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Effects of Environmental Factors on Corrosion Behavior of E690 Steel in Simulated Marine Environment

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 678-694页

作者： Jingjing Peng Jing Liu Shen Zhang Zhihui Wang Xian Zhang Kaiming Wu Collaborative Innovation Center for Advanced Steels Hubei Province Key Laboratory of Systems Science in Metallurgical ProcessThe State Key Laboratory of Refractories and MetallurgyWuhan University of Science and TechnologyWuhan430081China

The effects of hydrostatic pressure, dissolved oxygen, temperature and flow velocity, and their interaction on the corrosion rates of E690 high-strength steel (HSS) in simulated marine environments were studied using response surface methodology. The results show that the flow velocity exerts the most significant influence on the corrosion rate of E690 HSS. Consequently, the corrosion behavior of E690 HSS under varying flow velocities were analyzed profoundly from initial pitting corrosion to long-term corrosion properties. The results indicate that the flow state facilitates the mass transfer and enhances the adsorption tendency of Cl− by enhancing the electrochemical activity of the steel surface. These factors accelerate the electrochemical reactions, resulting in increased pitting density, depth and the long-term corrosion rates in dynamic seawater environments.

关键词： E690 steel Simulated marine environment Corrosion behavior flow velocity Response surface methodology(RSM)

Measurements and estimation of flow velocity in mobile bed rills

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International Journal of Sediment Research 2023年第1期38卷 97-104页

作者： Yunyun Ban China Agricultural University Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

Rills are primary sediment sources and hillslope water/sediment runoff transport channels. Water flow velocities in rills are easily affected by bed condition over eroding and non-eroding slopes, which is an important hydrodynamic process in soil erosion research. This research is done to demonstrate the poorly understood “feedback mechanism” related to slope independence of flow velocity to slope gradient. A series of experiments were done on silt loam soil slopes to measure water flow velocity in rills under nine unit width flow rates(q)(0.17 × 10-3, 0.33 × 10-3, 0.67 × 10-3, 1.33 × 10-3, 2.67 × 10-3,5.33 × 10-3, 10.67 × 10-3, 21.33 × 10-3, and 42.67 × 10-3m3/(s·m)) combined with four slope gradients(8.7%, 17.6%, 26.8%, and 36.4%), in which mobile bed rills were monitored. For unit flow velocity under q ≤ 1.33 × 10-3m2/s, independence of flow velocity to slope was obtained. However, the results indicated that slope gradient combined with a higher unit flow rate contributed to better velocity prediction and fitted with a segmented equation well(R2= 0.95). A feedback mechanism was able to verify that the increase in roughness directly dissipated flow energy to reduce flow velocity, but cannot completely counterbalances steep slope effect. The experimental results showed that erosion-caused morphological changes on soil slopes reduce flow velocity by half due to an increase in bed roughness. Therefore, the current experimental measurements considering a wide range of flow rate and slope gradient conditions is useful to reveal the steep slope effect in mobile bed rills. The analysis showed that, for the investigated conditions, the flow velocity is a slope gradient-and flow ratedependent parameter.

关键词： flow velocity flow rate Slope gradient Model fitting Slope morphology

Effects of flow velocity on water quality and ammonia excretion in recirculating aquaculture system culturing juvenile largemouth bass(Micropterus salmoides)

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International Journal of Agricultural and Biological Engineering 2022年第5期15卷 213-218页

作者： Runguo Xiao Ganxiang Wang Zhenlei Chen Zhangying Ye Songming Zhu Xueyan Ding Fan Zhou Jianlin Guo Jian Zhao College of Biosystems Engineering and Food Science Zhejiang UniversityHangzhou 310058China Pinghu Fisheries Technology Promotion Center Jiaxing 314200ZhejiangChina Ocean Academy Zhejiang UniversityZhoushan 316000ZhejiangChina Zhejiang Fisheries Technical Extension Center Hangzhou 310023China Key Laboratory of Healthy Freshwater Aquaculture Ministry of Agriculture and Rural AffairsKey Laboratory of Fish Health and Nutrition of Zhejiang Province/Zhejiang Institute of Freshwater FisheriesHuzhou 313001Zhejang Chna

flow velocity plays an important role in recirculating aquaculture systems(RAS)and the growing practice of culturing juvenile largemouth bass(Micropterus salmoides).In this study,the effects of flow velocity on the water quality as well as the ammonia excretion were discussed from the perspective of actual production,and a polynomial model of ammonia nitrogen excretion was established,using the juvenile largemouth bass.Results showed that the range of ammonia nitrogen and nitrite nitrogen decreased with flow velocity increasing,while the number and volume share of large particles increased.According to the polynomial model,compared with the medium flow velocity(11 cm/s,2.45 body length(bl)/s),the ammonia excretion of juvenile largemouth bass at high(18 cm/s,4.00 bl/s),and low(4 cm/s,0.90 bl/s)flow velocity changed faster with time,and the excretion rate peaked at the 6th hour after feeding,earlier than that under medium flow velocity.Therefore,it is suggested to increase the flow velocity at the 5th hour after feeding and then decreased it at the 10th hour,to ensure better water quality in RAS culturing juvenile largemouth bass.

关键词： flow velocity recirculating aquaculture system juvenile largemouth bass water quality ammonia excretion

flow characteristics and regime transition of aqueous foams in porous media over a wide range of quality,velocity,and surfactant concentration

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Petroleum Science 2023年第2期20卷 1044-1052页

作者： Bin-Fei Li Meng-Yuan Zhang Zhao-Min Li Anthony Kovscek Yan Xin Bo-Liang Li Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongPR China School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongPR China Department of Energy Resources Engineering Stanford UniversityStanfordCA94305USA

Aqueous foam is broadly applicable to enhanced oil recovery(EOR).The rheology of foam as a function of foam quality,gas and liquid velocities,and surfactant concentration constitute the foundation of its application.The great variations of the above factors can affect the effectiveness of N2 foam in EOR continuously in complex formations,which is rarely involved in previous relevant studies.This paper presents an experimental study of foam flow in porous media by injecting pre-generated N2 foam into a sand pack under the conditions of considering a wide range of gas and liquid velocities and surfactant concentrations.The results show that in a wide range of gas and liquid velocities,the pressure gradient contours are L-shaped near the coordinate axes,but V-shaped in other regions.And the surfactant concentration is a strong factor influencing the trend of pressure gradient contours.Foam flow resistance is very sensitive to the surfactant concentration in both the high-and low-foam quality regime,especially when the surfactant concentration is less than CMC.The foam quality is an important variable to the flow resistance obtained.There exists a transition point from low-to high-quality regime in a particular flow system,where has the maximum flow resistance,the corresponding foam quality is called transition foam quality,which increases as the surfactant concentration increases.The results can add to our knowledge base of foam rheology in porous media,and can provide a strong basis for the field application of foams.

关键词： Foam flow regime and transition Porous media Pressure gradient flow velocity Surfactant concentration Foam quality

Humic acid transport in saturated porous media:Influence of flow velocity and influent concentration

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Journal of Environmental Sciences 2014年第12期26卷 2554-2561页

作者： Xiaorong Wei Mingan Shao Lina Du Robert Horton State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Northwest A&F University Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Department of Agronomy Iowa State University Ames IA 50011 USA

Understanding the transport of humic acids（HAs） in porous media can provide important and practical evidence needed for accurate prediction of organic/inorganic contaminant transport in different environmental media and interfaces. A series of column transport experiments was conducted to evaluate the transport of HA in different porous media at different flow velocities and influent HA concentrations. Low flow velocity and influent concentration were found to favor the adsorption and deposition of HA onto sand grains packed into columns and to give higher equilibrium distribution coefficients and deposition rate coefficients, which resulted in an increased fraction of HA being retained in columns.Consequently, retardation factors were increased and the transport of HA through the columns was delayed. These results suggest that the transport of HA in porous media is primarily controlled by the attachment of HA to the solid matrix. Accordingly, this attachment should be considered in studies of HA behavior in porous media.

关键词： Attachment flow velocity Humic acid Initial concentration Porous media Transport

Quantitative study of degradation coefficient of pollutant against the flow velocity

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Journal of Hydrodynamics 2017年第1期29卷 118-123页

作者：黄本胜洪昌红杜欢欢邱静梁馨谭超刘达 Guangdong Research Institute of Water Resources and Hydropower Guangzhou 510610China Estuarine Water Technology National Local United Engineering Laboratory Guangzhou 510610China Zhongjiao Guangzhou Chanel Bureau Ltd. Guangzhou 510221China

The pollutant degradation coefficient is one of the key parameters to describe the water quality change, for establishing a reasonable water quality model and to determine the water carrying capacity and the environmental capacity. In this research, the environmental channel experiment is conducted to simulate the degradation evolution of the COD and NH3-N under different flow velocity conditions in typical pollution water. It is shown that the processes of the COD and the NH3-N＇s concentration over time are quite consistent with the first-order kinetic equation and the degradation coefficients increase with the increase of the flow velocity. When the flow velocity varies from 0 m＇s-1 to 0.87 m.s l, the degradation coefficients of the COD and NH3-N increase from 0.011 d-1 to 0.071 d-1 and 0.038 d-1 to 0.258 d-1, respectively. Moreover, the COD and NH3-N＇s degradation coefficients both have excellent correlation with the reaction time. There is a good linear relationship between the COD degradation coefficient and the flow velocity as well as a good power exponential function between the NH3-N degradation coefficient and the flow velocity. The compa- rative analysis of the Youth canal prototype monitoring and the calculation results shows that the quantitative formula obtained from the indoor water channel experiments gives results very close to the prototype observation results, which could reflect the degra- dation of pollutants in river water with varying flow velocity.

关键词： Degradation coefficient carrying capacity prototype observation flow velocity

Measuring flow velocity on frozen and non-frozen slopes of black soil through leading edge method

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International Soil and Water Conservation Research 2017年第3期5卷 180-189页

作者： Chao Chen Yunyun Ban Xuefeng Wang Tingwu Lei College of Water Resources and Civil Engineering China Agricultural UniversityQinghua DongluBeijing100083PR China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationChinese Academy of Science and Ministry of Water ResourcesYanglingShaanxi Province 712100PR China

flow velocity is a major parameter related to hillslope hydrodynamics erosion.This study aims to measure flow velocity over frozen and non-frozen slopes through leading edge method before being calibrated with accurate flow velocity to determine the correct coefficient for convenience of flow velocity measurement.Laboratory experiments were conducted on frozen and non-frozen soil slopes with flumes involving four slope gradients of 5°,10°,15°,and 20°and three flow rates of 1,2,and 4 L/min with a flume of 6 m long and 0.1 m wide.The measurements were made with a stopwatch to record the time duration that the water flow ran over the rill segments of 2,4 and 6 m long.Accurate flow velocity was measured with electrolyte trace method,under pulse boundary condition.The leading edge and accurate flow velocities were used to determine the correction coefficient to convert the former to the latter.Results showed that the correction coefficient on frozen soil slope was 0.81 with a coefficient of determination(R2)of 0.99.The correction coefficient on non-frozen soil slope was 0.79 with R2 of 0.98.A coefficient of 0.8 was applicable to both soil surface conditions.The accurate velocities on the four frozen black soil slopes were approximately 30%,54%,71%,and 91%higher than those on non-frozen soil slopes.By contrast,the leading edge flow velocities on the frozen soil slopes were 23%,54%,67%,and 84%higher than those on non-frozen soil slopes.The flow velocities on frozen soil slopes increased with flow rate at all four slopes,but they increased from 5 to 15°before getting stabilized.Therefore,rill flow velocity can be effectively measured with leading edge method by multiplying the leading edge velocity with a correction coefficient of 0.80.This study provides a strategy to measure rill flow velocity for studies on soil erosion mechanisms.

关键词： flow velocity Leading edge method Frozen/non-frozen soil

Optimal design of velocity sensor for open channel flow using CFD

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International Journal of Agricultural and Biological Engineering 2017年第3期10卷 130-142页

作者： Joseph Scot Dvorak Naiqian Zhang Department of Biosystems and Agricultural Engineering University of KentuckyLexingtonKentucky 40546-0276USA Department of Biological and Agricultural Engineering Kansas State UniversityManhattanKansas 66506USA

In this study,computational fluid dynamics(CFD)was used to design the geometry of a new velocity sensor for measuring open channel flows.This sensor determined velocity by observing the travel of dye carried in the flow.Evaluation of this design required the development of fluid dynamics models to determine potential errors in fluid velocity measurement due to velocity changes caused by intrusion of the sensor in the fluid.It also required an analysis technique to determine the expected sensor response to the flow fields that resulted from the CFD modeling.These models were then used to improve the geometry of the sensor to minimize the measurement error.Starting with a simple design for the sensor geometry,the CFD analysis modeled the open channel flow around the sensor as turbulent using both the k-ωand k-εReynolds Averaged Navier-Stokes(RANS)turbulence models.The model predicted that the original sensor design would underestimate the free-stream velocities of open channels by 7.9%to 2.0%across a range from 0.1 m/s to 5.0 m/s.After using CFD to improve the sensor design,the velocity measurement error was limited to less than 4%across the same velocity range.

关键词： computational fluid dynamics flow measurement sensors flow velocity open channel

Exploring spatial relationships between stream channel features,water depths and flow velocities during flash floods using HEC-GeoRAS and Geographic Information Systems

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Journal of Geographical Sciences 2022年第4期32卷 757-782页

作者： Miguel LEAL Eusébio REIS Pedro Pinto SANTOS Centre of Geographical Studies and Associated Laboratory TERRA Institute of Geography and Spatial PlanningUniversidade de Lisboa1600-276 LisbonPortugal Forest Research Centre and Associated Laboratory TERRA School of AgricultureUniversidade de LisboaTapada da Ajuda1349-017 LisbonPortugal

Water depths and flow velocities decisively influence the damage caused by flash floods.Geographic Information System(GIS)is a powerful and useful tool,allowing the spatial analysis of results obtained by hydraulic modelling,namely from the HEC-RAS/HEC-GeoRAS software.The GIS spatial analysis performed in this study seeks to explain and quantify the spatial relationships between the stream channel features and flow components during flash flood events.Despite these relationships are generically known,there are few studies exploring this subject in different geographic contexts.A 1D hydraulic model was applied in a small watershed in Portugal,providing good results in the definition of floodable areas,water depths and longitudinal velocities.No direct relationship was found between water depths and velocities in the floodable areas;however,negative strong correlations were found between the two flow components along the stream centerlines.Bed slope,channel and flood width,and roughness prove to be highly relevant on the longitudinal variations of water depths and velocities and on the location of maximum values.Increasing peak discharges and return periods(R;)can change the relationships between water depths and velocities at the same location.Results can be improved with more accurate elevation data for stream channels and floodplains.

关键词： flash floods water depth flow velocity geographic information systems(GIS) spatial analysis