With advancements in the 3D printing of explosives, the understanding how the shape of an explosive charge influences the energy expansion and subsequently the focusing of energy is becoming increasingly more important. Theoretically, explosive charges could be printed to focus the energy on targets of interest or to synthesize nanomaterials. The first step to quantifying the energy expansion and shock wave convergences for a 3D printed charge is to examine simple geometries of traditional explosive charges (non-3D printed). Detonation of 15 PETN-based primasheet charges in the spherical, cubic, cylindrical, and tetrahedral configurations have been examined in this study. Qualitative data was collected through the use of high-speed photography to examine the shock wave and fireball; production macroscopically. Quantitative pressure data was collected in the near and far field of the detonation reaction using free-field pressure probes, recording data both normal to charge faces as well as along charge vertices. In the near field, a lower pressure zone is created along charge vertices. In the far field, pressures along these bisecting axes increase as the shock front from adjacent facets intersect. These results shed a new light on the effect an explosive charges shape has on its ability to perform work on its surroundings. This paper will describe the methodology and findings of this study as well as examine the causality and implications of its results on our understanding of the detonation phenomena.

Unmanned aerial vehicles (UAV) have been used to monitor gas emissions for research projects, though downwash, the airflow produced by the UAV rotors, is potentially capable of artificially altering gas concentration measurements. Anemometers, placed at ten different distances below a 6-rotor UAV, measured air speeds in the downwash region. The collected data was used in combination with UAV rotor speed data to determine the stabilization time of the downwash region after the UAV has returned to a stable hovering position. The stabilization time will determine the amount of time after UAV movement until reliable concentration readings can be obtained within the downwash region. This paper presents stabilization times after vertical upward and rotational UAV movement.