Characteristics of Methanol and Iso-Octane under Flashing and Non-Flashing Conditions in ECN-G Spray

This paper investigated the spray characteristics of methanol under the flash and non-flash boiling conditions defined by the Engine Combustion Network (ECN) Spray G. As a counterpart, the spray features of iso-octane were also simulated and compared to methanol. The Volume of Fluid (VOF) approach under the Eulerian scheme was employed to model the internal nozzle flow details, which information was used to initialize the spray parcels and taken as input for the Lagrangian simulations, namely, the one-way coupling method. Since the Eulerian high-fidelity simulations allow capturing the effects of the flow inside the non-symmetrical injector, the rate of injection (ROI) profile, discharge coefficient, and plume angle et al. are not required for the Lagrangian simulations. The simulation results show that the flash boiling led to longer penetrations and higher evaporation compared to the non-flash boiling condition for both fuels. Compared to isooctane, methanol demonstrated a better mixing process owing to its unique physical properties resulting in a lower ratio between ambient and saturation pressure (Pa/Ps). To calibrate the experimental data, parametric simulations were conducted, and the effects of the turbulence model and spray break-up constants were investigated. The predicted spray penetrations were more sensitive to the spray breakup constants than to the turbulence parameters. The simulations under flash boiling conditions showed to be less sensitive to spray breakup constant calibration and required lower values for these constants.