Gravity affected break-up of laminar threads at low gas-relative-velocities

• Published in: Chemical engineering science Vol. 69; no. 1; pp. 181 - 192
• Main Authors: Mescher, Axel, Möller, Arne, Dirks, Martin, Walzel, Peter
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 13.02.2012; Elsevier
• Subjects: Applied sciences; Chemical engineering; Drop; droplet size; droplets; Exact sciences and technology; Fluid mechanics; Gas cross-flow; gravity; Hydrodynamics of contact apparatus; Laminar thread break-up; Multiphase flow; Parameter identification; Gas cross-flow; Fluid mechanics; Multiphase flow; Parameter identification; Laminar thread break-up; Drop; Particle size; Particle size distribution; Crossflow; Graphic method; Droplet
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2011.10.021

Due to gravity, initially slow threads are significantly attenuated until break-up occurs. In our experiments these threads are further subject to a gas cross-flow, covering the range of low gas-relative-velocities (<10 m/s). Thread contour data as well as information on the droplet size distribution (DSD), formed under these conditions, are obtained by a shadow-graphic method. The experimental results on the break-up length of the threads confirm the results of former investigations. In contrast, for the mean drop size an unexpected dependency on the gas-relative-velocity is observed, as larger droplets were found for intensified cross-flows. The width of the DSD was found to be also sensitive on the gas-relative-velocity. Even slightly intensified gas cross-flows distinctly increase the poly-dispersity of the DSD. ► Even low gas-relative-velocities influence the break-up of liquid threads. ► Break-up length, mean drop size and the width of DSD depend on the gas-influence. ► Gas–liquid interaction causes larger mean drop size and a broader distribution. ► In technical applications the gas-influence on the threads should be prevented.