Water temperature and concentration measurements within the expanding blast wave of a high explosive

Abstract

We present an application of absorption spectroscopy to directly measure temperature and concentration histories of water vapor within the expansion of a high explosive detonation. While the approach of absorption spectroscopy is well established, the combination of a fast, near-infrared array, broadband light source, and rigid gauge allow the first application of time-resolved absorption measurements in an explosive environment. The instrument is demonstrated using pentaerythritol tetranitrate with a sampling rate of 20 kHz for 20 ms following detonation. Absorption by water vapor is measured between 1335 and 1380 nm. Water temperatures are determined by fitting experimental transmission spectra to a simulated database. Water mole fractions are deduced following the temperature assignment. The sources of uncertainty and their impact on the results are discussed. These measurements will aid the development of chemical-specific reaction models and the predictive capability in technical fields including combustion and detonation science.

Accurate variational calculations for line lists to model the vibration–rotation spectra of hot astrophysical atmospheres

“…However, the line list has rather wide application for other scientific studies including For construction of the temperature and concentration histories of water vapor within the expansion of a highly explosive detonation126; For the design of high‐temperature gas sensors127; For high‐speed thermometry and tomographic imaging in gas engines and burners128,129 and for oxyfuel gas spectral radiation models130; As input for an improved theory of line‐broadening17; To validate the data used in models of the Earth's atmosphere and, in particular, simulating the contribution of weak water transitions to the so‐called water continuum131; For analyzing room temperature132,133 and hot134 laboratory experiments. …”

Thermobaric Effects of Cast Composite Explosives of Different Charge Masses and Dimensions

“…The recorded thermal effects from the thermobaric composition were much higher than from C-4. Absorption spectroscopy was also used in the determination of the temperature of water vapour within the expanding blast following the detonation, as a molecular thermometer to measure the dynamic thermal fields of an explosive event [20]. The dependence of the explosive effect on the sample size (regarding shock wave velocity, visible reaction i.e.…”

Use of a fast near-infrared spectrometer for absorption and emission measurements within the expanding blast wave of a high explosive

“…The spectrometer/array combination was controlled by the data acquisition system to acquire one spectrum every 25 μs (40 kHz repetition rate) so that a reference and transmitted spectrum could be acquired for every pulse of the light source, resulting in a relative transmission measurement (I/I ref ). Further details on the scheme can be found in Carney, et al [7].…”

“…3 is likely a result of the slight variation of the reflectivity of the fiber splitter and coupler as a function of polarization, which cannot easily be controlled from pulse to pulse or between the reference and transmitted fibers. Fortunately, the effect of this slowly varying baseline can be mitigated through a fourier filtering process or a number of data reduction schemes (see Carney, et al [7] for details). By comparing the shape of the spectrum to a simulated spectrum based on the BT2 database [8] and a lineshape model, the temperature of the water vapor can be deduced.…”