Papers by Keyword: Explosion

Abstract: Many pharmaceutical industries all around the world are facing the problem of dust mobilization during the productive process of medicines. This mobilization can be dangerous for the safety of the operators working in the factory and for the safety of the factory itself. It is therefore necessary to develop predictive models to simulate and forecast dust mobilization. The Quantum Electronics and Plasma Physics (QEP) Research Group of the University of Rome Tor Vergata has developed a facility to experimentally replicate dust mobilization in different critical conditions in an enclosed environment. The measurements performed with diagnostics available in the facility, provide the boundary conditions to run numerical simulations and to validate mobilization models . Even if the initial field of application of this novel facility is dust mobilization is nuclear fusion, the methodology developed can be used for the medicine industry, for the agribusiness and others. The authors will present the experimental and numerical results discussing new applications.

Abstract: Due to a particular complexity of the phenomenon of an explosion in a gaseous medium (air) the most appropriate approach to address it is using numerical methods. This paper presents a specific numerical solution to the phenomenon of the so-called point charge explosion from a one-dimensional perspective taking into account reflections from non-deformable partitions. Results of the numerical calculations were calibrated based on test results and their correctness was additionally verified using gas dynamics methods.

Abstract: The article describes the use of ultrasonic testing methods for examining slabs made from cement based materials. For the detection of cracks, in full-scale slabs before and after the explosion, ultrasonic pulse method was used. Data obtained before the explosion confirm the high quality of the cement based material. Another set of data taken after the explosion shows the scale of cracks in the slabs. The article compares material characteristics of the unreinforced concrete, steel fibre concrete and high performance fibre reinforced concrete on the basis of materials tested by using the passage ultrasonic method after the explosion.

Abstract: Basic physical problems of jet formation process on the basis of Lavrentiev-Birkhoff classical scheme are analyzed. It is shown that in process of realization of hypercumulation conditions for jet formation without complete stagnation point involving formation of the inner zone of constant pressure (dead zone), the flow mass is always greater than slug mass, that is unachievable in the known models. Smoothing effect of this zone on the development of different types disturbances, particularly, smoothing Rayleigh-Taylor instability for thin liner may be expected and shown in simulations.

Abstract: The collapse mechanism of plant oil storage tank was discussed in the paper. Observation made on the site indicated that No. 804 tank collapsed with disintegration. The incomplete penetration area was found by weld macro analysis. Stress intensity factor of crack in the tank which is calculated using the classical theory showed that the main reason for the accident was not the incomplete penetration weld. The hexane vapor explosion is presumably the dominant factor leading to the accident by calculation and analysis. The count measures are also proposed to prevent the similar accidents.

Abstract: The layered cylindrical shell is one of important structures of high pressure vessels. From 1977 to 2005 there were 8 urea synthesis reactors exploded. Seven of them were layered cylindrical shell structure. Therefore, there will be much more issues come out and waiting for us to study and explore. In this paper, we take the urea synthesis reactor exploded in 2005 in China as an example to study why and how a multi-layered exploded. Through the research work, we not only concluded why and how a multilayered vessel exploded but also established a method to analyze the serious explosion accident of complex vessels such as urea synthesis reactors.

Abstract: The terrorism and regional conflicts posed a threat to the world peace. Some terrorist explosions caused collapse of the buildings, which brought heavy tragedies to the human components. Therefore research on damage of structural components and resistance to damage have become the focus of our attention. Finite element software LS-DYNA was applied to simulating the response of reinforced concrete columns under blast loading. And analysis on dynamic response under different loading period was carried out. By studying on the stress and strain of reinforced concrete columns subjected to blast loading, the possible failure modes were obtained. In addition, the bearing capacities of concrete columns that are reinforced with carbon fiber and steel panel were analyzed, and the reinforcement effects were compared to provide reasonable reinforcement schemes for structures blast-resistant design.

Abstract: Due to the inefficiency problem of the cut blasting in rock excavation and rock breaking, a shell radial shaped charge device was proposed based of the ideal of ‘cutting to slotting’ and it was validated through experiments. For this device, the shell materials are used to be shaped materials and multiple shaped ring is designed on the circular tube. It can not only reduce charge quantity but also raise the utilization ratio of explosive energy. After explosion, multiple radial shaped charge jets can be formed along the axial line in sequence and then the surrounding rock mass would be cracked. The crack network will be formed along with the further extension of the fraction under the action of quasi static loading of detonation gas. The shell radial shaped charge device was tested through the cut blasting model experiment. Experimental results show that the utilization ratio of blasting hole nearly approaches 98% with this device. The blasting efficiency and cyclical footage can be improved effectively and the cost of drifting can also be reduced.

Abstract: In order to study the combustion and explosion characteristics of-10 military diesel and-35 military diesel, using combustion performance testing device tested the combustion performance of diesel, and analyzed the combustion performance at different temperatures. Using explosion sphere vessel tested the explosion parameters of the diesel to evaluate the explosion performance. The results show that the combustion performance of-35 military diesel are better than-10 military diesel, the maximum explosion pressure and maximum temperature have a rising trend with the pressure spray increase. The maximum explosion pressure of-10 military diesel is larger than that of-35 military diesel at the same spray pressure and the maximum explosion temperature of-35 military diesel is higher than that of-10 military diesel. The results of the two kinds of diesel can be used to evaluate their characteristics and safety.

Abstract: The development and present situation of methanol to olefin (MTO) process in China was introduced, and the safety technical requirement based on the development of MTO was then analyzed. Based on a demonstration plant, the process was divided into several units, and the hazards of each unit were discussed, including reactor-regenerator system, which is the core of the whole plant, filled with a large amount of methanol and olefin mixture. The flammable parameters of gas system composed of methanol and olefins were investigated, and the allowable concentration of oxygen in reactor was discussed. The process of several units were simulated by specific software, the influence of variety of multiple parameters on process were then calculated. According to the operation of the demonstration plant, problems may be encountered in scale-up were proposed.