Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Nonuniform three-layer models to predict transient flows in buoyancy-driven natural ventilation with a localized heat source
Two classes of nonuniform three-layer models were developed to examine the transient flows driven by a localized heat source. The buoyancy combination coefficient () was proposed, and the buoyancy of the near-ceiling layer was assumed to be a linear combination of the buoyancy of the plume at the ceiling and the buoyancy at the middle layer. The nonuniform models were validated by previous experimental and numerical results to be a universal model and could predict the transient flows more precisely than conventional well-mixed models. Besides, the performance of the modified Model II is superior to Model I. The prediction accuracy increases with the change of , and when , Model II shows the best performance. Compared with thermal stratification height, has a more significant effect on the time evolution of buoyancy. The thermal stratification temperature has a linear variation with the source buoyancy flux, the effective vent area, the floor area, and the enclosure height. With the improvment of prediction accuracy, the temperature difference between the middle layer and the near-ceiling layer becomes smaller, even if there is little effect on the thermal stratification height. Moreover, the enclosure returns to a two-layer space again if the steady state is reached.
Nonuniform three-layer models to predict transient flows in buoyancy-driven natural ventilation with a localized heat source
Two classes of nonuniform three-layer models were developed to examine the transient flows driven by a localized heat source. The buoyancy combination coefficient () was proposed, and the buoyancy of the near-ceiling layer was assumed to be a linear combination of the buoyancy of the plume at the ceiling and the buoyancy at the middle layer. The nonuniform models were validated by previous experimental and numerical results to be a universal model and could predict the transient flows more precisely than conventional well-mixed models. Besides, the performance of the modified Model II is superior to Model I. The prediction accuracy increases with the change of , and when , Model II shows the best performance. Compared with thermal stratification height, has a more significant effect on the time evolution of buoyancy. The thermal stratification temperature has a linear variation with the source buoyancy flux, the effective vent area, the floor area, and the enclosure height. With the improvment of prediction accuracy, the temperature difference between the middle layer and the near-ceiling layer becomes smaller, even if there is little effect on the thermal stratification height. Moreover, the enclosure returns to a two-layer space again if the steady state is reached.
Nonuniform three-layer models to predict transient flows in buoyancy-driven natural ventilation with a localized heat source
Zhuang, Jiawei (Autor:in) / Jiang, Qiuran (Autor:in) / Diao, Yongfa (Autor:in)
Science and Technology for the Built Environment ; 25 ; 643-655
28.05.2019
13 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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