Abstract
An (N+2)-field model proposed in our previous study was modified so as to be applicable to compressible two-phase flows by taking into account the dependence of phase densities on temperature and pressure. Then, a numerical method for solving the modified (N+2)-field model was developed. The main feature of the proposed method is that the numerical stability is not determined by the Courant–Friedrichs–Levy condition but by the Courant condition, and therefore, stable numerical solutions can be obtained with a time step Δt much larger than the one used in a standard numerical method for solving compressible two-phase flows.
The verification of the proposed method was carried out through three sample calculations, i.e., simulations of an adiabatic air-water bubbly flow in a vertical duct of 10 m in length, an air-water bubbly flow in a uniformly heated duct of 10 m in length and a bubbly flow in a large bubble column. As a result, it was confirmed that (a) the proposed method accurately predicts the effects of pressure and temperature on phase densities and volumetric fluxes and (b) a simulation of a compressible bubbly flow in a practical bubble column can be performed with Δt satisfying the Courant condition.
