In this paper, confined explosions of HMX-based aluminized explosives in a spherical chamber are studied. The effects of aluminum particles on the afterburning reaction and explosive performance are obtained by changing the size of the particles and the gas environment. The results show that the concentration of oxygen in air is not sufficient to support complete combustion of aluminum particles. The estimated oxidation rate of aluminum particles is 87–93%, and it tends to decrease with increasing particle size. Part of aluminum particles oxidize with detonation products, and the reaction can last for hundreds of microseconds. However, the degree of oxidation between the large-sized aluminum particles and detonation products is small. A new method is used to estimate the initial energy of detonation by observing the time difference between sensing the initial light and the pressure wave. This method leads to a conclusion that some of the aluminum particles are oxidized during detonation and provide additional energy to the primary blast wave. Small micron-sized aluminum particles in the range of 48.9 nm to 46.7 \(\mu\)m extend the duration of the fireball.

Investigating the structural evolution of particulate gels is a very challenging task due to their vulnerability and true flow characteristics. In this work, deeper insight into the rheological properties of gel fuels filled with fumed silica (FS) and aluminum microparticles (Al MPs) was gained by changing shear procedures. Firstly, the flow curves were found to no longer follow the monotonic power law and exhibited subtle thixotropic responses. As the shear rate increased, the gel structure underwent a transition from local shear to bulk shear in the nonlinear region after yielding. This finding reveals the prevalence of nonideal local shear in industry. Secondly, the time-dependent rheological responses demonstrated that the strength spectrum of gel fuels depends on the applied shear rate, with stress relaxation more easily observed at lower shear rates. Those results involved the structural disruption, recovery, and equilibrium of particulate gels from two scales of shear rate and shear time.

It is important to study the effect of ambient pressure on air blasts, and the explosion process of TNT explosives was calculated by using the AutoDyn-2D software in this paper. Moreover, the explosion parameters under different ambient pressure conditions were predicted, and the propagation characteristics and laws of the air blast waves were obtained. The results showed that the overpressure of the incident wave, reflected wave, and Mach wave was positively related to the ambient pressure. High ambient pressure resulted in a decrease in the barotropic time and velocity of the incident wave, but its impulse increased. The wavefront of the Mach wave propagated in a curved form, and the pressure distribution on the Mach stem was not uniform. The height of the triple points was inversely proportional to the increase in the ambient pressure, and this trend was significant with the increase in the distance.

The composite charge structure may have the potential to enhance the overall damage capability of the weapon. In this regard, three-dimensional LS-DYNA simulation software (dynamics calculation software from LSTC) was used to simulate the explosion process of charges in a partially confined space. The effects of different aluminized charge structures on the propagation and parameters of blast waves in a cubic cabin structure with a pressure relief port were obtained. The results showed that the reflected waves generated local pressure convergence at the junction and corner areas of adjacent walls in the cabin structure. The numbers of significant reflections of the blast waves at the center and corners of the wall were 3 and 2, respectively. The overpressure of the reflected wave at the corner was more than 3.2 times that at the center of the sidewall. Moreover, the number of reflections, overpressure ratio, and charge structure were not directly related. The advantages of composite structure charges in enhancing the overpressure and wave velocity of incident waves and the overpressure and impulse of reflected waves were not significant. However, the internal and external composite charge structure had more advantages than did the upper and lower structures, and its impulse TNT equivalent reached more than 70% of that of a single-structure explosive. The results can provide theoretical support and technical guidance for the design of charge structures and cabin structures.

In this paper, confined explosions of HMX-based thermobaric explosives containing oxidizers in a spherical chamber were studied by changing the type of the oxidizer and the oxygen concentration in the environment. Based on an in-house developed optical-electrical system, the optical radiation signals of Al₂O₃ during the afterburning reaction were recorded. The results show that aluminum particles (5.4 µm) were strongly dependent on the oxygen concentration in the environment. Increasing the oxygen concentration can prolong the oxidation duration of Al and enhance the optical radiation intensity of Al₂O₃. The optical radiation result for Al₂O₃ in O₂ and air showed that aluminum particles (the mass fraction was 33 %) were not completely oxidized in the air, and the oxidation duration was 500–700 µs. Moreover, the pressure data of the blast waves was obtained using a pressure-measurement system. The results showed that an increase in the oxygen concentration of the explosive could further enhance the total impulse, especially an addition of KP (its mass fraction was 10 %) could increase the total impulse by about 9 %.