Analytical two-phase flow void prediction method

An analytical formula has been derived, without empirical constants, that predicts the lower limit void fraction as a function of quality and pressure. The derivation utilizes a functional relationship for the slip and the boundary conditions at the limits as ~* 0 and x ~* !• The formula has been compared with two state-of-theart correlations, in the parameter range of operation of a Boiling Water Reactor (BWR) at steady state, and with some air-water data. It fits the first case data rather well, and correlates the air-water data with even greater accuracy. The potential applicability of this formula to countercurren t flow cases has not yet been explored. This paper concentrates on the derivation of the formula and comments on the data correlations. Nomenclature A = flow area, m2 (without subscript: total flow area) C0 = parameter defined in text F = intermediate function defined in text / = intermediate function defined in text g = intermediate function defined in text m = mass flow rate, kg/s (without subscript: total flow rate) S = slip, velocity ratio VgIVi V = average velocity of each phase Vgj = parameter defined in text a = void fraction, area ratio AgIA p = fluid phase density, kg/m3 X = flow quality, mass flow ratio mg/m Subscripts g = gas phase t = liquid phase