Application of Absorption Spectroscopy Techniques for Rapid Temperature and Speciation Measurements Under Engine-Relevant Conditions

Within laser absorption spectroscopy, there exist multiple techniques that can be utilized depending on the test environment and experiment specific requirements. In this work, an absorption spectroscopy-based sensor capable of rapidly switching techniques is constructed and applied across multiple combustion environments. Particular focus is placed on temperature and speciation measurements under engine- and turbine-relevant conditions. The sensor can measure temperature as well as H2O, CO, and CO2 speciation. The scanned-wavelength direct absorption spectroscopy capabilities of the sensor are demonstrated across a shock tube facility at low pressures and extreme temperatures behind a reflected shock wave. The scanned wavelength modulation spectroscopy capabilities of the sensor are demonstrated across a detonation facility at high pressures and extreme temperatures behind a detonation wave. Comparisons are provided concerning the benefits and limitations of each technique, along with recommendations for selecting the appropriate method under various operating conditions.