Visualization of air flow separation past dry and wet tubes

Abstract

This paper describes an optical investigation technique for visualizing the cross section of a vertical air stream flowing downward on a wet horizontal tube with moving liquid film. This method which associates the laser induced fluorescence and laser tomography techniques, uses Mie scattering tracers and fluorescent dye for marking the air and liquid flows, respectively. It allows us to visualize the air and liquid flows independently or simultaneously, and to measure the air flow separation angle. Results are compared with values obtained for a dry tube by the present and of other authors.