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uniform flow of Molten Metals in Rectangular Open Channels

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World Journal of Engineering and Technology 2022年第3期10卷 518-526页

作者： Miguel A. Barron Joan Reyes Dulce Y. Medina Departamento de Materiales Universidad Autonoma Metropolitana Azcapotzalco Mexico City Mexico

The flow of liquids in open channels has been studied since ancient Rome. However, the vast majority of published reports on flow in open channels are focused on the transport of drinking water and sewage disposal. The literature on the transport of molten metals in open channels is quite scarce. In this work, the uniform flow of pig iron and molten aluminum in rectangular open channels is studied. Specific energy curves are constructed and critical heights are analytically determined. The transition from subcritical to supercritical flow is analyzed as a function of the angle of inclination of the channel and the roughness of its walls. Manning’s equation is applied to the pig iron flow using data reported in the literature for molten aluminum. The need to correct the roughness coefficient for pig iron is observed in order to obtain results consistent with those previously reported.

关键词： Critical Height Froude Number Molten Metal flow Open Channel Rectangular Channel uniform flow

flow aeroacoustic damping using coupled mechanical electrical impedance in lined pipeline

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Chinese Physics B 2015年第5期24卷 410-414页

作者：陈勇黄奕勇陈小前白玉铸谭晓栋 College of Aerospace Science and Engineering National University of Defense Technology Department of Electronic Technology Officer’s College of CAPF

We report a new noise-damping concept which utilizes a coupled mechanical-electrical acoustic impedance to attenuate an aeroacoustic wave propagating in a moving gas confined by a cylindrical pipeline. An electrical damper is incorporated to the mechanical impedance, either through the piezoelectric, electrostatic, or electro-magnetic principles. Our numerical study shows the advantage of the proposed methodology on wave attenuation. With the development of the micro-electro-mechanical system and material engineering, the proposed configuration may be promising for noise reduction.

关键词： aeroacoustics mechanical-electrical impedance wave propagation uniform flow

维普期刊数据库

LAW OF BOUNDARY SHEAR IN OPEN RECTANGULAR CHANNELS WITH uniform ROUGHNESS

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Journal of Hydrodynamics 2004年第3期16卷 295-300页

作者： HUXu-yue ZENGGuang-ming XIEGeng-xin HUANGGuo-he LIJian-bing DepartmentofEnvironmentalScienceandEngineering HunanUniversityChangsha410082China

In accordance with the characteristics of the rectangular prismatic channel,the flow in the channel was divided into two parts, the bed part and the wall part. On the basis ofgeneral principles of mechanics, the area relation between the bed part and the wall part was workedout. A formula for determining the shear acting on the bed and the walls in rectangular channelswas derived, which has a simple form and is only related to the ratio of the breadth to the *** difference between the calculated value with the presented formula and the data published wasillustrated to be less than that with other, formulas, which shows that the formula is reasonableand can model the flow in the rectangular prismatic channel with higher accuracy and reliability.

关键词： uniform flow rectangular open channel bed walls boundary shear

维普期刊数据库

Influence of bank vegetation and gravel bed on velocity and Reynolds stress distributions

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International Journal of Sediment Research 2009年第2期24卷 236-246页

作者： Hossein AFZALIMEHR Subhasish DEY Department of Water Engineering Isfahan University of Technology Department of Civil Engineering Indian Institute of Technology

This paper presents the results of a laboratory flume experimental study on the interaction of bank vegetation and gravel bed on the flow velocity(primarily on the location of the maximum velocity,Umax) and the Reynolds stress distributions. The results reveal that the dip of the maximum velocity below the water surface is up to 35% of flow depth and the difference between Umax and the velocity at the water surface is considerable in the presence of vegetation on the walls. The zone of the log-law varies from y/h=2 up to 15 percent of flow depth and it does not depend on distance from the wall. Deviation of the velocity profile in the outer layer over a gravel bed with vegetation cover on the walls is much larger than the case of flow over a gravel bed without vegetation cover on the walls. The presence of vegetation on the walls changes uniform flow to non-uniform flow. This fact can be explained by considering the nonlinear Reynolds stress distribution and location of maximum velocity in each profile at different distances across the flume. The Reynolds stress distributions at the distance 0.02 m from the wall have negative values and away from the wall,they change the sign taking positive values with specific convex form with apex in higher location. Average of von Karman constant κ for this study is equal to 0.16. Based on κ=0.16,the methods of Clauser and the Reynolds stress are compatible for determination of shear velocity.

关键词： Bank vegetation uniform flow Reynolds stress Gravel bed Von Karman constant

Automated measurement of moving grains on bed deposits

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International Journal of Sediment Research 2011年第3期26卷 304-317页

作者： Amir H.N.CHEGINI Simon TAIT Lecturer of Civil Engineering Department Faculty of EngineeringUniversity of GuilanMain CampusI.R.of Iran School of Engineering Design and TechnologyUniversity of BradfordBradfordBD7 1DPUK.

The performance of gravel bedload predictor equations is particularly poor.A key reason for this situation is the current poor understanding of the physical mechanisms that are involved in the entrainment of grains from water-worked sediment *** has been caused,in part,by a lack of detailed data on the behaviour of moving sediment *** this study,observations of the entrainment, transport and deposition of many particles from a gravel bed has been collected and studied using an image-based *** system was used to measure the motion of hundreds of gravel particles moving as *** paper describes the development of the image-based system and the data processing methods used to provide the automated measurement of particle *** system was adapted from commercially available PIV equipment and was configured to obtain simultaneously data for the analysis of the moving grains and the near-bed flow *** techniques developed are relatively sensitive to sediment colour and shape by using related image processing algorithms and so could be applied to natural gravel *** results(image data)obtained from the techniques developed are amended in a program by using two functions(commands)of image processing called "Label2RGB",and "RegionProps" which distinguish the colour and shape of moving sediment grains *** data processing provided information that identified individual grain entrainments,*** accurately traced the motion of some,but not all,*** show that the system was able to estimate grain entrainment rates and indicate locations of preferential entrainment and deposition from data on hundreds of individual moving grains.

关键词： uniform flow Bed load Sediment transport Measurement Image processing