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Journal of Hydrodynamics 2024年第2期36卷 340-354页

作者： Mahboubeh Barahimi Jueyi Sui School of Engineering University of Northern British ColumbiaPrince GeorgeCanada

This study aimed to investigate the previously unexplored effects of ice cover and submerged vegetation on flow *** were undertaken under both open channel and ice-covered flow *** bed material consisted of three non-uniform *** findings revealed that when vegetation patches were present on the bed and an ice cover was present,the velocity profiles exhibited a distinctive pattern with two peak *** kinetic energy(TKE)also exhibited two peaks,one above the vegetation bending height and another at the sheath section,with a decreasing trend towards the ice ***,quadrant analysis showed that when the flow surface is covered by an ice cover,the contributions of inward and outward events increased compared with those observed in an open channel *** most cases,these contributions surpassed the sweep and ejection *** findings enhance our understanding of vegetation’s response to diverse surface conditions and have practical implications for river management and environmental engineering.

关键词： Ice cover vegetation flow structure Reynolds shear stress turbulent kinetic energy(TKE) quadrant analysis

flow structure and Short-Term Riverbed Evolution in Curved Flumes

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Fluid Dynamics & Materials Processing 2023年第2期19卷 487-500页

作者： Shuxian Gao Yonggang Cao Yuchuan Bai Yanhua Yang Tianjin Research Institute for Water Transport Engineering Ministry of TransportTianjinChina South China Sea Marine Survey and Technology Center State Oceanic AdministrationGuangzhouChina State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjinChina

River bending is the major effect responsible for bed topography and bank *** this study,fluid velocity(measured by a three-dimensional Doppler advanced point current meter)and bed topographical data have been collected in 40 sections of an experimental *** whole flume was composed of an organic glass bend,upstream and downstream water tanks,two transition straight sections,a circulation pump,and a connection *** section has been found to be characterized by a primary circulation and a small reverse circulation,with some sections even presenting three more or more circulation *** minimum circulation intensity has been detected in proximity to the top of the curved channel,while a region with small longitudinal velocity has been observed near the concave bank of each bend,corresponding to the flat bed formed after a short period of *** maximum sediment deposition and scour depth in the presence of a uniform distribution of living flexible vegetation within 10 cm of the flume wall have been found to be smaller than those observed in the tests conducted without vegetation.

关键词： Continuous curved flume experimental study flow structure bed short-term evolution living flexible vegetation

Research on bubble trajectory and flow structure in helical-axial multiphase pump

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水动力学研究与进展B辑:英文版 2023年第3期35卷 533-548页

作者： Hui Quan Chen-xi Sun Kai Song Ya-nan Li Xiao-yi Liu Xue-ling Yang Liang Wang College of Energy and Power Engineering Lanzhou University of TechnologyLanzhou 730050China College of Engineering Nihon UniversityKoriyamaFukushimaJapan Shenyang Shengtai Environmental Protection Technology Co.Ltd Shenyang 110122China

The oil-gas two-phase hybrid transportation technology is one of the innovative technology directions for the exploitation and transportation of marginal and deep ocean *** helical-axial multiphase pump is a key equipment for oil and gas *** this stage,most of the research on this kind of pump focuses on the improvement of the structure and conveying ***,because of insufficient understanding of the flow behavior and mechanism of bubbles,it is easy to cause the gas-liquid *** this paper,the numerical simulation and test are combined to explore the changes in the bubble trajectory and flow structure of the helical-axial multiphase *** results shown that when the speed is lower than 1200 r/min,the bubble reaches the maximum volume at 1/2 of the midline of the impeller blade and it contact with the pressure surface,broken to the suction *** the rotation speed is higher than 1450 r/min,the number of bubbles in the impeller increases and the size *** backflow occurs in the tip clearance and strength increases *** research results have important significance for the theoretical design and engineering application of the helical-axial multiphase pump.

关键词： Helical-axial multiphase pump gas-liquid two-phase flow visualization experiment bubble trajectory flow structure

Impact of depth ratio on flow structure and turbulence characteristics of compound open channel flows

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Water Science and Engineering 2022年第3期15卷 265-272页

作者： Shao-wei Ding Cheng Zeng Jie Zhou Ling-ling Wang Chen Chen College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China College of Mechanics and Materials Hohai UniversityNanjing 211100China

Compound open channel flows appear in most natural rivers are of great importance in river management and flood *** this study,large eddy simulations were carried out to simulate the compound open channel flows with four different depth ratios(hr=0.10,0.25,0.50,and 0.75).The main flow velocity,secondary flow,Reynolds stress,and bed shear stress were obtained from numerical *** depth-averaged stream wise momentum equation was used to quantify the lateral momentum exchange between the main channel and *** instantaneous coherent structures were presented by the Q criterion *** impact of hr on flow structure and turbulence charac-teristics was *** results showed that with the increase of hr,the high velocity area in the main channel shifted to the floodplain,and the dip phenomenon became more obvious;the Reynolds stress largely contributed to the lateral momentum exchange within the flows near the side walls of floodplain;and the vortex structures were found to significantly increase in the floodplain region.

关键词： Large eddy simulation Compound open channel Depth ratio flow structure Turbulence characteristics

flow structure AND SEDIMENT TRANSPORT WITH IMPACTS OF AQUATIC VEGETATION

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Journal of Hydrodynamics 2008年第4期20卷 461-468页

作者： LIU Cheng SHEN Yong-ming Pearl River Hydraulic Research Institute Guangzhou 510611 China State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116023 China State Key L-aborat-ory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116023China

Aquatic vegetation plays an important role in the flow structure of open channels and thus changes the fate and the transport of sediment. This article proposes a three-dimensional turbulence model by introducing vegetation density and drag force into the control equations of water flow in the presence of vegetation. The model was used to calculate the impacts of submerged vegetation on the vertical profiles of longitudinal flow velocities, the changes of the depth-averaged flow velocities in a compound channel with emergent vegetation in the floodplain, the removal of suspended sediment from the channels by emergent vegetation, and the bed changes around and in a vegetated island. Numerical investigations show that aquatic vegetation retards flow in the vegetation zone, reduces the sediment transport capacity, and contributes to erosion on both sides of the vegetated island. Calculated results agree well with experimental results.

关键词： three-dimensional turbulence model aquatic vegetation flow structure sediment transport suspended sediment bed surface topography change

flow structure and unsteady fluctuation with separation over a two-dimensional backward-facing step

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Journal of Hydrodynamics 2019年第6期31卷 1204-1217页

作者： Fang-fang Wang Shi-qiang Wu Biao Huang State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210029China Smart Cities Institute Zhengzhou UniversityZhengzhou 450001China

The flow over a backward-facing step(BFS)is a typical separation and reattachment *** flow structures and unsteady mechanisms are still not well *** this paper,the global velocity fields of a BFS are obtained by a synchronous particle image velocimetry(PIV)system with Reh=5345(Reynolds number)and Er=2(expansion ratio).flow structures are distinguished and defined by the fraction of the negative velocity(upn).The reattachment zone(Lr)is quantitatively defined as(u0.9,u/0.1)on the bottom *** distribution of the large-scale vortices couples well with the divided flow structures and their temporal evolution presenting four stages(forming,developing,shedding and redeveloping)when travel *** unsteady motions with various low frequencies are well explained by the coherent vortices and flow *** the unsteady low frequency motions,the Kelvin Helmholtz(KH)vortices and the oscillation of Xr(OX)come likely from the free shear *** KH vortices contribute to the unsteadiness of the temporal flow,and the OX is the primary response to the vortical fluctuations.

关键词： Backward-facing step flow structure large-scale vortices unsteady motion free shear layer

Inlet Recirculation Influence to the flow structure of Centrifugal Impeller

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Chinese Journal of Mechanical Engineering 2010年第5期23卷 647-654页

作者： YANG Ce CHEN Shan LI Du YANG Changmao WANG Yidi School of Mechanical Engineering Beijing Institute of Technology Beijing 100081 China Hunan TYENMachinery Co. Ltd. Hengyang 421005 China

Inlet recirculation is proved as an effective way for centrifugal compressor surge margin extension,and is successively used in some engineering *** its working mechanism is still not being well understood,which leads to redesigning of inlet recirculation mostly by ***,most study about inlet recirculation is steady to *** is necessary to study surge margin extension mechanism about inlet *** expose the mechanism in detail,steady and unsteady numerical simulations were performed on a centrifugal compressor with and without inlet *** results showed that,with inlet recirculation,the inlet axial velocity is augmented,relative Mach number around blade tip leading edge area is significantly reduced and so is the flow *** the flow angle decreased,the incidence angle reduced which greatly improves the flow field inside the ***,inlet recirculation changes the blade loading around blade tip and restrains the flow separation on the blade suction side at the leading edge *** unsteady results of static pressure around blade surface,entropy at inlet crossflow section and vorticity distributions at near tip span surface indicated that,at near stall condition,strong fluctuation exists in the vicinity of tip area due to the interaction between tip leakage flow and core *** inlet recirculation these strong flow fluctuations are eliminated so the flow stability is greatly *** these improvements mentioned above are the reason for inlet recirculation delays compressor *** research reveals the surge margin extension reason of inlet recirculation from an unsteady flow viewpoint and provides important reference for inlet recirculation structure design.

关键词： centrifugal compressor inlet recirculation flow field calculation flow structure unsteady

Axial flow structure of solids holdup in an 18-m high-density CFB riser based on pressure measurements

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Particuology 2021年第1期19卷 116-125页

作者： Xin Su Chengxiu Wang Xingying Lan Huajian Pei Xiaoyang Mao Jinsen Gao State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China

The axial flow structure in a high-density CFB riser having a height of 18 m is investigated on the basis of pressure *** circulation rates reach 1400 kg/(m2 s)at superficial gas velocities of 5-9 m/s and the apparent solids holdup exceeds 0.2,indicating high-density operations have been *** apparent solids holdup increases with the solids circulation rate increasing and/or superficial gas velocity *** distributions of the apparent solids holdup have exponential shapes with denser regions at the bottom and more dilute regions in the upper *** apparent slip velocity increases with the increasing solids holdup and reaches 14 m/s,showing that there are more opportunities of cluster formation in high-density ***,the apparent slip velocity has a power relation with the apparent solids holdup under a wide range of operating conditions.

关键词： Circulating fluidized bed Pressure measurement flow structure Solids holdup Slip velocity

Heat transfer and flow structure of two-dimensional thermal convection over ratchet surfaces

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Journal of Hydrodynamics 2021年第5期33卷 970-978页

作者： Cheng Wang Lin-feng Jiang He-chuan Jiang Chao Sun Shuang Liu Center for Combustion Energy Key Laboratory for Thermal Science and Power Engineering of Ministry of EducationDepartment of Energy and Power EngineeringTsinghua UniversityBeijing 100084China Department of Engineering Mechanics School of Aerospace EngineeringTsinghua UniversityBeijing 100084China Yau Mathematical Sciences Center Tsinghua UniversityBeijing 100084China

This paper presents a numerical study of the Rayleigh-Benard convection(RBC)in two-dimensional cells with asymmetric(ratchet)roughness distributed on the top and bottom *** consider two aspect ratios of roughness y=1,2 and the range of the Rayleigh number 1.0 xlO6flow structure are found to be strongly dependent on both Ra and the roughness *** find that the roughness can have a significant influence on the organization of the secondary comer rolls,and the comer rolls are evidently suppressed by the roughness for intermediate values of *** the presence of the roughness,a sharp jump of the Nu values is identified as the Ra value is slightly increased,accompanied with the dramatic changes of the large-scale flow structure and the plume *** influences of the ratchet orientation on the heat transfer and the flow structure are discussed and analyzed.

关键词： Turbulent convection ratchet roughness heat transfer flow structure

Experiment on the Effect of Sediment Concentration on flow structure

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四川大学学报（工程科学版） 2005年第S1期37卷 41-45页

作者： Chen, Li Wu, Menwu Deng, Xiaoli Huang, Rongmin Lab. of Water Resources and Hydropower Eng. Sci. Wuhan Univ. Wuhan 430072 China

The paper studies on the sediment-laden flow by using *** calibration has been conducted to determine the relationship between backscattered signal strength and sediment concentration. Based on the experimental data,the interactions between sediment and fluid in open channel flow are investi- *** experiment shows that there exist inner relation between sediment concentration and turbulence, and the relationship is distinctry related to the diameter of particle as well as the flow co...

关键词： turbulence intensity mean velocity sediment concentration flow structure