Scanned-wavelength-modulation spectroscopy near 2.5 μm for $ H_{2} $O and temperature in a hydrocarbon-fueled scramjet combustor

Abstract The design and demonstration of a two-color tunable diode laser sensor for measurements of temperature and $ H_{2} $O in an ethylene-fueled model scramjet combustor are presented. This sensor probes multiple $ H_{2} $O transitions in the fundamental vibration bands near 2.5 μm that are up t...
Ausführliche Beschreibung

Abstract The design and demonstration of a two-color tunable diode laser sensor for measurements of temperature and $ H_{2} $O in an ethylene-fueled model scramjet combustor are presented. This sensor probes multiple $ H_{2} $O transitions in the fundamental vibration bands near 2.5 μm that are up to 20 times stronger than those used by previous near-infrared $ H_{2} $O sensors. In addition, two design measures enabled high-fidelity measurements in the nonuniform flow field. (1) A recently developed calibration-free scanned-wavelength-modulation spectroscopy spectral-fitting strategy was used to infer the integrated absorbance of each transition without a priori knowledge of the absorption lineshape and (2) transitions with strengths that scale near-linearly with temperature were used to accurately determine the $ H_{2} $O column density and the $ H_{2} $O-weighted path-averaged temperature from the integrated absorbance of two transitions. Ausführliche Beschreibung