Fast mid-infrared spectroscopy of gases: Measurement method during a H2/O2 deflagration

• Published in: AIP conference proceedings 2020-11, Vol.2272 (1)
• Main Authors: Dabos, Marie, Tran, Khanh-Hung, Lecysyn, Nicolas, Baudin, Gérard, Genetier, Marc, Ranc-Darbord, Isabelle, Serio, Bruno, Osmont, Antoine
• Format: Article
• Language: English
• Subjects: Blackbody; Calibration; Cameras; Condensed matter physics; Deflagration; Detonation; Engineering Sciences; Flame propagation; Gas mixtures; Infrared spectra; Measurement methods; Measuring instruments; Mechanics; Optics; Photonic; Piezoelectricity; Polynomials; Spectrum analysis; Thermics
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/12.0000854

To study detonation products of condensed matter in the post-combustion phase, a preliminary work is carried out on deflagrations. The study of the radiative properties of molecules during this fast phenomenon is not simple in the mid-infrared range. As the flame front of a H2/O2/N2/CO2 gas mixtures spreads in a few tens of meters per second, a fast infrared detection system is required. Besides, there are no calibrating sources in that spectral range for the intensity and spectral position calibration. The important feature of the experimental set-up presented is the record of high-resolution spectra at high frequency, up to 10 kHz. The set-up is composed of a deflagration chamber with optical accesses. The pressure evolution is measured by a high speed piezoelectric sensor. The ignition is synchronized with the camera trigger. The radiation is focused into a monochromator and at its exit slit, a camera records the spectra in real time. The spectral intensity is calibrated using a blackbody. The correspondence between the spatial position of a pixel and the wavelength is fitted using an original method based on the application of a third degree polynomial, taking into account optical aberrations. The resulting spectra can be used to determine the temperature and the emissivity of gases.