Thermobaric Explosives Research Articles

Effects of main components on energy output characteristics of thermobaric explosive — A case study of typical formulations

As a kind of high-efficiency explosive with compound destructive capability, the energy output law of thermobaric explosives has been receiving great attention. In order to investigate the effects of main components on the explosive characteristics of thermobaric explosives, various high explosives and oxidants were selected to formulate five different types of thermobaric explosive. Then they were tested in both open space and closed space respectively. Pressure measurement system, high-speed camera, infrared thermal imager and multispectral temperature measurement system were used for pressure, temperature and fireball recording. The effects of different components on the explosive characteristics of thermobaric explosive were analyzed. The results showed that in open space, the overpressure is dominated by the high explosives content in the formulation. The addition of the oxidants will decrease the explosion overpressure but will increase the duration and overall brightness of the fireball. While in closed space, the quasi-static pressure formed after the explosion is positively correlated with the temperature and gas production. In addition, it was found that the differences in shell constraints can also alter the afterburning reaction of thermobaric explosives, thus affecting their energy output characteristics. PVC shell constraint obviously increases the overpressure and makes the fireball burn more violently.

Enhancement of explosive effect of thermobaric explosive by metal reactive material

AbstractReactive materials have mechanical properties comparable to metal materials and also have the reaction‐release energy characteristics of energetic materials. The calorific value of reactive materials is even higher than that of explosives. They can react under high pressure/high temperature and release a large amount of chemical energy. Therefore, reactive materials have a wide range of potential applications in aviation and national defense fields. This study examines the energy release characteristics of the metal reactive material casing (MRMC) under thermobaric explosives and compares them to traditional steel casing. The test specimens had the same casing‐charge mass ratio and size, with the only difference being the casing material: reactive material (with reactive elements Zr and Al) and AISI 1020 steel. The physical and chemical properties of the reactive materials were tested and analyzed using ICP‐MS, oxygen bomb calorimeter, and SHPB. Through explosion tests, the characteristic parameters of explosion fireball and ground shock wave overpressure were measured. And the reactive fragments recovered from the experiment were subjected to XRD testing. The results show that MRMC can significantly increase the diameter, duration, and temperature of the explosion fireball compared to steel casing data. The maximum fireball diameter of the MRMC specimen increased by 31.9 %, while the duration before attenuation increased by 47.3 %. MRMC can increase the area ratio of high‐temperature areas (greater than 1300 °C) in the fireball. MRMC increases the overall temperature of the fireball, not just in specific local areas. Additionally, MRMC significantly enhances far‐field shock waves. At a scaled distance of 2.54, the peak overpressure and positive impulse of the MRMC specimen were 50 % and 52 % higher than those of the steel specimen, respectively. This study provides new insights into the application, design, and energy release research of MRMC.

Effect of FOX-7 on Explosion Performances and Afterburning of HMX-Based Thermobaric Explosives

In this paper, confined explosions of HMX-based thermobaric explosives in a spherical chamber were studied. The effects of 1, 1-diamino-2, 2-dinitroethene (FOX-7) on the explosion performances and afterburning were obtained by changing its content. The results showed that the composition (HMX/FOX-7) enhanced the total impulse, but its effect on improving the initial energy and quasi-static pressure (QSP) was slight. The aluminum in thermobaric explosives burned incompletely, whereas FOX-7 promoted afterburning of aluminum particles. In addition, the promoting effect was more obvious with the increase of FOX-7 mass score in the composition. In conclusion, when the ratio of HMX to FOX-7 mass fraction in the composition was 3, the thermobaric explosive had low sensitivity and could maintain the energy level of the explosive.

Experimental study on internal explosion of thermobaric explosives containing metastable intermolecular composite (MIC) materials

In order to study the influence of metastable intermolecular composite (MIC) materials on the internal implosion properties of thermobaric explosive, the calorimetric bomb and closed chamber were used to measure the detonation heat, quasi-static pressure and energy impulse of five explosive formulations containing different MIC materials. Compared with the traditional aluminized warm compressed explosives, the energy release characteristics and output characteristics were analyzed. The results show that the explosive formula containing MIC material has lower detonation heat value in air and vacuum than that containing traditional Al powder; The quasi-static pressure and energy impulse of the former are higher than those of the latter, indicating that MIC materials can improve the output energy of thermobaric explosives. The results can be used to guide the formulation design of thermobaric explosives.

Performance of TKX‐50 in thermobaric explosives

AbstractIn this study, the behavior of the high‐nitrogen compound TKX‐50 in model thermobaric formulations was investigated. The addition of 10 % Al to TKX‐50 reduces the heat of detonation by approximately 90 J/g. Despite this, Al reacts with the detonation products of TKX‐50 in an exothermic manner, and the energy contribution was calculated to be approx. 375 J/g. In addition, the overpressure in the explosion chamber filled with argon after detonation of aluminized TKX‐50 charges containing 27 % Al is approx. 20 % higher than in the case of neat TKX‐50. Also the maximum temperature of the TKX‐50/Al explosion products in the argon filled chamber is higher by 370 K than that of measured after detonating TKX only. What is more aluminum oxynitride with a low nitrogen content has been identified in the solid detonation products of aluminized TKX‐50, but only for detonations in argon. Of course, charges made of TKX‐50/Al mixture generate significantly higher overpressure and radiant temperature values in a confined space when they are detonated in an air atmosphere. It all means that burning aluminum in nitrogen provides little energy, and even if the concentration of nitrogen in the post‐detonation products is much higher than that of oxygen, aluminum oxides are preferentially formed.

120 Blast-Related Traumatic Brain Injuries Secondary to Thermobaric Explosives: Implications for the War in Ukraine

INTRODUCTION: Advancements in modern weaponry have vastly increased the incidence and severity of craniospinal injuries. Specifically, thermobaric weapons can cause devastating blast-related traumatic brain injury (bTBI). With recent use of these weapons in the war in Ukraine, clinicians and laypersons alike may benefit from an improved understanding behind the dynamic interplay between explosive weaponry, its potential for bTBI, and the subsequent short and long-term consequences of these injuries. METHODS: A comprehensive review of thermobaric weapons and their use throughout history was performed. Mechanisms of action behind blast injuries and subsequent therapeutic advancements in neurosurgical management from pioneers of neurosurgery was conducted. We document long term neuropsychiatric sequela following bTBI and discuss its relevance in the current conflict in Ukraine. In addition, a quantitative analysis of the potential of thermobaric weapons to cause bTBI in a hypothetical scenario of its use in Ukrainian civilian zones was performed. RESULTS: A thermobaric weapon causes a prolonged blast pressure wave which can cause devastating injury through several mechanisms, including long-term neuropsychiatric sequela (notably PTSD). The origins of bTBI sequela date back to documentations in WWI of “shell-shock”, now widely known as PTSD. Trailblazers in neurosurgery, such as Harvey Cushing, and prominent psychologists, such as Charles Myers, were pivotal in identifying and treating early cases of bTBI. Our quantitative analysis demonstrates the significant potential of thermobaric weapons in causing bTBI. Construction of underground shelters may mitigate damage from the blast pressure wave. CONCLUSIONS: As humanitarian relief efforts set foot in Ukraine, results from our brief report may inform and assist the development of focused mitigation and rehabilitation strategies, especially in post-war reconstruction

Testing and evaluation of the thermal damage caused by an explosion of energetic materials

With the rapid development of the new generation of energetic materials, the testing and evaluation of the damage caused by these materials in an explosion has received much attention worldwide. To assess the thermal damage caused by an explosion of the energetic materials quantitatively, a system to measure the thermal effects is constructed with self-developed heat flux sensors. An evaluation model based on nonlinear regression is proposed. Static explosion tests of both bare TNT grains and typical thermobaric explosives are carried out under the same test conditions. The heat flux is acquired at different distances from the explosion by the contact heat flow density sensors based on the infrared principle. The thermal doses are obtained by integrating the heat flux. Based on the similarity principle for explosions, two basic evaluation models are established for TNT. The TNT equivalent of equal effect, which is utilized to assess the thermal damage of a typical thermobaric explosive, is calculated by substituting the thermal dose and the distance from the explosion center into the basic evaluation model, established for TNT. In our experiments, the maximum errors of the two TNT basic evaluation models are 14.12% and 12.18%, respectively, which can meet the accuracy requirements of an engineering test assessment of the thermal damage caused by an explosion of energetic materials for proportional distances within the range from 1.1672 to 2.280 m according to the test data.

DETERMINATION OF MAIN THERMODYNAMIC PARAMETERS OF THERMOBARIC AMMUNITION EXPLOSION

A large number of weapon systems have been emerged over the last few decades. Most of these parts create an explosive for poles using fragmentation or cumulative jet. Until recently, some combat units identified the explosion as a major factor. But new technologies have made it possible to develop warheads that improve the characteristics of the explosion and use it as one of the main methods of impacting the target, i.e thermobaric warheads.
 Ammunition equipped with mixed (multicomponent) thermobaric explosives has many advantages over ammunition equipped with conventional explosives. They are more economical (cheaper to manufacture), safer to use and have adjustable thermodynamic characteristics, as well as the composition of products, which allows you to choose the optimal filling of thermobaric ammunition to perform specific tasks.
 The article proposes calculations and methods for determining the main thermodynamic parameters of thermobaric ammunition explosion, namely: heat of explosion, volume of gaseous products, temperature and radius of high temperature area, excess pressure in front of the shock wave and its speed taking into account the physical characteristics of thermobaric explosive.
 The peculiarity of the above calculations and methods is to take into account the physical characteristics of the explosion of the explosive mixture.

Experimental Performance Assessment of Thermobaric Explosives in Free Field and Internal Blast Tests

Experimental Performance Assessment of Thermobaric Explosives in Free Field and Internal Blast Tests

Experimental Performance Assessment of Thermobaric Explosives in Free Field and Internal Blast Tests

Experimental Performance Assessment of Thermobaric Explosives in Free Field and Internal Blast Tests

ON CALCULATION OF OXYGEN BALANCE OF MULTICOMPONENT THERMOBARIC EXPLOSIVE SUBSTANCE

Most modern military confrontations take place near or directly in inhabited area. The use in such conditions of munition (warheads) which hit typical targets based on fragmentation (high-explosive) or cumulative action is impractical due to insufficient “selectivity” of hitting targets with such munition. At present, modern world tendency is the development of the latest munition (warheads) with increased properties of “destruction selectivity”. One of the directions is the development of munition based on thermobaric explosives. Such munitions can cause maximum damage due to high temperature and the impact of a shock wave with a low level of collateral damage, since thermobaric munition, especially in the open area, have a clearly defined or even limited area of effective damage, which determines the significance of their further development.
 Since modern thermobaric explosives include a large number of chemical elements (including chemically active metals), there is a need to calculate the physical balance of oxygen and oxygen coefficient to take into account the physical characteristics of modern multicomponent thermobaric explosives. The oxygen balance of multicomponent thermobaric explosives largely determines the nature of the reaction of its explosive transformation, i.e the composition of the explosive products and, consequently, the value of thermodynamic characteristics such as heat, temperature, volume and pressure of gas-like explosive products.
 The calculated ratio and coefficients for complex multicomponent thermobaric explosives should be calculated during the development of explosives, taking into account the composition of components and elements and their possible chemical reactions during the explosion. The abovementioned improved calculations of oxygen balance and oxygen coefficient of thermobaric explosives, which include aluminum, allows taking into account the physical characteristics of destruction of typical targets by thermobaric munitions.

OXIDIZER AND GAS-ENVIRONMENT EFFECTS ON AFTERBURNING REACTIONS AND EXPLOSION PERFORMANCES OF HMX-BASED THERMOBARIC EXPLOSIVES

In this paper, confined explosions of HMX-based thermobaric explosives containing oxidizers in a spherical chamber were studied by changing the type of the oxidizer and the oxygen concentration in the environment. Based on an in-house developed optical-electrical system, the optical radiation signals of Al2O3 during the afterburning reaction were recorded. The results show that aluminum particles (5.4 µm) were strongly dependent on the oxygen concentration in the environment. Increasing the oxygen concentration can prolong the oxidation duration of Al and enhance the optical radiation intensity of Al2O3. The optical radiation result for Al2O3 in O2 and air showed that aluminum particles (the mass fraction was 33 %) were not completely oxidized in the air, and the oxidation duration was 500–700 µs. Moreover, the pressure data of the blast waves was obtained using a pressure-measurement system. The results showed that an increase in the oxygen concentration of the explosive could further enhance the total impulse, especially an addition of KP (its mass fraction was 10 %) could increase the total impulse by about 9 %.

Vpliv PTFE na omejeno eksplozijo HMX termobaričnih eksplozivov

Vpliv PTFE na omejeno eksplozijo HMX termobaričnih eksplozivov

Performance of Magnesium, Mg‐Al Alloy and Silicon in Thermobaric Explosives – A Comparison to Aluminium

AbstractA direct comparison is made between the effectiveness of Al, Mg, their alloy (Al3Mg4), and Si powders as additional fuels in explosives using the thermobaric effect. The experiment produced calorimetric measurements of the detonation heat and a record of the overpressure histories which were used to determine the quasistatic pressure (QSP) in an explosion chamber after the detonation of charges from mixtures containing 30 % fuel and 70 % RDX passivated with wax. The measured heat values indicate that Al−Mg alloy is a more effective additional fuel during anaerobic post‐detonation reactions than Al and Mg separately. Silicon also exothermically reacts with the detonation products, but the released heat only compensates for the lower amount of RDX in the charge. Similar to the calorimetric measurements, the lowest value of QSP was obtained for the mixture with Si powder. In contrast to anaerobic conditions, silicon proved to be an equally effective thermobaric additive as Al, Mg, and Al−Mg powders in air explosions.

Effect of storage temperature on explosion characteristics of RDX-based thermobaric explosive

The effect of storage temperature on explosion characteristics of the free space explosion of RDX-based thermobaric explosives was studied, and the fireball and the overpressure were obtained. The results showed that the temperature and the volume of the fireball can reach 2400 K and 400 m3 respectively. Low temperature and temperature shock will reduce the temperature and the volume of the fireball and the overpressure. In addition, the aluminum powder does not burn completely, and the time to reach the maximum temperature will be delayed by at least 33 ms. The high temperature can slightly enhance the thermal effect and the pressure effect.

ОСОБЛИВОСТІ ФУНКЦІОНУВАННЯ ТА РОЗРОБКИ ТЕРМОБАРИЧНИХ БОЄПРИПАСІВ

У статті акцентовано увагу на особливості функціонування термобаричних вибухових речовин. Показано основні переваги та недоліки термобаричних вибухових речовин різних поколінь. Проведено оцінку стадій вибух термобаричних зарядів. Проаналізовано характер навантаження при оцінці уражаючої дії термобаричних вибухових речовин. Визначено, що характер навантаження пов'язаний зі співвідношенням тривалості фази стискання в ударній хвилі та періоду власних коливань об'єкта.

Destructive Effect of Zinc on TEX - A DFT Treatment

Various metal components like Al, B, Zr etc., as energetic particles are employed in thermobaric explosives. In composite systems compatibility of ingredients with each other is an important point to be considered. In the present study, effect of zinc on TEX, which is a caged explosive of nitramine type is investigated within the constraints of density functional theory at the levels of B3LYP/6-31+G(d), ωB97X-D/6-31G(d) and ωB97X-D/6-31+G(d). Various quantum chemical properties have been calculated for the TEX+Zn composite and compared with TEX. The zinc atom interacts with TEX molecule via destructive reduction of the explosive. The B3LYP/6-31+G(d) level of calculation predicts cleavage of one of the etheric bond of the cage as well as N-NO2 bond. Whereas, ωB97X-D/6-31G(d) and ωB97X-D/6-31+G(d) level of treatments show cleavage of only one of the N-NO2 bonds. In all the cases the zinc atom acquires some positive charge development.

Fabrication of Si@AP/NC metastable intermixed nanocomposites (MICs) by electrospray method and their thermal reactivity

In order to enhance the heat release of nanoparticles silicon, the Si@AP/NC metastable intermixed composites (MICs) Si@AP/NC with varied content of silicon (40%, 60%, and 80%) were designed and prepared by electrospray. Observation by scanning electron microscopy (SEM) has shown that the morphological characterization of those composites was homogeneously mixed. The thermal properties of those MICs were evaluated by means of DSC-TG techniques. Results show that the low- and high-temperature decomposition of AP transitioned from two separated stages to a one-step process. This was mainly caused by the interaction of thin silica on the surface of silicon and perchloric acid. The dependence of activation energy on the conversation rate was obtained by making use of state-of-the-art kinetic procedures. It has been found that decomposition of Si@NC/AP-40 and Si@NC/AP-60 followed the random chain scission model. With the strengthening of active centers of silica, the mechanism of proton migration of AP turned into the growth of the nucleus. The decomposition process of AP started on the surface of the crystal and gradually decomposed steadily as AP decomposition proceeded. Therefore, it is a first-order reaction model for Si@NC/AP-60 and Si@NC/AP-80 in their second-step reaction. Overall, manufacture spherical Si-NPs composites wrapped in polymer though electrostatic spray technology, a novel way of preparing nanoenergetic materials was created. These nanocomposites could be applied normally as fuels in thermobaric explosives or solid propellants.

Modeling and numerical simulation of afterburning of thermobaric explosives in a closed chamber

An Eulerian-Lagrangian simulation of the thermobaric explosion and the propagating detonation waves with aluminum particle combustion in a closed chamber is carried out and validated very favorably with the pressure histories measured experimentally. A novel numerical framework based on the space-time conservation-element and solution-element method (CE/SE) was employed to simulate the complex detonating flow with detailed chemistry. A discrete particle technique was adopted with either a mono-dispersed or poly-dispersed particle distribution. The results between the experiment and simulation on pressure histories and corresponding impulse forces are compared and showed good agreement. In addition, the effects of metal combustion on afterburning were discussed in detail in terms of the reaction mechanisms and particle dynamics.

Nanoscopic fuel-rich thermobaric formulations: Chemical composition optimization and sustained secondary combustion shock wave modulation

Advanced thermobaric explosives have become one of the urgent requirements when targeting caves, fortified structures, and bunkers. Highly metal-based systems are designed to exploit the secondary combustion resulted from active metal particles; thus sustained overpressure and additional thermal loadings can be achieved. This study, reports on a novel approach for chemical composition optimization using thermochemical calculations in an attempt to achieve the highest explosion power. Shock wave resulted from thermobaric explosives (TBX) was simulated using ANSYS® AUTODYN® 2D hydrocode. Nanoscopic fuel-rich thermobaric charge was prepared by pressing technique; static field test was conducted. Comparative studies of modeled pressure–time histories to practical measurements were conducted. Good agreement between numerical modeling and experimental measurements was observed, particularly in terms of the prediction of wider overpressure profile which is the main characteristics of TBX. The TBX wider overpressure profile was ascribed to the secondary shock wave resulted from fuel combustion. The shock wave duration time and its decay pattern were acceptably predicted. Effective lethal fire-ball duration up to 50ms was achieved and evaluated using image analysis technique. The extended fire-ball duration was correlated to the additional thermal loading due to active metal fuel combustion. The tailored thermobaric charge exhibited an increase in the total impulse by 40–45% compared with reference charge.