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Combustion, Explosion and Shock Waves

2019 year, number 3

1.
Recent Advances in Safe Synthesis of Energetic Materials: An Overview

D. M. Badgujar1, M. B. Talawar2, V. E. Zarko3, P. P. Mahulikar1
1School of Chemical Sciences, North Maharashtra University, Jalgaon, 425001 India
2High Energy Materials Research Laboratory, Pune, 411021 India
3Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: экологические методы, энергетические материалы, зеленая химия, ионные жидкости, микроволновое излучение, пентаоксид диазота, eco-friendly methods, energetic materials, green chemistry, ionic liquids, microwave irradiation, dinitrogen pentoxide

Abstract >>
The development of novel energetic materials with highest possible performance is of current interest. Synthesis of such materials is performed at various stages of pilot plant production all over the world. However, their synthesis involves hazardous production processes. This paper discusses relatively safe and eco-friendly approaches and techniques such as microwave technology and the use of ionic liquids for the synthesis of high-performance energetic materials that can be used as explosives and propellants. In addition, the use of dinitrogen pentoxide as an efficient nitrating agent for the synthesis of energetic materials is considered.



2.
Transition Processes During Flame Propagation in a Closed Vessel Partially Filled with a Porous Media

Ya. V. Kozlov, V. V. Zamashchikov, A. A. Korzhavin
Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: пламя, закрытый сосуд, пористая среда, flame, closed vessel, porous medium

Abstract >>
Flame propagation in a closed vessel containing a stoichiometric propane-air mixture and partially filled with a porous medium has been experimentally studied. It has been shown that the flammability limit in the porous medium is determined by the current pressure as the flame approaches it and by the transition process occurring as the wave enters the porous medium. The phenomenon of the dynamic limit - the flammability limit in a porous medium associated with a continuous pressure drop - has been investigated. It has been found that the range of initial pressures in which the dynamic limit is observed is determined not only by the change in the number of moles in the gas phase, as during flame propagation in vessels completely filled with a porous medium, but also by gas cooling in the free space. The initial pressure range in which the dynamic limit is possible can be significantly wider than that due to a change in the number of moles. This range is mainly determined by the heat exchange of the gas with the walls of the vessel in the region free from the porous medium.



3.
Improved Chemical Reactor Network Application for Predicting the Emission of Nitrogen Oxides in a Lean Premixed Gas Turbine Combustor

T. H. Nguyen
Nong Lam University of Ho Chi Minh City, Ho Chi Minh City, Viet Nam
Keywords: горение, вычислительная гидродинамика, система химических реакторов, газотурбинная камера сгорания с предварительным смешением, эмиссия оксидов азота, combustion, CFD, CRN, lean premixed gas turbine combustor, emission of nitrogen oxides

Abstract >>
This study presents the improvement and application of a 24-element chemical reactor network (CRN) model for predicting the emission of nitrogen oxides in a lean premixed gas turbine combustor. The 24-element CRN improvement is based on the results of CFD simulations. The emission of nitrogen oxides predicted by the 24-element CRN is in good agreement with the experimental data obtained at the Korea Electric Power Research Institute. The new CRN is able to handle complex chemical mechanisms. As there are few requirements for computation time, the CRN can be used as a tool for the analysis of combustion systems and can be integrated into gas turbine combustor designs.



4.
Determination of the Fuel Concentration Distribution in a Supersonic combustion Chamber

M. A. Goldfeld, A. V. Starov
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: сверхзвуковой поток, пробоотборник, смешение, керосин, горение, supersonic flow, sampling tube, mixing, kerosene, combustion

Abstract >>
Kerosene concentration distributions measured in the combustion chamber of a hotshot wind tunnel in the attached pipeline regime with the input Mach number of 2.89 are reported. Kerosene is injected through 12 jet injectors at an angle to the flow from the wall upstream of a cavity. The measurements are performed in three cross sections. Data on the kerosene concentration distribution in the initial region of the combustion chamber and its dependence on the ratio of the jet and main flow momenta are obtained. It is demonstrated that the absence of intense combustion in a model combustor under these conditions is caused by the fact that the local equivalence ratios are insufficient for ignition.



5.
Effects of Partitions on the Passage of Fitlering Combustion Waves Along a Porous Titanium Tape

S. G. Vadchenko
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, 142432 Russia
Keywords: фильтрационное и поверхностное горение, скорость горения титановых лент, влияние преграды, filtering and surface combustion, burning rate of titanium tapes, effect of partition

Abstract >>
Combustion of tapes in air, rolled from titanium powder, and the delay time of the combustion front motion in the presence of a one-sided partition, which limits the access of an oxidizer to the surface. It is shown that the combustion front is aligned with respect to the tape thickness at a long distance from the partition, which is two order of magnitude larger than its thickness. The critical width of the two-sided partition is determined. The largest portion of the tape, where the front is aligned with respect to the tape thickness with a one-sided partition, and the small critical width of the two-sided partition are due to the surface combustion.



6.
Effect of Heating Rate of the Original ASD-4 Powder and the ASD-4 Powder Modified by the V2O5 Oxide on the Phase Composition of Oxidation Products

V. G. Shevchenko1, D. A. Eselevich1, Z. S. Vinokurov2,3, A. V. Konyukova1
1Institute of Solid State Chemistry, Urals Branch, Russian Academy of Sciences, Yekaterinburg, 620990 Russia
2Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
3Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: алюминий, порошок, модификация, пентаоксид ванадия, окисление, скорость нагрева, фазовый анализ, aluminum, powder, modification, vanadium pentoxide, oxidation, heating rate, phase analysis

Abstract >>
X-ray diffraction with the help of synchrotron radiation is used to analyze a sequence of phase formation in the oxidation of original and modified Al powders in the case of heating in oxidizing gaseous media with rates of 10 and 100 K/min. It is established that an increase in the heating rate of the modified ASD-4 powder leads to an active growth of metastable phase (  - and  '-Al2O3) of aluminum oxide except for the  -Al2O3 phase. There are assumptions on the forms of existence of vanadium in the interaction products. It is shown that diffusion limitations in the core - shell system (Al-Al2O3) can be removed under the action of an oxidizing aluminum particle on physicochemical processes at interphase boundaries.



7.
Convective Combustion of a Ti + 0.5C Granulated Mixture. Domain of Existence and Fundamental Phenomena

B. S. Seplyarskii, R. A. Kochetkov, T. G. Lisina
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, 142432 Russia
Keywords: горение, гранулирование, смесь Ti + 0.5C, поток газа, конвективный теплоперенос, механизм горения, переход между режимами горения, combustion, granulation, Ti + 0.5C mixture, gas flow, convective heat transfer, combustion mechanism, transition between combustion regimes

Abstract >>
Combustion of a Ti + 0.5C granulated mixture with a varying rate of the concurrent flow of nitrogen is under consideration. Experimental data are used to determine the gas flow parameters responsible for the transition from conductive to convective propagation of the combustion wave, which is characterized by a stronger dependence of the burning rate on the value of the gas flow. A simple model for calculating the burning rate in convective combustion, and a method for determining the boundary between combustion regimes is developed. In accordance with this model, the burning rate not only depends on the combustion temperature of the mixture, but also on the ignition temperature of the mixture components in the flow of active gas.



8.
Dependences of the Burning Rate and Phase Composition of Condensed Products of a Ti + Ni Mixture on the Mechanical Activation Time

N. A. Kochetov, B. S. Seplyarskii, A. S. Shchukin
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, 142432 Russia
Keywords: горение, механическая активация, интерметаллиды, Ti + Ni, никелид титана, температура горения, фазовый состав продуктов, combustion, mechanical activation, intermetallides, Ti + Ni, titanium nickelide, combustion temperature, phase composition of products

Abstract >>
A method of preliminary mechanical activation is used to perform the combustion of a Ti + Ni mixture, which does not burn at room temperature. The dependences of the burning rate, maximal temperature of combustion, and elongation of samples on the mechanical activation time of the Ti + Ni powder mixture are described for the first time. Moreover, the microstructure and phase composition of activated mixtures of their combustion products are studied. The mechanical activation time (9 min) during which the burning rate of the mixture and the content of the main phase (TiNi intermetallide) in the combustion products is experimentally determined. In these conditions, the combustion propagates within a narrow zone - the maximal temperature corresponds to that in the combustion front.



9.
High-Energy Salts of 5,5'-Azotetrazolate. I. Thermochemistry and thermal Expansion

V. P. Sinditskii, L. E. Bogdanova, K. O. Kapranov, A. I. Levshenkov, V. I. Kolesov
Dmitry Mendeleev University of Chemical Technology of Russia, Moscow 125047, Russia
Keywords: соли 5,5'-азотетразола, термическое разложение, кинетика, теплота сгорания, энтальпия образования, 5,5'-azotetrazolate salts, thermal decomposition, kinetics, heat of combustion, enthalpy of formation

Abstract >>
Thermal decomposition of disubstituted salts of high-energy 5,5'-azotetrazolate (sodium, ammonium, hydrazine, guanidinium, aminoguanidinium, and triaminoguanidinium salts) under isothermal and nonisothermal conditions in solid and liquid phases is studied. The relationship between the avidity and the thermal stability of the 5,5'-azotetrazolate salt is demonstrated. The boundary of possible existence of 5,5'-azotetrazolate salts in terms of the avidity index p K a is determined. Gaseous and condensed products of decomposition are analyzed, and a mechanism of thermal decomposition of 5,5'-azotetrazolate is proposed. The enthalpies of formation of some 5,5'-azotetrazolate salts are determined, and the most reliable values are chosen on the basis of the analysis of the data obtained in the present study and those available in publications.



10.
Thermochemical and Energy Characteristics of Alcoxy-NNO-Azoxy Derivatives of Pyrazoles and Nitropyrazoles

I. N. Zyuzin1, A. I. Kazakov1, D. B. Lempert1, I. A. Vatsadze2, L. S. Kurochkina1, A. V. Nabatova1
1Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432, Russia
2Zelinsky Institute of Organic Chemistry, Russian Academybof Sciences, Moscow, 119991 Russia
Keywords: 1-(2,2-бис(метокси-NNO-азокси)этил)-пиразол, 1-(2,2-бис(метокси-NNO-азокси)этил)-3-нитропиразол, 1-(2,2-бис(метокси-NNO-азокси)этил)-4-нитропиразол, алкокси-NNO-азоксисоединения, пиразолы, нитропиразолы, энтальпия сгорания, энтальпия образования, смесевые твердые ракетные топлива, удельный импульс, 1-(2,2,2-bis(methoxy-NNO-azoxy)ethyl)-pyrazole, 1-(2,2-bis(methoxy-NNO-azoxy)ethyl)-3-niropyrazole, 1-(2,2-bis(methoxy-NNO-azoxy)ethyl)-4-niropyrazole, alkoxy-NNO-azoxy compounds, pyrazoles, nitropyrazoles, enthalpy of combustion, enthalpy of formation, solid composite propellants, specific impulse

Abstract >>
The standard enthalpies of formation of the compounds 1-(2,2-bis(methoxy-NNO-azoxy)ethyl)pyrazole, 1-(2,2-bis(methoxy-NNO-azoxy)ethyl)-3-nitropyrazole, and 1-(2,2-bis(methoxy-NNO-azoxy)ethyl)-4-nitropyrazole were measured experimentally to be 273.6 ± 6.7, 231.0 ± 3.3 and 213.8 ± 7.9 kJ/mol, respectively. These enthalpy values were used to determine the contribution of the replacement of H atoms at N atoms in heterocycles by CH2CH(N2O2Me)2 groups (151.9 kJ/mol). Calculations have shown that compared to HMX, 1-(2,2-bis(methoxy-NNO-azoxy)ethyl derivatives of pyrazole, 3- and 4-nitropyrazole, 3,4-diniteopyrazole, 3,4,5-ttrinitropyrazole, the bis-derivative bis-furazano[3,4-b;3',4'-e] piperazine are worse gasifying components of solid composite propellants in metal-free compositions with an active binder. Only the derivative 3,4-dinitropyrazole, which at low content and combined with ammonium perchlorate provides a specific impulse of 249 s in aluminum-free propellant compositions. Key



11.
Combustion of Aluminum and Boron Agglomerates Free Falling in Air. I. Experimental Approach

O. G. Glotov, G. S. Surodin
Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: алюминий, бор, частица, агломерат, горение, время горения, конденсированные продукты горения, сканирующий электронный микроскоп, энергодисперсионный анализ (EDS), aluminum, boron, particle, agglomerate, burning, burning time, condensed combustion products, scanning electron microscope, energy dispersive analysis (EDS)

Abstract >>
This paper presents a review of studies of the combustion of composite propellants containing a fuel based on aluminum and boron. A method for studying the combustion of large particles of a combined Al + B fuel in air is presented. Burning Al/B particles 300-700 m in diameter of agglomeration origin were obtained by ignition of miniature pieces of a mixed composition containing 32% binder and 68% micron size aluminum and boron powders in the ratio Al/B = 81/19 placed in a burning metal-free sample. Agglomerates formed by the merger of many small particles burned in free fall in air. The procedures for processing video records of the combustion process and studying condensed combustion products (residues of burning agglomerates) to determine the burning time and analyze the transformation of the combined fuel into oxide are described.



12.
Combustion of Aluminum and Boron Agglomerates Free Falling in Air. II. Experimental Results

O. G. Glotov, G. S. Surodin
Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: алюминий, бор, частица, агломерат, горение, время горения, конденсированные продукты горения, остаток горения, морфология, масса остатка, цериметрический химический анализ, неполнота сгорания, сканирующий электронный микроскоп, энергодисперсионный анализ (EDS), элементный состав, aluminum, boron, particle, agglomerate, burning, burning time, condensed combustion products, combustion residue, morphology, mass of residue, cerimetric chemical analysis, incomplete combustion, scanning electron microscope, energy dispersive analysis (EDS), elemental composition

Abstract >>
The combustion of Al/B agglomerates (0.81/0.19) with a diameter of 320-780 m in free fall in air was first studied by the method of model monodisperse agglomerates method. The dependence of the burning time on size was determined. Burning residue particles were subjected to morphological, chemical, mass, particle size, and elemental (EDS method) analyses. It has been found that the essential features of the combustion mechanism of Al/B agglomerates compared to aluminum are long combustion; the specific core-shell structure of the particles, with boron present in the core and absent in the shell; a slight change in mass and diameter of particles during combustion.



13.
Steric Stabilization of Colloidal Aluminium Particles for Advanced Metalized-Liquid Rocket Propulsion Systems

S. Elbasuney
School of Chemical Engineering, Kobry Elkoba, Cairo, Egypt
Keywords: жидкостный ракетный двигатель, коллоид, модификация поверхности, стерическая стабилизация, горючее на металлической основе, liquid rocket propulsion, colloid, surface modification, steric stabilization, metal-based fuel

Abstract >>
The achievement of stable colloidal suspensions of reactive metal powders in liquid propellants is crucial for obtaining enhanced thrust per unit mass. Aluminium is of interest due to its availability, stability, and high combustion enthalpy (32000 J/g). In this manuscript, ultrafine spherical aluminium particles with the average size of 15 m are produced by wet milling. Aluminium particles are effectively surface-modified with a polymeric surfactant and sterically stabilized in an organic solvent (toluene). Organically modified aluminium demonstrates a drastic change in surface properties from hydrophilic to hydrophobic, with effective transfer from the aqueous to organic phase. The stabilized particles are effectively dispersed in a liquid rocket propellant (hydrazine). The impact of aluminium particles on hydrazine combustion characteristics is evaluated by using a thermodynamic code named ICT (Institute of Chemical Technology in Germany, 2008). Aluminium particles offer an increase in the combustion temperature, oxygen balance, characteristic exhaust velocity, and specific impulse. The optimum solid loading level of aluminium in the hydrazine fuel is found to be 6 wt%.



14.
Numerical Simulation of the Flowfield in a Boron-Based Slurry Fuel Ramjet

Y.-L. Xiao, Zh.-X. Xia, L.-Y. Huang, L.-K. Ma, D.-L. Yang
College of Aerospace Science and Engineering, National University of Defense Technology, 410073, Changsha, People's Republic of China
Keywords: суспензия, прямоточный воздушно-реактивный двигатель, бор, агломераты, slurry, ramjet, boron, agglomerate

Abstract >>
By considering the parametric variation of an individual boron particle in a boron agglomerate, the heat transfer, and the mass transfer between the boron particle agglomerate and the surroundings, an ignition and combustion model of a boron agglomerate is proposed. An experiment of a ramjet combustor using a boron-based slurry fuel is designed and operated for the purpose of validating the ramjet configuration and verifying the combustion of boron particles. Then a mathematical model for simulating a multiphase reacting flow within the combustor of a boron-based slurry fuel ramjet is established. Kerosene droplets and boron particles are injected discretely to the burner flowfield, and their trajectories are traced using the discrete phase model. The influence of the agglomerate size, bypass air mass flow rate, initial boron particle diameter, and boron particle content on the combustion efficiency of the slurry fuels is analyzed in detail. The results show that the combustion efficiency decreases with an increase in the agglomerate radius, initial boron particle diameter, and boron particle content. The combustion efficiency increases with an increase in the mass flow rate of bypass air. If the agglomerate diameter is greater than 100 m or the bypass air mass flow rate is smaller than 50 g/s, the boron particles cannot be fully burned.