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The Japan Society of Multiphase Flow*; Special Committee for Examination of Thermohydraulic Analysis Code based on Three-Fluid Model*
PNC TJ9565 94-001, 530 Pages, 1994/03
The purpose of the present study is to improve a numerical prediction method for multiphase flows based on the three-fluid model. Conducted were (1)improvement of a numerical method, (2)survey and examination on constitutive equations for mass transfer terms in annular-mist flow, (3) survey and verification of constitutive equations for momentum transfer terms, (4)collection of experimental database on steam-water and air-water annular-mist flows and numerical analyses of the database to verify the prediction method, (5)extensivc survey on expelimental techniques for annular-mist flow and (6)examination on the governing equations. As a result, the following conclusions were obtained: (a)multi-fluid modeling for all flow regimes were completed, (b)numerical stability of the three-fluid model was darified, (c)stability-enhanced solution method was developed, (d)ill-posedness of the equation system was revealed, (c)a physically-rational and well-posed multi-fluid model was proposed for dispersed flows, (f)systematic survcy and evaluation of constitutive equations for entrainment and deposition were conducted and summarized, (g)a theoretical method for evaluating film thickness, interfacial shear stress and wall shear stress was presented, and (h)it was confirmed that FIDAS-1DS can accurately predict critical heat fluxes under atmosphelic pressure, and that it can givc qualitatively good predictions concerning film thickness, droplet flow rate and so forth of the air-water annular-mist flow.
The Japan Society of Multiphase Flow*; Special Committee for Examination of Thermohydraulic Analysis Code based on Three-Fluid Model*
PNC TJ9565 93-001, 265 Pages, 1993/04
The purpose of the present study is to improve a numerical method for multiphase flows based on the three-fluid model. Conducted were (1) improvement of a numcrical scheme, (2)examination on the validity of governing equations, (3)survey and verification of available constitutive equations, (4)development of theoretical constitutive equations and (5) numerical analyses of experimental database on steam-water and air-water annular-mist flows. As a result, the following conclusions were obtained: (a)multi-fluid modelling for all flow regimes were completed, (b)numerical stability of the three-fluid model was clarified, (c)stability-enhanced solution method was developed, (d)a physically-rational and well-posed multi-fluid model was proposed for dispersed flows, (e)systematic survey and evaluation of available constitutive equations for entrainment was conducted and summarized, (f)a theoretical method for the evaluation of film thickness and interfacial shear stress was presented, and(g)it was confirmed that FIDAS-1DS can accurately predict critical heat fluxes under atmospheric pressure, and that it can give qualitatively good predictions conserning film thickness, droplet flow rate and so forth of the air-water annular-mist flow.
Tsukimori, Kazuyuki
PNC TN9410 91-393, 152 Pages, 1992/12
There can be some imperfections in actual shell structures. In order to achievehighuality in manufacturing structures, the imperfections should be restricted within reonable tolerance ranges through design or examinations. In this paper, the governingquations to solve the dynamic buckling problems of shell structures, which consider namic fluid-structure interaction, model coupling in both axial and circumferential rections, and circumferential imperfections,are derived by using Variationl PrinciplApplying finite element method (FEM) to these equations, the matrix equation of motiois formulated to apply to computer analyses. Therough the implementation of some exames, the influence of the amplitude and pattern of imperfections on the buckling streth is descussed. Also, the validity and applicability of this method to the design ofhell structures is discussed.
