EXPERIMENTAL SIMULATION AND ANALYTICAL MODELING OF 2-PHASE FLOW UNDER ZERO-GRAVITY CONDITIONS

A series of experiments are described in which an attempt was made to simulate two-phase flow behavior under zero-gravity conditions by the flow of two immiscible liquids of nearly equal densities. Pressure drop and void fraction data were obtained for the steady flow of two different liquid pairs for widely varying flow conditions. The two-phase flow in these experiments was in either the bubbly or annular flow regime. Values of the two-phase multiplier and void fraction obtained from the measured data were found to correlate well in terms of the Martinelli parameter Xu, but the resulting variations of these parameters with Xu differs significantly from the well-known correlation of Martinelli for these quantities. An analytical study of annular flow under zero-gravity conditions was also conducted using a one-dimensional two-phase flow model. Using slightly modified versions of available correlations for the interfacial friction factor and the turbulent eddy diffusivity, it was found that predictions of this model agreed well with the data obtained over a wide range of conditions. While some useful insight can be gained from experiments of this type, the results of this study indicate that the flow of two liquids of equal density fails to model some important aspects of liquid-vapor two-phase flow at zero gravity. The limitations of this type of experimental simulation are discussed in some detail. © 1990.