Nonintrusive Augmentor Sensors

The primary objective of this Phase-I research effort is to perform a feasibility study of the femtosecond (fs) laser-based frequency comb pair and CW Raman fiber comb pair for measuring temperature and H2O concentration at data rate greater than 10 kHz near 2.5 ìm. Tomographic reconstruction using proper orthogonal decomposition will be used in conjunction with multiple beams to obtain coarse temperature images. A key attribute of the proposed solution is the use of advanced hyperspectral sources (rather than diode lasers) to monitor H2O absorption features. Despite using absorption spectroscopy for determining the temperature and H2O concentration from hyperspectral frequency comb, this technology is fundamentally different from typical diode laser-based absorption sensors and has many advantages, specifically, allowing the acquisition of many spectral lines covering wide spectral range at very high speeds (>10 kHz, typically 30 kHz) and thereby providing better temperature accuracy and power spectral density (PSD) functions. This feasibility study will pave the way for designing the optimum source for the implementation in an augmentor test facility at WPAFB during the Phase-II research effort along with user-friendly software for tomographic reconstruction of the flow field.