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Your search keyword '"Yakush, S. E."' showing total 134 results
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134 results on '"Yakush, S. E."'

12. Numerical modelling of shock waves and detonation in complex geometries

Author

Nevmerzhitskiy, Y. V. and Yakush, S. E.

Subjects
Physics - Computational Physics
Abstract

Cumulation of shock snd detonation waves was considered. Computations were carried out by use of second-order central-difference scheme. Cumulation of waves in cone region with scales of 1 meter was studied. Pictures of flow in shock and detonation waves during different time moments were obtained as well as time dependences and maximum pressures for different corner angles., Comment: 55 pages, 132 figures

Published
2012

13. Numeric modeling of fire suppression by organophosphorous inhibitors

Author

Makhviladze, G. M., Yakush, S. E., and Zykov, A. P.

Subjects
Physics - Chemical Physics
Abstract

Numerical calculations of the effect of organophosphorous inhibitor (CF3CH2O)3P and its mixtures with carbon dioxide on propane flames are carried out using the three dimensional Reynolds-averaged Navier-Stokes (RANS) equations in the low Mach number approximation. The k-e model of turbulence, the EDC combustion model and the weighted-sum-of-gray-gases model of radiation are used. The Westbrook global-kinetic scheme with fractional order of reaction was used for the calculation of chemical reaction rate of propane combustion. The empirical expression for the correction factor for the chemical reaction rate was used to model the effect of organophosphorous inhibitor no the reaction. Two series of test calculations for different values of the correction factor are carried out. Dependences of the minimum extinguishing concentration of the inhibitor per carbon dioxide volume concentration in the extinguishing mixtures were obtained. The results of test calculations are shown to agree reasonably with the experimental data. A calculation of the compartment fire extinguishment was carried out using the result of test calculations. Temperature and inhibitor volume concentration fields at the moment of fire extinguishment are obtained. The results of calculation are used to find out the optimum position of the extinguish mixture source., Comment: 18 pages, 9 figures

Published
2008

14. Numerical simulation of water jet impact on molten material layer.

Author

Yakush, S. E. and Sivakov, N. S.

Subjects
*WATER jets, *COMPUTER simulation, *FREE surfaces, *WATER depth, *ZONE melting, *THIN films
Abstract

High-temperature melt spreading under a shallow water layer can lead to energetic interaction, known as the stratified steam explosion. One of the key uncertainties in the current understanding of this phenomenon is the mechanism for the formation of a premixed zone above the melt layer. It is known that the most energetic steam explosions occur when dispersed melt droplets are mixed with water in a certain proportion. There exists experimental evidence that high-temperature melt spreading is featured by intensive disturbances of the melt surface, visible as sporadic splashes to the height of about few centimeters. In this work, numerical simulations are performed on the interaction of a melt pool with water jets impinging on the free melt surface. Three phases are considered: melt, water, and vapor; the interfaces are modeled by the Volume of Fluid (VOF) method. Phase change is taken into account on the water-vapor interface. The problem is solved numerically in two- and three-dimensional framework. Firstly, impingement of a short-duration vertical water jet on the melt surface is studied, with the parametric analysis performed to establish the effect of the jet characteristics (mass, velocity, diameter) on the primary (due to development of a cavity on the melt surface) and secondary (central jet due to cavity collapse) splashes. Secondly, three-dimensional simulations are presented demonstrating the development of vapor film instability in an initially three-layered configuration (melt and water layers separated by a thin vapor film). Implication for the steam explosion problem is discussed. [ABSTRACT FROM AUTHOR]

Published
2023
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18. Numerical simulation of equilibrium air plasma flow in the induction chamber of a high-power plasmatron.

Author

Vasil'evskii, S. A., Kolesnikov, A. F., Bryzgalov, A. I., and Yakush, S. E.

Subjects
AIR flow, PLASMA equilibrium, NUMERICAL solutions to Navier-Stokes equations, NONEQUILIBRIUM plasmas, PLASMA torch, COMPUTER simulation, PLASMA flow
Abstract

Multi-parameter study on the subsonic equilibrium air plasma flows in the cylindrical discharge channel of an induction RF-plasmatron IPG-3 with the maximum operating power of 1 MW is presented. Simulations are carried out by numerical solution of full Navier–Stokes equations coupled with a two-dimensional equation for high-frequency electric field; the discretization of the equations is performed on a staggered Cartesian mesh. An effective method for calculation of the transport coefficients for ionized multi-component air (including the plasma conductivity) in the temperature range 300–15000 K is applied, with the higher-order approximations by the Sonine polynomial in the Chapman–Enskog method. Simulation results are presented, including the flow fields, electric field, and thermodynamic parameters of the air plasma in the discharge channel of a high-power induction plasmatron. The results obtained reveal for the first time the structure and parameters of a plasma torch in a large-diameter (200 mm) discharge channel at powers up to 300 kW, providing the axial specific enthalpies at the channel outlet as high as 68 MJ/kg. [ABSTRACT FROM AUTHOR]

Published
2023
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36. On the evaluation of dryout conditions for a heat-releasing porous bed in a water pool

Author

Yakush, S. E., Kudinov, Pavel, Yakush, S. E., and Kudinov, Pavel

Abstract

This work is motivated by the problem of restraining temperature escalation inside a porous heat-releasing media submerged in a pool of liquid coolant. When coolant temperature reaches saturation, boiling begins in the bulk of the porous bed, with void generation rate determined by the heating power. Amount of void determines hydrostatic pressure difference that drives natural circulation of two-phase flow through the porous material. At a certain critical value of the heat release rate, the driving head cannot overcome drag of the two phase porous media flow, which results in complete evaporation of coolant in some zone. Temperature of material in the dry zone increases significantly due to deterioration of heat exchange with single phase vapor flow in comparison with boiling flow heat transfer. The paper considers the problem of determining the critical conditions for onset of dryout in a heat-releasing porous bed of an arbitrary shape. The well-known one-dimensional problem for a flat top-flooded bed is revisited, and the functional form of the dryout boundary (expressed as the dryout heat flux, DHF) is derived using non-dimensional parameters. Asymptotic behavior of the solution is analyzed, and, by the method of asymptotic interpolation, a surrogate model is proposed consisting of three single-argument, non-dimensional functions. It is shown that such a model provides acceptable accuracy even in the cases where complete similarity of solutions is not achieved. The results obtained provide important insights into the physics of the problem, reduce the number of free parameters, and enable fast evaluation of dryout conditions without the need of numerical solution of algebraic equations involved in the exact formulation. The ultimate goal of the surrogate model development, i.e. its application to multidimensional configurations, is discussed., QC 20190326

Published
2019
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42. Modeling of liquefying material interaction with hot gas flow in application to hybrid rocket engines.

Author

Yakush, S. E., Rashkovskiy, S. A., Fomin, Vasily, and Shiplyuk, Alexander

Subjects
*ROCKET engines, *NITROUS oxide, *TURBULENCE, *GAS flow
Abstract

Results of numerical modeling of solid fuel melting and shedding by hot gas flow are presented. The computational model is based on the Volume-of-Fluid approach, implemented on a two-dimensional Cartesian grid, with one-equation turbulence model. Simulations are presented for a slab of wax interacting with a parallel gas flow, with the properties taken to be typical of hybrid engines (nitrous oxide). Development of Kelvin-Helmholtz instability in the melt layer is demonstrated, including the wave formation and droplet shedding by the flow. [ABSTRACT FROM AUTHOR]

Published
2020
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