ABSTRACT
Research Interests:
The process of initiation and propagation in shock tube of stationary detonations in suspensions of the Al-particles of various size and shape has been investigated experimentally. The Al-suspensions of mean size which is more than 10 μm... more
The process of initiation and propagation in shock tube of stationary detonations in suspensions of the Al-particles of various size and shape has been investigated experimentally. The Al-suspensions of mean size which is more than 10 μm didn’t ignited neither in air medium nor in the oxygen one. Al-air-suspensions with scales-like particles of thickness about 1 μ and diametrical size 10–15 μm have the same detonation ability as gaseous fuel-air mixture. Spherical Alparticles of diameter 1 μm had some more high detonation ability, i.e. detonation ability of Al-suspensions increases essentially with the particle size decreasing. It was no success to obtain stationary spherical detonation of Al-particles of diameter 3.5 μm dispersed in the oxygen-medium due to the finite size of the cloud.
Research Interests:
Research Interests:
Research Interests: Detonation and Metal
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Theoretical models describing convective combustion are complex and usually analyzed by numerical methods. This paper applies a method of estimating the terms of the equation to the model of the process under consideration, to obtain a... more
Theoretical models describing convective combustion are complex and usually analyzed by numerical methods. This paper applies a method of estimating the terms of the equation to the model of the process under consideration, to obtain a system of algebraic equations that approximates the initial system of partial differential equations and the boundary conditions. The time scale is determined. It is found that the pressure drop acting along the charge and growing with the lapse of time causes a redistribution of the propellant particle mass. The specific form of the dependence w on the properties of the propellant t and the instantaneous pressure pB is determined by the energy transfer mechanism in the ignition wave. The formulas derived are compared to the results of numerical integration of the problem and are found to be in good agreement. This new data relative to the mechanism and properties of the convective combustion of a wave must be taken into account in constructing a complete theory of the transition of porous system combustion into detonation.
Research Interests:
Theoretical models describing convective combustion are complex and usually analyzed by numerical methods. This paper applies a method of estimating the terms of the equation to the model of the process under consideration, to obtain a... more
Theoretical models describing convective combustion are complex and usually analyzed by numerical methods. This paper applies a method of estimating the terms of the equation to the model of the process under consideration, to obtain a system of algebraic equations that approximates the initial system of partial differential equations and the boundary conditions. The time scale is determined. It is found that the pressure drop acting along the charge and growing with the lapse of time causes a redistribution of the propellant particle mass. The specific form of the dependence w on the properties of the propellant t and the instantaneous pressure pB is determined by the energy transfer mechanism in the ignition wave. The formulas derived are compared to the results of numerical integration of the problem and are found to be in good agreement. This new data relative to the mechanism and properties of the convective combustion of a wave must be taken into account in constructing a complete theory of the transition of porous system combustion into detonation.
Research Interests:
Research Interests:
Research Interests: Physics and Combustion
The basic results of experimental investigations on reinitiation processes in diffracting multifront detonation wave (DW) are discussed in connection with problem of practical application of new ecological technology for worn-out tire... more
The basic results of experimental investigations on reinitiation processes in diffracting multifront detonation wave (DW) are discussed in connection with problem of practical application of new ecological technology for worn-out tire destruction, where the cooled worn-out tire destroys with the help of gaseous detonation. The experimental results for various fuel-oxygen and fuel-air mixtures are presented at wide range of mixture compositions, initial pressure and temperature, geometrical sizes of experimental equipment, symmetry types, dilution of inert gases, etc. Classical and nontraditional schema of DW-diffraction are investigated, such as multipointed initiation, DW-excitation by circular charge, initiation space-oriented longitudinal charges, initiation by circular charge, diffraction on concave boundary, diffraction on contact surface of different mixtures, flame diffraction, etc. The main characteristic parameters are identified for each diffraction schema. The physical pr...
Research Interests:
Research Interests:
The existing models of the reaction center formation caused by the compression of high explosives (HE) in shock waves, for example, Mader's mechanism of "hydrodynamic hot spots," do not allow any explanation of the... more
The existing models of the reaction center formation caused by the compression of high explosives (HE) in shock waves, for example, Mader's mechanism of "hydrodynamic hot spots," do not allow any explanation of the relatively high sensitivity of solid HE containing 0.1-10-y voids to the shock waves with amplitudes of the order of 1 GPa. In the present paper, the dynamics of void collapse is analyzed. It is shown that the latter occurs in solid HE in a substantially viscous regime, and almost all energy to be evolved in the course of collapse is converted by viscous and plastic forces into heat in the vicinity of a void. Unlike Mader's mechanism (which is typical for large pores with sizes ^ 1-10 mm), the temperature rise near a collapsing void in this case is not accompanied by a local pressure increase in the hot spot. Thus the "lifetime11 of a hot spot is controlled by thermal conductivity of HE rather than by diverging hydrodynamic waves (as in the case of Mader's mechanisms), and is long enough to provide the conditions for the initiation of a reaction even if the voids are as small as 1 u. The values of a pore surface temperature rise, ignition delays, and critical pressures required to generate reaction centers behind a shock are estimated. The calculated critical pressures agree by an order of magnitude with the available experimental ones. The calculations demonstrate a high effectiveness of the considered mechanism Presented at the 8th ICOGER, Minsk, USSR, Aug. 23-26, 1981.
Research Interests:
of reaction in hot spots are estimated for the limiting cases when the chemical reactions occur only in the solid phase and when they occur only in the gas phase. Based on the comparison of mean pore size in the explosive material with... more
of reaction in hot spots are estimated for the limiting cases when the chemical reactions occur only in the solid phase and when they occur only in the gas phase. Based on the comparison of mean pore size in the explosive material with the critical one that is sufficient for initiating and sustaining the chemical reaction, an explanation is given of the experimental data on nonmonotonic dependence of the shock sensitivity of porous explosives on their microstructure. The dependence of the critical pore size on the initiating shock wave amplitude is presented.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
An experimental setup has been designed which permits to study the initiation and propagation of a detonation in liquid fuel sprays in controlled (granulometry and concentration of the spray) and reproducible conditions. It was shown that... more
An experimental setup has been designed which permits to study the initiation and propagation of a detonation in liquid fuel sprays in controlled (granulometry and concentration of the spray) and reproducible conditions. It was shown that it is possible to initiate a detonation in liquid fuel in air under standard initial conditions of temperature and pressure without preheating the mixture. One can detonate weakly volatile fuel sprays (decane, dodecane) under the condition that the droplet size is sufficiently small. A numerical model including the mechanical disintegration of droplets by interaction with the leading shock front has been built. Numerical simulations performed with this model are in good agreement with the experimental results.
Present work has permitted to define the characteristics of an experimental configuration relevant to study the direct initiation of aluminium-oxygen suspensions, based on an estimation of the critical initiation energy of 1kg TNT and the... more
Present work has permitted to define the characteristics of an experimental configuration relevant to study the direct initiation of aluminium-oxygen suspensions, based on an estimation of the critical initiation energy of 1kg TNT and the critical detonation radius of the order of magnitude of 1m. The experimental plant has been built. First experiments have displayed that a shock front velocity of about 1600 m/s could be reached at 1.94m from the initiation point, which is very close to the theoretical CJ value of 1623 m/s and permit to validate our predictions on the detonability of aluminium/oxygen suspensions.
Comparative analysis is performed of 2D numerical solutions of Euler equations coupled with standard (density independent) reaction rate law with that taking into account the effect of density. It is shown that in the case of detonation... more
Comparative analysis is performed of 2D numerical solutions of Euler equations coupled with standard (density independent) reaction rate law with that taking into account the effect of density. It is shown that in the case of detonation diffraction from a tube to a space the predictions based on the reaction rate law depending on density reasonably agree with experimental trends. On the contrary, the standard detonation model does not correspond to physical reality since it is insensitive to local layers of elevated gas density favorable for propagation of transverse waves, which are crucial in many detonation problems. Thus, it is worth to be careful with the conclusions based on the standard detonation model.
The model of detonation initiation and propagation is proposed for lead azide and is tested numerically for confined and unconfined charges. Two-dimensional Euler equations coupled with the visco-plastic model of void deformation were... more
The model of detonation initiation and propagation is proposed for lead azide and is tested numerically for confined and unconfined charges. Two-dimensional Euler equations coupled with the visco-plastic model of void deformation were solved by a high order finite-volume TVD scheme. In view of absence of thermodynamic data of lead containing detonation products we have developed a special equation of state
(EOS) similar to the HOM EOS. The equations of state of solid lead azide at theoretical maximum density and its detonation products were derived based on a limited number of experimental detonation velocities and some general features of behaviour of Gruneisen coefficient of detonation products of typical secondary explosives. The effect of charge diameter on detonation velocity, structure and curvature of detonation front is then studied numerically for confined and unconfined charges. Since the model developed takes into account the void deformation, these simulations were performed in a wide range of initial density of lead azide and consistent results were obtained. Thus, the proposed gasdynamic model could be also applied for a thorough study of initiation of primary explosives by pulsed laser and high-current electron beam irradiation.
(EOS) similar to the HOM EOS. The equations of state of solid lead azide at theoretical maximum density and its detonation products were derived based on a limited number of experimental detonation velocities and some general features of behaviour of Gruneisen coefficient of detonation products of typical secondary explosives. The effect of charge diameter on detonation velocity, structure and curvature of detonation front is then studied numerically for confined and unconfined charges. Since the model developed takes into account the void deformation, these simulations were performed in a wide range of initial density of lead azide and consistent results were obtained. Thus, the proposed gasdynamic model could be also applied for a thorough study of initiation of primary explosives by pulsed laser and high-current electron beam irradiation.
Research Interests:
Research Interests:
Research Interests: Physics and Detonation
Research Interests:
The effect of a plane obstacle located normally in front of a detonation tube exit on critical conditions of detonation diffraction is experimentally studied for a stoichiometric C 2 H 2 /O 2 mixture. The results not only complement the... more
The effect of a plane obstacle located normally in front of a detonation tube exit on critical conditions of detonation diffraction is experimentally studied for a stoichiometric C 2 H 2 /O 2 mixture. The results not only complement the data base obtained by Murray and Lee (1983) and Vasil'ev et al. (2003) but provide perfect records of detonation transition or failure history. Numerical two-dimensional unsteady simulations of the effect of the obstacle on detonation diffraction were performed assuming a single-step but density-dependent Arrhenius reaction and reasonable agreement was obtained with experiment. Introduction For common hydrocarbons/O 2 /N 2 mixtures the critical diameter (d cr) of the tube ensuring the detonation transition to a space scales with the detonation cell thickness λ, namely d cr ≈13λ (Mitrofanov and Soloukhin [1], Matsui and Lee [2]). However, for some applications, such as pulse-detonation engines (PDE), it is necessary to facilitate detonation diffra...