CFD Cook‐Off Simulation and Thermal Decomposition of Confined High Energetic Material

Abstract

[a] 1Introduction TNT known as 2,4,6-trinitrotoluene is one of the most commonly used explosives for military and industrial applications some decades of years past and present day.I ti s valued partly because of its insensitivity to shock and friction which reduces the risk of accidental detonation compared to other more sensitiveh igh explosivess uch as nitroglycerin. TNT melts at 80 8C [ 1,2] which is far below the temperature it wills pontaneously detonate allowing it to be poured and safely combined with other explosives [3]. TNT neither absorbs nor dissolvesi nw ater which allows it to be used effectively in wete nvironments. Additionally it is stable compared to other high explosives. With the fact that tons of TNT are produced each year,s torage is inevitable as they are not readily used [4].S torage of ammunitions over the years has seen several accidentsr ecorded in ammunition depots which are mainly due to human negligence. Someo fs uch accidents documented include Russia, Syria, Turkey and the most devastating happened in Congo [5,6].I na ll of these incidences, there were scoreso fd eath recorded accompanied by life threatening conditions. The bottom line for most of these explosions wasa saresult of some ammunition undergoing slow and fast cook-off due to poor storagec onditions [7].F or safety reasons, this phenomenonh as been investigatedb yu sing variousm ethods and popular amongst these included One Dimensional Time-to-Explosion (ODTX). There is however al imitation associated with experiment-related works when dealing with powerful explosives such as TNT in large volumes. In that regard numerical methods are the best tools to fill this gap. Some specialized codes which have beend evelopedt on umerically solve explosive related problems include TEPLO [8],H ERMEX [9] and REActive CONduction (REACON) [10]. In the case of REACON, a2 Dn umerical code was developed in order to simulate both fast and slow cook-off. Though the validationw as made using FLUENT results and literature values obtained,t he explosive involved as well as the geometry wasn'tt he same as the one in this study. However almost similarg raph profile was recorded where there was an indication of thermalr unaway.T he workd one by Hobbs [11] soughtt oi nvestigate the convection effects and the non-convection phenomena whichc ontribute to the detonationo fc onfined energetic material. COMSOL Multi-physics CFD tool was employed in the execution of the simulation work.I nt heir studies TNT was heated in ac onfined geometry where the convection effects and the Abstract:T he handling, storagea nd safety before deployment of explosivesa re major key issues that confront the ammunition industry.P recautions have to be taken not to cause premature detonationsa nd fatal accidents by studying their thermalb ehaviour.R esearch has been conducted to investigate the thermal stability of some secondary explosives such as RDX, HMX and TNT and their response to thermal stimuli. For the fact that real experimentw hich involves large amount of ex...

Application of the Peng–Robinson Equation of State to Energetic Materials RDX and TNT: Pure Components, Liquid Mixtures, and Solid Mixtures

“…Hence, the density data also determines B. This leaves only two unknownsA and Z l,s since Z v can be calculated from A, B, and Z l,s using (8). The two equations that we solve to find A and Z l,s are (S9) and (6).…”

“…Numerical simulations are increasingly being used as a means to study their behavior. One active area of research concerns cookoff models, in which energetic materials placed inside a sealed container are heated on time scales ranging from microseconds to days until they explode. − This area has applications to the behavior of explosives in naval shipboard fires and to the safe handling and storage of explosives in general. The heating raises the temperature of the energetic materials, causing them to eventually reach temperatures where chemical decomposition becomes significant.…”

“…These two compounds are commonly abbreviated as RDX and TNT, respectively. Past studies have used the Peng−Robinson EOS to represent the gaseous products released by RDX and TNT during cookoff 8 or to predict the solubility of RDX in CO 2 . 22 But until now, there has not been an attempt to use this equation of state to model pure RDX and TNT in their condensed phases, as well as liquid and solid mixtures of the two compounds.…”

Experiments and simulations on cookoff characteristics of a DNAN based cast explosive

“…A buoyancy-driven flow model is further included to account for multiphase fluid movement in Comp-B explosives [10]. Asante et al [11] developed an enthalpy-porosity method to investigate the melting process of TNT. Chen et al [18] and Liu et al [19] applied this method to DNAN and obtained ideal results.…”

Numerical simulation study on the slow cook-off response characteristics of PBX explosive

“…Erdogan aydemir [5] developed a slow baking experimental device, and conducted a slow baking experiment on PBXN-110 charge, measured the temperature changes at different positions inside the explosive, obtained the ignition time, ignition temperature and ignition position, and obtained the dynamic parameters of the explosive through TGA test. Daniel O. Asante [6] used CFD simulation software to simulate the fast and slow Cook-off of M107 grenade loaded with TNT explosive, and obtained the results that the melting time, melting area and internal pressure increased exponentially with the reaction rate. The above research mainly obtains the temperature rise curve, ignition temperature, ignition time and other response characteristics of thermal decomposition of energetic materials through experiments and numerical simulation, but the heat transfer and response characteristics of energetic binder PBX explosive need to be further explored.…”