ИСТИНА

Tunable Diode Laser Absorption Spectrometry (TDLAS) is a powerful tool for contactless measurements of gas concentration and temperature in hot zones. The technique we used is based on the registration of the experimental transient absorption spectra of water molecules and fitting of the experimental spectra by the simulated ones constructed using the spectroscopic databases [1]. Wavelength scale, frequency, temperature, pressure, baseline and the concentration of water molecules were the parameters of the fitting. The advantages and limitations of the developed technique will be discussed in the talk with the emphasis on the problems of the experimental spectra fitting and different fitting algorithms. The efficiency of the developed technique was exemplified by the measurement of the temperature and water vapor concentration in the hot zone of plasma-assisted combustion in air-fuel supersonic flow. The combustion is ignited and sustained by the pulsed electric discharge in experimental aerodynamic tube, characterized by rather strong fluctuations, vibrations and different optical and electrical noises. The flow parameters were: Mach number = 2, total pressure 150-300 Torr. Air was used as the oxidant, hydrogen or ethylene were used as the fuel. The mean temperature of the hot tail of the combustion zone varied within 800 1200 K for hydrogen and 700-1000 K for ethylene, the water concentration varied within 10-20 Torr. The high signal-to-noise ratio enabled to obtain the temporal profile of both parameters with the resolution of ~ 1 ms.