Spectroscopic Measurements and Nonequilibrium Modeling for High Enthalpy Air
Abstract
Considerable recent effort has been devoted to understanding and modeling internal energy relaxation and dissociation in hypersonic flows using first principles calculations. However, the validation and implementation of models, ranging in fidelity and computational cost, is hampered by the lack of experimental data in hypervelocity flowfields that are more than just surface measurements. A research collaboration between Caltech, Stanford, and the University of Minnesota is proposed to apply spectroscopic measurement techniques to probe molecular and atomic states in hypervelocity, nonequilibrium air flows directly, using complementary emission and absorption techniques. First principles modeling efforts will be extended to recombination chemistry and electronic energy relaxation. Experimental configurations and conditions will be selected collaboratively with a focus on both postshock and expanding flows. The key scientific goals are: i) quantitative tunable diode laser absorption spectroscopy (TDLAS) and emission measurements of nonequilibrium temperatures (translational, rotational, vibrational), individual quantum state populations, and flow velocity in collaboratively designed hypervelocity flowfield experiments, ii) the use of quantum mechanical electronic structure calculations and global fitting procedures to develop potential energy surfaces for the most relevant electronically excited states. The extension of both Quasi Classical Trajectory and Direct Molecular Simulation methods to accurately include recombination reactions and electronically nonadiabatic dynamics, iii) computational fluid dynamics simulations (utilizing newly developed models for air) used to optimize experimental tests at each stage of the collaborative research, and ultimately perform verification-validation studies, and iv) spectroscopic characterization of facility operation and freestream composition for two types of high enthalpy ground test facilities.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 14, 2022
- Source ID
- FA95501910219
Entities
People
- Joanna Austin
Organizations
- Air Force Office of Scientific Research
- California Institute of Technology
- United States Air Force