RT Journal Article
T1 Bubble pressure requirements to control the bubbling process in forced co-axial air-water jets
A1 Bolaños Jimenez, Rocio
A1 Ruiz-Rus, J.
A1 Sevilla Santiago, Alejandro
A1 Martínez Bazan, Jesús Carlos
AB We analyse the controlled generation of bubbles of a given size at a determined bubbling rate in a co-flowing water stream forcing the gas flow. The temporal evolution of the bubble size, R(t), the air flow rate, Qa(t), and the pressure evolution inside the bubble, pb(t), during the bubbling process are reported. To that aim, the temporal evolution of the bubble shape and the pressure inside the air feeding chamber, pc(t), where a harmonic perturbation is induced using a loudspeaker, are obtained from high-speed images synchronized with pressure measurements. A model is developed to describe the unsteady motion of the gas stream along the injection needle, coupled with the Rayleigh-Plesset equation for the growing bubble, allowing us to obtain pb(t). Thus, the minimum pressure amplitudes required inside the forming bubble to control their size and bubbling frequency are provided as a function of the gas flow rate, the liquid velocity, uw, and the forcing frequency, ff. Two different behaviors have been observed, depending on the liquid-to-gas velocity ratio, . For small enough values of Λ, the critical pressure amplitude is given by  associated to a rapid pressure increase taking place during an interval of time of the order of the acoustic time. However, for larger values of Λ,  Here ρ and ρa are the liquid and gas densities respectively, c the speed of sound in air and  and  the Strouhal and Weber numbers, where ro denotes the outer radius of the injector.
PB Elsevier
SN 0301-9322
YR 2020
FD 2020-12-01
LK https://hdl.handle.net/10016/35676
UL https://hdl.handle.net/10016/35676
LA eng
NO This work has been supported by the Spanish MINECO and European Funds under projects DPI2017-88201-C3-2-R and DPI2017-88201-C3-3-R. JRR wants to acknowledge the Spanish MINECO for the financial support provided by the Fellowship BES-2015-071329. Support from the Red Nacional para el Desarrollo de la Microfluídica, RED2018102829T, is also acknowledged.
DS e-Archivo
RD 1 sept. 2024