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The effects of piston bowl and fuel injector offsets on combustion and emissions in a D.I. diesel engine have been investigated by using a KIVA CFD code. In this investigation, modeling combustion and emissions in the diesel engine at different regimes is performed, including the model of the single spray sector without piston bowl and fuel injector offsets, the model of the full cylinder of 360 degrees without piston bowl and fuel injector offsets, and the model of the full cylinder of 360 degrees with both a piston bowl offset and a fuel injector offset, respectively. In addition, the corresponding experiments are conducted to validate the modeling. The fuel spray patterns are compared for different models. The cylinder pressure, the heat release rate, and the emissions of NOx and soot are examined.

A droplet deformation and rotation model (DDR) has been developed and implemented in the KIVA II CFD code for better describing characteristics of liquid fuel sprays in diesel engines, including the distribution of sprays in combustion chamber space and the spray/wall impingement. The DDR model accounts for the effects of both the droplet's frontal area and its drag coefficient as a function of its deformation and rotation on droplet drag and droplet breakup. Therefore, the DDR model can be used for calculating the fuel droplet's drag and breakup in the process of combustion in diesel engines. This makes it possible to model the highly distorted droplet's frontal area variation and its effect on the drag coefficient in sprays. The new version of the KIVA II code with the DDR model has been tested for a case of the spray/wall impingement and a case of the combustion process in a diesel engine.

A modified drop drag (MOD) model based on the droplet deformation and breakup (DDB) model has been developed and implemented in the KIVA II code for describing fuel spray impingement against the walls of the combustion chamber in D.I. diesel engines. The model accounts for the effects of both the drop's frontal area and its drag coefficient as a function of its distortion. In the MDD model, the stochastic rotation of drops that have impacted and bounced off the wall is considered. This makes it possible to model the highly distorted drop's frontal area variation and its effect on the drag coefficient in sprays. At the same time, the distribution of sizes of drops formed from parent drops after their breakups is modeled by using a stochastic model. A modified RNG κ - ε model is also included in the present computations. The details of fuel spray impingement against a wall were investigated by using the present models.

Based on diesel engine type S1100A, the cylinder bore is expanded from 100 mm to 102mm and the swirl chamber combustion system is substituted by the direct injection combustion system, as a result, a new type of single cylinder direct injection diesel engine with horizontal cylinder, i.e., diesel engine type 1102, has been developed, in which the rated speed has increased from 2200 rpm to 2300 rpm, the rated output has increased from 11 kw to 12.5 kw, and the specific fuel consumption has reduced by 19 g/kw.h, from 253 g/kw.h to 234 g/kw.h at the rated condition. This paper presents the design idea, the principal engine specifications, the structural features, and the experimental results of the single cylinder direct injection diesel engine type 1102 with horizontal cylinder. The experimental results have shown that the diesel engine type 1102 has obtained the good indexes of performance.