Flapping instability of a liquid jet

Abstract

We measure experimentally the frequency of the large-scale instability developing on a liquid jet incompletely atomized by a parallel fast gas stream. We demonstrate that this "flapping instability" can be triggered by different mechanisms: in a first regime it is synchronized with the shear instability developing upstream, provided the wavelength of this shear instability is larger than the liquid jet diameter HL. When the shear instability exhibits wavelengths shorter than HL, a second regime is observed where the flapping instability becomes independent of the gas stream velocity. This second regime is characterized by a constant Strouhal number, provided the Froude number of the jet is correctly taken into account.

Characterization of the bubble swarm trajectory in a jet bubbling reactor

“…Therefore, the periodic jet flapping motion occurred. In view of the fact that the periodic movement phenomenon of bubble vortices observed in this article has many similarities with the flapping motion of the liquid jet . Thus, it is expected that the jet flapping oscillation also happens under the experimental conditions employed in this article.…”

Impact of inlet gas turbulence on the formation, development and breakup of interfacial waves in a two-phase mixing layer

“…2020), which could capture the interfacial stability when the symmetric mode is dominant. A full simulation with both gas streams will be required to resolve the asymmetric instability mode and breakup dynamics (Delon, Cartellier & Matas 2018).…”

Spray dispersion regimes following atomization in a turbulent co-axial gas jet

“…2019). These processes are often coupled with large-scale instabilities causing strong lateral excursions of the liquid jet known as ‘flapping’ (Delon, Cartellier & Matas 2018) or ‘dilatational waves’, resulting in clustered break-up of a high-momentum liquid core (Engelbert, Hardalupas & Whitelaw 1995; Kumar & Sahu 2020).…”