Modelling of Gasoline and Ethanol Hollow-Cone Sprays Using OpenFOAM 2011-01-1896

Over the past few years, an open-source code called OpenFOAM has been becoming a promising CFD tool for multi-dimensional numerical simulations of internal combustion engines. The primary goal of the present study is to assess the feasibility of the code for computations of hollow-cone sprays discharged by an outward-opening pintle-type injector by simulating the experiments performed recently by Hemdal et al., (SAE 2009-01-1496) with gasoline and ethanol sprays under the following conditions: air temperature T_air = 295 or 350 K, air pressure p_air = 6 bar, fuel temperature T_fuel = 243, or 295, or 320 K, and fuel injection pressure p_inj = 50, or 125, or 200 bar. To simulate the experiments, a pintle injector model and the physical properties of gasoline were implemented in OpenFOAM. The flow field calculated using the pintle injector model is more realistic than that yielded by the default unit injector model normally used in OpenFOAM. Moreover, a number of modifications were made to the standard implementation of several spray models in OpenFOAM, with modifications in the implementation of the KHRT model having noticeable effects on the accuracy of the simulated liquid penetration and Sauter mean diameter (SMD). Results of numerous simulations performed by running OpenFOAM and activating various spray models indicate that (i) a combination of the Rosin-Rammler distribution with Reitz-Diwakar secondary breakup model and (ii) the KHRT model yield the best agreement between the measured and computed spray penetration length, with the latter model showing the best performance as far as the SMD obtained from high-pressure (200 bar) sprays is concerned.