A non-isentropic model and the method of characteristic line for the post-detonation expansion of aluminized explosives

The entropy of the flow field could not keep constant due to a strong exothermic reaction of aluminum powders during the post-detonation expansion of the aluminized explosives. Therefore, a non-isentropic model incorporating the aluminum oxidation in the detonation products was established. To solve the non-isentropic expansion process analytically, it was assumed that the whole expansion process was divided into several time ranges and the flow field was isentropic in each time range. Besides, the method of characteristic line was applied to theoretically calculate the velocity of the metal plate driven by aluminized explosives. Moreover, the effects on the pressure, density, sound speed, and temperature of detonation products due to the change of the entropy were analyzed. Finally, the metal plate-pushing tests were conducted to measure the velocity of metal plate driven by aluminized explosives through the Photonic Doppler Velocimetry system, and the degree of aluminum reaction was calculated indirectly from the test results. By comparing the results based on the isentropic model and novel non-isentropic model, it was proved that the non-isentropic model could more correctly describe the driving process of detonation products of aluminized explosives.