Tunable Diode Laser Absorption Spectroscopy Verification Analysis for Use in the Combustion Optimization and Analysis Laser Laboratory

by Christina R. Serianne

The AFIT Combustion Optimization and Analysis Laser (COAL) laboratory has state-of-the-art laser diagnostic capability for combustion process. The research for this thesis served to enhance the COAL lab's capability. Currently, there are no known commercially available tunable diode lasers that produce Ultra-Violet radiation required for this analysis. Sum-frequency generation at 313.5 nm was utilized for high speed OH absorption and temperature measurements at a rate of 2kHz. The Tunable Diode Laser Absorption Spectroscopy system was validated by comparison with theoretical and well characterized experimental data by operating the system over a wide range of conditions for an H2 laminar flame produced by a Hencken burner. The TDLAS system was able to perform at reasonable accuracy. After validation, the system was also characterized for a turbulent environment by comparing turbulent and flame structure theory with results obtained from a C2H4/N2 jet flame. The testing was also conducted for a range of conditions and produced reasonable results. The accuracy of the system is sufficient for utilization in investigating behavior in a turbulent, combusting environment.