Upward vs downward injection of droplets for the optimization of a radiative shield |
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| Authors: | S Lechêne Z Acem G Parent G Jeandel P Boulet |
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| Affiliation: | 1. MedImmune, One MedImmune Way, Gaithersburg, MD 20878, USA;2. AstraZeneca, One MedImmune Way, Gaithersburg, MD 20878, USA;3. HealthCore, Inc., 800 Delaware Ave, 5th Floor, Wilmington, DE 19801, USA;4. University of Louisville, 201 South 5th Street, Bardstown, Suites 102 & 104, Louisville, KY 40004, USA;1. College of Environment and Energy Engineering, Anhui Jianzhu University, Hefei, Anhui 230022, China;2. College of Mechanical Engineering and Automation, Huaqiao University, Xiamen, Fujian 361021, China;3. Jiangsu Key Laboratory of Fire Safety in Urban Underground Space, China University of Mining and Technology, Xuzhou 221116, China;4. College of Civil Science and Engineering, Yangzhou University, Yangzhou, Jiangsu 225127, China;5. Department of Engineering Physics, Tsinghua University, Beijing 100091, China;6. School of Automotive and Transportation Engineering, Hefei University of Technology, Hefei, Anhui 230009, China;1. State Key Lab. of Fire Science, University of Science and Technology of China, Hefei 230026, China;2. Faculté Des Sciences, Université De Lorraine, 34 Cours Léopold, Nancy 54000, France;1. Department of Mechanical Engineering, Tokyo Denki University, 5 Senju-Asahicho, Adachi-ku, Tokyo 120-8551, Japan;2. Fire Prevention Division, Fire and Disaster Management Agency, 2-1-2 Kasumigaseki, Chiyoda-ku, Tokyo 100-8927, Japan |
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| Abstract: | A numerical and experimental study of a spray has been carried out at the laboratory scale, focusing on the comparison between downward and upward injection situations. The simulation has been carried out thanks to a dedicated numerical code addressing the two-phase flow with an Eulerian–Lagrangian approach, and treating the radiative transfer with a Monte Carlo method. The experimental setup involves a FTIR spectrometer and an IR camera, both characterizing simultaneously the spectral attenuation through the spray when irradiated by a blackbody. Numerical results and experimental data both show a better ability of the spray to attenuate radiation when injected upward. The residence time of droplets is highly increased when they are injected upward. This results in an increased attenuation ability of the spray. A gain by a factor 3 or more is possible regarding the attenuation of radiation if water is injected upward. This observation has to be considered with care however because of a possible poor stability of the spray. The influence of an air flow affecting the spray dynamics has also been investigated numerically, tests being done with a 2 m/s air flow. The droplet motion is strongly altered and the radiation attenuation is affected. In the upward injection case the deformation of the spray may be so strong in its upper part that the attenuation tends to zero because droplets are carried away. |
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