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

Abstract

In the present work, we have simulated the homogeneous condensation of carbon dioxide and ethanol using the Bhatnagar-Gross-Krook based approach. In an earlier work of Gallagher-Rogers et al. [J. Thermophys. Heat Transfer 22, 695 (2008)], it was found that it was not possible to simulate condensation experiments of Wegener et al. [Phys. Fluids 15, 1869 (1972)] using the direct simulation Monte Carlo method. Therefore, in this work, we have used the statistical Bhatnagar-Gross-Krook approach, which was found to be numerically more efficient than direct simulation Monte Carlo method in our previous studies [Kumar et al., AIAA J. 48, 1531 (2010)], to model homogeneous condensation of two small polyatomic systems, carbon dioxide and ethanol. A new weighting scheme is developed in the Bhatnagar-Gross-Krook framework to reduce the computational load associated with the study of homogeneous condensation flows. The solutions obtained by the use of the new scheme are compared with those obtained by the baseline Bhatnagar-Gross-Krook condensation model (without the species weighting scheme) for the condensing flow of carbon dioxide in the stagnation pressure range of 1-5 bars. Use of the new weighting scheme in the present work makes the simulation of homogeneous condensation of ethanol possible. We obtain good agreement between our simulated predictions for homogeneous condensation of ethanol and experiments in terms of the point of condensation onset and the distribution of mass fraction of ethanol condensed along the nozzle centerline.

A unified stochastic particle Bhatnagar-Gross-Krook method for multiscale gas flows

“…The stochastic particle method based on the BGK model was proposed by Macrossan [27] and Gallis and Torczynski [28] independently. Recently, the application of this method has been extended to complex gas flows [29][30][31][32]. Note that in the current stochastic particle BGK method, computational particles mimic the kinetic equations in two stages, i.e.…”

Supersonic gas separators: Review of latest developments

“…The model is validated against experimental data from[83] and simulations presented in[84] with respect to condensation of ethanol in an air-ethanol mixture. The model is then used for the prediction of the performance of supersonic nozzles in dehumidification of wet methane (methane and water vapor) as well as sweetening of sour gas (methane and hydrogen In later work[56], Mahmoodzadeh and Shahsavand used the software package COMSOL MULTIPHYSICS to solve continuity and momentum equations for an axis-symmetric flow of inviscid gas through supersonic nozzles with swirl.…”