Simulation of Subcritical Primary Atomization in a Rule-Based CFD Framework Using Stochastic Modeling

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or liquid rocket engines, operating in subcritical pressure situations, multiphase models are required which employ one or more sub-models such as volume-of-fluid models, droplet atomization models, droplet secondary breakup models or droplet evaporation models, along with Eulerian/Lagrangian particle tracking, to simulate the interaction of the liquid droplets and the gas phase. There is a critical need for a multiscale strategy which can robustly simulate the entire spray combustion process in rocket injectors. The objective of the work is to perform accurate modeling of subcritical atomization – which is an essential component of spray combustion modeling – in liquid rocket engines. It is important to accurately model the unsteady liquid core (i.e, its shape, size, surface location, and unsteadiness) which not only provides the liquid droplets to the Lagrangian particle solver but also is a source of primary (large) eddies which affect the gaseous phase in the combustor. Stochastic (randomized) algorithms are being developed to mitigate the computational burden associated with small time and length scales. A key objective of the proposed work is to integrate the developed models into advanced CFD solvers. Owing to the computational complexity of the primary atomization process, a stochastic modeling framework has been developed. The shape of the liquid core is modeled as a stochastic process defined within the domain of the combustion chamber. The dynamics of the liquid-core is modeled using a Fokker-Planck equation and the corresponding Langevin equations. Both steady and unsteady atomization are considered.