Numerical study of the postcombustion effects on the underwater explosion of an aluminized explosive by a novel nonisentropic model for the detonation products

An aluminized explosive detonating in the water is distinguished by the nonideal effects caused by the postcombustion of the aluminum additives. These effects play a big role in the noncontact underwater explosion phenomena, but they are usually ignored or smoothed in the conventional experimental tests, as well as in the numerical simulations with empirical models fitting to those test data. Here we propose a nonisovolumic and nonisentropic slow reaction model and then utilize the method of characteristics to analyze how and how much the postcombustion effects the entire flow field. Numerical examples show the near-field flow properties are appropriately obtained, the geometric dissimilarity of the product expansion is embodied and the enforcement of the additional energy release is tracked. These results imply the proposed methods can be used to reveal the mechanism of the postcombustion effects and shock wave enforcement.