Explosion Condition Research Articles

Lung injury severity changes in response to different blast shock waves in rabbits

Objective To observe the effect of different explosion on rabbit lung injury and decide the death curve, so as to provide a reference for the prediction of lung injury. Methods Six healthy male New Zealand white rabbits with weight of 2.0-2.5 kg and age of (6±1)months were selected. The rabbits were put 0.5 m, 0.6 m, 0.7 m, 0.9 m, 1.0 m, and 1.2 m away from 90 g TNT to carry out the blast injury experiment. The characteristic parameters of blast shock wave and general lung injury were recorded. Based on the experimental results combined with theoretical analysis, the changes of rabbit lung injury depending on the explosion distance as well as the rabbit death curve were determined. Results After the 90 g TNT explosion, the peak overpressure of shock wave and the corresponding specific decreased quickly with the increase of explosion distance. The peak overpressure was 0.79 MPa and the specific was 82 Pa·s at the explosion distance of 0.5 m. The peak overpressure was 0.1 MPa and the specific was 34 Pa·s at the explosion distance of 1.2 m. The rabbits at 0.5 m and 0.6 m died, the rabbit at 0.7 m was severely injured, and the rabbits at 0.9 m, 1.0 m, and 1.2 m were slightly injured. The dependence of lung injury degree on the explosion distance under 90 g TNT explosion was established based on dimensional analysis theory. The lung injury degree was exponentially attenuated with the explosion distance: ϕ= (R/0.6)-5.64 (ϕ represented lung injury degree, and R represented the explosion distance). Considering the combined injury effects of peak overpressure of shock wave and its specific on rabbit lung, the death curve of rabbit was determined: (p-0.1)(I-59)=2.6(p represented peak overpressure, and I represented specific impulse). The criterion of overpressure-specific impulse was used to estimate the death of rabbit, and the death curve of rabbit was determined as (p-0.1)(I-59)=2.6(p represented peak overpressure and I represented specific impulse). The critical overpressure was 0.1 MPa and the critical specific was 59 Pa·s. Conclusions Under the explosion condition of 90 g TNT, the relationship between degree of lung injury in rabbits and explosion distance is established. Death curve of rabbits is determined based on the damage effect of shock wave peak overpressure and specific on the lungs of rabbits, which is significant for predicting the blast injury. Key words: Blast injuries; Lung injury; Rabbits; Injury prediction

How Turbulence Enables Core-collapse Supernova Explosions

Abstract An important result in core-collapse supernova (CCSN) theory is that spherically symmetric, one-dimensional simulations routinely fail to explode, yet multidimensional simulations often explode. Numerical investigations suggest that turbulence eases the condition for explosion, but how it does it is not fully understood. We develop a turbulence model for neutrino-driven convection, and show that this turbulence model reduces the condition for explosions by about 30%, in concordance with multidimensional simulations. In addition, we identify which turbulent terms enable explosions. Contrary to prior suggestions, turbulent ram pressure is not the dominant factor in reducing the condition for explosion. Instead, there are many contributing factors, with ram pressure being only one of them, but the dominant factor is turbulent dissipation (TD). Primarily, TD provides extra heating, adding significant thermal pressure and reducing the condition for explosion. The source of this TD power is turbulent kinetic energy, which ultimately derives its energy from the higher potential of an unstable convective profile. Investigating a turbulence model in conjunction with an explosion condition enables insight that is difficult to glean from merely analyzing complex multidimensional simulations. An explosion condition presents a clear diagnostic to explain why stars explode, and the turbulence model allows us to explore how turbulence enables explosion. Although we find that TD is a significant contributor to successful supernova explosions, it is important to note that this work is to some extent qualitative. Therefore, we suggest ways to further verify and validate our predictions with multidimensional simulations.

One-pot lignin extraction and modification in γ-valerolactone from steam explosion pre-treated lignocellulosic biomass

A one-pot route to extract and chemically modify lignin from a pre-treated Phragmites australis lignocellulosic biomass is proposed herein. The lignocellulosic biomass was first pre-treated through steam explosion at two different severity factors. Lignin was then extracted from the steam-exploded biomasses through a microwave-assisted organosolv extraction method, solely using γ-valerolactone as solvent. The most severe steam explosion condition yielded a delignification of 78%. Morphological analysis, spectroscopic investigation and thermal characterization showed that essentially pure lignin was extracted through this process. Lignin was then chemically modified in the γ-valerolactone extraction solution, through acetylation and Mannich condensation. This work provides proof-of-evidence that pure lignin can be solvent-extracted in high yields from a pre-treated biomass without the addition of any further chemicals and successfully modified in a one-pot route through a cleaner process. The modified lignin could be used as building block for the development of novel bio-based polymer materials.

Effect of Steam Explosion Pretreatment on Bioethanol Production from Populus euramericana as Alternative Feedstock

Populus euramericana is emerging as a viable feedstock for producing bioethanol from renewable resources. Steam explosion pretreatment of P. euramericana can solubilize a significant portion of the hemicellulosic component and enhance the glucose conversion of the remaining cellulose for fermentation into ethanol. In this study, steam explosion condition of P. euramericana is performed in a steam explosion reactor at severity log Ro 4.02 and severity log Ro 4.37. Glucose conversion varied from 72.3% to 80.1% of steam exploded P. euramericana at severity log Ro 4.02 and severity log Ro 4.37. Ethanol yields(%) based on sugar content after enzymatic hydrolysis after 48 h fermentation ranged from 87.0% to 88.4%. As a result, from 100 g of raw material, 14.0 g of ethanol are recovered of 47.3 g available cellulose content. This research of steam explosion pretreatment was a promising method to improve glucose conversion and ethanol yield for bioethanol production.

Modeling of Reinforced Concrete for Reactor Cavity Analysis under Energetic Steam Explosion Condition

Background: Steam explosions may occur in nuclear power plants by molten fuelecoolant interactions when the external reactor vessel cooling strategy fails. Since this phenomenon can threaten structural barriers as well as major components, extensive integrity assessment research is necessary to ensure their safety. Method: In this study, the influence of yield criteria was investigated to predict the failure of a reactor cavity under a typical postulated condition through detailed parametric finite element analyses. Further analyses using a geometrically simplified equivalent model with homogeneous concrete properties were also performed to examine its effectiveness as an alternative to the detailed reinforcement concrete model. Results: By comparing finite element analysis results such as cracking, crushing, stresses, and displacements, the WillameWarnke model was derived for practical use, and failure criteria applicable to the reactor cavity under the severe accident condition were discussed. Conclusion: It was proved that the reactor cavity sustained its intended function as a barrier to avoid release of radioactive materials, irrespective of the different yield criteria that were adopted. In addition, from a conservative viewpoint, it seems possible to employ the simplified equivalent model to determine the damage extent and weakest points during the preliminary evaluation stage.

Mobile laboratory “Explosive destruction of natural materials”: Investigation of the behavior of ice and limestone under explosive loading

In the paper, the behavior of ice and natural limestone under explosion condition was investigated. The objects of study were the river ice and natural limestone quarry on Siberia. The practical significance of research due to the need to increase production of oil and gas in permafrost regions, the fight against ice jams, etc. We organized a mobile laboratory ’’Explosive destruction of the natural materials” at the National Research Tomsk State University. The main purpose of the laboratory is express analyzing of explosive destruction of natural materials. The diameters and depths of explosive craters in the limestone and explosive lane in the ice were obtained. The results can be used to test new models and numerical methods for calculating shock and explosive loading of different materials, including ice.

Distributed Wireless Measurement System for Transient Pressure with Data Extraction Technology

Transient pressure measurement system applied in an explosion field is usually characterized by non-real-time measurement due to the conflict between quick signal acquisition and limited communication bandwidth. The correct signal acquisition is launched by triggering, but the false triggering often leads to measurement failure due to the fact that the operating status of system cannot be real-time detected in an explosion condition. A distributed wireless measurement system with data extraction technology is proposed in this paper to improve the reliability of transient pressure measurement. A long-time signal acquisition is achieved by mass data storage to eliminate the trigger mode. On the other hand, an effective data segment is extracted by signal identification, which improves the efficiency of data transmission and data processing. A measurement system based on data extraction technology was designed and implemented in an explosion field, and the measurement node was characterized by sampling rate of 1 Msps, data storage of 128 Gb, effective data segment of 512 kW, and Wi-Fi wireless network coverage.

Enhancement of flavonoids extraction from fig leaf using steam explosion

Effects of plants’ structures on bioactive compounds extraction were rarely reported, which limited the research improvement of extraction efficiency from an intrinsic perspective. In this work, the structural properties of untreated and steam exploded fig leaves as well as their effects on flavonoids extraction were systematically studied. Results implied that internal diffusion became the limiting factor of flavonoids extraction from untreated fig leaf when liquid–solid ratio exceeded 75mL/g-dry. After steam explosion pretreatment (0.2MPa and 3min), flavonoids yield extracted from fig leaf was increased by 55.9% compared with that from untreated fig leaf. However, more drastic steam explosion condition (0.4MPa and 3min) did not lead to higher flavonoids yield, which may be caused by the damage of flavonoids at high pretreatment temperature. A finite reaction model was proposed to demonstrate the mechanisms of flavonoids extraction from steam exploded fig leaf, and it was well consistent with the practical extraction. Therefore, steam explosion pretreatment with proper intensity should be a novel technology to enhance the extraction performance.

The intrinsic mechanism of methane oxidation under explosion condition: A combined ReaxFF and DFT study

In order to develop efficient suppression techniques and isolation materials for gas explosion, it is greatly vital to understand the intrinsic mechanism of gas explosion at atomic level. The methane explosion process was systematically explored by reactive force field molecular dynamics (MD) simulation and density function theory (DFT) calculations. The results show that the initiation step of the gas explosion process is mainly induced by OH free radical, and the chain transfer process is primarily carried by the conversion from HO2 to OH radical. The number of free radicals, such as CH3, HO2 and OH, greatly affect the reaction velocity during the gas explosion process. These results not only identify the critical reaction intermediates and main radical carriers of methane explosion process, but also they will provide significant theoretical guide for development of the novel and efficient gas explosion suppression methods and isolation materials.

Analysis of Reaction Products of Lysozyme under the Explosion Condition by Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry

Identification and determination of explosives and explosive residues were a subject of continuing strong interest in analytical chemistry and forensic science. In this paper, the reaction products of lysozyme under the explosion condition were analyzed by a MALDI-TOFMS (Matrix-assisted laser desorption ionization time-of-flight mass spectrometry) method. There was no difference in the tryptic digest between the normal lysozyme and the reaction products generated by detonator, while some adduct peaks such as [MH+17]+, [MH+18]+, [MH+28]+, [MH+32]+, and [MH+44]+ were discovered in the explosives. This may be attributed to the reaction between the lysozyme and the active small molecule gases such as NH3, H2O, CO/N2, O2, CO2, which were generated during the explosion. Characteristic peaks which were produced by lysozyme and the active small molecule gases from different explosives can be used to discriminate the six explosives. For example, H2O molecules which were generated during the exploration by tri-nitrotoluene (TNT) can specifically react with VFGRCELAAAMKRHGLDNYR (m/z 2307) to produce a characteristic peak at m/z 2325 (2307+18). Also, H2O molecules which were generated by hexahydro-1,3,5-trinitroazine (RDX) can completely react with IVSDGNGMNAWVAWRNRCK (m/z 2177) to produce a characteristic peak at m/z (2177 + 18). Characteristic peak at m/z 1301 was produced by GYSLGNWVCAAK (m/z 1269) and O2 molecules for the identification of pentaerythritol tetranitrate (PETN). While for black powder, O2 and H2O can both react with IVSDGNGMNAWVAWR (m/z 1676) to produce product ions peaks at m/z 1694 and 1708. However, only the O2 molecules can react with IVSDGNGMNAWVAWR for pyrotechnic composition. As for ammon explosive, which is a mixture of inorganic explosives and organic explosives, CO2 molecules can react with a plurality of reaction sites of lysozyme to produce a series of characteristic peaks signals such as m/z 1313 (1269+44), 1720 (1676+44), 1848 (1804+44), 2722 (2678+44).

Homogeneous Boiling Explosion Condition: From an Energy Point of View

When a liquid undergoes boiling by homogeneous nucleation during non-equilibrium heating is very important as the characteristics of the system before and after the occurrence of homogeneous boiling explosion is significantly different. In the present study, we studied homogeneous boiling explosion condition from an energy point of view: how much energy is required to boil the liquid by homogeneous nucleation from a given initial temperature. As a representative one, water heating at atmospheric pressure has been considered under three different heating conditions namely; i) linear heating at the boundary ii) high heat flux pulse heating and iii) liquid contact with high temperature surface. The analytical formulations for cumulative energy distribution in the liquid under various liquid heating conditions have been derived and the cumulative energy density within the liquid are calculated. It has been found that the instantaneous cumulative energy density very near to the liquid boundary is several times higher than that corresponding to the thermal penetration depth for all liquid heating cases. The present study shows that, the cumulative energy density at the boiling explosion over a characteristic liquid cluster being equal to the size of a critical embryo is independent of the heating parameter and for a given initial condition, it has been found to be almost constant for all liquid heating conditions. However, the cumulative energy density at the boiling explosion decreases as the liquid initial temperature increases for all liquid heating cases. The obtained results are compared with other numerical results reported in the literature for water subjected to uniform volumetric heating at atmospheric pressure.

Characteristics of Homogeneous Nucleation Boiling in Ethanol during Rapid Linear Boundary Heating

The characteristics of homogeneous boiling in ethanol subjected to rapid heating with a linearly increasing boundary temperature condition have been studied by applying a theoretical model. A finite liquid control volume or cluster at the liquid boundary hasbeen considered in this model where energy is stored due to external heating while some energy is consumed due to bubble nucleation and subsequent growth. A particular state of liquid heating has been defined as the boiling explosion condition when massive scale vaporization causes the liquid sensible energy to decrease. As the size of liquid cluster, two different length scales have been adopted such as, size of a critical vapor embryo (2rc) and thermal penetration depth ▪. For ethanol heating with initial and boundary conditions identical to those reported in the literature, the model predicts the time of the homogeneous boiling explosion with reasonable agreement with the experiments with the liquid cluster size being assumed to be that of a critical vapor embryo (2rc); while the consideration of the thermal penetration depth ▪ results in late prediction of the occurrence of boiling explosion. However, the temperature at the boiling explosion essentially corresponds to the same for both sizes of the liquid cluster. The obtained results have been presented and discussed in terms of the average liquid temperature rise inside the liquid cluster, maximum attainable cluster temperature and time to reach the boiling explosion condition for a wide range of boundary heating rates (10-109 K/s).

Mass synthesis of high performance (La0.75Sr0.25)0.95MnO3±δ nano-powder prepared via a low-carbon chemical solution method

A novel low-carbon chemical solution method is established and successfully scaled up to prepare (La0.75Sr0.25)0.95MnO3±δ(LSM) nano-powders, in which acetate and acrylic acid have been used as raw materials. Distinguish from the traditional chemical solution methods, nitrate and amino compound are non-used in this method and without causing any fire hazard or explosion condition which are usually found in most of the solution synthesis reactions. The organic compound emission is reduced to a quarter of that in the citric acid–nitrate method. This optimization is attributed to the low application amount and high effect of acrylic acid by means of the co-operation of ethylenic linkage and carboxyl group. As-prepared powders are high purity, single phase, slight aggregation with grain size less than 100 nm. The conductivity of the sintered LSM sample is measured about 220 S cm−1 in air at 700–1000 °C. The polarization resistance of LSM–YSZ cathode is less than 0.1 Ω cm2 at 800 °C. Anode supported Cells with configuration of Ni + YSZ/YSZ/LSM + YSZ exhibit the power density of 0.54 W cm−2 at 800 °C and 0.7 V. These results indicate that the novel acetate–acrylic method is very suitable for mass synthesis of high performance LSM powders.

Thermally activated dynamics of spontaneous perpendicular vortices tuned by parallel magnetic fields in thin superconducting films

We report magnetotransport measurements on a superconducting molybdenum-germanium (MoGe) film of thickness $d=50$ nm in parallel magnetic fields and show evidence of a transition from a Meissner state to a resistive state of spontaneous perpendicular vortices generated by thermal fluctuations above a certain temperature $T>{T}_{v}(B)$. Here ${T}_{v}$ appears to match the vortex core explosion condition $d\ensuremath{\approx}4.4\ensuremath{\xi}({T}_{v})$, where $\ensuremath{\xi}$ is the coherence length. For $T>{T}_{v}$, we observed that a nonlinear current-voltage ($I$-$V$) response (Ohmic at low currents and the power law $V\ensuremath{\propto}{I}^{\ensuremath{\beta}}$ at higher $I$) is exponentially dependent on ${B}^{2}$. We propose a model in which the resistive state at $T>{T}_{v}$ is due to thermally activated hopping of spontaneous perpendicular vortices tuned by the pairbreaking effect of the parallel $B$.

Isotopic r-process abundances produced by supernova explosions

The rapid neutron capture process (r-process) is one of the major nucleosynthesis processes responsible for the synthesis of heavy nuclei beyond iron. Isotopes beyond Fe are most exclusively formed in neutron capture processes and more heavier ones are produced by the r-process. Approximately half of the heavy elements with mass number A>70 and all of the actinides in the solar system are believed to have been produced in the r-process. We have studied the r-process in supernovae for production of heavy elements beyond A=40 with the newest mass values available. The supernovae envelopes at a temperature >109 K and neutron density of 1024 cm−3 are considered to be one of the most potential sites for the r-process. We investigate the r-process in a site-independent, classical approach which assumes a chemical equilibrium between neutron captures and photodisintegrations followed by a β-flow equilibrium. We have studied the r-process path corresponding to temperatures ranging from 1.0×109 K to 3.0×109 K and neutron density ranging from 1020 cm−3 to 1030 cm−3. The primary goal of the r-process calculations is to fit the global abundance curve for solar system r-process isotopes by varying time dependent parameters such as temperature and neutron density. This method aims at comparing the calculated abundances of the stable isotopes with observation. The abundances obtained are compared with supernova explosion condition and found in good agreement. The elements obtained along the r-process path are compared with the observed data at all the above temperature and density range.

Damage evaluation of the steel tubular column subjected to explosion and post-explosion fire condition

Fires following explosion are considered one of the most serious secondary disasters in the blast events, which are frequently occurring in the terrorist attacks and other blast accidents. In the recent decades, a significant amount of research work has been carried out to study the structural response under blast loads, and it is found that due to the superior mechanical properties of steel material, steel structures are adequate to withstand a medium-scaled blast loading. However, since the strength of steel is sensitive to temperature, the post-explosion fire action should be involved in the evaluation of structural damage in the blast events. This paper is devoted to introduce a numerical method for predicting the integrative damage of steel tubular column subjected to blast load and the following fire action. The damage caused by blast load would significantly reduce the fire resistance of steel column, which includes two aspects: mechanical damage and geometrical damage. In order to describe the mechanical damage under the blast loading, a damage scalar is defined in the constitutive model, and it is used to represent the reduction of material strength. The geometrical deformation induced by blast load is treated as the initial condition in the fire analysis. Pressure–Impulse diagram is employed to describe the damage of the steel tubular column under blast loading. In the second step, fire analysis for the explosion-survived column is carried out. Obviously, the residual vertical capacity of steel column is related with the fire exposure time. In order to clarify the interaction between the explosion and the post-explosion fire action, a more inclusive function, characterized by three variables: pressure, impulse and fire exposure time, is presented in this paper, and it can be used to predict the residual capacity of the steel column subjected to blast load and exposed to fire for a specific time. In the last section, parametric studies are conducted to observe the effects of geometric size on the failure evolution of steel columns. The main objective of this research work is to provide guidance for assessing damage level of the steel tubular columns that have survived blast loading and expose to the following fire condition.

Research of the early debris expansion from high-altitude nuclear explosions

Based on magnetohydrodynamic theory a shell model is developed to describe debris motion of high-altitude nuclear explosion. The debris motion parameter of Starfish is simulated. The model is verified by comparison with the results available from the literature. For the comparison between typical high-yield and low-yield nuclear explosion, the debris motions of kiloton and megaton at 100 km, 400 km and 1500 km are especially simulated. The difference in expansion law, caused by explosion yield, is analyzed. The results show that explosion condition and atmospheric environment have a significant influence on the expansion of the law of the debris cloud, and the debris environmental parameters in different directions are significantly different from each other.

Homogeneous Boiling Explosion during High Heat Flux Pulse Heating of Water

A model based on one-dimensional heat conduction and classical homogeneous nucleation has been applied to study the boiling explosion phenomena during high heat flux pulse heating of water. In this model, a characteristic liquid cluster at the liquid boundary is taken into consideration and the boiling explosion condition is defined by considering the energy balance in that cluster. The model describes that the boiling explosion corresponds to a particular stage of liquid heating at which the energy consumption in the cluster due to bubble nucleation and growth exceeds the energy deposition to the cluster by external heating. By applying this model, the occurrence of the boiling explosion condition in water at atmospheric pressure has been determined for a wide range of boundary heat fluxes (15–1000 MW/m2) at various liquid initial temperatures (293 K–373 K). The effects of the boundary heat flux and the liquid initial temperature on various boiling explosion characteristics such as the liquid temperature and the time of the boiling explosion, heat flux across the liquid vapor interface, number of bubbles generated per unit area at the boiling explosion etc. are determined and discussed in context with other relevant information. The boiling explosion time as obtained in the present model is found to be in good agreement with that reported by other researchers for identical liquid heating conditions. With the consideration of a characteristic time period of 1 millisecond for the occurrence of the boiling explosion, the present study corresponds to a limiting boundary heat flux of about 15 MW/m2 for water at atmospheric pressure.

Field Test Study of the Blast-Resistance Performance of Optimal Composite Anchorage Structure

This paper introduced the comparison test of new optimal composite anchorage structure and single anchorage structure. The measured results show that the particle acceleration of single anchorage structure is 2.22 times higher than that of the optimal composite anchorage structure. The dynamic strain of the former is 5.3~4.5 times higher than that of the latter. The blast-resistance of the optimal composite anchorage structure is 5.10 times higher than that of the single anchorage structure. Under the limit damage condition, the former is 4.13~3.40 higher than that of the latter. The optimal composite anchorage structure has excellent blast-resistance. Optimal weakened zone is between the reinforced support structure and the surround rock. Under the explosion condition, weakened zone is firstly deformed, cracked, crushed or densified, and at the same time, a great deal of blast energy is absorbed. Therefore, the crisis of the reinforced support structure is transferred into the weakened zone.

Model for boiling explosion during rapid liquid heating

The process of rapid liquid heating with a linearly increasing boundary temperature condition has been simulated by applying the analytical solution of 1D semi-infinite heat conduction in association with the molecular theory of homogeneous nucleation boiling. A control volume having the size of a characteristic critical cluster at the liquid boundary is considered, and the corresponding energy balance equation is obtained by considering two parallel competing processes that take place inside the control volume, namely, transient external energy deposition and internal energy consumption due to bubble nucleation and subsequent growth. Depending on the instantaneous rate of external energy deposition and boiling heat consumption within the control volume, a particular state is defined as the boiling explosion condition in which bubble generation and growth cause the liquid sensible energy to decrease. The obtained results are presented in terms of the average liquid temperature rise within the control volume, maximum attainable liquid temperature before boiling explosion and the time required to achieve the condition of boiling explosion. The model is applied for the case of water heating at atmospheric pressure with initial and boundary conditions identical to those reported in the literature. Model predictions concerning boiling explosion are found to be in good agreement with the experimental observations. The boiling explosion condition as predicted by the present model is verified by comparing the heat flux across the liquid–vapor interface with the corresponding limit of maximum possible heat flux, q max , max , at the time of boiling explosion. A comparative study between the actual heat flux and the limit of maximum heat flux, q max , max , at the time of boiling explosion for different rates of boundary heating indicates that, with much higher boundary heating rates, it is possible to heat the liquid to a much higher temperature before theoretical instantaneous boiling explosion occurs.