High-Fidelity Simulation of Primary Breakup of a “Spray G” Gasoline Jet with an Adaptive Mesh Refinement and Volume-of-Fluid Method 2020-01-0826
Primary breakup of a liquid jet is a process of enormous complexity, involving interfacial dynamics, topology changes, and turbulence. In macro-scale simulations for practical problems, the primary breakup is usually too expensive to be fully resolved and thus is typically represented by phenomenological models. The recent advancement of numerical methods and computer power enables large-scale high-fidelity simulations of primary breakup. The high-level details provided by simulation can be used to verify the assumptions made in existing models and also to develop new models through both physics- or data-based approaches. The present paper will present the state-of-the-art high-fidelity simulation of the primary breakup of a gasoline surrogate jet. The simulation parameters were chosen following the Engine Combustion Network (ECN) ``Spray G" conditions and thus are similar to realistic engine conditions. The surrogate fuel has a low volatility so fuel evaporation does not occur in the atomization process. The present study focuses on the near field where inter-jet interaction is not important and only one of the eight jets in the original injectors is simulated. In the numerical model, the liquid is injected from the inner-hole, through the counterbore, into a chamber with pressurized stagnant gas. An angle between the injection velocity and the inner-hole axis is introduced to mimic the effect of internal flow over the needle into the inner-hole. A parametric study on the inlet angle was performed, and the numerical results are compared to the experimental data (Duke et al., Exp. Therm. Fluid Sci. 88 608-621, 2017) for the jet deflection angle and the temporal variation of penetration length to identify the proper inlet angle to be used in the model. The Basilisk solver was used for the present simulation, in which the gas-liquid interface is captured by the geometric volume-of-fluid method, and an octree mesh is use to discretize the domain to allow local adaptive mesh refinement in regions with interface and small flow scales.