Numerical simulation of one-dimensional aluminum particle–air detonation with realistic heat capacities

Abstract

a b s t r a c t Aluminum (Al) particle-air detonation is very complicated because it includes multi-phase combustion phenomenon. Thus numerical simulations are often over-simplified. Here, the detonation is simulated by solving one-dimensional equations with more realistic heat capacities that vary with the dust mixture temperature. The effect on detonation parameters from the realistic heat capacities for the solid particles is investigated with a hybrid combustion model. The calculated results indicate that the detonation pressure, temperature and velocity vary significantly with changes in the heat capacity. Except for the velocity, these parameters are overestimated in numerical simulations when a constant heat capacity of the pre-shock mixtures is used. Furthermore, the realistic heat capacities have a strong effect on small diameter particles, but a weak effect on large diameter particles. Thus, when constant heat capacities are used, the combustion characteristic lengths are a function of the particle diameters with a power dependence of 1.77, whereas the power dependence decreases to 1.49 when realistic heat capacities are used. Moreover, if realistic heat capacities are applied, an ''abnormal'' strong detonation wave may appear in a dust mixture having large diameter particles. This phenomenon is consistent with the current combustion model, but it indicates that the value of heat released should also vary with the gas temperature in a fashion similar to that of the heat capacities.

Effects of different product phases in aluminum dust detonation modeling

“…Self-sustained detonation occurs and a constant speed of detonation of 1828 m/s is gradually reached. This result has been discussed and compared with experimental and numerical results before [22]. Although the velocity is higher than the experimental one, it is reasonable due to the simplification of the multi-phase combustion model.…”

“…This induces the inconsistency, and the reaction rate thus needs to be adjusted to get closeto-experiment results. Furthermore, the constant heat release introduces other problems as reported in our previous research [22]. To model the Al dust detonation accurately requires abandoning the constant heat release.…”

“…When the temperature reaches above the alumina decomposition temperature, the exothermal reaction is replaced by the endothermic reaction, thus ensuring the product temperature is in a reasonable range. Another way to change the heat release is to introduce latent heat [20,22], which is also used in this paper above. The results for different latent heat methods are shown in Table 1.…”

“…Briand et al [21] used this model for cellular detonation simulations, and they compared results with those obtained with the classic diffusion model. Teng and Jiang [22] studied the effect of realistic heat capacities used for the Al particle internal energy, and improved numerical results by introducing heat capacities that varied with the temperature.…”

The vitiation effects of water vapor and carbon dioxide on the autoignition characteristics of kerosene

“…There are several kinds of fuel used in the hypersonic engines, including gaseous, solid and liquid [3][4][5]. In last decades, liquid hydrocarbon is studied widely due to its potential use in hypersonic flight at relatively low Mach number [6].…”