The complex flow and acoustic fields generated by high-speed jets and ballistic systems are critically important design considerations for both propulsion and weapon systems. Large noise levels associated with blast waves or acoustic feedback loops can cause vibrations capable of damaging components and can be extremely detrimental to the health and safety of nearby personnel. Recent efforts at The University of Tennessee Space Institute (UTSI) have used a high-speed shadowgraph system with a specialized LED and background to study the near-muzzle ballistic fields of conventional firearms that may accurately model larger-scale ballistic systems such as artillery pieces. In contrast to implementing expensive transducers that are intrusive in nature, this flow visualization technique is a more pragmatic approach to studying the dynamic flow and acoustic fields generated by such platforms. Several projectiles of various sizes and muzzle velocities were imaged with this system at a frame rate of 12.5 kHz using a high-speed camera. In some cases, high-pressure gases discharging from the muzzles form a highly underexpanded jet that is characterized by the presence of acoustic radiation and strong shock structures, similar to the flow fields of larger jets. The image analysis techniques presented herein are compared to pressure measurements of similar flow fields with promising results.
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