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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.
Hiroi, Hiroshi*; Miyake, Osamu; *
PNC TN941 82-37, 170 Pages, 1982/02
Blowdown tests of high temperature and pressure water from a long pipe were carried out to validate the computer code SWAC-11 which is used for the calculation of the water leak rate from a failed heat transfer tube in an LMFBR's SG. The steady leak rate, and transients of pressure and thrust force of the pipe were measured. Especially, the short term transient of thrust force can be obtained by a new measuring method using the spring-mass model. These data were compared with calculation results of SWAC-11. As for steady data, the Moody's model of the critical flow and the effect of the two-phase multiplier were studied. Major conclusions are as follows: (1)The calculation results of SWAC-11 almost agreed with the steady data. But in detail, SWAC-11 inclined to predict 10 
15% less than experimental data of water leak rate and thrust force in the case of high pressure saturated water. This discrepancy will be reduced by introducing the Thom's correlation as the two-phase multiplier. (2)The calculation results of SWAC-11 also agreed with the experimental data after 5 msec since the blowdown was initiated. (3)The flow model of SWAC-11 can be applied to the blowdown of the subcooled water. (4)The thrust force (F) immediately after the blowdown is the sum of the wave force and the blowdown force. The relation of F, the initial pressure P
, and cross section S can be given by the expression, F/S
P=1.36. (5)Compared with calculation results in detail, the profiles of experimental data were found to be more complicated. This tendency was observed markedly in the case of the subcooled water blowdown. (6)Test results of superheated steam blowdown agreed with SWAC-11 predictions as for unsteady data as well as steady data.
