Measurements of low concentration hydrocarbons at elevated temperatures and pressures using supercontinuum laser absorption spectroscopy

High-speed speciation of simple hydrocarbon fuels at small concentrations is demonstrated using near-infrared supercontinuum laser absorption spectroscopy (SCLAS). Absorption-based diagnostics, particularly when combined with optical fiber components, have significantly enhanced and enabled novel measurements of combustion phenomena. However, most techniques are subject to limitations prohibiting optimal measurements under advanced combustion regimes. SCLAS is a novel laser-based diagnostic technique that has been shown to overcome the aforementioned limitations and provide accurate, quantitative, and high-speed concentration measurements for various reacting flow environments. In this study, an SC laser is used to probe small concentrations of simple hydrocarbon species at elevated pressures and temperatures. Absorption spectra of CH4 and C2H2 were measured at various concentrations, pressures, and temperatures and statistically analyzed to determine the accuracy and sensitivity of the diagnostic strategy. Experimental results agreed well with models generated using the HITRAN database.