Download the full version of the article (in PDF format)

P. E. Trofimenko, M. V. Naida, A. V. Khomenko
«Formation of Liquid Film on a Static Film Former»
565–576 (2020)

PACS numbers: 47.20.Ib, 47.27.wg, 47.61.-k, 62.20.Qp, 62.25.-g, 68.08.-p, 68.15.+e

The theoretical foundations of converting a jet of liquid into a film on an inclined plane are considered. The obtained patterns can be used for the design and fabrication of structures of low-energy (energy-saving) intensive spray devices, which serve to create a highly developed phase-contact surface in small-size heat–mass-exchange devices. In many heat–mass exchange apparatuses, to obtain a highly developed interfacial surface and to maintain a high rate of renewal of the phase-contact surface, dispersion (spraying) of thin liquid films is used. A thorough study of both methods for the fabrication of thin films with industry-acceptable characteristics and methods for their high-quality dispersion with minimal energy consumption has not lost its significance in our time. For the low-energy (energy-saving) dispersion of a liquid, it must first be turned into a film of the smallest possible thickness, since, only in such a film, even turbulent fluctuations insignificant in absolute value caused by external influence can penetrate it through, and thereby, they cause almost instantaneous, closed to spontaneous dispersion (destruction) of the liquid film. For the low-energy conversion of any form of the initial liquid jet into thin films of uniform thickness, it is necessary to choose such constructions of film formers, in which forces appear that ‘flatten’ a jet into a film, and for the occurrence of which, it is necessary to supply as low energy as possible. Gravitational forces and any other forces or their components, which are perpendicular to the velocity of fluid flow, are low-energy-consuming ‘free’ forces. According to the definition of work, forces directed perpendicular to the speed of movement of the body do not perform mechanical work, but they can most actively influence the processes of formation of thin films. Among such forces in rotating nozzles, the main role is assigned, as we shall see, to the Coriolis forces and forces arising from the components of centrifugal inertia forces. The main theoretical task of solving this problem is the choice of such film-forming configurations and their operating modes, under which the forces acting on the fluid flow and which determine the dispersion of the liquid, would use the minimum amount of energy, but, at the same time, would most effectively influence the conversion of any form of a liquid jet into a thin film. We have justified the simple design of devices for the fabrication of films of uniform thickness at the required width for the industry. The basic idea underlying the principle of operation of a static film former is very simple. The simplest of these devices is a static flat-film former.

Keywords: liquid, film, jet, dispersion, film former, turbulence