Experimental study on detailed structure of air-water two-phase flow in a vertical pipe related to development of interfacial area concentration transport model

Abstract

Study of understanding and investigation of the phenomena of two-phase flow of air-water in tubes was carried out. Specifically, experimental as well as numerical studies on flow structure in vertical co-current flow of air-water in pipes were conducted. Among the models developed for understanding the thermal-hydraulics of a two-phase flow, two fluid model is considered to be the most accurate and detailed model [5]. In the two fluid model, separate sets of governing conservation equations are considered for each phase. Constitutive relations that bridge the gab between the two phases of the flow are derived using experimental data. Because, the mathematical determination of these constitutive or closure relations are not yet fully developed. Constitutive relations represent the key information on interactions between the two phases. Constitutive relations consist of interfacial transfer terms that are proportional to interfacial area concentration and driving forces [4]. Estimation of interfacial area concentration has been one of the main objectives of both the numerical computer cord development and experimental work that leads to understanding of the two-phase flow structure. Void fraction, bubble interface velocity, bubble cord length are required for the estimation of inter facial area concentration.