Ultrasensitive Diagnostics for Hypersonic Propulsion Systems

In this Small Business Innovative Research effort, Los Gatos Research, Inc. proposes to develop two laser-diagnostic instruments to accurately quantify CH4, C2H4, CO, CO2, O2, N2, and H2O in hypersonic, air-breathing propulsion systems. The first sensor will provide in situ measurements of specific key fuels and combustion species via both line-of-sight and internal probe deployments. The second will employ fast extractive sampling coupled with multiplexed Off-Axis Integrated Cavity Output Spectroscopy (Off-Axis ICOS) to measure the above species in real-time. These instruments will enhance the capabilities of numerical simulations and ground tests in predicting the actual performance of in-flight propulsion systems. Additionally, by measuring key chemical species in the flow, the validity of modeling assumptions can be gauged, resulting in more accurate numerical simulations and higher efficiency engines, a major goal of AFRL’s Propulsion Directorate. In Phase I, LGR has demonstrated technical feasibility by developing a multiplexed Off-Axis ICOS system that is readily scalable and reconfigurable with no custom equipment. The sensor’s accuracy, linearity, and dynamic range were gauged by measuring both combustion precursors and products over a wide concentration range. Finally, both in situ and extractive measurements were implemented in a hypersonic test facility at Wright Patterson Air Force Base.