Comparing pyrometry and thermography in ballistic impact experiments. (15th February 2022)

• Record Type: Journal Article
• Authors: Woodruff, Connor; Dean, Steven W.; Cagle, Colton; Luke Croessmann, Charles; Pantoya, Michelle L.
• Is Part Of: Measurement. Volume 189(2022)
• Publication Date: 2022-02-15
• Subjects: High-Velocity Impact -- Optical Diagnostics -- Thermal Radiation -- Emissivity -- Aluminum Combustion; Weights and measures -- Periodicals; Measurement -- Periodicals; Measurement; Weights and measures; Periodicals; 530.8
• DOI: 10.1016/j.measurement.2021.110488
• Languages: English
• ISSNs: 0263-2241

Abstract

Graphical abstract: Highlights: Calibrate for spectral lamp temperature corresponding to measurement wavelengths. Pyrometry is better applied at impact when saturated light emission is present. Thermography provides spatial resolution of reacting fragments at later times. Graybody emissivity applies at early times during optically thick ballistic impact. Inverse wavelength squared emissivity applies at later times as fragments disperse. Abstract: Thermal analyses of projectile impact and subsequent combustion are investigated for aluminum projectiles using a high-velocity impact ignition system. Temperature measurements are compared using pyrometry and thermography. The implementation of these techniques is discussed, as well as their benefits and limitations in ballistic experiments. Results show pyrometry is best for measuring temperatures in the immediate vicinity surrounding the impact location, while thermography better quantifies temperature dissipation downstream from impact as the combusting debris cloud disperses. Temperatures comparable to the predicted adiabatic flame temperature are observed with the pyrometer. For thermography, emphasis is placed on the treatment of emissivity in temperature calculations. Three combustion stages are identified in the thermography data and attributed to 1) ignition and growth of the combustion front, 2) thermal dissipation due to initial particle burnout, and 3) a slower dissipation stage caused by reduced heat exchange between the burning debris cloud and surroundings.