Two-dimensional reconstructions of gas temperature and concentration in combustion based on tunable diode laser absorption spectroscopy

Abstract

Based on the tunable diode laser absorption spectroscopy, the combustion gas concentration and temperature distribution are reconstructed using algebraic iterative reconstruction technique (ART). Time division multiplexing technology is adopted to scan two H2O absorption transitions (7205.25 cm-1 and 7416.05 cm-1) simultaneously at 1 kHz repetition rate. The influences of projected angle and the number of beams on the temperature and concentration field reconstruction are studied. Compared with the thermocouple readings, the temperature distribution reconstruction has a well agreement except a low temperature area in the middle of the combustion field. Aiming to achieve an optimal reconstruction with a limited number of beams, a few virtual beams are added to the ART method. Through this method, the effectivenesses of temperature and concentration field reconstructions increase, but there is not an obvious improvement when a large gradient of temperature exists between two lines.