Plenary Speech:

Non-equilibrium effects in thermal and mechanical interaction of droplets with streaming flows

Prof. Nickolay N. Smirnov
Faculty of Mechanics and Mathematics,
Moscow M.V. Lomonosov State University,
Moscow 119992, Leninskie Gory, 1
RUSSIA

E-mail: ebifsin1@mech.math.msu.su

 

Abstract: Investigations of acute problems of phase transitions in continua mechanics need adequate modeling of evaporation, which is extremely important for the curved surfaces in the presence of strong heat and mass diffusion fluxes. Working cycle of heat pipes is governed by the active fluid evaporation rate. Combustion of most widely spread hydrocarbon fuels takes place in a gas-phase regime. Thus, evaporation of fuel from the surface of droplets turns to be one of the limiting factors of the process as well. The problems of fuel droplets atomization, evaporation being the key factors for heterogeneous mixtures reacting mixtures, the non-equilibrium effects in droplets atomization and phase transitions will be taken into account in describing thermal and mechanical interaction of droplets with streaming flows. In the present lecture processes of non-equilibrium evaporation of small droplets will be discussed. The rate of droplet evaporation is characterized by a dimensionless Peclet number (Pe). A new dimensionless parameter characterizing the deviation of phase transition from the equilibrium will be introduced, that makes it possible to investigate its influence on variations of the Peclet number and to determine the range of applicability for the quasi-equilibrium model. It will be demonstrated, that accounting for non-equilibrium effects in evaporation for many types of widely used liquids is crucial for droplets diameters less than 100 microns, while the surface tension effects essentially manifest only for droplets below 0.1 micron. Investigating the behavior of individual droplets in a heated air flow allowed to distinguish two scenarios for droplet heating and evaporation. Small droplets undergo successively heating, then cooling due to heat losses for evaporation, and then rapid heating till the end of their life time. Larger droplets could directly be heated up to a critical temperature and then evaporate rapidly. Atomization of droplets interferes the heating and evaporation scenario.

 
Brief Biography of the Speaker:
Prof., Dr.Sc. habilitat Nickolay N.Smirnov received his M.S. and Ph.D. degrees in Physics and Mathematics from Moscow M.V.Lomonosov State University in the years 1976 and 1980 respectively. He defended habilitation dissertation in 1990 and got a degree of Dr.Sc.-hab. Degree of Scenior Scientist was awarded in 1987, degree of full Professor was awarded in 1994. He is currently full professor in the Faculty of mechanics and Mathematics and deputy dean, Head of Wave Processes Laboratory and deputy director of Gas and Wave Dynamics Department. He was Visiting Professor in the Karlsruhe University, Germany (in 1994), in Free University of Brussels, Belgium (1995/96 and 2000). Prof. N.N. Smirnov was elected the Corresponding Member to Russian Academy of Technological Sciences in 1992. He received Shuvalov's prise (1993) for the book "Heterogeneous Combustion". Since 1992 he is a member of the Combustion Institute (Int.), since 2007 President of the Combustion Institute Russian Section. Full member of the Scientific Council of Russian Academy of Sciences on Combustion and Explosion since 1995, since 1999 – Vice President of the Council. Member of the Microgravity Science Committee of the International Astronautical Federation since 1995. Member of the Scientific Council on Ecology of the Russian Space Agency since 1994. Corresponding Member of Russian Academy of Natural Sciences since 1998, academician since 2007. Corresponding Member of International Academy of Astronautics since 2005, Commission 1 Space Physical Sciences Secretary. He is a member of the board of Combustion and Flame, Acta-Astronautica and other national and international journals, science foundations, congresses. He was awarded Kapitsa Gold Medal of the Academy of Natural Sciences for the scientific discovery, S.P. Korolev and M.V. Keldysh medals of the Russian Federation of Cosmonautics.
Published 8 books and more then 150 papers in peer reviewed journals, and 150 communications to scientific meetings in the fields of Mechanics, Physical Chemistry, Wave Dynamics, Combustion and Explosion, Space Physical Sciences.