Computer simulation for prediction of performance and thermodynamic parameters of high energy materials
Introduction
Intensive search is on all over the globe to develop new high energy materials (HEMs) to meet the futuristic needs. With the advancement of information technology and revolution in the dissemination of scientific information through World Wide Web network, scientists and technologists are making dedicated efforts to explore the knowledge and expertise available in the area of information technology for application in the field of HEMs. This will lead to quantum jump in the advancement of science and technology of HEMs. Of particular importance in designing new explosives, is the ability to predict performance of compounds before the laborious and expensive task of synthesizing them [1]. Rigorous mathematical approaches developed at present, allow one to formalize the knowledge of specialists in synthesis [2]. The search of energetic materials is best carried out presently using thermodynamics and molecular engineering approaches, which help in designing efficient materials. In recent past, theoretical calculations to predict detonation behavior of explosives have evinced great interest [3], [4], [5]. Theoretical screening of notional materials allows for identification of promising candidates for additional study and elimination of poor candidates from further consideration, and thus, reducing costs associated with synthesis, and evaluation of the materials [1]. This capability leads to better designs and shorter design cycles. One of the most important parameters used during performance parameters calculation is the density and the most widely used manual method currently available in literature for its prediction is the Stine’s method [1]. The two most widely used versatile codes to calculate detonation properties are CHEETAH and TIGER [6]. The former is available only to limited agencies while the latter is available commercially.
This paper documents an integrated code named Linear Output Thermodynamic User-friendly Software for Energetic Systems (LOTUSES), which is based on the known logic and has been validated with the experimentally obtained values for well-established explosives. The main objective of this research was to conduct a retrospective analysis of theoretical approaches of estimating the explosive detonation parameters and to make a theoretical performance prediction for a number of promising HEMs based on the currently used calculation methods. The explosives ranging from nitroaromatics, cyclic and linear nitramines, nitrate esters, nitro-nitrato aliphatics and zero hydrogen explosives were studied and results obtained are presented in this paper. Various numerical methods that were developed in the last two decades following World War II onwards have been analyzed to develop this software. It combines Stine’s approaches to compute density, KW rule [7] for predicting possible decomposition products and Rothsteine’s method [8] for predicting detonation factor as well as velocity of detonation (VOD) and Cooper method [9] for estimating C–J pressure. In this article, we describe the use of computational approach in predictions of the heats of detonation, heat of explosion, volume of explosion products gases of various HEMs.
Section snippets
Balancing explosion reaction process
A great quantity of energy deposited into a relatively small volume, manifests itself by a rapid expansion of hot gases, which in turn can create a shock wave or propel fragments outwards at high speed. Chemical explosions may be distinguished from other exothermic reactions by the extreme rapidity of the reactions. In addition to the violent release of energy, chemical explosions must provide a means to transfer the energy into mechanical work. This is accomplished by readily expanding the
Performance parameters of HEMs
Molecular weights and atomic compositions for explosives were derived, respectively, from the sum of the weighed average molecular weights and the weighed average sums of each elemental mole fraction, which were automatically calculated by the software from the molecular formula. The explosives ranging from nitro aromatics, cyclic, and linear nitramines, nitrate esters and nitro-nitrato aliphatics and zero hydrogen explosives were studied in the present work. Predicted density and corresponding
Conclusion
The present paper reports the newly developed user friendly code named LOTUSES for the theoretical performance prediction of parameters such as density, decomposition products, detonation factor (F), VOD, and Pcj for wide range of explosives. The linear regression coefficient R2=0.83 and 0.91 are obtained for experimental versus predicted density and velocity of detonation. It reflects that the predicted values are close to experimentally determined velocity of detonation as reported in
Acknowledgements
Authors are highly grateful to Shri AS Rajagopal, Director, Armament Research & Development Establishment, Pashan, Pune and Dr. Haridwar Singh, Director, High Energy Material Research Laboratory, Pune for providing infrastructure and permission to carry out this work and present this paper. Authors express their deep sense of gratitude to Shri S.R. Madhavan, Scientist ‘E’, OSD-to-Director, ARDE for his inspiration and constant motivation. We record our thanks to Staffs and Officers of TIRC of
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