球座標系による球形タンク内LNGの熱流動解析

概要

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Turbulent thermal buoyancy driven flow of liquefied gas, LNG and LH_2 (Liquefied hydrogen gas) in the spherical enclosure having a free evaporation surface and uniformly insulated outer wall was analyzed with the two-dimensional spherical coordinate system. Turbulent kinematic viscosity ν_t was prescribed using a 0-equation turbulent model and the Boussinesq approximation was applied. Two-dimensional equations of motion were converted to the vorticity equation and stream function ψ was solved by means of the SOR method corresponding to the vorticity ω value of each time step, and the finite difference method was applied for the numerical calculation. For the spherical coordinate system the numerical satisfaction of the equation of continuity in the nonconservative form is not ensured after discretizing due to the geometric change of each cell size depending on the position of radius and latitude and to the finite difference approximation of the first order from differential equation. Author introduced the equalized flow function for the convection terms of equations of energy and vorticity. Application of this new controller function enabled the author the automatic satisfaction of flow continuity over the entire range of control volumes and the stable numerical solutions were obtained.
社団法人日本船舶海洋工学会の論文
1993-03-29