Melting Point of Carbon Particles behind the Gas Detonation Front

A mathematical model of gas detonation of fuel-enriched mixtures of hydrocarbons with oxygen has been formulated, which makes it possible to numerically study the equilibrium flows of detonation products in the presence of free carbon condensation. Reference data for graphite were used to describe the thermodynamic properties of carbon condensate. The calculations are compared with the known results of experimental studies in which, when detonating an acetylene-oxygen mixture in a pipe closed at one end, it is possible to obtain nanoscale particles from a carbon material with special properties. It is assumed that the melting point of such a material is lower than that of graphite and is about 3100 K. Only with such an adjustment of the melting temperature, the best agreement (with an accuracy of about 3 %) was obtained between the calculated and experimental dependence of the detonation front velocity on the molar fraction of acetylene in the mixture.

EXPRESS METHOD FOR CALCULATING THE SPECIFIC HEAT OF EXPLOSIVE TRANSFORMATION OF CHNO CONDENSED EXPLOSIVES

Разработан экспресс-метод расчета теплоты взрыва СаHbNcOdконденсированных взрывчатых веществ с различным кислородным балансом от резко отрицательного до положительного. Предложенный метод использует минимальный набор входных данных, состоящих из элементного состава, плотности энтальпий образований исходного взрывчатого вещества и его продуктов детонации. Расчет теплоты взрыва основывается на корреляционной связи между минимальной и максимальной теплотами взрыва с плотностью высокоэнергетического соединения. В статье подробно приведены реакции разложения взрывчатых веществ для случаев с минимальной и максимальными теплотами взрыва. Проведены расчеты теплоты взрыва по новому способу и методу Пепекина по представленной в статье базы взрывчатых веществ, а также приведены результаты сравнения, которые показали большую точность (в 2,3 раза) предложенного метода. An express method has been developed for calculating the explosion heat of cahbncod condensed explosives with different oxygen balance from sharply negative to positive. The proposed method uses a minimal set of input data consisting of the elemental composition, enthalpy density of the formations of the initial explosive and its detonation products. The calculation of the heat of explosion is based on the correlation between the minimum and maximum heat of explosion with the density of a high-energy compound. The article describes in detail the decomposition reactions of explosives for cases with minimum and maximum explosion heats. Calculations of the heat of explosion according to the new method and the pepekin method are carried out according to the explosives database presented in the article, and comparison results are also presented, which showed a better accuracy (2.3 times) of the proposed method.

Gas hazard of explosives used in the mining industry

Reducing emissions of hazardous pollutants that have a negative impact on the environment and human health has been approved as one of the strategic objectives of Russia's development. More than 90% of minerals in mined using blast energy. Despite an increase in the share of non-explosive component mixtures used in mining, blasting still poses a hazard to miners as the gaseous detonation products are potentially dangerous. The composition of blast gaseous products is extremely important in underground blasting because air exchange is difficult under these conditions and the blast products can contaminate the atmosphere of underground excavations, causing illness or poisoning of miners. Currently, there are no uniform requirements for obtaining information on the amount of gaseous blast products that would be hazardous to the human organism. Available documents do not contain information on the permissible amounts of toxic oxides per 1 kg of explosive detonated. The article compares the results of studying gas toxic hazard of industrial explosives obtained by different methods and based on different criteria.

Natural and anthropogenic risks after a giant landslide in the Russian Far East

At the Bureiskoe Reservoir (Far East, Russia) in December 2018 at a temperature of 36°C below zero the giant landslide is occurred. Landslide with a total volume of 24.5 million m3 blocked the reservoir from one shore to the opposite one, disrupting the access of water to a large hydroelectric power station downstream. Blasting operations were carried out with the use of trinitrotoluene and hexogen to revive the water flow. As a result of the landslide natural hazards (direct impact of the landslide, and tsunami) were happened, and the further strong impact was caused by humans (blasting). Volatile organic compounds (VOCs) and elemental composition were accepted as the main indicators of water quality. Parameters of these indicators varied at different near-shore sites above and below the landslide area. More significant changes are recorded after blasting operations. Hexane and toluene dominated the water passing the artificial channel. The genesis of VOCs can be associated with the biogeochemical processes of methanogenesis, methanotrophy, and the detonation products of explosives. Mercury, methanol, toluene, and xylenes in water samples were detected. This is evidence of the presence of a prerequisite for the formation of toxic methylmercury, a risk factor for aquatic biota.

Modelling the influence of gaseous products of explosive detonation on the processes of crack treatment while rock blasting

Purpose is mathematical modeling of fracturing as well as influence of gaseous products of explosive detonation on the changes in rock strength. Methods. Mathematical model, using foundations of Griffith theory, has been developed. To explain conditions of bridge formation while exploding lead azide charges, a two-stage description of solid particle condensation at a crack surface and inside it has been applied using the smoothed particle hydrodynamics. The analysis, involved electronic microscope, has helped verified the results experimentally. Findings. The effect of rock mass disturbance, resulting from explosive destruction, is manifested maximally right after the action. Subsequently, it decreases owing to the gradual relaxation of the formed defects. Therefore, an urgent problem is to develop ways slowing down strength restore of the blasted rock mass fragments. The process of rock fragment strength restoring may be prevented by microparticles getting into the microcrack cavities together with the detonation products. The research simulates their action. The data correlate to the simulation results confirming potential influence of the blasted rock on the dynamics of changes in the strength characteristics of the rock mass. Various compositions of charges with shells made of inert solid additions have been applied which solid particles can avoid the process of microcrack closure. Originality. For the first time, the possibility of deposition formation within rock micro- and macrocracks has been proposed and supported mathematically. Practical implications. Strength properties of the finished product and the energy consumption during impulse loading as well as subsequent mechanical processing of nonmetallic building materials depend on the strength properties of rock mass fragments. Hence, the ability to control the strength restore has a great practical value. Moreover, it can be implemented during the blasting operations.

Equation of state for the detonation products of energetic materials

Energetic materials (EMs) are one of the necessities in many military and civilian applications. Measuring the thermodynamic behaviors of detonation products of EMs at high temperature and high pressure, their equations of state (EOSs) not only serve as a basis in the design of novel materials, but also provide valuable information for their practical applications. The EOS study has a long history, but keeps moving all the time. Various EMs have been developed, the EOS of detonation products provides abundant information in the thermochemistry, hydromechanics and detonation physics, which in turn feedbacks the development of novel EMs and their EOSs. With the development of experimental techniques and computer simulations, many EOSs have been proposed for various explosives in recent years. While experiments keep their fundamental roles, integrated theory-experiment study has become the main approach to the EOS establishment for novel EMs. Moreover, computer simulations based on interatomic and/or intermolecular interaction will have great potential in the future when big data and artificial intelligence are introduced into the field.

Numerical study of fragments from cylindrical casing with one of end caps fully constrained

In order to study the process and characteristic of the fragments in the warhead with one end cap under full constraint condition, we established a cylindrical casing with two end caps which one of them was fully constrained using the simulation analysis. The result showed that the fragmentation of cylindrical casing with one end full constrained has its own characteristic. The Mach stem was generated when the detonation wave propagated to the fully constrained end cap under the condition of one end detonation, working on unreactive explosives and causing the nearby fragment subjected to nearly 2.5 times the normal pressure to obtain a higher speed. The cylindrical casing first ruptured at the contact surface with the fully constrained end, and then at the end cover of the initiating end, and then the rupture extends to the whole cylindrical casing. The detonation products started to leak out from the rupture. driving fragments to fly, and forming two dense flying areas. The analysis of this paper can provide a reference for the optimal design of this kind of warhead.

Air-Argon-Steam or Organic Fluid Combined Power Cycle With Pulse Detonation Combustion for Electric Power Plants

Gas turbine engines with pulse detonation combustion show the superior performance in terms of specific work output and thermal efficiency when compared to the conventional gas turbine engines with isobaric combustion. But, a quasi-steady expansion of detonation products through the gas turbine results in an unsteady operation. Moreover, as the detonation products during quasi-steady expansion are initially at a very high temperature (over 2500 K), they cannot be expanded in the turbine as it is. To overcome the above difficulties associated with pulse detonation combustion in gas turbine engines, Air-Argon-Steam or organic fluid Combined Cycle (AASCC) is proposed in the present work. AASCC comprises two gas turbine cycles, viz. the Humphrey cycle with the air as the working fluid and the Brayton cycle with the argon as the working fluid and a steam turbine cycle, viz. the Rankine or organic Rankine cycle with the steam or organic substance as the working fluid. The temperature of the hot detonation products is reduced to Turbine Inlet Temperature (TIT) by exchanging heat energy between detonation products and compressed argon in a Detonation Products to Argon Heat Exchanger (DPAHE) and in turn, raising the temperature of the compressed argon to Argon Turbine Inlet Temperature (ATIT). The residual energy of both detonation products and argon after the expansion in the respective turbines is utilized to generate the steam or organic fluid vapor in the Heat Recovery Generators (HRGs) to operate a steam or organic fluid turbine. AASCC with pulse detonation combustion is analyzed based on quasi-steady state one dimensional formulation, and a computer code is developed in MATLAB to simulate the cycle performance at different compressor pressure ratios and TITs. C2H4/air is taken as the fuel-oxidizer. The performance of AASCC with pulse detonation combustion is compared with that of a conventional Air-Steam Combined Cycle (ASCC) with constant pressure combustion. It is found that the thermal efficiency of AASCC with pulse detonation combustion can go up to 44.5%–46.5% depending on the working fluid used in the bottoming Rankine cycle as against 37.8%–41.0% of ASCC at a TIT of 1400 K. The maximum specific work output of AASCC at a TIT of 1400 K is found to vary from 1143.0 to 1202.0 kJ/kg air as against to 335.0 to 364.0 kJ/kg air of ASCC.