Spatially resolved mass flux measurements with dual comb spectroscopy

Providing an accurate, representative sample of mass flux across large open areas for atmospheric studies or the extreme conditions a hypersonic engine is challenging traditional intrusive point-based sensors. Here, we demonstrate that laser absorption spectroscopy with mode-locked frequency combs can simultaneously measure all components (velocity, temperature, pressure, and species mole fraction) low uncertainty, spatial resolution corresponding to line sight, no supplemental sensor readings. The uncertainty provided by broad spectral bandwidth, high resolution, extremely well-known controlled axis stabilized, combs. We these capabilities using dual comb (DCS) in isolator ground-test supersonic propulsion at Wright-Patterson Air Force Base. measurements are consistent within 3.6% facility-level air supply values. A vertical scan beams measures spatially resolved flux, which compared computational fluid dynamics simulations. rigorous analysis demonstrates instrument ~0.4%, total (including non-instrument sources) ~7% measurements. These DCS as low-uncertainty variety applications.