Journal articles: 'Air-water flows'

1

Reinauer, R., and W. H. Hager. "Shockwave in air-water flows." International Journal of Multiphase Flow 22, no. 6 (November 1996): 1255–63. http://dx.doi.org/10.1016/0301-9322(96)00049-3.

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2

Beecham, Simon, and Terry Lucke. "Air water flows in building drainage systems." Urban Water Journal 12, no. 6 (October 24, 2013): 455–67. http://dx.doi.org/10.1080/1573062x.2013.820335.

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3

Granata, Francesco, Giovanni de Marinis, and Rudy Gargano. "Air-water flows in circular drop manholes." Urban Water Journal 12, no. 6 (April 14, 2014): 477–87. http://dx.doi.org/10.1080/1573062x.2014.881893.

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4

Chanson, H. "Air-water flows in partially-filled conduits." Journal of Hydraulic Research 35, no. 5 (September 1997): 591–602. http://dx.doi.org/10.1080/00221689709498396.

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5

Pothof, I. W. M., A. D. Schuit, and F. H. L. R. Clemens. "Influence of Surface Tension on Air-Water Flows." Journal of Hydraulic Engineering 139, no. 1 (January 2013): 44–50. http://dx.doi.org/10.1061/(asce)hy.1943-7900.0000637.

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6

Ptasińska, Sylwia, Józef Dąbek, and Leszek Michalak. "Formation of water dimers in expanding air flows." Vacuum 70, no. 2-3 (March 2003): 403–9. http://dx.doi.org/10.1016/s0042-207x(02)00677-2.

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7

Wang, Xia, and Xiaodong Sun. "Three-dimensional simulations of air–water bubbly flows." International Journal of Multiphase Flow 36, no. 11-12 (November 2010): 882–90. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2010.08.004.

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8

CHANSON, H. "Air-water interface area in self-aerated flows." Water Research 28, no. 4 (April 1994): 923–29. http://dx.doi.org/10.1016/0043-1354(94)90100-7.

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9

Turney, Damon E., and Sanjoy Banerjee. "Air–water gas transfer and near-surface motions." Journal of Fluid Mechanics 733 (September 26, 2013): 588–624. http://dx.doi.org/10.1017/jfm.2013.435.

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AbstractRates of gas transfer between air and water remain difficult to predict or simulate due to the wide range of length and time scales and lack of experimental observations of near-surface fluid velocity and gas concentrations. The surface renewal model (SR) and surface divergence model (SD) provide the two leading models of the process, yet they remain poorly tested by observation because near-surface velocity is difficult to measure. To contribute to evaluation of these models, we apply new techniques called interfacial particle imaging velocimetry (IPIV) and three-dimensional IPIV (3D-IPIV) for measuring water velocities within a millimetre of a moving deformable air–water interface. The latter technique (3D-IPIV) simultaneously measures the air–water interface topography. We apply these techniques to turbulent open-channel water flows and wind-sheared water flows with microscale breaking waves. Additional measurements made for each flow condition are bulk turbulent length scales, bulk turbulent velocity scales, air–water gas transfer rates, friction velocities, and wave characteristics. We analyse these data to test the surface divergence models for interfacial gas transfer. The first test is of predictions from the Banerjee (Ninth International Heat Transfer Conference, Keynote Lectures, vol. 1, 1990, pp. 395–418, Hemisphere Press) surface divergence model for gas transfer for homogeneous isotropic turbulence interacting with a planar free surface. The second test is of predictions from the McCready, Vassiliadou and Hanratty (AIChE J., vol. 32(7), 1986, pp. 1108–1115) surface divergence model, as applied in both open-channel flow and wind-sheared wavy flows. We find the predictions of the Banerjee and McCreadyet al. models to agree with the experimental data taken for open-channel flow conditions. On the other hand, for wind-driven flows with wind waves we find disagreement between the McCreadyet al. predictions and our direct measurements of the gas transfer coefficient. The cause of the disagreement is investigated by Lagrangian tracking of surface divergence of surface water patches, and by analysis of the corresponding Lagrangian time series with advection–diffusion concepts. A quantitative criterion based on surface divergence strength and lifetime is proposed to distinguish the effectiveness of each near-surface motion toward causing interfacial gas transfer. Capillary waves are found to contribute to surface divergence but to have too short a time scale to cause interfacial gas transfer. As wind speed increases, the presence and intensity on the air–water interface of capillary waves and other ineffective near-surface motions is diminished by the rise of turbulent wakes from microscale breaking waves thus causing the disagreement of the surface divergence model’s predicted transfer rates with measurements. A model of air–water gas transfer that combines the surface renewal and surface divergence models is formulated and found to agree with the data from both open-channel flows and wind-driven flows without requiring an empirical coefficient.

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10

Mykytyn, Ihor, and Olha Lopatko. "WATER AND AIR FLOWS TEMPERATURE PREDICTION USING NEURAL NETWORK." Measuring Equipment and Metrology 79, no. 3 (2018): 37–41. http://dx.doi.org/10.23939/istcmtm2018.03.037.

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11

Hetsroni, G., J. H. Yi, B. G. Hu, A. Mosyak, L. P. Yarin, and G. Ziskind. "Heat transfer in intermittent air–water flows—Part II." International Journal of Multiphase Flow 24, no. 2 (March 1998): 189–212. http://dx.doi.org/10.1016/s0301-9322(97)00056-6.

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12

Vassallo, P. "Near wall structure in vertical air–water annular flows." International Journal of Multiphase Flow 25, no. 3 (April 1999): 459–76. http://dx.doi.org/10.1016/s0301-9322(98)00052-4.

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13

Beceiro, Paula, Maria do Céu Almeida, and Jorge Matos. "Numerical modelling of air-water flows in sewer drops." Water Science and Technology 76, no. 3 (April 28, 2017): 642–52. http://dx.doi.org/10.2166/wst.2017.246.

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The presence of dissolved oxygen (DO) in water flows is an important factor to ensure the aerobic conditions recognised as beneficial to preventing the occurrence of detrimental effects. The incorporation of DO in wastewater flowing in sewer systems is a process widely investigated in order to quantify the effect of continuous reaeration through the air-liquid interface or air entrained due to the presence of singularities such as drops or junctions. The location of sewer drops to enhance air entrainment and subsequently reaeration is an effective practice to promote aerobic conditions in sewers. In the present paper, vertical drops, backdrops and stepped drops were modelled using the computational fluid dynamics (CFD) code FLOW-3D® to evaluate the air-water flows due to the turbulence induced by the presence of these types of structures. An assessment of the hydraulic variables and an analysis of the air entrainment based on the available experimental studies were carried out. The results of the CFD models for these structures were validated using measurements of discharge, pressure head and water depth obtained in the corresponding physical models. A very good fit was obtained for the hydraulic behaviour. After validation of numerical models, analysis of the air entrainment was carried out.

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14

Gonzalez, C. A., and H. Chanson. "Turbulence and cavity recirculation in air–water skimming flows." Journal of Hydraulic Research 46, no. 1 (January 2008): 65–72. http://dx.doi.org/10.1080/00221686.2008.9521843.

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15

Sun, Xiaodong, Sidharth Paranjape, Seungjin Kim, Basar Ozar, and Mamoru Ishii. "Liquid velocity in upward and downward air–water flows." Annals of Nuclear Energy 31, no. 4 (March 2004): 357–73. http://dx.doi.org/10.1016/j.anucene.2003.08.002.

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16

Amani, Pouria, Suzanne Hurter, Victor Rudolph, and Mahshid Firouzi. "Comparison of flow dynamics of air-water flows with foam flows in vertical pipes." Experimental Thermal and Fluid Science 119 (November 2020): 110216. http://dx.doi.org/10.1016/j.expthermflusci.2020.110216.

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17

MATSUZAKI, Yu, Susumu NAKANO, Yoichi TAKEDA, and Kunihiro SATOU. "ICOPE-15-1064 A fundamental study on breakup patterns of water film splashed into air flows." Proceedings of the International Conference on Power Engineering (ICOPE) 2015.12 (2015): _ICOPE—15——_ICOPE—15—. http://dx.doi.org/10.1299/jsmeicope.2015.12._icope-15-_47.

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18

Acunha Jr, I. C., and P. S. Schneider. "NUMERICAL SIMULATION OF AIR – WATER FLOWS IN AN EVAPORATIVE CONDENSER." Revista de Engenharia Térmica 8, no. 1 (June 30, 2009): 24. http://dx.doi.org/10.5380/reterm.v8i1.61877.

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Evaporative condensers present a hard problem for numerical modeling because of the complex phenomena of heat and mass transfer outside of the bundle tubes in turbulent flows. The goal of this work is to study the air and water behavior inside an evaporative condenser operating with ammonia as the refrigerant fluid. A commercial CFD software package (FLUENT) is employed to predict the two-phase flow of air and water droplets in this equipment. The air flow is modeled as a continuous phase using the Eulerian approach while the droplets water flow is modeled as a disperse phase with Lagrangian approach. The coupling between pressure and velocity fields is performed by the SIMPLE algorithm. The pressure, velocity and temperature fields are used to perform qualitative analyses to identify functional aspects of the condenser, while the temperature and the relative humidity evolution contributed to verify the agreement between the results obtained with the numerical model and those presented by equipment manufacturer.

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19

Pfister, Michael, and Hubert Chanson. "Two-phase air-water flows: Scale effects in physical modeling." Journal of Hydrodynamics 26, no. 2 (April 2014): 291–98. http://dx.doi.org/10.1016/s1001-6058(14)60032-9.

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20

Kodres, C. A. "Coupled water and air flows through a bioremediation soil pile." Environmental Modelling & Software 14, no. 1 (October 1998): 37–47. http://dx.doi.org/10.1016/s1364-8152(98)00021-8.

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21

Costigan, G., and P. B. Whalley. "Measurements of the speed of sound in air-water flows." Chemical Engineering Journal 66, no. 2 (February 1997): 131–35. http://dx.doi.org/10.1016/s1385-8947(96)03169-5.

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22

Chanson, Hubert. "Unsteady air?water flow measurements in sudden open channel flows." Experiments in Fluids 37, no. 6 (October 30, 2004): 899–909. http://dx.doi.org/10.1007/s00348-004-0882-3.

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23

Felder, Stefan, and Hubert Chanson. "Triple decomposition technique in air–water flows: Application to instationary flows on a stepped spillway." International Journal of Multiphase Flow 58 (January 2014): 139–53. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2013.09.006.

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24

Kyto¨maa, H. K., and C. E. Brennen. "Some Observations of Flow Patterns and Statistical Properties of Three Component Flows." Journal of Fluids Engineering 110, no. 1 (March 1, 1988): 76–84. http://dx.doi.org/10.1115/1.3243514.

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Vertical air-water flows, solids-water flows and three component air-solids-water flows were investigated in a Three Component Flow Facility. Visual observations of the flow patterns show that three component flows undergo transition and can exhibit strong unsteady vortical motions. Measurements of the fluctuations in cross-sectionally averaged volume fraction measurements were made. The statistical properties of the fluctuations are presented in terms of their amplitude and coherent time scale in the form of the Signal To Noise Ratio (STNR) and the Time Constant (ξ), respectively. Remarkably, the solids-water flows and the dispersed bubbly air-water flows exhibit almost identical values of STNR for the same volume fraction. Equally remarkable in the linear relationship between the Time Constant and the mean bubble or particle velocity; this relationship is found to have the same constant of proportionality for both species in the well behaved disperse regime. In the two-component churn-turbulent and the three-component agitated vortical regimes, the variables ξ and STNR significantly deviate from their dispersed regime values. The onset of large coherent structures characteristic of these regimes is reflected by a rise in the amplitude of the fluctuations and a marked increase in their coherent time scale. The results of this study demonstrate the large information content in the fluctuations of the measured quantity, both as a flow regime indicator and as a measure of flow quantities in two- and three-component flows.

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25

Shakouchi, Toshihiko, Ryosuke Ozawa, Fumi Iwasaki, Koichi Tsujimoto, and Toshitake Ando. "OS23-5 Flow and Heat Transfer of Petal Shaped Double Tube : Water and Air-Water Bubbly Flows(Thermo-fluid dynamics(2),OS23 Thermo-fluid dynamics,FLUID AND THERMODYNAMICS)." Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2015.14 (2015): 282. http://dx.doi.org/10.1299/jsmeatem.2015.14.282.

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26

Yang, James, Penghua Teng, Qiancheng Xie, and Shicheng Li. "Understanding Water Flows and Air Venting Features of Spillway—A Case Study." Water 12, no. 8 (July 24, 2020): 2106. http://dx.doi.org/10.3390/w12082106.

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For safe spillway discharge of floods, attention is paid to the water flow. The resulting air flow inside the facility, an issue of personnel security, is sometimes disregarded. The spillway in question comprises two surface gates and two bottom outlet gates lying right below. Air passages to the outlet gates include an original gallery and a recently constructed vertical shaft. To understand water-air flow behavior, 3D CFD modelling is performed in combination with the physical model tests. The simulations are made with fully opened radial gates and at the full pool water level (FPWL). The results show that the operation of only the bottom outlets leads to an air supply amounting to ~57 m3/s, with the air flow rates 35 and 22 m3/s to the left and right outlets. The air supply to the right outlet comes from both the shaft and the gallery. The averaged air velocity in the shaft and the gallery are approximately 5 and 7 m/s. If only the surface gates are fully open, the water jet impinges upon the canal bottom, which encloses the air space leading to the bottom outlets; the air flow rate fluctuates about zero. If all the four gates are open, the total air demand is limited to ~10 m3/s, which is mainly attributable to the shear action of the meeting jets downstream. The air demand differs significantly among the flow cases. It is not the simultaneous discharge of all openings that results in the largest air demand. The flood release from only the two outlets is the most critical situation for the operation of the facility. The findings should provide reference for spillways with the same or similar layout.

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27

Badriev, A. I., V. N. Sharifullin, S. M. Vlasov, and N. D. Chichirova. "Study of operation of natural draft cooling tower, with its hydraulic load reduced." Safety and Reliability of Power Industry 12, no. 4 (January 25, 2020): 268–73. http://dx.doi.org/10.24223/1999-5555-2019-12-4-268-273.

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A survey has been held of a BG-2600 natural draft cooling tower of thermal power plants, in the reduced hydraulic load mode. The technical condition of the reinforced concrete tower, the skeleton frame, the irrigation device, the water distribution system and the air duct windows has been inspected. Defects of the cooling tower structural elements have been identified. These include: horizontal sagging of the irrigation device, considerable gaps between its blocks and their partial destruction, problems with nozzles and structures of air duct windows. The identified defects are attributed to the causes of irregular water and air flows. The degree of irregularity of irrigation density and air flow in the tower has been estimated. Over the cross-section of the tower, a significant standard deviation from the average value or irregularity of irrigation density (30%) and irregularity of air flow (23.5%) has been established. The temperature and cooling curves of the cooling tower have been plotted taking into account irregularities of irrigation density and air flow rate. Normal and defective sections of the cooling tower have been identified based on working characteristics. Standard characteristics of the BG-2600 cooling tower have been plotted based on a nomogram. A comparative analysis of the working and standard characteristics has been held. The degree of influence produced by irregularities in water and air flows on the cooling process has been established. It has been found that the established irregularities in water and air flows result in a decrease in the temperature difference on average by 2°C and a decrease of cooling capacity by 7.3 Mcal/m2∙hr with a hydraulic load of 8840 m3/h. The results indicate a significant impact produced by irregularities of flows on cooling effect. The tasks to eliminate irregularities in distribution of flows as well as to increase the tower cooling efficiency have been formulated.

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28

Cummings, P. D., and H. Chanson. "Air Entrainment in the Developing Flow Region of Plunging Jets—Part 1: Theoretical Development." Journal of Fluids Engineering 119, no. 3 (September 1, 1997): 597–602. http://dx.doi.org/10.1115/1.2819286.

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Air-water bubbly flows are encountered in many engineering applications. One type of air-water shear flows is the developing flow region of a plunging jet. The mechanisms of air entrainment by plunging liquid jets are discussed in the light of new experimental evidence. Then the air bubble diffusion is analyzed analytically in the near-flow field of both circular and two-dimensional plunging jets. The theoretical developments are compared with existing circular plunging jet data and new experiments performed with a two-dimensional vertical supported jet. The study highlights two mechanisms of air entrainment at the plunge point depending upon the jet impact velocity and results suggest that the dispersion of air bubbles within the shear layer is primarily an advective diffusion process.

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29

Sun, Xiaodong, Sidharth Paranjape, Seungjin Kim, Hiroshi Goda, Mamoru Ishii, and Joseph M. Kelly. "Local Liquid Velocity in Vertical Air-Water Downward Flow." Journal of Fluids Engineering 126, no. 4 (July 1, 2004): 539–45. http://dx.doi.org/10.1115/1.1777235.

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This paper presents an experimental study of local liquid velocity measurement in downward air-water bubbly and slug flows in a 50.8 mm inner-diameter round pipe. The axial liquid velocity and its fluctuations were measured by a laser Doppler anemometry (LDA) system. It was found that the maximum liquid velocity in a downward two-phase flow could occur off the pipe centerline at relatively low liquid flow rates and this observation is consistent with other researchers’ results. The comparisons between the liquid flow rates measured by a magnetic flow meter and those obtained from the local LDA and multi-sensor conductivity probe measurements showed good agreement. In addition, based on the local measurements the distribution parameter and the drift velocity in the drift-flux model were obtained for the current downward flow tests.

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30

Murgan, Irina, Florentina Bunea, Adrian Nedelcu, and Gabriel Dan Ciocan. "Experimental setup to study two phase flows for environmental applications." E3S Web of Conferences 85 (2019): 07010. http://dx.doi.org/10.1051/e3sconf/20198507010.

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The air water mix is a major concern for the environmental application. This paper proposes an experimental method to accede simultaneously at the water flow velocity field and at the void fraction. Instantaneous and mean fields, as well as the evolution with the flow parameters variation are obtained in cavitation or aerated flows. This method allows a good accuracy for the flow velocity fields (2%) and void (vapours or air) contours (4%).

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31

Zamankhan, Piroz. "Simulation of Cavitation Water Flows." Mathematical Problems in Engineering 2015 (2015): 1–16. http://dx.doi.org/10.1155/2015/872573.

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The air-water mixture from an artificially aerated spillway flowing down to a canyon may cause serious erosion and damage to both the spillway surface and the environment. The location of an aerator, its geometry, and the aeration flow rate are important factors in the design of an environmentally friendly high-energy spillway. In this work, an analysis of the problem based on physical and computational fluid dynamics (CFD) modeling is presented. The numerical modeling used was a large eddy simulation technique (LES) combined with a discrete element method. Three-dimensional simulations of a spillway were performed on a graphics processing unit (GPU). The result of this analysis in the form of design suggestions may help diminishing the hazards associated with cavitation.

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32

Zboray, Robert, Volker Dangendorf, Ilan Mor, Kai Tittelmeier, Benjamin Bromberger, and Horst-Michael Prasser. "Time-resolved Fast Neutron Radiography of Air-water Two-phase Flows." Physics Procedia 69 (2015): 551–55. http://dx.doi.org/10.1016/j.phpro.2015.07.078.

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33

Chanson, H., and L. Toombes. "Air–water flows down stepped chutes: turbulence and flow structure observations." International Journal of Multiphase Flow 28, no. 11 (November 2002): 1737–61. http://dx.doi.org/10.1016/s0301-9322(02)00089-7.

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34

Dinesh Kumar, E., S. A. Sannasiraj, and V. Sundar. "Phase field lattice Boltzmann model for air-water two phase flows." Physics of Fluids 31, no. 7 (July 2019): 072103. http://dx.doi.org/10.1063/1.5100215.

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35

KIMURA, Shigeo. "0506 Velocity Vector Sensors - Applications for Ground Water and Air Flows." Proceedings of Conference of Hokuriku-Shinetsu Branch 2012.49 (2012): 050601–2. http://dx.doi.org/10.1299/jsmehs.2012.49.050601.

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36

YOSHIDA, Keisuke, Satoru USHIJIMA, and Iehisa NEZU. "DIRECT NUMERICAL SIMULATION OF AIR-WATER TURBULENT FLOWS WITH DEFORMED INTERFACE." PROCEEDINGS OF HYDRAULIC ENGINEERING 49 (2005): 709–14. http://dx.doi.org/10.2208/prohe.49.709.

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37

Wei, Wang-ru, Wei-lin Xu, Jun Deng, Zhong Tian, and Fa-xing Zhang. "Experimental study of air-water interface properties in self-aerated flows." Journal of Hydrodynamics 31, no. 5 (December 27, 2018): 940–48. http://dx.doi.org/10.1007/s42241-018-0162-y.

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38

Su, Yuliang, Mingyuan Zhang, Xianran Zhu, Qihui Hu, and Yanhong Geng. "Measurements of wall shear stress in horizontal air–water bubbly flows." Flow Measurement and Instrumentation 21, no. 3 (September 2010): 373–81. http://dx.doi.org/10.1016/j.flowmeasinst.2010.04.008.

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39

Gualtieri, C., and H. Chanson. "Physical and numerical modelling of air-water flows: An Introductory Overview." Environmental Modelling & Software 143 (September 2021): 105109. http://dx.doi.org/10.1016/j.envsoft.2021.105109.

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40

Felder, S., and H. Chanson. "Air–water flow measurements in a flat slope pooled stepped waterway." Canadian Journal of Civil Engineering 40, no. 4 (April 2013): 361–72. http://dx.doi.org/10.1139/cjce-2012-0464.

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Air–water flows on stepped spillways were investigated experimentally in the last decades with a focus on steep slope chutes equipped with flat horizontal steps. Detailed air–water flow properties were recorded herein with three stepped geometries down a slope of θ = 8.9° with: flat horizontal steps, pooled steps, and a combination of flat and pooled steps. The data included the distributions of basic air–water flow properties, as well as the energy dissipation and flow resistance data deduced from the air–water flow measurements. The results on the flat slope showed that the pooled stepped design enabled a greater rate of energy dissipation, but the pooled stepped geometries were affected by some flow instabilities and unsteady flow processes for a range of flow rates.

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41

Déronzier, G., Ph Duchène, and A. Héduit. "Optimization of oxygen transfer in clean water by fine bubble diffused air system and separate mixing in aeration ditches." Water Science and Technology 38, no. 3 (August 1, 1998): 35–42. http://dx.doi.org/10.2166/wst.1998.0170.

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The influence of design parameters on the transfer of oxygen was studied in different ring ditches equipped with fine bubble membrane air diffusers and separate mixing. The results produced evidence that the oxygen transfer efficiency (OTE) decreases when the air flow rate per diffuser increases. OTE increases asymptotically with the horizontal water flow (50% for velocity up to 0.5 m/sec). It increases also when the diffuser modules are brought closer together. Theoretical analysis enabled ranking of the impact of the design parameters on which the oxygen transfer is dependent, namely the interfacial area (a) and the oxygen transfer coefficient (Kl). The increase in the air flow rate per diffuser essentially reduces the interfacial area by an increase in the diameter of the initial air bubbles and by a reduction of the contact time due to an acceleration of the “spiral flows” (vertical rotation of water flow). The horizontal rotation of water increases the interfacial area most probably by decreasing the diameter of the initial air bubbles and by a lengthening of the contact time resulting from a reduction in the large spiral flows. Bringing the diffuser modules closer together makes longer the contact time by a reduction in the large spiral flows.

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42

Chanson, H., and L. Toombes. "Experimental investigations of air entrainment in transition and skimming flows down a stepped chute." Canadian Journal of Civil Engineering 29, no. 1 (February 1, 2002): 145–56. http://dx.doi.org/10.1139/l01-084.

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Stepped spillways have been used for about 3500 years. The last few decades have seen the development of new construction materials, design techniques, and applications, for example, embankment overtopping protection systems. Although it is commonly acknowledged that free-surface aeration is significant in stepped chutes, experimental data are scarce, often limited to very steep slopes (α ~ 50°). This paper presents an experimental study conducted in a large-size stepped chute (α = 22°, h = 0.1 m, W = 1 m). Observations demonstrate the existence of a transition flow pattern for intermediate flow rates between nappe and skimming flows. Detailed airwater flow measurements were conducted in both transition and skimming flows, immediately downstream of the inception point of free-surface aeration where uniform equilibrium flow conditions were not achieved. In skimming flows, a complete characterization is developed for the distributions of void fraction, bubble count rate, and velocity, and flow resistance data are compared with other studies. Transition flows exhibit significantly different airwater flow properties. They are highly aerated, requiring the design of comparatively high chute sidewalls.Key words: stepped spillway, air entrainment, two-phase flow properties, skimming flow, transition flow.

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43

Kökpınar, Mehmet Ali, and Mustafa Göğüş. "High-speed jet flows over spillway aerators." Canadian Journal of Civil Engineering 29, no. 6 (December 1, 2002): 885–98. http://dx.doi.org/10.1139/l02-088.

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The characteristics of high-speed air-entrained jet flow over a spillway aerator were investigated using experimental data. Three different ramp designs (as well as the case of no ramp) were tested in a channel where the bed slope was adjusted to 0, 0.17, and 0.57, respectively. The effects of aerator geometry and flow condition on the air-entrainment process within the water jet and on the pressure fluctuations in the impact region are the main focus of the investigation. An extensive data analysis was performed for data obtained from this study and from a similar laboratory study conducted by another investigator. Experimental relations were derived for nondimensional parameters of jet length, aerator cavity subpressure number, and aeration rates through the lower and upper nappes of the water jet. Scale effects for lower nappe aeration and aerator cavity subpressure number were considered and a good correlation was determined with prototype aerator measurements of Emborcaçao, Foz do Areia, and Keban dams for lower nappe aeration and Guri Dam for aerator cavity subpressure numbers. An aerator without a ramp may be subjected to excessive pressure fluctuations at the impact region due to insufficient air entrainment. Key words: air entrainment, aerator, scale effect, jet length, cavity subpressure.

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44

Gonzalez, C. A., and H. Chanson. "Interactions between cavity flow and main stream skimming flows: an experimental study." Canadian Journal of Civil Engineering 31, no. 1 (January 1, 2004): 33–44. http://dx.doi.org/10.1139/l03-066.

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In the last two decades, research on the hydraulics of skimming flows down stepped chutes was driven by needs for better design guidelines. Skimming flows are characterized by significant momentum transfer from the main stream to the recirculation zones. Investigations are difficult because of the complex nature of the flow, the strong flow aeration, and the interactions between entrained air and turbulence. This study provides a comprehensive database on main stream and cavity flow interactions in skimming flows down a stepped chute. Measurements were conducted on a large facility (α = 15.9°, h = 0.05 and 0.1 m, W = 1 m) with precise instrumentation based upon a Froude similitude. Air–water velocity and turbulence measurements demonstrated a well-defined mixing layer developing downstream of each step edge in which the velocity profiles had the same shape as classical monophase flow results. A comparative analysis of air–water flow properties for Froude similar flow conditions showed a good agreement between the two step heights in terms of dimensionless distributions of air content, velocity, and turbulence intensity, but dimensionless bubble count rates, turbulence levels, and bubble chord sizes were improperly scaled.Key words: stepped chute, skimming flow, flow recirculation, momentum exchange, physical modelling.

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Sassi, Paolo, Youssef Stiriba, Julia Lobera, Virginia Palero, and Jordi Pallarès. "Experimental Analysis of Gas–Liquid–Solid Three-Phase Flows in Horizontal Pipelines." Flow, Turbulence and Combustion 105, no. 4 (May 9, 2020): 1035–54. http://dx.doi.org/10.1007/s10494-020-00141-1.

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AbstractThe dynamics of three-phase flows involves phenomena of high complexity whose characterization is of great interest for different sectors of the worldwide industry. In order to move forward in the fundamental knowledge of the behavior of three-phase flows, new experimental data has been obtained in a facility specially designed for flow visualization and for measuring key parameters. These are (1) the flow regime, (2) the superficial velocities or rates of the individual phases; and (3) the frictional pressure loss. Flow visualization and pressure measurements are performed for two and three-phase flows in horizontal 30 mm inner diameter and 4.5 m long transparent acrylic pipes. A total of 134 flow conditions are analyzed and presented, including plug and slug flows in air–water two-phase flows and air–water-polypropylene (pellets) three-phase flows. For two-phase flows the transition from plug to slug flow agrees with the flow regime maps available in the literature. However, for three phase flows, a progressive displacement towards higher gas superficial velocities is found as the solid concentration is increased. The performance of a modified Lockhart–Martinelli correlation is tested for predicting frictional pressure gradient of three-phase flows with solid particles less dense than the liquid.

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Ko, Min Seok, Sung Yong Lee, Bo An Lee, Byong Jo Yun, Kyung Youn Kim, and Sin Kim. "An electrical impedance sensor for water level measurements in air–water two-phase stratified flows." Measurement Science and Technology 24, no. 9 (July 26, 2013): 095301. http://dx.doi.org/10.1088/0957-0233/24/9/095301.

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Swean, T. F., and A. N. Beris. "Dynamics of Free-Surface Flows With Surfactants." Applied Mechanics Reviews 47, no. 6S (June 1, 1994): S173—S177. http://dx.doi.org/10.1115/1.3124399.

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There is ample quantitative evidence (through, for example, surface tension measurements) of the presence of surfactants at the air-sea interface in sufficient quantities to influence the sea surface dynamics and its interactions with ambient flow turbulence. The importance of the role of the surfactants can also be judged from independent observations of phenomena such as suppression of short wavelength capillary waves and the presence of long-lived slick structures at the ship wakes. Although there is consensus on the presence of surfactants as the underlying reason behind these phenomena, the capability of quantitative predictions is still lacking for most of them. The objective of the present work is to introduce to the general engineering mechanics community the governing equations and the relevant issues associated with the study of free surface flows with surfactants. In particular, we focus on the interactions between a high Reynolds number flow, interface deformation and surfactant distribution next to and at the water-air interface. In addition, recent progress is briefly reviewed. Then, the remaining outstanding issues to allow the understanding of the dynamics of nonlinear interactions between turbulent flow and surfactant structure and concentration at the air-water interface are outlined.

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Carrillo, José M., Patricio R. Ortega, Luis G. Castillo, and Juan T. García. "Air–Water Properties in Rectangular Free-Falling Jets." Water 13, no. 11 (June 5, 2021): 1593. http://dx.doi.org/10.3390/w13111593.

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This study analyzes the air–water flow properties in overflow nappe jets. Data were measured in several cross-sections of rectangular free-falling jets downstream of a sharp-crested weir, with a maximum fall distance of 2.0 m. The flow properties were obtained using a conductivity phase-detection probe. Furthermore, a back-flushing Pitot-Prandtl probe was used in order to obtain the velocity profiles. Five specific flows rates were analyzed, from 0.024 to 0.096 m3/s/m. The measurements of the air–water flow allowed us to characterize the increment of the air entrainment during the fall, affecting the flow characteristic distributions, reducing the non-aerated water inner core, and increasing the lateral spread, thereby leading to changes in the jet thickness. The results showed slight differences between the upper and lower nappe trajectories. The experimental data of the jet thickness related to a local void fraction of 50% seemed to be similar to the jet thickness due only to gravitational effects until the break-up length was reached. The amount of energy tended to remain constant until the falling distance was over 15 times greater than the total energy head over the weir crest, a distance at which the entrained air affected the entire cross-section, and the non-aerated core tended to disappear. The new experiments related with air–water properties in free-falling jets allow us to improve the current knowledge of turbulent rectangular jets.

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Shin, Sangmook. "SIMULATION OF WATER-OIL-AIR FLOWS AROUND OIL BOOMS UNDER RELATIVE MOTION." Journal of computational fluids engineering 21, no. 3 (September 30, 2016): 31–38. http://dx.doi.org/10.6112/kscfe.2016.21.3.031.

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Chanson, Hubert, and Carlos A. Gonzalez. "Physical modelling and scale effects of air-water flows on stepped spillways." Journal of Zhejiang University SCIENCE 6A, no. 3 (March 2005): 243–50. http://dx.doi.org/10.1631/jzus.2005.a0243.

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Journal articles on the topic 'Air-water flows'

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