Technology to study early explosive development and fireball expansion

Characterizing blast events and how they affect structures is critical to infrastructure development. It provides information to engineers that allows them to protect such infrastructure from events such as explosions.

However, there is a lack of high-quality data regarding the characterization of explosive events that occur in a confined space, in part due to the lack of suitable measuring instruments.

This is where the research of Dr Matthew Hobbs, a lecturer in the Department of Electronics and Electrical Engineering, comes in. This paper, led by Matthew, was published last year when he was working as a researcher and lecturer in the department, alongside a team of other researchers, including Prof John Willmott, Professor of Metrology.

The published article was published in Sensors, and is titled “A High-Speed ​​Infrared Radiation Thermometer for Probing Early Explosive Development and Fireball Expansion.” Other authors of this paper include members of the Blast and Impact Group from the Department of Civil and Structural Engineering at the University of Sheffield.

By incorporating a customized, high-speed, non-contact infrared thermometer into a combined explosive event measurement setup, the temperature of the explosive fireball can be accurately characterized. By combining their new approach with traditional pressure gauges, the team is able to discover new information about the early stages of fireballs as they expand and develop.

The explosive research was carried out at world-leading facilities in the dormant fields above Buxton. None of the nearby sheep were disturbed, however, as the explosions were carried out on a platform in a controlled chamber.

The infrared thermometer created by the researchers opens new positions in the world of explosive events regarding the characterization of fireballs and explosions. Previously, because the work was done in a confined space and the explosions that were created were of a size that would destroy any recording camera in that space, the inner workings of these explosions were difficult to measure. The Blast group in Sheffield relied on traditional pressure gauges and numerical modeling of fireballs – this meant that in the first few microseconds there were features that their sensors were too slow to pick up, and that the group only knew about these features from their models.

This new, non-contact temperature measurement tool means that the microseconds immediately following an explosion can be analyzed in great depth and lead to findings that can help engineers protect infrastructure from threats such as targeted attacks.

“Working closely together, we were able to develop instruments capable of measuring the temperature of a confined explosive event. Such research would not have been possible without the mutual expertise of the two research groups; we were able to apply our new research within the temperature measurements to their new application of blast load characterization,” says Dr Matthew Hobbs, lecturer in the Department of Electronic and Electrical Engineering.