Diode laser absorption tomography for swirl flames application

Tunable Diode Laser Absorption Spectroscopy (TDLAS) has been one of the most powerful techniques for combustion diagnostics in different kinds of burners. Combined with Hyperspectroscopy Tomography (HT), TDLAS can improve its spatial solution. This study reports a TDLAS-tomography system and its application in a swirl burner. The diagnostics system composed of sixteen beams (13X13, 13 parallel beams and 13 vertical beams). Four water vapor absorption lines, 7185.6 cm-1, 7444.3 cm-1, 7466.3 cm-1, and 6807.8 cm-1, were utilized in each beam using time-division-multiplexed (TDM) method at total measuring frequency of 2.5 kHz. A reconstruction routine based on simulated-annealing algorithm was used to deduce distributions of temperature T and water partial pressure PX. Dynamic data was obtained during the ignition of hydrogen fuel at the exit of the scramjet combustor. T and PX distribution of cross section indicate the flame location and its intensity. Successful experiments show great performance of this diagnostic method.