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Combustion, Explosion and Shock Waves

2015 year, number 2



Catalytic Combustion: Achievements and Problems

V. N. Parmon1,2, A. D. Simonov1, V. A. Sadykov1,2, S. F. Tikhov1
1Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
2Novosibirsk State University, Novosibirsk, 630090 Russia
Keywords: catalytic combustion, fluidized layer, catalysts, reactor, deactivation, sintering, attrition, structured catalysts, cermet

Abstract >>
A catalytic method of combustion of a solid fuel in a fluidized bed is compared with a noncatalytic method. It is shown that the use of catalysts reduces the fuel consumption and sizes of heat generators approximately by an order of magnitude, while the specific load on the reactor volume increases by more than a factor of 20. Emission of toxic substances with fuel combustion products drastically decreases. Comparative stability of oxide non-platinum catalysts is estimated in the course of catalytic burning of the fuel with addition of an inert material. In burning fuels with a large content of sulphur, the maximum deactivation is found to occur within the first several tens of hours; this process is accompanied by sulphur accumulation in catalysts. Later on, the catalyst activity remains almost unchanged. It is found that a critical factor of catalyst stability is attrition resistance. The prospects of fuel burning in a layer of cermet honeycomb catalysts are demonstrated.


Superadiabatic Temperature Phenomenon in the Combustion Processes Due to a Competition between Chemical Reactions

V. S. Babkin, V. A. Bunev, T. A. Bolshova
Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: superadiabatic temperatures, flammability limits, autoignition, dimethyl ether, methane, propane

Abstract >>
The existence of a new type of superadiabatic temperature phenomenon in flames and during autoignition due to a competition between chemical reactions is inferred from literature data and the results of mathematical modeling of chemical kinetics and numerical experiments. The mechanisms, conditions for the occurrence, and nature of the phenomenon are discussed. It is noted that this phenomenon may have promising academic and practical applications.


Near-Wall Flows of Chemical Reactants: A Review of the Current Status of the Problem

V. V. Lukashov1, V. V. Terekhov2, V. I. Terekhov2
1Novosibirsk State University, Novosibirsk, 630090 Russia
2Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: near-wall flow, heat and mass transfer, combustion, turbulence, evaporation, porous injection, flame front, ignition and flame extinction

Abstract >>
This paper presents a review of the current status of research on aerodynamics and heat and mass transfer in near-wall reacting flows with injection or evaporation of fuel from the wall. Laminar and turbulent flow regimes at subsonic flow velocities are considered. The effect of many factors on the flow structure, heat and mass transfer, and combustion stability are analyzed.


Combustion of Nano Aluminum Particles (Review)

D. S. Sundaram1, V. Yang1, V. E. Zarko2,3
1School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
2Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
3Research Institute of Applied Mathematics and Mechanics, Tomsk, 634050 Russia
Keywords: combustion, nanoparticles, aluminum, continuum, flame temperature, free-molecular heat transfer burning time, oxygen, combustion mechanism

Abstract >>
Nano aluminum particles have received considerable attention in the combustion community; their physicochemical properties are quite favorable as compared with those of their micron-sized counterparts. The present work provides a comprehensive review of recent advances in the field of combustion of nano aluminum particles. The effect of the Knudsen number on heat and mass transfer properties of particles is first examined. Deficiencies of the currently available continuum models for combustion of nano aluminum particles are highlighted. Key physicochemical processes of particle combustion are identified and their respective time scales are compared to determine the combustion mechanisms for different particle sizes and pressures. Experimental data from several sources are gathered to elucidate the effect of the particle size on the flame temperature of aluminum particles. The flame structure and the combustion modes of aluminum particles are examined for wide ranges of pressures, particle sizes, and oxidizers. Key mechanisms that dictate the combustion behaviors are discussed. Measured burning times of nano aluminum particles are surveyed. The effects of the pressure, temperature, particle size, and type and concentration of the oxidizer on the burning time are discussed. A new correlation for the burning time of nano aluminum particles is established. Major outstanding issues to be addressed in the future work are identified.


Specific Features of Ignition and Combustion of Composite Fuels Containing Aluminum Nanoparticles (Review)

A. M. Starik, A. M. Savel'ev, N. S. Titova
Baranov Central Institute of Aviation Motors, Moscow, 111116 Russia
Keywords: nanoparticles, ignition, combustion, composite fuel, reaction mechanism, condensed phase, nonstationary nucleation

Abstract >>
Modern research of properties of aluminum nanoparticles and specific features of their combustion in various media is reviewed. Particular attention is paid to the mechanism of combustion of Al nanoparticles in air and water vapor. Results of experimental and theoretical investigations are presented, which testify to the validity of the gas-phase concept of combustion of Al nanoparticles. A large part of the paper deals with numerical studies of combustion of a composite fuel consisting of a hydrocarbon (methane) and Al nanoparticles in air. The kinetic mechanism of Al combustion in the gas phase is presented. The mechanisms of ignition of this fuel are analyzed. The methodology of simulating the formation of the condensed phase consisting of Al2O3 particles is discussed. Results of experimental investigations of ignition and combustion of liquid and vaporized hydrocarbon fuels containing a moderate amount of Al nanoparticles are presented.


Research in Mechanics of Reacting Homogeneous and Heterogeneous Media at the Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences

V. M. Fomin, A. V. Fedorov
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: combustion, ignition, detonation, homogeneous/heterogeneous medium, physical and mathematical modeling

Abstract >>
Investigations in the field of mechanics of reacting media performed at the Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences since the 1950s up to now are briefly reviewed.


Energy Efficiency of a Continuous-Detonation Combustion Chamber

S. M. Frolov1,2,3, V. S. Aksenov1,2,3, A. V. Dubrovskii1,2,3, V. S. Ivanov1,2, I. O. Shamshin1,2,3
1Center of Pulse Detonation Combustion, Moscow, 119991 Russia
2Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, 119991 Russia
3MEPhI National Research Nuclear University, Moscow, 115409 Russia
Keywords: continuous-detonation combustor, energy efficiency, experiment, three-dimensional calculation

Abstract >>
Systematic experimental and computational studies of the energy efficiency of continuous-detonation combustors (CDCs) have been performed. A small-size and a large-size CDCs using hydrogen as fuel and oxygen or air as oxidizer have been developed and tested. It was first experimentally proved that the Zel'dovich thermodynamic cycle with continuous-detonation combustion of a hydrogen-oxygen mixture in an annular combustor is more efficient than the Brayton thermodynamic cycle with continuous combustion of the mixture, other things being equal. The specific impulse of a small-size bench-scale rocket engine with a 50 mm diameter CDC operating in the continuous-detonation mode was 6–7% higher than that in the continuous combustion mode of operation. The measured fuel specific impulse for the large-size CDC of 406 mm diameter running on a hydrogen-air mixture was at a level of 3000 s. Three-dimensional calculations to optimize the structure and operation mode of the large-size CDC have shown that when running on a combustible mixture with a nearly stoichiometric integral composition, the specific impulse can be increased to »4200 s.


Detonation of a Gas Fuel Based on Methyl Acetylene and Allene

V. Yu. Ul'yanitskii, A. A. Shtertser, I. S. Batraev
Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: gaseous detonation, detonation parameters, cell structure, composite fuel MAF, detonation spraying

Abstract >>
A special facility for investigating gaseous detonation was designed using a CCDS2000 computerized detonation-spraying complex to implement flow-through supply of the components of an explosive mixture and activation of deflagration-to-detonation transition in a long cylindrical channel. The detonation velocity and the cell size of the detonation front in mixtures of a composite fuel based on methyl acetylene and allene with oxygen were experimentally determined, and the concentration limits of steady-state detonation in a tube of 26 mm diameter were obtained. Detonation parameters were calculated and compared with experimental values. For comparison, the detonation of mixtures of acetylene and propane-butane with oxygen under similar conditions was studied.


Gas-Disperse Synthesis of Metal Oxide Particles

A. N. Zolotko, N. I. Poletaev, Ya. I. Vovchuk
Institute of Combustion and Unconventional Technologies, Mechnikov Odessa National University, Odessa, 65082 Ukraine
Keywords: gas suspension of metal particles, dust flame, gas-disperse synthesis, flame ionization, metal oxide nanoparticles, nucleation, coagulation

Abstract >>
The main results of years of research of metal dust flames aimed at the development of the scientific basis for the method of gas-disperse synthesis of metal oxide nanopowders are discussed. Methods of burning metal dust in oxide-containing media, the key problems of gas-disperse synthesis, and possible ways to solve these problems are considered. The ways of controlling the disperse composition of vapor-phase and gas-phase combustion products of metal particles by variation of the macroparameters of the dust flame and ionization of condensed and gaseous phases in the combustion zone with the help of adding easily ionized atoms to the fuel are analyzed. It is shown that an adequate description of condensation in a flame is impossible without consideration for the influence of electrophysical processes on nucleation and coagulation in the flame. It is established that ionization of the condensed phase is the most significant factor during coagulation of nano-oxide particles in a dust flame. This allows expecting that the influence on particle ionization may turn out to be an effective method of controlling the dispersion of the target products of gas-disperse synthesis.


Deformation Models under Intense Dynamic Loading (Review)

L. A. Merzhievskii
Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: deformation models, dynamic deformation, shock-wave processes

Abstract >>
This paper considers currently available models of irreversible deformation processes of materials under dynamic, in particular shock-wave, loading. The models can be divided into three groups: (1), macroscopic (continuum) models-traditional models of continuum mechanics, primarily classical models of elastic-plastic deformation, their various generalizations to the case of dynamic processes and models of viscoelastic relaxation media; (2) microstructural models based on the description of microstructural mechanisms of irreversible deformation (usually, the concept of the kinetics of a dislocation ensemble); (3) atomistic molecular dynamics models and calculations. A special category includes the most promising (from the point of view of the author) multilevel models which combine the advantages of each of these approaches and consider deformation mechanisms of various levels. Examples of calculations using such models are presented.