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Numerical study of a ventilation system based on wall confluent jets
University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering. Department of Management and Engineering, Linköping University, Linköping, Sweden .
University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering. Department of Management and Engineering, Linköping University, Linköping, Sweden .ORCID iD: 0000-0003-3472-4210
2014 (English)In: ASHRAE Transactions, ASHRAE , 2014, 272-284 p.Conference paper (Refereed)
Abstract [en]

This study presents a numerical investigation of an air supply device based on wall confluent jets in a ventilated room. Confluent jets can be described as multiple round jets issuing from supply device apertures. The jets converge, merge, and combine at a certain distance downstream from the supply device and behave as a united jet or so-called "confluent "jets. The numerical predictions of the velocity flow field of isothermal confluent jets with three Reynolds-averaged Navier-Stokes (RANS) turbulence models (RNG k-ε, realizable k-ε, and SST k - ω) are reported in the present study. The results of the numerical predictions are verified with detailed experimental measurements by hot-wire anemometer and constant-temperature anemometers for two airflow rates. The box method is used to provide the inlet boundary conditions. The study of the airflow distribution showed that a primary wall jet (wall confluent jet) exists close to the supply device along the wetted-wall and a secondary wall jet is created after the stagnation region along the floor. It is presented that the flow field of the primary and secondary wall jet predicted by turbulence models is in good agreement with the experimental data. The current study is also compared with the literature in terms of the velocity decay and the spreading rate of the primary and secondary wall jet, the results of which are consistent with each other. Velocity decay and the spreading rate of the secondary wall jet in vertical and lateral directions were studied for different inlet airflow rates and inlet discharge heights. The comparative results demonstrate that the flow behavior is nearly independent of the inlet flow rate. Inlet discharge height is found to have impact close to the inlet, where the velocity decays faster when the jet discharges at a higher level. The decay tendency is similar as the jet enters into the room for all discharge heights. 

Place, publisher, year, edition, pages
ASHRAE , 2014. 272-284 p.
Series
ASHRAE Transactions, ISSN 0001-2505 ; 120
Keyword [en]
Air, Anemometers, Flow fields, Forecasting, Jets, Navier Stokes equations, Oceanography, Turbulence models, Turbulent flow, Velocity, Ventilation, Airflow distribution, Constant-temperature anemometers, Hot wire anemometers, Numerical investigations, Numerical predictions, Reynolds-Averaged Navier-Stokes, Stagnation regions, Ventilation systems, Fighter aircraft
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:hig:diva-20078ScopusID: 2-s2.0-84937834516ISBN: 978-193650482-4OAI: oai:DiVA.org:hig-20078DiVA: diva2:844941
Conference
2014 ASHRAE Annual Conference, 28 June-2 July 2014, Seattle, USA
Available from: 2015-08-10 Created: 2015-08-10 Last updated: 2017-01-03Bibliographically approved

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Janbakhsh, SetarehMoshfegh, Bahram
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