Hsu, Andrea G. (2009-05). Application of Advanced Laser and Optical Diagnostics Towards Non-Thermochemical Equilibrium Systems. Doctoral Dissertation. Thesis uri icon

abstract

  • The Multidisciplinary University Research Initiative (MURI) research at Texas A and M University is concerned with the experimental characterization of non-thermal and non-chemical equilibrium systems in hypersonic (Mach greater than 5) flowfields using experimental diagnostics, and is an interdisciplinary collaboration between the Chemistry and Aerospace Engineering departments. Hypersonic flight conditions often lead to non-thermochemical equilibrium (NTE) state of air, where the timescale of reaching a single (equilibrium) Boltzmann temperature is much longer than the timescale of the flow, meaning that certain molecular modes such as vibrational modes, may be much more excited than the translational or rotational modes of the molecule leading to thermal-nonequilibrium. A nontrivial amount of energy is therefore contained within the vibrational mode, and this energy cascades into the flow as thermal energy, affecting flow properties through the process of various vibrational-vibrational (V-V) and vibrational-translational (V-T) energy exchanges between the flow species. The research is a fundamental experimental study of these NTE systems and involves the application of advanced laser and optical diagnostics towards hypersonic flowfields. The research is broken down into two main categories: the application and adaptation of existing laser and optical techniques towards characterization of NTE, and the development of new molecular tagging velocimetry techniques which have been demonstrated in an NTE flowfield, but may be extended towards a variety of flowfields.
  • The Multidisciplinary University Research Initiative (MURI) research at Texas
    A and M University is concerned with the experimental characterization of non-thermal and
    non-chemical equilibrium systems in hypersonic (Mach greater than 5) flowfields using
    experimental diagnostics, and is an interdisciplinary collaboration between the
    Chemistry and Aerospace Engineering departments. Hypersonic flight conditions often
    lead to non-thermochemical equilibrium (NTE) state of air, where the timescale of
    reaching a single (equilibrium) Boltzmann temperature is much longer than the timescale
    of the flow, meaning that certain molecular modes such as vibrational modes, may be
    much more excited than the translational or rotational modes of the molecule leading to
    thermal-nonequilibrium. A nontrivial amount of energy is therefore contained within the
    vibrational mode, and this energy cascades into the flow as thermal energy, affecting
    flow properties through the process of various vibrational-vibrational (V-V) and
    vibrational-translational (V-T) energy exchanges between the flow species. The research
    is a fundamental experimental study of these NTE systems and involves the application
    of advanced laser and optical diagnostics towards hypersonic flowfields. The research is
    broken down into two main categories: the application and adaptation of existing laser
    and optical techniques towards characterization of NTE, and the development of new
    molecular tagging velocimetry techniques which have been demonstrated in an NTE
    flowfield, but may be extended towards a variety of flowfields.

publication date

  • May 2009