超临界雷诺数下桥墩紊流宽度的计算方法

桥墩紊流宽度的计算与水流雷诺数的范围关系较大,将影响到计算成果的合理性。结合山区河流超临界雷诺数条件,采用格子Boltzmann方法模拟桥墩三维紊流流场,并结合大涡模拟和运动边界处理方法,分析不同来流、河形等条件下的桥墩三维紊流宽度,由此建立了顺直河道和弯曲河道中圆型桥墩相对紊流宽度与弗劳德数之间的耦合关系。该研究成果通过四川邓家坝大桥航宽验算,与经验法及祖小勇算法比较,发现该方法得出的桥墩紊流宽度略小、其数值趋于合理。     

桥墩周围紊流区宽度研究

通过数值模拟的研究方法,就桥墩附近的紊流区宽度展开了研究,利用圆柱绕流的研究成果,使用紊流理论,借助大型流场分析计算软件FLUENT,对桥墩周围水流流场进行模拟,分析计算了单圆柱桥墩和双圆柱桥墩群在不同水流条件下周围的紊流区宽度,得到一些有意义的结果.     

淮河干流临淮岗—鲁台子段航道整治

淮河干流临淮岗—鲁台子段河道,河势复杂,洪水工况组合多,航道整治难度大。为了优化本段航道整治工程方案,针对河段特点,构建二维水动力数学模型,采用多场次洪水进行率定与验证,确定"以淮干为主"的洪水组合是对刘台子航道最不利的洪水组合,并模拟刘台子弯道段现状河道、弯曲半径480和550 m方案的流场进行对比分析。结果表明,在水流流态和横向流速方面,弯曲半径480 m方案优于550 m方案。淮河干流可通航水面宽度较大,可通过增加通航水域宽度来适当降低航道弯曲半径,方案对原河道改变较小,河势相对稳定,流态更加平顺,并节约工程投资。     

桥墩紊流宽度的试验研究

由于我国现行的《内河通航标准》(GB50139-2004)中,没有桥墩紊流宽度的计算方法,桥梁设计人员为了保证船舶航行安全,通常将桥梁跨度加大,这样既增加了结构设计的难度,又增加了工程的投资。通过水槽定床和动床试验,分析了行近流速、行近水深、来流角度、桥墩尺寸、桥墩墩型、桥墩冲刷等因素对桥墩紊流宽度的影响,利用量纲分析法对实测数据进行整理,推导出了桥墩紊流宽度的计算公式。     

非淹没丁坝三维绕流数值模拟

通过应用非线性三维紊流数值模型,并采用有限体积法对模型控制方程进行离散,对非淹没丁坝绕流进行数值模拟仿真分析,给出了三维流场、压力分布场、剪应力分布场等信息,计算结果均基本符合非淹没丁坝绕流的实际情况,结果表明该非线性模型是可取的,数值模拟结果具有一定的可信度.     

三峡两坝间水田角河段航道整治三维水流数学模型应用研究

水田角河段水流湍急,流态紊乱,船舶航行较困难,是三峡两坝间河段急需整治的重点河段之一。基于平面正交坐标和立面σ坐标拟合河道平面形态、地形和自由水面的不规则分布,建立了三维紊流数学模型。采用物理模型实测的三维流速分布对模型进行验证,模拟的流速值与实测值吻合良好,将模型应用于水田角河段航道整治工程实施前、后的三维流场计算,给出了水田角河段的分层和断面二次流流速分布。分析结果表明,炸礁、抛填等整治措施的综合利用能有效调整河段流速分布,是有效的整治方案,可供设计参考。     

基于MIKE21对防撞设施桥墩处紊流宽度的研究

目前,对航道中桥墩处紊流宽度计算一般使用E=K_cK_sf(v,b,h)公式。但该公式并没有涉及航道地形的参数,也没有考虑到后续防撞设施的影响。为了研究防撞设施的布设对于桥墩处紊流宽度造成的实际影响,本文采用MIKE21软件,结合中运河桥和茹塘大桥实例,建立二维水流数学模型。通过对比数模与公式结果的误差发现,该一般性公式只适用于墩前水流较简单的情况。MIKE数模能更好地还原研究区域水文条件,直观反映紊流宽度,弥补了公式中关于桥墩附近复杂地形的空白,对将来公式修正提供了科学参考依据。     

基于Fluent 6.0的风机流场模拟与噪声预估

利用Fluent 6.0计算流体软件对风机的三维流场进行了模拟分析,同时进行了风机噪声的预估.流场模拟的紊流模型采用RNGk-ε模型,风机旋转区与非旋转区的耦合采用了移动参考坐标系模型MRF.对原风机模型和叶片穿孔后的风机模型进行了噪声预估,噪声预估采用非稳态隐式求解,紊流模型采用LES大涡模拟,旋转流体边界采用滑移网格,同时对模拟结果进行了分析.模拟结果有助于了解风机内流场的运动规律,为进一步优化风机结构,降低风机噪声提供了有益参考.     

液舱晃荡与浮体运动耦合的二维与三维SPH模拟影响研究

采用DualSPHysics开源代码对矩形液舱晃荡过程中的砰击载荷及强非线性流固耦合现象进行了模拟，通过检验与验证分析证明了论文SPH求解器的准确性，并对不同方法的模拟结果进行了基准性研究。通过对菱形液舱内晃荡流动的模拟，研究了不同装载高度工况下二维与三维模拟对于舱壁砰击压力和晃荡流动的影响。最后针对载液浮箱在波浪中运动的内外域流动耦合问题进行模拟，分析了浮体运动和液舱晃荡二维与三维模拟结果的差异。研究表明，三维模拟中由于流场存在沿液舱宽度方向的运动分量，使得二维与三维液舱晃荡结果存在一定的差异，且低载液率工况的结果差异更大。     

具有弯曲特性河道上桥梁通航宽度的探讨

根据船舶操纵性能，结合水流在弯道上的运动特性，提出影响航道宽度的因素，探讨具有弯曲特性河道上桥梁通航所需要的宽度。论文给出全新的计算方法，并与我国2004年“内河通航标准”中的方法进行比较，指出了“内河通航标准”中计算方法的不足。     

Experimental study on the width of the turbulent area around bridge pier

At present, the method of calculating the turbulent flow width around the bridge pier is not given in the "Standard for Inland River Navigation" (GB50139-2004) in China, and the bridge designer usually increases the bridge span in order to ensure the navigation safety, which increases both of the structural design difficulty and the project investments. Therefore, it is extremely essential to give a research on the turbulent flow width around the bridge pier. Through the experiments of the fixed bed and the mobile bed, the factors influencing the turbulent flow width around the bridge pier have been analyzed, such as the approaching flow speed, the water depth, the angles between the bridge pier and the flow direction, the sizes of bridge pier, the shapes of the bridge pier, and the scouring around the bridge pier, etc. Through applying the dimension analytic method to the measured data, the formula of calculating the turbulent flow width around the bridge pier is then inferred.     

天然弯曲河道跨河建筑物跨度确定方法

研究天然弯道(不考虑潮流影响),以航道宽度作为弯道跨河建筑物的最小跨度,提出弯道跨河建筑物最小跨度的确定方法。结果表明,天然弯道跨河建筑物的最小跨度与船舶的航迹带宽度、风致漂移量、流致漂移量和建筑物墩部紊流范围密切相关。航迹带宽度、风致漂移量、流致漂移量和建筑物墩部紊流范围越大,弯道跨河建筑物的最小跨度也越大。从通航安全角度出发,提出天然弯道流致漂移量、建筑物墩部紊流范围和弯道跨河建筑物最小跨度的数学计算模型。     

航道边线与桥墩之间安全距离的研究

合理地确定通航桥梁的最小净空宽度,保证船队航行和桥梁安全,是桥梁建设和航道建设均应重视的问题。文章提出了计算通航桥孔宽度的计算公式。当桥梁轴线的法线方向与水流方向的偏角超过5°时,通航桥孔净空宽度应在一般航道宽度的基础上增加考虑水流产生的船舶横向漂移,并在桥墩和航道边线之间留有足够的安全距离。利用PIV技术,获得桥墩周围流场的准确信息,从水流紊动的角度,提出了安全距离的确定方法。     

熵格子Boltzmann方法的重整化群代数湍流模型

重整化群理论所建立的湍流模型能够最大程度地减小模型经验性,因此文章尝试将重整化群代数湍流模型引入到熵格子Boltzmann方法中,建立新型的计算模型以对高雷诺数湍流进行模拟研究。同时为了进行比较研究,还建立了熵格子Boltzmann方法的标准大涡模拟模型。完成了对高雷诺数湍流绕流场的模拟计算。结果表明:所建立的熵格子Boltzmann方法重整化群代数湍流模型能够有效地模拟高雷诺数湍流流动问题;其对紧贴壁面处较小尺度湍涡的模拟结果趋近于大涡模拟的结果;重整化群代数湍流模型在对高雷诺数湍流的模拟中表现出耗散模型的特征。     

Comparison of Scour and Flow Characteristics Around Circular and Oblong Bridge Piers in Seepage Affected Alluvial Channels

The present study examines scour geometry and turbulent flow characteristics around circular and oblong piers in alluvial channel with downward seepage. Experiments were conducted in plane sand bed of non-uniform sand under no seepage, 10% seepage and 15% seepage conditions. Scour depth at oblong pier is significantly lesser than the scour depth at circular one. However, the scour depth at both piers reduces with downward seepage. The measurements show that the velocity and Reynolds stresses are negative near the bed at upstream of piers where the strong reversal occurs. At downstream of oblong pier near the free surface, velocity and Reynolds stresses are less positive; whereas, they are negative at downstream of circular pier. The streamline shape of oblong pier leads to reduce the strength of wake vortices and consequently reversal flow at downstream of pier. With application of downward seepage turbulent kinetic energy is decreasing. The results show that the wake vortices at oblong pier are weaker than the wake vortices at circular pier. The strength of wake vortices diminishes with downward seepage. The Strouhal number is lesser for oblong pier and decreases with downward seepage for both oblong and circular piers.     

受渗流影响的冲积河道中圆型和矩形桥墩受腐蚀情况和流动特性比较（英文）

The present study examines scour geometry and turbulent flow characteristics around circular and oblong piers in alluvial channel with downward seepage. Experiments were conducted in plane sand bed of non-uniform sand under no seepage, 10% seepage and 15% seepage conditions. Scour depth at oblong pier is significantly lesser than the scour depth at circular one.However, the scour depth at both piers reduces with downward seepage. The measurements show that the velocity and Reynolds stresses are negative near the bed at upstream of piers where the strong reversal occurs. At downstream of oblong pier near the free surface, velocity and Reynolds stresses are less positive; whereas, they are negative at downstream of circular pier. The streamline shape of oblong pier leads to reduce the strength of wake vortices and consequently reversal flow at downstream of pier. With application of downward seepage turbulent kinetic energy is decreasing. The results show that the wake vortices at oblong pier are weaker than the wake vortices at circular pier. The strength of wake vortices diminishes with downward seepage.The Strouhal number is lesser for oblong pier and decreases with downward seepage for both oblong and circular piers.     

Numerical simulation of three-dimensional combustion flows

A finite-rate method is used to simulate the three-dimensional combustion process in a plasma generator with CH4 as the fuel. The simulation was run with RNG k-ε model to simulate turbulence, with eddy-dissipation-concept （EDC） model to simulate the combustion and with discrete ordinates model to simulate radiation. The numerical results show that the flow field characteristics and the parameter distributions are under the condition of rich fuels, and these results provide valuable information when optimizing the plasma generator design and organizing its flow fields.     

PIV velocity field measurements of flow around a KRISO 3600TEU container ship model

The main purpose of this investigation was to demonstrate a useful application of the particle image velocimetry (PIV) method to analyze the complex flow characteristics around a ship. For a sample illustration, the KRISO 3600TEU container ship model was chosen. The flow structure in the stern and near-wake region of the model has been investigated experimentally in a circulating water channel. Instantaneous velocity fields measured by the PIV velocity field measurement technique have been ensemble-averaged to give details of flow structures such as the spatial distributions of the local mean velocity, vorticity, and turbulent kinetic energy. The free-stream velocity was fixed at U _o = 0.6m/s, and the corresponding Reynolds number based on the length between perpendiculars was about 9.0 × 10⁵. The container ship model shows a complicated three-dimensional flow structure in the stern and near-wake regions. The PIV results clearly revealed the formation of large-scale bilge vortices in the stern region and their effect on the flow in the near-wake. The results shown here provide valuable information for hull form design and the validation of viscous ship flow codes and of turbulence models.