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Development of Improved Molecular Excitation Models
Final rept. 1 Sep 2008-30 Sep 2009
PENNSYLVANIA STATE UNIV STATE COLLEGE
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With respect to our modeling of condensation in supersonic expansions, we have used molecular dynamics to derive condensation based models for DSMC for non-Lennard Jonesian gases such as water, carbon dioxide, and ammonia, common combustion products found in rocket plumes. The challenge was to incorporate charge polarization terms in the cluster potential, develop and automate a strategy for recognizing the formation of clusters in an MD study of a supersonic expansion, and utilize a parallel MD code to deduce the important cluster formation mechanism in a large scale MD simulation of a jet expansion. In addition, we have extended our research to model heterogeneous condensation, a necessary feature for realistic plume flows which often include multiple species types. The developed MD models have been incorporated into the DSMC simulations, a process that takes the fine-grained simulation results and transfers them to the propulsionnozzle system level. DSMC simulations have been compared with published Raman and Rayleigh scattering laboratory measurements, high lighting the need for this data for more molecular systems.
APPROVED FOR PUBLIC RELEASE