High-Speed Infrared Radiation Thermometer for the Investigation of Early Stage Explosive Development and Fireball Expansion

• Published in: Sensors (Basel, Switzerland) Vol. 22; no. 16; p. 6143
• Main Authors: Hobbs, Matthew J., Barr, Andrew, Woolford, Scott, Farrimond, Dain, Clarke, Sam D., Tyas, Andrew, Willmott, Jon R.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 17.08.2022; MDPI
• Subjects: blast loading; Blast loads; Blasting (explosive); Carbon; Communication; confined blast; Explosions; Explosives; Field programmable gate arrays; fireball; Fireballs; Gas laws; Heat; High speed; High temperature; Ideal gas; Infrared radiation; infrared radiation thermometer; Investigations; Laws, regulations and rules; Measurement; Measurement techniques; Physical instruments; Pressure gages; Pressure gauges; Pressure measurement; Pressure transducers; Radiance; Radiation; radiation thermometry; Shock waves; Software; Static pressure; Temperature measurement; Temperature measurements; Thermometers; Thermometry
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s22166143

The understanding of blast loads is critical for the development of infrastructure that protects against explosions. However, the lack of high-quality experimental work on the characterisation of such loads prevents a better understanding of many scenarios. Blast loads are typically characterised by use of some form of pressure gauge, from which the temperature can be inferred from a pressure measurement. However, such an approach to temperature measurement is limited; it assumes ideal gas laws apply throughout, which may not be the case for high temperature and pressure scenarios. In contrast, infrared radiation thermometers (IRTs) perform a measurement of temperature based upon the emitted radiance from the target object. The IRTs can measure fast changes in transient temperature, making them seemingly ideal for the measurement of a fireball’s temperature. In this work, we present the use of a high-speed IRT for the measurement of early-stage explosive development and fireball expansion within a confined blast, with the temperature of the explosive fireball measured from its emitted radiance. The temperature measured by the IRT was corroborated against the temperature inferred from a pressure gauge measurement; both instruments measured the same temperature from the quasi-static pressure (QSP) point onwards. Before the QSP point, it is deduced that the IRT measures the average temperature of the fireball over a wide field-of-view (FOV), as opposed to that inferred from the singular shocks detected by the pressure gauge. Therefore, use of an IRT, in tandem with a pressure gauge, provides a potential invaluable measurement technique for the characterisation the early stages of a fireball as it develops and expands.