In-situ, multi-species combustion sensor using a multi-section diode laser

Abstract

Preliminary results of a near-IR diode laser sensor for in-situ monitoring of combustor and engine exhaust species have been demonstrated. A new laser technology which achieved nearly 100 nm quasi-continuous tuning using only injection current control in a foursection Grating-Coupler, Sampled-Reflector (GCSR) laser was used to simultaneously detect CO and CO 2 in room-temperature gas mixtures. The GCSR laser was used to perform in-situ measurements of CO, H 2 O, and OH in the exhaust gases of a methane/air flame. An initial demonstration of two-line absorption thermometry based on vibrational transitions in OH was also completed.

Diode laser sensors for aeroengines - Lessons learned and future promises

“…Several basic problems need to be resolved here, including improved sensitivity to overcome the reduction in individual absorption linestrengths with temperature and the pernicious interference of water vapor transitions at temperatures American Institute of Aeronautics and Astronautics above 1000 K. Figure 13 shows recent results from our laboratory where in-situ measurements of CO in the near-IR have been performed, although the present sensitivity is limited to about 1000 ppm by nearby water vapor interference and further work is required to find more optimal transitions. 5 In exhaust applications with temperatures below 1000 K, water vapor interference is expected to be greatly reduced and work is underway to demonstrate in-situ NO, NO 2 , and CO detection in exhaust gases at these temperatures.…”

“…We have demonstrated detection of both CO and NO in laboratory flames 4,5 , but the basic spectroscopic approach for a practical sensor requires further work. These results and on-going efforts to demonstrate applications to practical aeroengine systems are described last.…”

Continuous water vapor mass flux and temperature measurements in a model scram jet combustor using a diode laser sensor

“…IR viewer was used to confirm ignition, flamelet 4,35 The experimental setup of the burner optics is shown stability, and overall flame shape. schematically in Figure 4.…”