed, by which aerodynamic optimization of two compressor blade profiles are presented.

关键词: definition     objective distribution     fitting precision     combination     numerical aerodynamic    

Aerodynamic interference effects and mitigation measures on vortex-induced vibrations of two adjacent

Xiaoliang MENG, Ledong ZHU, Zhenshan GUO

《结构与土木工程前沿(英文)》 2011年 第5卷 第4期   页码 510-517 doi: 10.1007/s11709-011-0129-3

摘要: By examining the two neighboring Haihe Bridges with semi- and full-closed bridge decks, the aerodynamic interference between the two decks on the vortex-induced vibration (VIV) and the corresponding aerodynamic mitigation measures are investigated via a series of wind tunnel tests with a spring-suspended sectional model aided with computational fluid dynamics (CFD) method. The results show that the VIV responses of both bridges can be significantly affected by the aerodynamic interference and that the extent of the influence varies with the shapes of the windward and leeward decks. The VIV amplitudes of the windward bridge are often fairly close to those of the single bridge. However, those of the leeward bridge are magnified substantially by aerodynamic interference if the same structural and aerodynamic configurations are adopted for the two bridges. Otherwise, the VIV responses are not significantly increased and may even be reduced by the aerodynamic interference if different configurations are employed for the two bridges. Furthermore, an effective combined measure of adding wind barriers and sharpening the wind fairing noses of the two box decks is presented for mitigating both the vertical and torsional VIV responses of the windward and leeward bridges.

关键词: separated parallel decks     vortex-induced vibration     aerodynamic interference     aerodynamic mitigation measure     semi-closed box deck     full-closed box deck    

Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ

《环境科学与工程前沿(英文)》 2022年 第16卷 第4期 doi: 10.1007/s11783-021-1480-9

摘要:

• RED performance and stack resistance were studied by EIS and LSV.

关键词: Reverse electrodialysis     Electrochemical impedance spectroscopy     Concentration polarization     Spacer shadow effect    

Passive convergence-permeable reactive barrier (PC-PRB): An effective configuration to enhance hydraulic

《环境科学与工程前沿(英文)》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1591-y

摘要:

● A novel PRB configuration based on passive convergent flow effect was proposed.

关键词: Passive convergence-permeable reactive barrier (PC-PRB)     Permeable reactive barrier configuration     Numerical simulation     Hydraulic performance evaluation     Sensitivity analysis    

Aerodynamic impact of train-induced wind on a moving motor-van

Jiajun HE; Huoyue XIANG; Yongle LI; Bin HAN

《结构与土木工程前沿(英文)》 2022年 第16卷 第7期   页码 909-927 doi: 10.1007/s11709-022-0833-1

摘要: The newly-built single-level rail-cum-road bridge brings the issue of the aerodynamic impact of train-induced wind on road automobiles. This research introduced a validated computational fluid dynamics (CFD) model regarding this concern. Such an aerodynamic impact mechanism was explored; a relationship between the transverse distance between train and motor-van (hereinfafter referred to as van) and the aerodynamic effects on the van was explored to help the optimization of bridge decks, and the relationship between the automobile speed and aerodynamic variations of a van was fitted to help traffic control. The fitting results are accurate enough for further research. It is noted that the relative speed of the two automobiles is not the only factor that influences the aerodynamic variations of the van, even at a confirmed relative velocity, the aerodynamic variations of the van vary a lot as the velocity proportion changes, and the most unfavorable case shows an increase of over 40% on the aerodynamic variations compared to the standard case. The decay of the aerodynamic effects shows that not all the velocity terms would enhance the aerodynamic variations; the coupled velocity term constrains the variation amplitude of moments and decreases the total amplitude by 20%–40%.

关键词: rail-cum-road bridge     aerodynamic impact     train-induced wind     CFD     aerodynamic force     quantitative analysis     fitting    

Numerical investigation of aerodynamic performance influenced by circumferentially pre-swirling coming

WANG Qikun, CHEN Kangmin

《能源前沿(英文)》 2007年 第1卷 第4期   页码 435-440 doi: 10.1007/s11708-007-0063-5

摘要: Numerical investigation is implemented on aerodynamic performance inside the crossover and de-swirling cascade of a multistage centrifugal compressor. The emphasis is put on the aerodynamic performance influenced by the circumferent

关键词: aerodynamic     investigation     centrifugal     de-swirling     circumferent    

运动规划的高效配置空间构建与优化 Article

潘佳, Dinesh Manocha

《工程(英文)》 2015年 第1卷 第1期   页码 46-57 doi: 10.15302/J-ENG-2015009

摘要:

配置空间是算法机器人学领域使用较为广泛的一种基本概念。机器人学、计算机辅助设计与相关领域的诸多应用都可归类为配置空间方面的计算问题。本文将对近期与配置空间相关的两项重大挑战的解决方案成果进行探讨:①如何高效计算高维配置空间的近似表达;②如何在高维配置空间内高效执行几何学接近度与运动规划查询。基于机器学习与几何学近似技术,笔者在此提出几种新型配置空间构建算法。上述算法对多个配置样本进行碰撞查询。得出的碰撞查询结果将用来计算配置空间的近似表达,可快速聚合至准确的配置空间;同时还提出了基于并行图形处理器(GPU)的算法,以便加速配置空间优化与搜索计算的性能情况。笔者特别设计出了基于GPU的并行k最近邻算法与并行碰撞检测算法,并使用这些算法来加快运动规划。

关键词: 配置空间     运动规划     图形处理器(GPU)并行算法    

标题 作者 时间 类型 操作

Flutter control effect and mechanism of central-slotting for long-span bridges

YANG Yongxin, GE Yaojun, XIANG Haifan

期刊论文

Aerodynamic stability evolution tendency of suspension bridges with spans from 1000 to 5000 m

期刊论文

一种小展弦比高升力飞机的气动布局研究

宋文骢,谢品,郑遂,李玉璞

期刊论文

Numerical analysis of aerodynamic noise radiated from cross flow fan

CHEN Anbang, LI Song, HUANG Dongtao

期刊论文

Effects of green roof damping and configuration on structural seismic response

期刊论文

Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

期刊论文

Experimental study of aerodynamic interference effects on aerostatic coefficients of twin deck bridges

Zhiwen LIU , Zhengqing CHEN , Gao LIU , Xinpeng SHAO ,

期刊论文

Optimizing the configuration of a clearwell by integrating pilot and full-scale tracer testing

LIU Wenjun, DU Zhipeng, JIN Junwei

期刊论文

New response surface model and its applications in aerodynamic optimization of axial compressor blade

LIU Xiaojia, NING Fangfei

期刊论文

Aerodynamic interference effects and mitigation measures on vortex-induced vibrations of two adjacent

Xiaoliang MENG, Ledong ZHU, Zhenshan GUO

期刊论文

Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ

期刊论文

Passive convergence-permeable reactive barrier (PC-PRB): An effective configuration to enhance hydraulic

期刊论文

Aerodynamic impact of train-induced wind on a moving motor-van

Jiajun HE; Huoyue XIANG; Yongle LI; Bin HAN

期刊论文

Numerical investigation of aerodynamic performance influenced by circumferentially pre-swirling coming

WANG Qikun, CHEN Kangmin

期刊论文

运动规划的高效配置空间构建与优化

潘佳, Dinesh Manocha

期刊论文