Effect of tube diameter on two-phase flow patterns in mini tubes

The effect of tube diameter on two-phase flow patterns was investigated in circular tubes with inner diameters of 0.6, 1.2, 1.7, 2.6, and 3.4 mm using air and water. The gas and liquid superficial velocity ranges were 0.01–50 and 0.01–3 m/s, respectively. The gas and liquid flow rates were measured and the two-phase flow pattern images were recorded using high-speed CMOS camera. The flow patterns observed were dispersed bubbly, bubbly, slug, slug-annular, wavy-annular, stratified, and annular flows. These flow patterns were not observed in all the test diameters, but were found to be unique to particular tube diameters, confirming the effect of tube diameter on the flow pattern. The data obtained were compared to existing experimental data and flow regime transition maps which show generally reasonable overall agreement at the larger diameters, but significant differences were observed with the smaller diameter tubes. On a analyse l'effet du diametre des tubes dans des modeles d'ecoulement biphase dans des tubes circulaires avec des diametres internes de 0,6, 1,2, 1,7, 2,6 et 3,4 mm en utilisant de l'air et de l'eau. Les ecarts de vitesse superficielle de gaz et de liquide etaient de 0,01–50 m/s et 0,01–3 m/s respectivement. Les debits de gaz et de liquide ont ete mesures et les images des modeles d'ecoulement biphase ont ete enregistrees a l'aide d'un appareil photo CMOS haute vitesse. Les modeles d'ecoulement observes etaient l'ecoulement a bulles, a bulles, en piston, en piston annulaire, ondule annulaire, stratifie et annulaire. Ces modeles d'ecoulement n'ont pas ete observes dans tous les parametres d'essai, mais on a constate qu'ils etaient uniques aux diametres de tubes particuliers, ce qui confirme l'effet du diametre des tubes sur le modele d'ecoulement. Les donnees obtenues ont ete comparees aux donnees experimentales existantes et aux cartes de transition des regimes d'ecoulement qui demontrent un accord global raisonnable de facon generale aux parametres plus grands, mais des differences importantes ont ete observees dans les tubes aux diametres plus petits.