OPTICAL CHARACTERISATION OF THE THERMO-CHEMICAL-GEOMETRIC STATE OF HIGH EXPLOSIVE FIREBALLS
Abstract
This project will involve using a specifically filtered high speed camera capable of tracking reaction gasses, in conjunction with a stereo digital Schlieren system to capture the tomography of the emerging fireball and the associated shock front. These methods will be combined with an existing pressure measurement system, the Characterisation of Blast Loading (CoBL) apparatus at the University of Sheffield’s blast laboratory, which is capable of measuring the effect of local variations in the fireball on the magnitudes and spatial distribution of the loading. Currently a single High Speed Video (HSV) camera is used to assess the state of the fireball and to allow correlations between the measured loading and the features of the fireball. The digital Schlieren techniques can also be utilised to track both the shock front (which is common place) but also the breakout of the fireball in 3D. The combination of these will give insight into the fundamental mechanism driving the observed plumes. These 3D Schlieren techniques can be also combined with tracking of the specific gas species via infrared spectroscopy. This has not been attempted at the high speed required to track the gasses and detonation products generated in explosive events. The project aims to provide an unparalleled method for the characterisation of the reactive front in explosive events providing a full field of validation data for numerical modelling. This will be achieved by filtering the wavelengths seen by a state-of-the-art high speed 3-5 micron wavelength camera to be able to track reaction gasses e.g. NO2 pre-reaction in TNT detonations. This, combined with the ability to use an existing system to achieve high speed temperature readings would allow the state characterisation of the expanding fireball post detonation.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2021
- Source ID
- FA86552017015
Entities
People
- Sam Clarke
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Sheffield