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Multi-physics methodology for phase change due to rapidly depressurised two-phase flows.

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Title: Multi-physics methodology for phase change due to rapidly depressurised two-phase flows.
Authors: Chávez-Modena, M.1,2 (AUTHOR) m.chavez@upm.es, Rubio, G.1,2 (AUTHOR), Valero, E.1,2 (AUTHOR), Mira, D.3 (AUTHOR), Lehmkuhl, O.3 (AUTHOR)
Source: International Journal of Multiphase Flow. Nov2021, Vol. 144, pN.PAG-N.PAG. 1p.
Subjects: Fire extinguishing agents, Theory of change, Firefighting, Spray nozzles, Two-phase flow, Atomization, Nozzles
Abstract: • CFD methodology to couple with a Zonal modelling for fire-extinguishing systems. • Atomization characterization of Novec-1230 agent through a nozzle. • A multiphase conservative level set LES predicts the primary breakup atomization. • A particle based/URANS method solves the spreading of the agent and phase change. Zonal modeling is a common technique for the numerical certification of fire-extinguishing systems, however it is not valid to simulate the complex physical phenomena that occurs near the agent injection. We present a multi-scale method for the accurate generation of inflow boundary conditions valid for zonal modeling based on the description of the phase change of a rapidly depressurised mist of a fire suppression system. The generation of accurate boundary conditions includes the characterization of the injection of the fire suppression agent from atomization to evaporation and mixing. The multi-scale methodology is based on the use of a high fidelity multiphase conservative level set LES for the characterization of the nozzle to develop an empirical model for primary breakup. Secondly, a low fidelity particle-based method with phase change and unsteady RANS is used for parametric studies. This multi-scale approach requires an affordable computational effort. The multi-scale methodology is tested in a system consisting of a pressurised fire extinguishing agent (Novec-1230) that is injected into the ambient through a nozzle that produces the atomization of the agent. The accuracy of the developed approach is compared with the experimental data. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:• CFD methodology to couple with a Zonal modelling for fire-extinguishing systems. • Atomization characterization of Novec-1230 agent through a nozzle. • A multiphase conservative level set LES predicts the primary breakup atomization. • A particle based/URANS method solves the spreading of the agent and phase change. Zonal modeling is a common technique for the numerical certification of fire-extinguishing systems, however it is not valid to simulate the complex physical phenomena that occurs near the agent injection. We present a multi-scale method for the accurate generation of inflow boundary conditions valid for zonal modeling based on the description of the phase change of a rapidly depressurised mist of a fire suppression system. The generation of accurate boundary conditions includes the characterization of the injection of the fire suppression agent from atomization to evaporation and mixing. The multi-scale methodology is based on the use of a high fidelity multiphase conservative level set LES for the characterization of the nozzle to develop an empirical model for primary breakup. Secondly, a low fidelity particle-based method with phase change and unsteady RANS is used for parametric studies. This multi-scale approach requires an affordable computational effort. The multi-scale methodology is tested in a system consisting of a pressurised fire extinguishing agent (Novec-1230) that is injected into the ambient through a nozzle that produces the atomization of the agent. The accuracy of the developed approach is compared with the experimental data. [ABSTRACT FROM AUTHOR]
ISSN:03019322
DOI:10.1016/j.ijmultiphaseflow.2021.103788