Results of experiments on the dynamics of the formation, evolution, and dissipation of a tornado-like eddy in a viscous liquid are presented. Photographs of eddies and graphical materials based on results of their processing are presented. An explanation is proposed for the influence exerted by various factors on the development of eddy flows.Hydrodynamic devices and vessels, the operation of which is based on the use of circulation, helical, and eddy flows, are widely used in the chemical and some other branches of industry. In similar vessels, the classification of which includes hydrocyclones, liquid separators, sedimentation and filtering centrifuges, mass-exchange columns with vortex elements, vortex tubes, static mixers, etc., the separation of different classes of heterogeneous systems (liquid and gaseous suspensions, emulsions, colloids, vapor-liquid systems) is based on the effect of centrifugal forces that develop in any swirling flows [1,2].In different vessels with mixing devices, the forced circulation flow of a continuous medium is also restricted during rotation of the mixer [3]. A change in the geometry of the mixer (number of blades, area, configuration, angle of attack, etc.) will lead to a change in the relationship between the components of the total-velocity vector in a three-dimensional flow (eddy): radial, linear, and circumferential [4].During artificially induced swirling of continuous media, eddy structures (funnels, and tornado-and waterspout-like eddies) develop in these vessels. Their formation, evolution, and dissipation in each specific case is accomplished ambiguously due to the major influence exerted on this process by a multitude of factors (physical, process, structural).The effect of natural eddy formation, i.e., the development of a funnel during circulation movement of a liquid, is manifested as the liquid is discharged from a container through a circular opening in the bottom of the vessel [5]; this is a result of both geometric asymmetry, and also fluctuation of physical and production parameters in the system. It should be pointed out that in engineering practice, vessels are rarely employed, where eddies form under conditions of known geometric asymmetry; this will appreciably effect the efficiency of the production process ("washing-machine" effect) [5].Increased interest by specialists in the problem of eddy formation in continuous media, which is suggested by a number of studies [6-9], has recently been noted. Despite the existence of voluminous theoretical and experimental data on the structure of eddy flows and laws governing the processes that occur in them, modeling of eddies remains one of the urgent problems in the design of industrial plants.Let us examine the dynamics of the formation, evolution, and dissipation of a tornado-like eddy (TE) in a viscous liquid, and also laws governing the behavior of TE affected by various factors (amount of energy supplied, geometric dimensions of vessel subassemblies, the scale parameters of the system, etc.).To conduct the i...

Results are presented for investigation of the flow of rippling liquid films across vertical surfaces. It is demonstrated that developed engineering solutions can be used to generate waves artificially on the surface of flowing films to intensify mass-exchange processes in film vessels.In sheet-packed film vessels, the liquid film flowing across the flat vertical surfaces is nearly always covered with waves, which exert a major influence on processes of interphase transfer between a liquid and gas [1-3] In some cases, wave formation on the surface of flowing liquid films will increase the mass-transfer coefficient to 100% [2]. The effect of wave formation on the rate of mass exchange should therefore be considered in analyzing mass-exchange processes for thin flowing films of liquid.Despite the large number of theoretical studies conducted in this field [1][2][3][4][5], there is still no clear-cut and welldefined representation of the mechanism responsible for wave formation on the surface of flowing films, and its effect on mass exchange.The following experimental study was conducted to establish an interrelation between visco-fluid and wave characteristics in flowing liquid films: a liquid (water) was passed over flat plates with built-in roughness (hemispheres of different diameters, placed right up to, or at different intervals from one another). The flow rate Q of water was varied to develop different thicknesses h of flowing film. The wave patterns generated were recorded on photographic film; here, illumination was provided in a manner such that the crests (vertices) and troughs of the waves would be most clearly visible.The front of the wave and its transverse form ( Fig. 1) were recorded during the course of the experiments. It was sufficiently accurate to measure the wavelength λ from the photographs, but significant difficulties arose when recording the wave amplitude A. Considering that the wave amplitude on the surface of the flowing film is, on average, an order smaller than the film thickness [6], it is possible, proceeding from the film thickness, to calculate roughly the wave amplitude from the relationship A ≈ 0.1h.Processing of the photographs obtained consisted in statistical measurement of the wavelength λ for different roughnesses (wave generators in the form of hemispheres with diameters d 1 = 0.55 mm and d 2 = 0.115 mm), and liquid flow rates Q 1 = 28.57⋅10 -6 m 3 /sec and Q 2 = 16.66⋅10 -6 m 3 /sec. Table 1 presents results of processing of the photographs, which link the velocity parameters (w res , w long , and w tran are, respectively, the resultant, longitudinal, and transverse wave velocities) of a rippling film with a thickness h to wave characteristics of the waves generated: length λ, amplitude A, period T, and pulsation frequency ƒ = 1/T.As is apparent from Fig. 1, the relationships between the velocity components vary with varying wave geometrythe steepness of the envelope of the curve, which depends on the length of the wave and its amplitude. Its steepness increases with decre...

Results of experimental studies on artificial wave generation using obstacles in the form of grains of various diameters are examined. Relationships between the following parameters are presented: the length of the wave generated and the diameter of the grain and flow rate of liquid; the spread of the wave and the diameter of the generator; and the length of the wave and its spread for different spacings between generators.Owing to their relative simplicity, low cost, and potential for rather easy realization of a production process, film absorbers have come into the most widespread use among various surface types of absorbers in the chemical industry [1][2][3].The basis of the absorption process is the diffusion of gas in a liquid. On the boundary of contiguity (contact) between the liquid and gas, the liquid dissolves, and selectively absorbs the required component from the gaseous mixture. Here, a gaseous film of some of the gaseous phase not dissolved in the liquid (passive) remains on the contact boundary between the phases. Continued passage of the soluble gaseous component into the liquid occurs as it is displaced from the overall mass of gas into the near-boundary film due to diffusion caused by a difference in partial pressures of the component being extracted in the overall mass of gas and in the near-boundary layer in which the absorptive power of the liquid is sustained due to displacement of the absorbed component of gas from the near-boundary layer to the deep layers of the liquid.It is known [4-6] that owing to its instability, the surface of a liquid film flowing through a packing is covered with waves, which exert a major influence on interphase transfer between the liquid and gas. It is established [4,7] that the coefficient of mass transfer can be increased by more than 100% due to the existence of regular two-dimensional waves on the surface of the flowing film. Virtually nothing is known, however, about the artificial generation of regular two-dimensional waves on the surface of a flowing film.It is known [8,9] that as a solid body moves in an incompressible liquid, a system of standing regular two-dimensional waves (so-called ship waves) is formed in advance of the body. It is obvious that the reverse process -the ascent of a liquid flow over a solid obstacle -should produce the same wave-formation effect. In analyzing the problem of artificial wave generation, therefore, the task reduces to search for a solid obstacle of the required geometry -a wave generator. For this purpose, we conducted a series of experiments on different obstacles: rolls, grooves, openings, and cylindrical dowels, as well as their combinations. The experiments indicated that the best guaranteed results relative to wave generation are achieved for separate cylindrical dowels.The surfaces of the packings (sheets and tubes) in film absorbers have appreciable dimensions, and, consequently, point-type wave generators of the required size should be placed in a certain sequence in the absorbers.

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