Analysis of the interaction of Spray G and in-cylinder flow in two optical engines for late gasoline direct injection

Abstract

An investigation of the interaction between the in-cylinder flow and the spray topology in two spray-guided direct injection optical engines is reported. The bulk flow field in the combustion chamber is characterized using particle image velocimetry. Geometrical parameters such as the axial penetration and the spray angle of the liquid spray are measured using Mie scatter imaging and/or diffuse back-illumination. The measured parameters are compared with data from a constant volume chamber available in the literature. For a late injection strategy, the so-called ECN Spray G standard condition, the mean values of the spray penetration do not seem to be significantly perturbed by the in-cylinder flow motion until the plumes approach the piston surface. However, spray probability maps reveal that cycle-to-cycle fluctuations of the spatial distribution of the liquid spray are affected by the magnitude of the in-cylinder flow. Particle image velocimetry during injection shows that the flow field in the vicinity of the spray plumes is heavily influenced by air entrainment, and that an upward flow in-between spray plumes develops. Consistent with previous research that demonstrated the importance of the latter flow structure for the prevention of spray collapse, it is found that increased in-cylinder flow magnitudes due to increased intake valve lifts or engine speeds enhance the spray-shape stability. Compared with cases without injection, the influence of the spray on the in-cylinder flow field is still noticeable approximately 2.5 ms after the start of injection.

Deep feature learning of in-cylinder flow fields to analyze cycle-to-cycle variations in an SI engine

“…Rigorous experimental research is required to provide detailed data for the development of accurate models of engine phenomena and the reduction of CCVs. 1 Over the last decades, advancements in laser and imaging technology have enabled IC engine research to expand to high-speed, crank angle-resolved 2–4 and high-resolution boundary layer velocity and fuel film measurements 5–8 as well as multi-parameter measurements to examine the propagation of the early flame kernel. 9 With the increase in technology, also comes the ability of generating better statistics for flow and flame data obtained from advanced laser diagnostics in IC engines and the subsequent use of machine learning (ML)-based processing and analysis techniques to better understand the phenomena involved in engine CCV.…”

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.…”

Impact of Grid Density on the Analysis of the In-Cylinder Flow of an Optical Engine

“…Thermo-physical processes taking place in the cylinder are extremely complex and they strictly influence the engine efficiency, both in terms of pollution and performance [1]. Using a CFD tool it is possible to study a multitude of ICE phenomena, among which fuel/air entrainment and mixing [2][3][4][5][6][7][8][9][10], combustion [11][12][13], heat transfer [14][15][16][17][18] and pollutant formation [19][20][21][22][23]. The available literature acknowledges the remarkable potential of Large Eddy Simulation (LES) as opposite to the more standardized Reynolds Averaged Navier Stokes (RANS) to simulate the turbulent nature of engineering flows [24].…”