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Aiming at the demand for improving the heat release performance of solid propellants for high energy and complex practical application scenarios, the B–Mg–Al ternary alloy is proposed as a metal fuel additive. Based on the unique phase distribution of B–Mg–Al ternary metal alloy and the existing theory of ignition and combustion of metal particles, the kinetic simulation of ignition and combustion of B–Mg–Al ternary metal alloy particles in complex alternating atmosphere is carried out by combining with the virtual alternating atmosphere environment. The model calculates the combustion time tc of 10 μm B–Mg–Al alloy particles in H2O(g), H2O(g)/Air alternating mode, and Air to be 3.50 ms, 3.98 ms, and 4.60 ms, respectively, and the comparative errors with the experimental measurement of combustion time are kept around 5%, which verifies the reliability of the model results. The simulation study shows that the order of thermal oxidation reaction and the order of combustion of the monomolecular group elements of B–Mg–Al ternary alloy particles are Mg, Al, and B, which to some extent indicates that the addition of Mg and Al has the potential to improve the ignition and combustion performance of B. In addition, there are obvious differences in the ignition and combustion performance and heat transfer performance of the alloy particles under H2O(g) and that of Air with the same concentration, which leads to significant instability in both ignition and combustion processes at variable medium. [ABSTRACT FROM AUTHOR]

The ignition and combustion behaviors of single-particle aluminum in a water vapor environment are among the most important basic research aspects of metal fuels and solid propulsion technologies. In this paper, the ignition and combustion behaviors of aluminum particles in a water vapor environment were modeled based on a traditional aluminum particle ignition model and the finite difference method. In addition, a metal single-particle ignition combustion test system was used to carry out relevant validation experiments. The validation results showed that the average error of the model remained within 10%. In addition, an initial oxide layer fusion module was established in conjunction with the results of a material mechanics study of Al/Al2O3. Moreover, the model was used to calculate the ignition behavioral parameters (ignition delay time and ignition temperature) of the aluminum particles under different initial parameters. Finally, an intrinsic mechanism model was created to evaluate the influences of the relevant parameters on the ignition behaviors of the aluminum particles. The model results showed that the initial oxide layer ruptured during the aluminum melting stage, the phase transition stress was the main factor leading to oxide layer rupture, the ambient temperature had a great influence on the ignition temperature, and all four initial parameters were negatively correlated with the ignition delay time. [ABSTRACT FROM AUTHOR]

Aluminum particles have the problems of difficult ignition, easy agglomeration, incomplete combustion, etc. Therefore, it is of great scientific significance and engineering value to find ways to improve the ignition and combustion performance of aluminum particles in order to promote the full release of energy of aluminum particles. In this paper, spherical nano-sized ferric oxide (nFe2O3) and ammonium perchlorate (AP), a commonly used oxidizer in propellants, were used to synergistically improve the ignition and combustion performance of aluminum particles. AP modified the aluminum particles by both mixing and coating methods, respectively. On the basis of coating AP, nFe2O3 was added in order to further enhance the ignition and combustion performance of the aluminum particles. Scanning electron microscope, laser particle size analyzer, thermal analysis system and laser ignition experiment system were used to test the physicochemical properties and ignition combustion performance of different samples. The results showed that AP and nFe2O3 could be coated relatively uniformly on the surface of aluminum particles using the recrystallization method. The thermal reaction behavior of the samples showed that coating was beneficial to the decomposition of AP compared with mixing, and the addition of nFe2O3 could further improve the decomposition efficiency of AP. Ignition and combustion experiments showed that coating AP was more conducive to improving the ignition and combustion performance of aluminum particles than mixing AP, and the addition of nFe2O3 could further significantly enhance the combustion intensity and flame propagation speed of the sample. However, the addition of nFe2O3 increased the ignition delay time of the sample, which may be related to the cold agglomeration phenomenon caused by the nanoparticles. The microscopic combustion flame morphology of different samples showed that coating AP and the introduction of nFe2O3 could significantly reduce the agglomeration phenomenon of aluminum particles. Overall, coating AP reduces the distance between the aluminum particles and the oxidizer, thus significantly improving the ignition and combustion performance of the aluminum particles. The addition of nFe2O3 can further improve the combustion performance of aluminum particles, but at the same time, it also increases the ignition delay time. Hence, the cold agglomeration problem caused by nanoparticles should be fully considered when nFe2O3 is used to improve the ignition and combustion performance of aluminum particles. [ABSTRACT FROM AUTHOR]

Glycidyl azide polymer (GAP)/Hexanitrohexaazaisowurtzitane (CL-20) composite propellants have significant advantages, such as high energy density and low characteristic signal. However, the lack of understanding of its ignition combustion and agglomeration mechanism limits its large-scale engineering application in solid rocket motors. In this paper, the ignition, combustion and agglomeration processes of GAP/CL-20 propellants were studied in detail by using modern analytical and testing instruments, such as high-speed cameras, CO2 laser ignition devices and laser particle size analyzers. First, the ignition and combustion process of the GAP/CL-20 composite propellant were observed with a high-speed camera, and its ignition and combustion mechanism were analyzed. On the basis of the BDP model, a multiple flame structure model suitable for the GAP/CL-20 composite propellant was proposed. Then, the agglomeration of aluminum particles in the combustion process of the GAP/CL-20 composite propellant was observed, and an agglomeration mechanism suitable for the GAP/CL-20 composite propellant was proposed based on the pocket model and skeleton layer theory. Subsequently, the particle size distribution, micromorphology and crystal structure of the condensed phase combustion products were analyzed. The particle size distribution of the condensed combustion products (CCPs) showed three modes, and the CCPs contained active aluminum, which indicated that aluminum particles were not fully oxidized during the combustion process of the propellant. Finally, several further research directions were proposed. The research results may have reference value for the engineering application of GAP/CL-20 propellants. [ABSTRACT FROM AUTHOR]