Choking Criterion for One-Dimensional Critical Multiphase Flow in Ducts and Open Channels

Abstract

From averaged conservation equations for a multiphase flow, a mathematically equivalent 3 equations system is defined and used to study the choking phenomenon. Choking criterion for flow in ducts and in open channels are obtained. They correspond respectively to a minimum in the flow impulse and to an extremum in the flow energy with respect to the gas velocity. Mechanical and thermal nonequilibrium are fully taken into account. For flow in ducts, the criterion is shown to be in agreement with a previous analysis. Comparison of the predictions of this criterion with several experimental data for air-water flow and steam-water flow yields a very good agreement.