Small scaled reactive materials combustion test facility

Abstract

Combustion of reactive materials forms an active area of research for reactive fragment and structural materials applications. Currently, reactive fragment tests involve high velocity (1-2 km/s), large caliber projectiles directed into blast chambers where overpressure is measured to quantify output. Unfortunately, these existing facilities suffer many issues including high cost per test, which limits the ability to perform true parametric studies, as well as limited access in some cases for diagnostics other than transient pressure. To address these issues, we developed a small-scale reactive materials combustion test facility based on the Remington .17 caliber rifle which safely launches projectiles at velocities approaching 1.3 km/s. By making custom projectiles and firing these into a small chamber with complete optical access, we are able to obtain transient pressure and capture high-speed imagery. The setup also allows for optical measurements including pyrometry and spectroscopy. In this work the diagnostic measurements are primarily the bullet velocity and chamber overpressure. After completion of the design and installation of the laser optical chronograph and the appropriate pressure transducers, several tests at velocities of 1.2 km/s were performed comparing inert bullets with those comprised of reactive metals in air, 100% nitrogen, and 40% oxygen rich environments. Therefore this paper outlines the major components of the combustion test facility, the system diagnostics and the effect that different intermetallics in various environments have on combustion performance. Results indicate that the facility performed as intended by capturing quantitative differences in the chemical energy release of various energetic systems. Further, through the post-processing of specimen residue with X-ray diffraction, the identification of reaction products provided better insight into the chemical reactions contributing to the observed energy release assisting in the determination of elements responsible for combustion performance.