Validation of a comprehensive computational fluid dynamics methodology to predict the direct injection process of gasoline sprays using Spray G experimental data

Abstract

A detailed prediction of injection and air–fuel mixing is fundamental in modern direct injection, spark-ignition engines to guarantee a stable and efficient combustion process and to minimize pollutant formation. Within this context, computational fluid dynamics simulations nowadays represent a powerful tool to understand the in-cylinder evolution of spray and air–fuel charge. To guarantee the accuracy of the adopted multidimensional spray sub-models, it is mandatory to validate the computed results against available experimental data under well-defined operating conditions. To this end, in this work, the authors proposed the calibration and validation of a comprehensive set of spray sub-models by means of the simulation of the Spray G experiment, available in the context of the engine combustion network. For a suitable validation of the proposed numerical setup in addition to the baseline condition, gasoline direct injection operating points typical of early injection with homogeneous operation, late injection with high ambient density and flash boiling with enhanced fuel evaporation were also simulated. Numerical computations were validated against a wide set of available experimental data by means of an accurate post-processing analysis taking into account axial liquid and vapor penetrations, gas-phase velocity between spray plumes, droplet size, plume liquid velocity, direction and mass distribution. Satisfactory results were achieved with the proposed setup, which is able to predict gasoline spray evolution under different operating conditions.

Coupled in-nozzle flow and spray simulation of Engine Combustion Network Spray-G injector

“…The experimental images showing the liquid phase were obtained using the Mie scattering technique and vapor phase were obtained using schlieren technique. [48][49][50] The Spray-G1 morphology predicted by the simulations shows a good agreement with the experimental spray images. Figure 20 shows the comparison between experimental 18 and computed spray evolution at different time instants after the start of injection for Spray-G2.…”

Engine combustion network special issue

“…Going into details of what is included in this special issue, we have 16 new papers [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] covering all aspects of engine combustion network activities. There are 10 papers related to compression ignition engines [23][24][25][26][27][28][29][30][31][32] while there are 6 papers related to gasoline direct injection, [33][34][35][36][37] indicating that the research community is still trying to improve diesel engines even though the bad reputation they are facing lately.…”

“…Going into details of what is included in this special issue, we have 16 new papers 23–37 covering all aspects of engine combustion network activities. There are 10 papers related to compression ignition engines 23–32 while there are 6 papers related to gasoline direct injection, 33–37 indicating that the research community is still trying to improve diesel engines even though the bad reputation they are facing lately. Dividing the papers into experimental or CFD work, we have 5 papers 23–25,33,34 that deal with advance experimental diagnostics while 13 papers deal with CFD, 26–32,35–37 this is also a trend in the research community moving more and more into modeling work.…”

“…There are 10 papers related to compression ignition engines 23–32 while there are 6 papers related to gasoline direct injection, 33–37 indicating that the research community is still trying to improve diesel engines even though the bad reputation they are facing lately. Dividing the papers into experimental or CFD work, we have 5 papers 23–25,33,34 that deal with advance experimental diagnostics while 13 papers deal with CFD, 26–32,35–37 this is also a trend in the research community moving more and more into modeling work. The final division that could be performed is between internal nozzle flow and spray characteristics with 11 papers related to this field, and 5 papers related to combustion around the original n-dodecane Spray A case 6 and some variations.…”

Effects of direct water injection and injector configurations on performance and emission characteristics of a gasoline direct injection engine: A computational fluid dynamics analysis

“…36 The Kelvin–Helmholtz and Rayleigh–Taylor (KH-RT) breakup length model is used to capture primary and secondary breakup of water and fuel spray. 24,37 The breakup model is based on liquid/gas instability mechanism. Liquid blobs are injected with a diameter equal to the diameter of the nozzle, assuming that the liquid core exists near the nozzle region.…”