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 Prof. Igor Palymskiy Siberian State University of Telecommunications and Information Sciences, Russia |
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| 简介： Presentation Title: On Control the Intensity of Convective Processes in a Chemically Reactive Equilibrium Gas by Adding Chemically Inert Micro-particles I.B. Palymskiy, A.V. Trilis, P.A. Fomin Over the past decades, various modes of convection of a chemically inert medium have been intensively studied [1]. But for technological devices, convection of a chemically reacting equilibrium gas is more typical where chemically inert particles of micron size are introduced to increase the flow stability [2]. The work uses the chemical equilibrium model [3], where the density of a chemically equilibrium ideal gas is a function of only absolute temperature, since the external pressure is assumed to be given and constant, and convection of the gas mixture is considered in the Boussinesq approximation for incompressible fluid. All numerical values of the constants correspond in a stoichiometric hydrogen-oxygen mixture with added Al2O3 micro-particles. In the linear theory of stability, the coexistence of two conflicting trends is noted. It is shown that the ongoing chemical reactions cause an actual increase in the value of the Rayleigh number (super-criticality), a decrease in its critical value, and an increase in convective instability. On the other hand, the addition of inert micro-particles to the reaction mixture reduces the specific heat and, as a result, increases the critical value of the Rayleigh number, thereby increasing the convective stability of the flow [4]. The aim of this work is to study the nonlinear regimes of such convection. Numerical calculations showed that an increase in the mass concentration of micro-particles causes suppression of convective motion. However, in the nonlinear case, the result of this suppression is not unequivocal, since a decrease in the Nusselt number coexists with an increase in kinetic energy at a high value of super-criticality and small mass concentration of micro-particles. An increase in the mass concentration of micro-particles leads to a significant (up to 4 times) decrease in heat transfer (Nusselt number) and a corresponding decrease in the rms temperature. However, the average wave number in this case shows non-monotonic behavior, decreasing at a low concentration of micro-particles and increasing at high. The work was performed as part of the RFBR Project No. 20-08-00903. 1. Gershuni G Z and Zhukhovitskii E M 1976 Convective Stability of Incompressible Fluids (Jerusalem: Israel Program for Scientific Translations) 2. Fedorov A V, Fomin P A, Fomin V M, Tropin D A and Chen J R 2012 Mathematical Analysis of Detonation Suppression by Inert Particles (Kaohsiung: Kao Tech Publishing) 3. Nikolaev Yu A and Fomin P A 1982 Analysis of equilibrium flows of chemically reacting gases Comb., Expl. Sh. Wav. 18(1) 53-58 4. Palymskiy I B, Fomin P A 2018 Rayleigh-Benard convection in a chemically equilibrium gas containing chemically Inert micro-particles. Comb., Expl. Sh. Wav. 54(4) 38-44 | |
