JOURNAL OF ENERGETIC MATERIALS
Year:2008 | Volume:2 | Issue:2|Papers Count:8

The caged polynitramine explosive (CL-20) is one of the most powerful explosives whose performance parameters such as pressure and velocity of detonation, heat of formation, penetration and density are higher than the other common explosives. In this paper, all the synthetic methods and the explosion parameters of CL-20 have been reviewed and the most convenient method has been selected, clarified and optimized. Also, optimizing parameters such as crystallization solvents for CL-20 (ethyl acetate-heptane) and its intermediates (for HBIW, ethyl acetate), reaction temperature (for converting HBIW to TADB, 38-42oC), and catalyst (Pd/C, 5% wet), a new nitration composition (nitric acid-sulforic acid, with ratio 1:1) has been introduced.

An important phenomenon in gaseous detonations is the formation of high velocity jets of products and their influence on the detonation front. In this paper، an adaptive second-order Godunov scheme along with a front tracking algorithm is used to carry out two-dimensional numerical simulation of gaseous detonation in a channel. For the chemical kinetic, a single-step Arrhenius rate law is utilized. The initiation of detonation is performed using a plane blast wave. The structure of the front (that includes triple points ,transverse waves ,incident shock ,and mach stem) is fully formed as the detonation propagates in the channel. The results show that the origin of high velocity jet from product is the interaction of two transverse waves and their corresponding triple points ,or the impact of one triple point to the wall boundary. The influence of the high velocity jets on the detonation front and the increase of mixing between unburned and burned gases is investigated.

In this paper, the solid rocket motor's grain starting process is simulated numerically by solving Navier-Stockes equations in an axisymmetric, transient laminar mode. Explicit maccormack technique is used for solving the equations. Also, to reach the actual state of grain surface burning and to predict its temperature a suitable heat transfer model is used. So that the preheating of the fuel by the flame can be modeled. By solving the conservative equations of mass, momentum, and energy along with related boundary conditions, one can predict the burning time of the first element of the fuel, its place, and the direction of flame propagation. In addition, the time required for the burning of all the surfaces of the fuel and the time in which the motor burning reaches to a steady state condition could be estimated. Results show that a two-dimensional axisymmetric model is suitable for predicting the transient combustion process in solid fuel motors. Also, a motor designer can design the best igniter based on grain type and size. The numerical results are compared with the results of the experimental tests and their accuracy is evaluated.

KRH process is a new way for producing titanium aluminide intermetallic compound on the basis of a complex reaction between tio2,  Al, Ca and kclo4 reacting materials. In this study ,the occurred phenomena in different temperature regions were investigated and a temperature region which the reaction had a self-propagating behavior was determined by temperature measurement in the reaction vessel and DTA analysis. It was found that the process was ignited via the reaction between kclo4 and Ca. A self propagating reaction started after the ignition of process.

In this study, the efficiency of UASB reactor method for treatment of HTPB plant wastewater was investigated. For this purpose, a UASB reactor with a volume of 227 liters was used. The HTPB plant wastewater includes ethanol, oxygen peroxide, various compounds of HTPB resin and water. The UASB reactor was started up with the feed concentration of 500 mgcod/l. To make sure of the sludge granulizing process during the start-up period, various analyses such as TSS, VSS and methanogenic activity were carried out over sludge samples. These analyses indicated that the sludge was successfully granulated into the UASB reactor. Also, results of effluent analysis showed that treatment efficiency was progressively raised. Treatment efficiency was 78% at the end of start-up period. After stabilization of the treatment process, effect of feed concentration and liquid apparent velocity were evaluated. Results of the reactor experiments indicated that feed concentration of 10000 mgcod/l and apparent velocity of 1.3 m/h are the optimum conditions for treatment of HTPB plant wastewater. Under this condition, the removal efficiency of contaminants was 95%.

In a self sustained detonation, the energy required for leading shock propagation is provided by exothermic reactions at reaction zone. There is a locus at the reaction zone where the particle velocity (with respect to the shock attached frame) is equal to the speed of sound. Flow is supersonic in the downstream of the sonic locus. Therefore, only that part of the reaction zone which located between the leading shock and the sonic locus affects the detonation front dynamics. Variation of detonation front curvature will change the distance of sonic locus from lead shock. Here reactive Euler equations are solved in the reaction zone between sonic locus and leading shock, and a relation derived between detonation propagation velocity (D) and reaction products with detonation front curvature (k). We carry out this analysis by a method that known as "Detonation shock dynamics" (DSD) method for weakly-curved quasi-steady detonation waves. Comparison of the results with direct numerical solution (DSD) of reactive Euler equations shows that the DSD method has very good results for weakly-curved detonations. According to this analysis, increment of curvature lead to detonation velocity reduction and in general D-k curve has a Z-shape with two turning points that upper and lower turning points are associated with detonation extinction an initiation respectively.

In this paper the shaped charge and its analysis methods are introduced and explosion process, liner collapse and jet formation are simulated using LSDYNA960 software. After making sure about the correction of the simulation process and its results, the effects of the main parameters of the shaped charge on the jet properties are investigated. The results of this study show that decreasing the liner apex angle and increasing the detonation velocity of the charge increase the jet velocity. Also decreasing the thickness of the liner near the apex leads to an increase in the jet velocity. Using an appropriate case for the shaped charge also increases the jet velocity about 10%. The results of the simulations are in good agreement both with analytical results and the results of the simulations done by other researchers.