Diode laser sensors for aeropropulsion monitoring and control

Recent advances in room-temperature tunable diode lasers, fiberoptic beam transport, and sensitive detection strategies now permit in-stream sensing of numerous parameters relevant to aeropropulsion monitoring and control. These include density measurements of important flow constituents such as O2, H2O, CO2, and NOx. Based on path-averaged absorption measurements, the basic density measurements can be expanded to include other gasdynamic properties such as temperature and velocity. Simultaneous, multiparameter measurements allow determination of high order system parameters such as mass flux and thrust continuously and in real-time. This paper describes several sensor development efforts, exhaust mass flux, and emissions monitoring. Example measurements from laboratory configurations are presented along with performance projections for test-stand and flight systems. Integration issues with full-scale hardware and control opportunities are also discussed.