Formation of bubble chains over twin nozzles

Abstract

In the paper the formation of bubble chains over two nozzles has been experimentally investigated and modelled. Bubbles were generated from twin brass nozzles (with the inner diameter equal to 1 mm) to distilled water. The appearance and disappearance of alterative bubble departures have been investigated. It has been found that during disappearance of alternative bubble departures bubbles depart from nozzle outlets simultaneously. The PIV method was used to reconstruct the liquid velocity field around the bubble chains. The results of experiment were comparing with results of numerical simulation in which the Level Set method has been used. The PIV method show that during the alternate bubble departures the range of the velocity field formed by the bubble chain is smaller than in case when bubbles depart in non-alternative way. In this case the bubbles velocity above the nozzles outlet is greater in comparison with bubble velocity during the simultaneously bubble departures. The numerical simulations show that in alternative bubble departures bubble just after its departure is attracted to the common bubble chain. The hydrodynamic interactions between departing bubbles lead to uniform distribution of bubbles in bubble chain.