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Mechanics
Interaction of falling drop with liquid surface is one of classical hydrodynamics problems, which for many years draws attention of researchers. Reviews on the given problem are submitted in [1, 2]. The basic part of the published results is devoted to an experimental research of an interaction process qualitative pattern. Results of the numerical solution of a problem about cavities decay within the framework of ideal fluid model were surveyed in [2, 3]. The physics of process of shock drop interaction with liquid surface, is of interest at the solution of some applied problems, such as to predict the depth of craters that form due to a cumulative effect during micrometeorites impact with the space vehicle [4], obtaining of underwater noise parameters generated by rain drops interaction with a sea surface [5] etc. In particular, this problem was considered in works of academician M.A. Lavrentyev at the analysis of underwater explosion, in the hydrodynamic theory of a cumulative effect, at vortex formation due to Taylor`s instability [4]. One from the important ecological problems is the forecasting of toxic drops distribution at impact of rain drops on a surface of basins located at the chemical, nuclear and other industry enterprises. For solution of this problem it is necessary to know the quantitative characteristics of mass transfer and parameters of secondary drops produced during the shock interaction of rain drops with liquid surface. In the present report results of an experimental research and analytical estimations of the quantitative characteristics of mass transfer at secondary drops formation as a result of shock interaction between the falling drop and liquid surface are submitted. Experiments were carried out on the installation consisting of the drops generator, system of interaction process visualization of and also system of impinging drops parameters before collision measuring. The drops sizes were determined by weight and visual methods, impact velocity was determined by a time-of-flight laser method. In experiments as a model fluid distilled water was used, diameters of initial drops were varied in a range mm, the height of drop falling – in a range m. Thus interaction velocity was changed in a range 0.1 7.0 m/s. Interaction of drops was filmed by two video cameras, allowing to restore a spatial pattern of the investigated process. The dimensional analysis shows, that the given problem (in case of a spherical initial drop) is completely characterized by three similitude parameters – Reynolds, Weber and Froude numbers. As a result of the carried out experiments dependences of produced cavity radius, height and diameter of Rayleigh column, quantity, sizes and uprise height of secondary drops were generated at crown and Rayleigh column decay from the determining similitude parameters were obtained. The analytical estimation of the basic process parameters - radius of a cavity and height of Rayleigh column were obtained on the basis of energy balance equations within the framework of some simplifying assumptions. The received analytical formulas allow to estimate the character of explored dependences qualitatively. Experimental results analysis of drops and liquid surface shock interaction process has shown, that in an explored ranges of determining parameters some mechanisms of secondary drops formation (decay of a crown, decay a of Rayleigh column and decay of a secondary of Rayleigh column) are realized. Acknowledgments This work was supported, in part, by the Russian Foundation for Basic Research (project No. 02-01-01246) and by Ministry of Education of the Russian Federation (project No. E02-12.3-108). References 1. Solovyev A.D. Drops coalescence at collisions // Physics of clouds and simulated actions: Proc. of Central Aerologic Observatory. Ì., 1969. Vol. 89. P. 3-25. 2. Oguz H.N., Prosperetti A. Bubble entrainment by the impact of drop on liquid surfaces//J. Fluid Mech. 1990. V. 219. P. 143-179. 3. Korotkov G.G. Numerical experiment in problems of an ideal incompressible fluid with the free boundaries: Ph. D. thesis of physical and mathematical sciences. Kemerovo, 2002. 4. Lavrentyev M.A., Shabat B.V. Problems of hydrodynamics and their mathematical models. M.: the Science, 1977. 5. Pumphrey H.C., Crum L.A., Bjorno L. Underwater sound produced by individual drop impacts and rainfall //J. Acoust. Soc. Amer. 1989. V. 85. P. 1518-1526.
Note. Abstracts are published in author's edition
Last update: 06-Jul-2012 (11:52:45)