The research on interfacial area transport equation in rectangular channels: Experimental research and models development of sink and source terms

Abstract

Interfacial area concentration is a crucial constitutive parameter to close the two-fluid model, the accuracy of whose prediction is vital, so the interfacial area transport equation (IATE) has been proposed. According to the analysis of experimental results involving bubble interaction mechanisms in the rectangular channel from the bubbly-to-slug flow, new sink and source terms in a one-group IATE are put forward in this study. The new source term aroused by random collision is considered with relative velocity inducing collision and the effect of gap size on coalescence efficiency. Besides, the number density of small and large bubbles is considered respectively to model the source term of wake entrainment. Combined with the source terms of break up brought by turbulent impact and expansion caused by the pressure gradient, a new one-group IATE applicable to rectangular channels are completed. The coefficients in the newly-derived model are determined by experimental results of 4 × 66 mm and 8 × 66 mm vertical rectangular channels under co-current upward air-water two-phase flow, and the average relative error is 11.9%. Furthermore, the new model is also testified by the experimental result in the 6 × 66 mm rectangular channel independently, and the average relative error is 14.4%. Generally, the new model is feasible to predict the change of the interfacial area concentration in different rectangular channels.