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Bubble entrainment, spray and splashing at hydraulic jumps

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第8期7卷 1396-1405页

作者： chanson hubert Division of Civil Engineering The University of Queensland Brisbane QLD 4072 Australia

The sudden transition from a high-velocity, supercritical open channel flow into a slow-moving sub-critical flow is a hydraulic jump. Such a flow is characterised by a sudden rise of the free-surface, with some strong energy dissipation and air entrainment, waves and spray. New two-phase flow measurements were performed in the developing flow region using a large-size facility operating at large Reynolds numbers. The experimental results demonstrated the complexity of the flow with a developing mixing layer in which entrained bubbles are advected in a high shear stress flow. The relationship between bubble count rates and void fractions was non-unique in the shear zone, supporting earlier observations of some form of double diffusion process between momentum and air bubbles. In the upper region, the flow consisted primarily of water drops and packets sur-rounded by air. Visually significant pray and splashing were significant above the jump roller. The present study is the first com-prehensive study detailing the two-phase flow properties of both the bubbly and spray regions of hydraulic jumps, a first step towards understanding the interactions between bubble entrainment and droplet ejection processes.

关键词：水跃气泡夹带物理模拟两相流

Energy dissipation on stepped spillways and hydraulic challenges—Prototype and laboratory experiences

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Journal of Hydrodynamics 2022年第1期34卷 52-62页

作者： hubert chanson School of Civil Engineering The University of QueenslandBrisbaneAustralia

Stepped cascades, chutes and spillways have been in use for more than three millennia. With the introduction of new construction materials and techniques, the staircase chute design has regained some interest within the last forty years. The stepped invert increases significantly the energy dissipation occurring above the steep chute and reduces the size of the required downstream stilling structure. The application of stepped chutes further encompasses in-stream re-aeration and water treatment plant cascades, to enhance the air-water transfer of atmospheric gases and of volatile organic components. However, the engineering design of stepped spillways is not simple because of the hydrodynamic challenges, with several markedly different flow regimes, some complicated two-phase air-water fluid dynamics and massive rate of energy dissipation above the stepped chute. Simply, the technical challenges in the hydraulic design of stepped spillways are massive. This review paper examines the hydraulic characteristics of stepped chute flows and develops a reflection on nearly three decades of active hydraulic research, including recent field measurements during major flood events. The author aims to share his passion for the complicated hydraulic engineering, as well as some advice for engineering professionals and researchers.

关键词： Stepped spillways hydraulic modeling field measurements energy dissipation and design multiphase air-water flows

Physical modelling and scale effects of air-water flows on stepped spillways

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2005年第3期6卷 243-250页

作者： chanson hubert GONZALEZ Carlos A. Department of Civil Engineering The University of Queensland Brisbane 4072 AustraliaDepartment of Civil Engineering The University of Queensland Brisbane 4072 Australia

During the last three decades, the introduction of new construction materials (e.g. RCC (Roller Compacted Concrete), strengthened gabions) has increased the interest for stepped channels and spillways. However stepped chute hydraulics is not simple, because of different flow regimes and importantly because of very-strong interactions between entrained air and turbu- lence. In this study, new air-water flow measurements were conducted in two large-size stepped chute facilities with two step heights in each facility to study experimental distortion caused by scale effects and the soundness of result extrapolation to pro- totypes. Experimental data included distributions of air concentration, air-water flow velocity, bubble frequency, bubble chord length and air-water flow turbulence intensity. For a Froude similitude, the results implied that scale effects were observed in both facilities, although the geometric scaling ratio was only Lr=2 in each case. The selection of the criterion for scale effects is a critical issue. For example, major differences (i.e. scale effects) were observed in terms of bubble chord sizes and turbulence levels al- though little scale effects were seen in terms of void fraction and velocity distributions. Overall the findings emphasize that physical modelling of stepped chutes based upon a Froude similitude is more sensitive to scale effects than classical smooth-invert chute studies, and this is consistent with basic dimensional analysis developed herein.

关键词：泄洪道物理模型刻度空气-水流体设计方案水下隧道

Experiments on two-phase flow in hydraulic jump on pebbled rough bed:Part 2–Bubble clustering

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Water Science and Engineering 2023年第4期16卷 369-380页

作者： Farhad Bahmanpouri Carlo Gualtieri hubert chanson Civil Architectural and Environmental Engineering Department(DICEA)The University of Napoli Federico IIVia Claudio 21Napoli 80125Italy School of Civil Engineering The University of QueenslandBrisbaneQLD 4072Australia

A survey on bubble clustering in air–water flow processes may provide signiﬁcant insights into turbulent two-phaseﬂow.These processes have been studied in plunging jets,dropshafts,and hydraulic jumps on a smooth bed.As a first attempt,this study examined the bubble clustering process in hydraulic jumps on a pebbled rough bed using experimental data for 1.70

关键词： Hydraulic jump Pebbled rough bed Clustering analysis Interparticle arrival time Two-phase flow

Aeration performances and air—Water mass transfer on steep stepped weirs with horizontal and inclined steps

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Journal of Hydrodynamics 2022年第5期34卷 904-916页

作者： Yvan Arosquipa Nina Rui Shi Davide Wüthrich hubert chanson The University of Queensland School of Civil EngineeringBrisbaneAustralia Department of Hydraulic Engineering Delft University of TechnologyDelftThe Netherlands

At hydraulic structures,some strong interactions may develop between fast flowing waters and the air adjacent to the water in motion that enhance the air-water transfer of atmospheric and volatile gases in the flow.In turn,in-stream structures may contribute to the aeration and re-oxygenation during overflow.The present study aims to characterize the aeration performance of a steep stepped weir,based upon a detailed physical investigation of air-water interfacial properties across a relatively wide range of discharges.The data showed a strong fragmentation of the air-water flows,a very broad range of entrained bubbles and drops,and a large amount of particle clustering.The results implied a monotonic increase in re-aeration with increasing rate of energy dissipation,while the largest aeration efficiency was observed on the horizontal step weir chute,with the smallest on the 1V:2.33H inclined downward steps.Altogether,the study showed that a steep stepped chute can make a sizeable contribution to the re-oxygenation of the waters,although the downward inclined steps reduce the re-aeration performances.

关键词： Stepped weirs aeration re-oxygenation physical modeling flow fragmentation

Turbulence and suspended sediment processes in the Garonne River tidal bore in November 2016

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International Journal of Sediment Research 2019年第5期34卷 496-508页

作者： David Reungoat Xinqian Leng hubert chanson Université de Bordeaux I2MLaboratoire TREFLE CNRS UMR 5295 The University of Queensland School of Civil Engineering

A tidal bore is a water discontinuity at the leading edge of a flood tide wave in estuaries with a large tidal range and funneling topography. New measurements were done in the Garonne River tidal bore on14–15 November 2016, at a site previously investigated between 2010 and 2015. The data focused on long, continuous, high-frequency records of instantaneous velocity and suspended sediment concentration(SSC) estimate for several hours during the late ebb, tidal bore passage and flood tide. The bore passage drastically modified the flow field, with very intense turbulent and sediment mixing. This was evidenced with large and rapid fluctuations of both velocity and Reynolds stress, as well as large SSCs during the flood tide. Granulometry data indicated larger grain sizes of suspended sediment in water samples compared to sediment bed material, with a broader distribution, shortly after the tidal bore. The tidal bore induced a sudden suspended sediment flux reversal and a large increase in suspended sediment flux magnitude. The time-variations of turbulent velocity and suspended sediment properties indicated large fluctuations throughout the entire data set. The ratio of integral time scales of SSC to velocity in the x-direction was on average TE,SSC/TE,～0.16 during the late ebb tide, compared to TE,SSC/TE,～0.09 during the late flood tide. The results imply different time scales between turbulent velocities and suspended sediment concentrations.

关键词： Tidal bore Garonne River Hydrodynamics Suspended sediment Field observations Turbulence-sediment suspension interactions

EXTREME RESERVOIR SEDIMENTATION IN AUSTRALIA : A REVIEW

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International Journal of Sediment Research 1998年第3期13卷 59-67页

作者： hubert chanson 1 Department of Civil Engineering The University of Queensland

ＥＸＴＲＥＭＥＲＥＳＥＲＶＯＩＲＳＥＤＩＭＥＮＴＡＴＩＯＮＩＮＡＵＳＴＲＡＬＩＡ：ＡＲＥＶＩＥＷＨｕｂｅｒｔＣＨＡＮＳＯＮ１ＡＢＳＴＲＡＣＴＩｎｔｈｅｐａｐｅｒ，ｔｈｅａｕｔｈｏｒｒｅｖｉｅｗｓｔｈｅｐｒｏｂｌｅｍｏ... 详细信息

ＥＸＴＲＥＭＥＲＥＳＥＲＶＯＩＲＳＥＤＩＭＥＮＴＡＴＩＯＮＩＮＡＵＳＴＲＡＬＩＡ：ＡＲＥＶＩＥＷＨｕｂｅｒｔＣＨＡＮＳＯＮ１ＡＢＳＴＲＡＣＴＩｎｔｈｅｐａｐｅｒ，ｔｈｅａｕｔｈｏｒｒｅｖｉｅｗｓｔｈｅｐｒｏｂｌｅｍｏｆｒｅｓｅｒｖｏｉｒｓｉｌｔａｔｉ...

关键词： Reservoir sedimentation Australia Siltatio records Extreme siltation data Reservoir failtures

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小型亚热带半日潮河口中的湍流

人民珠江 2007年第1期28卷 16-22,38页

作者： hubert chanson Mark TREVETHAN 萧洁儿（翻译）昆士兰大学工程学院土木工程系布里斯班澳大利亚不详

在天然河口,污染物的输送是由湍流动量混合驱动的,而弥散的大小却难以被准确地预测。这是由于对河口的湍流结构缺乏基础的认识而造成的。介绍在一个小型的亚热带半日潮河口进行的高频率及连续50 h的湍流实地测量的情况。在研究的浅水(... 详细信息

在天然河口,污染物的输送是由湍流动量混合驱动的,而弥散的大小却难以被准确地预测。这是由于对河口的湍流结构缺乏基础的认识而造成的。介绍在一个小型的亚热带半日潮河口进行的高频率及连续50 h的湍流实地测量的情况。在研究的浅水(低潮水深小于0．5 m)小型河口中,使用了最适用于这种水体的声学多普勒流速仪进行测量,并进行了完整的后处理工作。河口水流是一个波动的过程,各种宏观流动参数随潮周期和其它大尺度的过程而波动,但是湍流特性是由即时局部流动特性所决定,它们基本不受流动历程的影响,其结构和瞬时变化受多种机理影响。这导致其只与水流剪切力引起的湍流边界层平衡相关。所有湍流特性在潮周期中均有大波动是本次研究数据的一个显著特征,这一特征在此前少有记载,但本次的测量数据与过往数据的一大差别是,数据连续测量的时间长且频率高。这将为波动特性的动量交换系数及积分时间和长尺度提供新的信息,这些湍流特性不应被视为不变的。

关键词：湍流亚热带河口(亚热带河口系统) 动量混合湍流雷诺应力湍流积分时间耗散时间尺度声学多普勒流速仪实地测量

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滩面涌潮水流实验室模拟研究

滩面涌潮水流实验室模拟研究