Modeling the effect of spray/wall impingement on combustion process and emission of DI diesel engine

Abstract

This work is presented to study the effect of spray impinging on the combustion process and emissions in a direct injection diesel engine at various engine speeds. Computations are carried out using a three-dimensional modeling for sprays, spray-wall interactions, flow field, emission, and combustion process. Results indicate an increase in engine speed leads to increased spray impinging (wall film formation), turbulence intensity and average wall temperature in cylinder. The enhanced air/fuel mixing and intensified evaporation of wall film decreases soot emission by reducing the extent of the fuel rich regions specially in impinging zones. Also at higher engine speeds, combustion is delayed and fuel is consumed in a shorter time period by the enhanced air and fuel mixing. The shorter combustion duration provides less available time for soot and NOx formations. However, only a few attempts have been made to address the effect of impingement of spray with piston walls on the emissions and combustion process. The results of model in addition to approving the corresponding data in the literature are also compared with the experimental data and shown good agreement.

Computational fluid dynamics simulation of the combustion process, emission formation and the flow field in an in-direct injection diesel engine

“…The spray/wall interaction model used in this simulation was based on the spray/wall impingement model [22] which has previously been utilized by authors to investigate effects of fuel injection mode and spray impingement on diesel combustion [1,2]. The Shell auto--ignition model was used for modeling of the auto ignition [23].…”

“…The other approach which has become a dominant factor in the engine research in the recent years is the application multi-dimensional CFD codes which can gain insight into the in-cylinder flow field and combustion process by solving the governing flow field and species transport equations [1,2]. The other approach which has become a dominant factor in the engine research in the recent years is the application multi-dimensional CFD codes which can gain insight into the in-cylinder flow field and combustion process by solving the governing flow field and species transport equations [1,2].…”

Effects of Injection Pressure and Ambient Gas Density on Fuel - Ambient Gas Mixing and Combustion Characteristics of D.I. Diesel Spray

“…In cold start or the operation condition with the medium wall temperature, the direct interaction of liquid phase and wall results in the poor fuel/air mixing and higher soot emission level Wang et al, 2011;Song et al, 2003]. However, the relatively high wall temperature and the interaction of gas phase and wall may also improve the turbulent mixing and air entrainment, which is beneficial to the low soot combustion [Katsura et al, 1989;Jafarmadar et al, 2009;Pickett et al, 2005]. It implies that the effect of injection parameters, combustion chamber configuration and engine load on the spray/wall interaction and subsequent combustion characteristics still deserves more careful investigation.…”

Turbulence-combustion interaction in direct injection diesel engine

“…Currently, great help seems to be offered by the use of the CFD tools in order to guide researchers to better understanding and predicting compres- sion ignition engine performances and emission levels. Indeed, an enhanced understanding of the processes taking place in the combustion chamber and the link between parameters in order to explore new solutions reduces the cost and improves the efficiency [3,4]. KIVA-3v code developed at Los Alamos National laboratory is one of the most widely used packages for three dimensional engine simulation tools using an arbitrary Lagrangian-Eulerian methodology [5][6][7][8].…”