Modeling of CO₂Homogeneous and Heterogeneous Condensation Plumes

Abstract

A pure CO2 homogeneous condensation flow is simulated with a new direct simulation Monte Carlo (DSMC)-based condensation model, and comparisons of the measured [Ramos, A.; Fernández, J. M.; Tejeda, G.; Montero, S. Phys. Rev. A 2005, 72, 3204] and simulated CO2 cluster size and number density distributions were found to agree well for low stagnation pressures. The same carbon dioxide homogeneous condensation model was then applied to the study of an expanding heterogeneous condensation flow of a 5% CO2 and 95% mixture [Williams, W. D.; Lewis, J. W. L. DTIC Paper No. AEDC-TR-80-16, 1980]. To simulate this case, a new kinetic-based model of N2 molecules condensing on CO2 nuclei was developed using molecular dynamics techniques and was implemented in the DSMC simulation of the expanding mixture. Pure nitrogen flow for the same expansion conditions was observed to not produce any clusters. It was found that incorporation of the heterogeneous condensation process of N2 molecules condensing on CO2 nuclei causes the average N2 cluster size to increase from 10 (the homogeneous condensation result) to about 2000. The simulated Rayleigh scattering intensity results were found to agree well with the experimental data.

Modeling of carbon dioxide condensation in the high pressure flows using the statistical BGK approach

“…In Sec. V, we present a comparison of our simulations obtained using the BGK based condensation model for stagnation pressures of 1-5 bar with the DSMC simulations of Li et al 17 for the lower stagnation pressures of 1-3 bar experiment. In addition to that, the BGK solutions are also compared with the new DSMC solutions that use the new heat accommodation model.…”

“…17 Recently, Jansen et al 18 have compared the nonequilibrium argon and water cluster size distributions with experiments and obtained good agreement. In Ref.…”

“…17, we also simulated a heterogeneous condensation system of carbon dioxide and nitrogen system and obtained good comparison with Rayleigh scattering data. 17 The motivation for the present work comes from the earlier work of Li et al 17 in which condensation models were proposed and used in the DSMC method to simulate the flow of CO 2 from supersonic expansions of small nozzles into near-vacuum conditions. The work involved the development of a comprehensive DSMC based condensation model taking into account the processes of nucleation, clustermonomer sticking and non-sticking collision, cluster evaporation, and cluster-cluster coalescence.…”

Simulation of homogeneous condensation of small polyatomic systems in high pressure supersonic nozzle flows using Bhatnagar–Gross–Krook model

“…The weighting scheme for nucleation and coalescence models is the same in both the BGK and DSMC methods and may be found in Ref. 36.…”

“…2. 20,36 The Navier-Stokes CFD solutions of the previous work 36 were used again to obtain the flowfield inside the cylindrical nozzle. The CFD calculations for different stagnation pressures were carried out earlier by the authors of the previous work 36 using the GASP (Ref.…”