Ultrafast Laser Spectroscopy for Reacting Systems and High-Speed Flows

The design and optimization of next-generation aerospace propulsion and combustion systems requires detailed knowledge of thermodynamic properties such as temperature and density. Turbulence, nonequilibrium, and high-pressure and temperature conditions relevant for modern combustors make for a challenging measurement environment that can exhibit significant spatial variation and fast temporal dynamics. Although conditions are challenging, experimental measurements are critical to validate and improve chemical kinetic and fluid dynamic models in order to design and test new vehicles and propulsion devices. For useful comparison with modeling results, measurements must be sufficiently accurate, include a careful characterization of boundary conditions, and, in the case of unsteady events, simultaneously measure multiple relevant parameters.

This seminar will discuss the development and implementation of hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) to address these requirements. Challenges in applying gas-phase spectroscopy-based techniques to high pressures and nonequilibrium conditions will be discussed. Results relevant to high-speed vehicles, detonations, and plasma-enhanced combustion systems will be highlighted.