Effect characteristics of aluminum content on reactive jet mesoscale formation and implosion overpressure

To reveal the influence mechanism of aluminum content on the formation and implosion overpressure of polytetrafluoroethylene/aluminum (PTFE/Al) reactive jets, mesoscale numerical simulations are introduced and performed to characterize the mesoscale formation process of reactive jets. The present study innovatively obtains the influences of aluminum content on formation behavior, including the relative flow behavior of two materials and the velocity, pressure, temperature, and material distribution characteristics on a mesoscale dimension. Then, the mechanical-thermal correlation during reactive jet formation is discussed. In addition, a predictive model for the implosion overpressure of reactive jets is developed to quantitatively analyze the effects of chemical energy release on implosion overpressure, with the consideration of jet mass loss during the formation process. To validate the model accuracy, static implosion overpressure experiments of reactive jets are conducted. The findings show that the density disparity between aluminum and PTFE results in velocity differences and relative motion. The aluminum content significantly influences the spatial distribution, deformation extent, and flow behavior of the materials, thereby affecting the velocity, pressure, and temperature distribution characteristics of the jets. Data from deflagration tests in a 13 L quasi-confined chamber indicate that the overpressure rise time is approximately 5-7 ms, whereas the depressurization time exceeds 40 ms. For aluminum contents of 26.5%, 36.5%, and 46.5%, the peak overpressures of reactive jets in the chamber are 2.86, 2.34, and 2.18 MPa, respectively, highlighting a strong correlation between peak overpressure and chemical energy release.