Flashing Flow of Initially Subcooled Water in Convergent–Divergent Nozzles

This paper presents results from a research program conducted a number of years ago on the problem of flashing flow of water in nozzles. In a previous paper [1] we presented results for the case of stagnation states in the low quality two-phase region. The present paper reports results for stagnation states in the subcooled region at pressures up to 9.05 × 10³ kN/m² and subcooling from 0 to 60° C. Pressure profiles and flow rates are reported. The results are compared with limiting cases of Bernoulli flow (meta-stable liquid flow) and homogeneous equilibrium flow. As expected neither was able to predict the experimental results. A two-step model based upon nucleation delay, “discontinuous” transition to two-phase flow followed by frozen composition gave reasonable predictions of the flowrates and pressure profiles in the convergent section.