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Detonation Velocity (detonation + velocity)
Selected AbstractsCalculation of the Detonation Velocities and Detonation Pressures of Dinitrobiuret (DNB) and Diaminotetrazolium Nitrate (HDAT-NO3)PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2004Janna Geith Abstract The enthalpies of combustion (,combH) of dinitrobiuret (DNB) and diaminotetrazolium nitrate (HDAT-NO3) were determined experimentally using oxygen bomb calorimetry: ,combH(DNB)=5195±200,kJ kg,1, ,combH(HDAT-NO3)=7900±300,kJ kg,1. The standard enthalpies of formation (,fH°) of DNB and HDAT-NO3 were obtained on the basis of quantum chemical computations at the electron-correlated ab initio MP2 (second order Møller-Plesset perturbation theory) level of theory using a correlation consistent double-zeta basis set (cc-pVTZ): ,fH°(DNB)=,353,kJ mol,1, ,1,829,kJ kg,1; ,fH°(HDAT-NO3)=+254,kJ mol,1, +1,558,kJ kg,1. The detonation velocities (D) and detonation pressures (P) of DNB and HDAT-NO3 were calculated using the empirical equations by Kamlet and Jacobs: D(DNB)=8.66,mm,,s,1, P(DNB)=33.9,GPa, D(HDAT-NO3)=8.77,mm,,s,1, P(HDAT-NO3)=33.3,GPa. [source] The Effects of Containment on Detonation VelocityPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2004Clark Souers Abstract Reactive flow cylinder code runs on six explosives were made with rate constants varying from 0.03 to 70,,s,1. Six unconfined/steel sets of original ANFO and dynamite data are presented. A means of comparing confinement effects both at constant radius and at constant detonation velocity is presented. Calculations show two qualitatively different modes of behavior. For Us/Co,1.2, where Us is the detonation velocity and Co the zero-pressure sound speed in steel, we find a sharp shock wave in the metal. The shock passes through the steel and the outer wall has a velocity jump-off. For Us/Co,1.04, we find a pressure gradient that moves at the detonation velocity. A precursor pulse drives in the explosive ahead of the detonation front. The outer wall begins to move outward at the same time the shock arrives in the explosive, and the outer wall slowly and continuously increases in velocity. The Us/Co,1.2 cylinders saturate in detonation velocity for thick walls but the Us/Co<<1.04 case does not. The unconfined cylinder shows an edge lag in the front that approximately equals the reaction zone length, but the highly confined detonation front is straight and contains no reaction zone information. The wall thickness divided by the reaction zone length yields a dimensionless wall thickness, which allows comparison of explosives with different detonation rates. Even so, a rate effect is found in the detonation velocities, which amounts to the inverse 0.15,0.5 power. [source] Theoretical investigation of an energetic fullerene derivativeJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 12 2010Bisheng Tan Abstract A self-consistent estimation method for the thermochemical properties of N -methyl-3-(2,,4,,6,-trinitrobenzene)-fulleropyrrolidine (MTNBFP) is presented. This method is based on enthalpy of formation (,fH) and enthalpy of combustion obtained from BLYP/DNP calculations of the total energies and frequencies for MTNBFP. The enthalpy of formation was calculated by an optimized set of isodesmic reactions given the available experimental ,fH of relative compounds. MTNBFP has a high enthalpy of formation, 2782.2 kJ/mol. Detonation velocity and detonation pressure were also presented in terms of Kamlet and Jacobs equations. Drop hammer impact sensitivity tests and blasting point per 5 s tests indicate MTNBFP may be a potential candidate primary explosive. To understand the test results well, we proposed a series of chemical reaction mechanisms and interpreted the relationship between impact sensitivity and electronic structures from the viewpoint of nitro group charge, electrostatic potential, and vibrational modes. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] Detonation and Blast Wave Characteristics of Nitromethane Mixed with Particles of an Aluminium,Magnesium AlloyPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2010Waldemar Abstract Investigation of detonation parameters, blast wave characteristics and quasi-static pressures (QSPs) for the mixtures of nitromethane and particles of an aluminium and magnesium (Al3Mg4) alloy was carried out. The mixtures of gelled nitromethane containing 15,60,wt.-% AlMg alloy were tested. Detonation velocity and Gurney energy were determined. Parameters of blast waves produced by charges of the investigated explosives were measured. QSP measurements were conducted in a steel chamber of 0.15,m3 volume filled with air. Thermochemical and gasdynamical calculations were also performed. The degree of combustion of the metallic addition with the gaseous products during detonation and expansion is discussed. [source] Theoretical Study on Thermodynamic and Detonation Properties of PolynitrocubanesPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2009Xue-Hai Ju Abstract We investigated the heat of formation (,fH) of polynitrocubanes using density functional theory B3LYP and HF methods with 6-31G*, 6-311+G**, and cc-pVDZ basis sets. The results indicate that ,fH firstly decreases (nitro number m=0,2) and then increases (m=4,8) with each additional nitro group being introduced to the cubane skeleton. ,fH of octanitrocubane is predicted to be 808.08,kJ mol,1 at the B3LYP/6-311+G** level. The Gibbs free energy of formation (,fG) increases by about 40,60,kJ mol,1 with each nitro group being added to the cubane when the substituent number is fewer than 4, then ,fG increases by about 100,110,kJ mol,1 with each additional group being attached to the cubic skeleton. Both the detonation velocity and the pressure for polynitrocubanes increase as the number of substituents increases. Detonation velocity and pressure of octanitrocubane are substantially larger than the famous widely used explosive cyclotetramethylenetetranitramine (HMX). [source] Structural and Preliminary Explosive Property Characterizations of New 3,4,5-Triamino-1,2,4-triazolium (Guanazinium) SaltsPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 5 2008Chaza Darwich Abstract Two new highly stable energetic salts were synthesized in reasonable yield by using the high nitrogen-content heterocycle 3,4,5-triamino-1,2,4-triazole and resulting in its picrate and azotetrazolate salts. 3,4,5-Triamino-1,2,4-triazolium picrate (1) and bis(3,4,5-triamino-1,2,4-triazolium) 5,5,-azotetrazolate (2) were characterized analytically and spectroscopically. X-ray diffraction studies revealed that protonation takes place on the nitrogen N1 (crystallographically labelled as N2). The sensitivity of the compounds to shock and friction was also determined by standard BAM tests revealing a low sensitivity for both. B3LYP/6,31G(d,,p) density functional (DFT) calculations were carried out to determine the enthalpy of combustion (,cH(1)=,3737.8,kJ mol,1, ,cH(2)=,4577.8,kJ mol,1) and the standard enthalpy of formation (,fH°(1)=,498.3,kJ mol,1, (,fH°(2)=+524.2,kJ mol,1). The detonation pressures (P(1)=189×108,Pa, P(2)=199×108,Pa) and detonation velocities (D(1)=7015,m s,1, D(2)=7683,m s,1) were calculated using the program EXPLO5. [source] The Effects of Containment on Detonation VelocityPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2004Clark Souers Abstract Reactive flow cylinder code runs on six explosives were made with rate constants varying from 0.03 to 70,,s,1. Six unconfined/steel sets of original ANFO and dynamite data are presented. A means of comparing confinement effects both at constant radius and at constant detonation velocity is presented. Calculations show two qualitatively different modes of behavior. For Us/Co,1.2, where Us is the detonation velocity and Co the zero-pressure sound speed in steel, we find a sharp shock wave in the metal. The shock passes through the steel and the outer wall has a velocity jump-off. For Us/Co,1.04, we find a pressure gradient that moves at the detonation velocity. A precursor pulse drives in the explosive ahead of the detonation front. The outer wall begins to move outward at the same time the shock arrives in the explosive, and the outer wall slowly and continuously increases in velocity. The Us/Co,1.2 cylinders saturate in detonation velocity for thick walls but the Us/Co<<1.04 case does not. The unconfined cylinder shows an edge lag in the front that approximately equals the reaction zone length, but the highly confined detonation front is straight and contains no reaction zone information. The wall thickness divided by the reaction zone length yields a dimensionless wall thickness, which allows comparison of explosives with different detonation rates. Even so, a rate effect is found in the detonation velocities, which amounts to the inverse 0.15,0.5 power. [source] Prediction of the non-ideal detonation performance of commercial explosives using the DeNE and JWL++ codesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 14 2005S. Esen Abstract The non-ideal detonation performance of two commercial explosives is determined using the DeNE and JWL++ codes. These two codes differ in that DeNE is based on a pseudo-one-dimensional theory which is valid on the central stream-tube and capable of predicting the non-ideal detonation characteristics of commercial explosives as a function of the explosive type, rock properties and blasthole diameter. On the other hand, JWL++ is a hydrocode running in a 2-D arbitrary Lagrangian,Eulerian code with CALE-like properties and can determine the flow properties in all stream lines within the reaction zone. The key flow properties (detonation velocity, pressure, specific volume, extent of reaction and reaction zone length) at the sonic locus on the charge axis have been compared. In general, it is shown that the flow parameters determined using both codes agree well. The pressure contours determined using the JWL++ are analysed in detail for two explosives at 165 mm blastholes confined in limestone and kimberlite with a view to further investigate the explosive/rock interface. The DeNE and JWL++ codes have been validated using the measured in-hole detonation velocity data. Copyright © 2005 John Wiley & Sons, Ltd. [source] A theoretical investigation on the structures, densities, detonation properties, and pyrolysis mechanism of the nitro derivatives of phenolsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 9 2010Guixiang Wang Abstract The nitro derivatives of phenols are optimized to obtain their molecular geometries and electronic structures at the DFT-B3LYP/6-31G* level. Detonation properties are evaluated using the modified Kamlet,Jacobs equations based on the calculated densities and heats of formation. It is found that there are good linear relationships between density, detonation velocity, detonation pressure, and the number of nitro and hydroxy groups. Thermal stability and pyrolysis mechanism of the title compounds are investigated by calculating the bond dissociation energies (BDEs) at the unrestricted B3LYP/6-31G* level. The activation energies of H-transfer reaction is smaller than the BDEs of all bonds and this illustrates that the pyrolysis of the title compounds may be started from breaking OH bond followed by the isomerization reaction of H transfer. Moreover, the CNO2 bond with the smaller bond overlap population and the smaller BDE will also overlap may be before homolysis. According to the quantitative standard of energetics and stability as a high-energy density compound, pentanitrophenol essentially satisfies this requirement. In addition, we have discussed the effect of the nitro and hydroxy groups on the static electronic structural parameters and the kinetic parameter. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source] Theoretical studies on four-membered ring compounds with NF2, ONO2, N3, and NO2 groupsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 4 2008Xiao-Wei Fan Abstract Density functional theory (DFT) method has been employed to study the geometric and electronic structures of a series of four-membered ring compounds at the B3LYP/6-311G** and the B3P86/6-311G** levels. In the isodesmic reactions designed for the computation of heats of formation (HOFs), 3,3-dimethyl-oxetane, azetidine, and cyclobutane were chosen as reference compounds. The HOFs for N3 substituted derivations are larger than those of oxetane compounds with ONO2 and/or NF2 substituent groups. The HOFs for oxetane with ONO2 and/or NF2 substituent groups are negative, while the HOFs for N3 substituted derivations are positive. For azetidine compounds, the substituent groups within the azetidine ring affect the HOFs, which increase as the difluoroamino group being replaced by the nitro group. The magnitudes of intramolecular group interactions were predicted through the disproportionation energies. The strain energy (SE) for the title compounds has been calculated using homodesmotic reactions. For azetidine compounds, the NF2 group connecting N atom in the ring decrease the SE of title compounds. Thermal stability were evaluated via bond dissociation energies (BDE) at the UB3LYP/6-311G** level. For the oxetane compounds, the ONO2 bond is easier to break than that of the ring CC bond. For the azetidine and cyclobutane compounds, the homolysises of CNX2 and/or NNX2 (X = O, F) bonds are primary step for bond dissociation. Detonation properties of the title compounds were evaluated by using the Kamlet,Jacobs equation based on the calculated densities and HOFs. It is found that 1,1-dinitro-3,3-bis(difluoroamino)-cyclobutane, with predicted density of ca. 1.9 g/cm3, detonation velocity (D) over 9 km/s, and detonation pressure (P) of 41 GPa that are lager than those of TNAZ, is expected to be a novel candidate of high energy density materials (HEDMs). The detonation data of nitro-BDFAA and TNCB are also close to the requirements for HEDMs. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [source] Theoretical Study on Thermodynamic and Detonation Properties of PolynitrocubanesPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2009Xue-Hai Ju Abstract We investigated the heat of formation (,fH) of polynitrocubanes using density functional theory B3LYP and HF methods with 6-31G*, 6-311+G**, and cc-pVDZ basis sets. The results indicate that ,fH firstly decreases (nitro number m=0,2) and then increases (m=4,8) with each additional nitro group being introduced to the cubane skeleton. ,fH of octanitrocubane is predicted to be 808.08,kJ mol,1 at the B3LYP/6-311+G** level. The Gibbs free energy of formation (,fG) increases by about 40,60,kJ mol,1 with each nitro group being added to the cubane when the substituent number is fewer than 4, then ,fG increases by about 100,110,kJ mol,1 with each additional group being attached to the cubic skeleton. Both the detonation velocity and the pressure for polynitrocubanes increase as the number of substituents increases. Detonation velocity and pressure of octanitrocubane are substantially larger than the famous widely used explosive cyclotetramethylenetetranitramine (HMX). [source] Calculation of the Energy of Explosives with a Partial Reaction Model.PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2006Comparison with Cylinder Test Data Abstract The energy delivered by explosives is described by means of the useful expansion work along the isentrope of the detonation products. A thermodynamic code (W-DETCOM) is used, in which a partial reaction model has been implemented. In this model, the reacted fraction of the explosive in the detonation state is used as a fitting factor so that the calculated detonation velocity meets the experimental value. Calculations based on such a model have been carried out for a number of commercial explosives of ANFO and emulsion types. The BKW (Becker-Kistiakowsky-Wilson) equation of state is used for the detonation gases with the Sandia parameter set (BKWS). The energy delivered in the expansion (useful work) is calculated, and the values obtained are compared with the Gurney energies from cylinder test data at various expansion ratios. The expansion work values obtained are much more realistic than those from an ideal detonation calculation and, in most cases, the values predicted by the calculation are in good agreement with the experimental ones. [source] The Effects of Containment on Detonation VelocityPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2004Clark Souers Abstract Reactive flow cylinder code runs on six explosives were made with rate constants varying from 0.03 to 70,,s,1. Six unconfined/steel sets of original ANFO and dynamite data are presented. A means of comparing confinement effects both at constant radius and at constant detonation velocity is presented. Calculations show two qualitatively different modes of behavior. For Us/Co,1.2, where Us is the detonation velocity and Co the zero-pressure sound speed in steel, we find a sharp shock wave in the metal. The shock passes through the steel and the outer wall has a velocity jump-off. For Us/Co,1.04, we find a pressure gradient that moves at the detonation velocity. A precursor pulse drives in the explosive ahead of the detonation front. The outer wall begins to move outward at the same time the shock arrives in the explosive, and the outer wall slowly and continuously increases in velocity. The Us/Co,1.2 cylinders saturate in detonation velocity for thick walls but the Us/Co<<1.04 case does not. The unconfined cylinder shows an edge lag in the front that approximately equals the reaction zone length, but the highly confined detonation front is straight and contains no reaction zone information. The wall thickness divided by the reaction zone length yields a dimensionless wall thickness, which allows comparison of explosives with different detonation rates. Even so, a rate effect is found in the detonation velocities, which amounts to the inverse 0.15,0.5 power. [source] | ||||||||||