Radiation characteristics of water droplets in a fire-inspired environment: A Monte Carlo ray tracing study. (June 2018)

• Record Type: Journal Article
• Authors: Wu, Bifen; Zhao, Xinyu
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 212(2018)
• Page Start: 97
• Page End: 111
• Publication Date: 2018-06
• Subjects: Water mist radiation -- Anisotropic scattering -- Monte Carlo -- Tabulation method; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2018.03.023
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: A MCRT radiation solver that accounts for nongray gas, soot and water mist is developed. The radiation attenuations by monodispersed/polydispersed water mists systems are evaluated in a three-dimensional cubic enclosure. Fourteen available benchmark results are provided. The importance of considering anisotropic scattering behaviors for water mists is investigated. Interactions between soot and water mist are parametrically studied. A tabulated method is proposed to account for the radiative properties of water mists based on the Mie theory. The tabulation method performs accurately and efficiently. Abstract: The effects of radiation of water mists in a fire-inspired environment are numerically investigated for different complexities of radiative media in a three-dimensional cubic enclosure. A Monte Carlo ray tracing (MCRT) method is employed to solve the radiative transfer equation (RTE). The anisotropic scattering behaviors of water mists are modeled by a combination of the Mie theory and the Henyey-Greestein relation. A tabulation method considering the size and wavelength dependencies is established for water droplets, to reduce the computational cost associated with the evaluation of the nongray spectral properties of water mists. Validation and verification of the coupled MCRT solver are performed using a one-dimensional slab with gray gas in comparison with the analytical solutions. Parametric studies are then performed using a three-dimensional cubic box to examine radiation of two monodispersed and one polydispersed water mist systems. The tabulation method can reduce the computational cost by a factor of one hundred. Results obtained without any scattering model better conform with results obtained from the anisotropic model than the isotropic scattering model, when a highly directional emissive source is applied. For isotropic emissive sources, isotropic and anisotropic scattering models predict comparable results. The addition of different volume fractions of soot shows that soot may have a negative impact on the effectiveness of water mists in absorbing radiation when its volume fraction exceeds certain threshold.