EXTENSION OF A KINETIC APPROACH TO CHEMICAL REACTIONS TO ELECTRONIC ENERGY LEVELS AND REACTIONS INVOLVING CHARGED SPECIES WITH APPLICATION TO DSMC SIMULATIONS
EXTENSION OF A KINETIC APPROACH TO CHEMICAL REACTIONS TO ELECTRONIC ENERGY LEVELS AND REACTIONS INVOLVING CHARGED SPECIES WITH APPLICATION TO DSMC SIMULATIONS
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Date
2013
Authors
Liechty, Derek Shane
Advisor
Lewis, Mark J.
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Abstract
The ability to compute rarefied, ionized hypersonic flows is becoming more
important as missions such as Earth reentry, landing high mass payloads on Mars, and
the exploration of the outer planets and their satellites are being considered. Recently
introduced molecular-level chemistry models that predict equilibrium and
nonequilibrium reaction rates using only kinetic theory and fundamental molecular
properties are extended in the current work to include electronic energy level
transitions and reactions involving charged particles. These extensions are shown to
agree favorably with reported transition and reaction rates from the literature for nearequilibrium
conditions. Also, the extensions are applied to the second flight of the
Project FIRE flight experiment at 1634 seconds with a Knudsen number of 0.001 at
an altitude of 76.4 km. In order to accomplish this, NASA’s direct simulation Monte
Carlo code DAC was rewritten to include the ability to simulate charge-neutral ionized flows, take advantage of the recently introduced chemistry model, and to
include the extensions presented in this work. The 1634 second data point was
chosen for comparisons to be made in order to include a CFD solution. The Knudsen
number at this point in time is such that the DSMC simulations are still tractable and
the CFD computations are at the edge of what is considered valid because, although
near-transitional, the flow is still considered to be continuum. It is shown that the
inclusion of electronic energy levels in the DSMC simulation is necessary for flows
of this nature and is required for comparison to the CFD solution. The flow field
solutions are also post-processed by the nonequilibrium radiation code HARA to
compute the radiative portion of the heating and is then compared to the total heating
measured in flight.