Real drive emissions (RDE) regulation were introduced from Euro6-d regulation. In order to achieve the regulation value of PM(Particulate Matter) emission in the RDE regulation, it is effective to install GPF(Gasoline Particulate Filter) system. To prevent GPF corruption , GPF system needs “PM emission amount estimation model” that estimates PM emission amount from direct injection gasoline engine to estimate PM corrected amount. Some models, for example packet model and map-based model, have been proposed as PM emission amount estimation model. However, these models have problems in terms of calculation load and accuracy for On-board calculation. Purpose of this research is to study On-board PM emission amount estimation model . We proposed a new model method of physical quantities that dominate PM production. Developed model uses probability density function of mixture fraction space so that mixture and fuel adhesion can be treated uniformly as a fuel distribution in cylinder. Also, variance of mixture-derived probability density function and fuel adhesion ratio are functionalized by a second-order polynomial of engine control parameters, and can be applied to multiple operating conditions. The developed model was verified by comparison with measurement data. Under 25 degC of coolant temperature(19 operation points), the estimated error was during 0% and 59% and average estimated error was 19%.

It is necessary to reduce the particulate matter (PM) in the exhaust gas of internal combustion engines. In gasoline direct injection engines, a fuel has more probability to attach to the wall than in port fuel injection engines because the fuel is directly injected into the combustion chamber. Fuel wetting to the combustion chamber wall and injector tip generates deposits, which results in PM occurrence. Therefore, precise prediction of the spray formation is required. In this study, we investigated the effects of injector-valve motion, especially off-axis valve motion, on internal nozzle flow and spray shape using a numerical simulation method combining the volume of fluid method and discrete droplet model. The results are summarized as follows. (1) In the case of y-axis offset, which is the direction parallel to the symmetrical plane of hole location and geometry, the spray shape and footprint was more symmetrical than in the case of the non-offset because the flows near the hole inlet stabilized due to the off-axis valve motion. (2) In the case of y-axis offset, which is vertical to the symmetrical plane, asymmetrical footprint and spray shape was observed, which indicates that the off-axis valve motion in the asymmetrical direction effect the spray shape. Specifically, the sac inner flow at low valve lift exhibited larger velocity than that of high valve lift, which results in changing the spray-tip shape.