Application of Synthetic Wall Jets for Pressure-Less, Counter-Current Conveyance of Thin Liquid Layers

The entrainment by pulsed or rather so-called synthetic wall jets can be used to sustain a pressure-less transport of thin liquid layers along ducts. These jets exhibit zero-net-mass-flow conditions and lead to a break of symmetry in the flow pattern during one oscillation cycle. Therefore, only a net impulse is transferred in jet direction and induces a directed movement of the ambient liquid by entrainment according to the jet direction. The aim is to investigate the applicability of the principle to counter-current contactors as an alternative to pressure drop or gravity as driving forces typically applied e.g. in counter-current liquid-liquid contactors. Experiments are performed with an apparatus containing wall-jet flow drives with a multitude of narrow slit-openings (slit-width s = 190 μm) along a channel for synthetic wall jet generation. Firstly, one single wall-jet flow drive is investigated regarding its conveying performance at different related oscillation amplitudes (e_slit/s = 7–25) and frequencies (f = 1–5 Hz). Subsequently, the apparatus is extended by a second identical device, arranged in parallel but above and oriented in the opposite conveying direction. This is to demonstrate the applicability of synthetic wall jets for counter-current operations.