The dual-mode, turbulent jet ignition system is a promising combustion technology to achieve high diesel-like thermal efficiency at medium to high loads and potentially exceed diesel efficiency at low-load operating conditions. The dual-mode, turbulent jet ignition systems to date proved a high level of improvement in thermal efficiency compared to conventional internal combustion engines. However, some questions were still unanswered. The most frequent question regarded power requirements for delivering air to the pre-chamber of a dual-mode, turbulent jet ignition system. In addition, there was no study available to predict the expected efficiency of a dual-mode, turbulent jet ignition engine in a multi-cylinder configuration. This study, for the first time, predicts the ancillary work requirement to operate the dual-mode, turbulent jet ignition system. It also presents a novel, reduced order, and physics-based model of the dual-mode, turbulent jet ignition engine with a pre-chamber valve assembly. The developed model was calibrated based on experimental data from the Prototype II dual-mode, turbulent jet ignition engine. The simulation results were in good agreement with the experimental data. The validity of the model was observed based on the standard metric of the coefficient of determination as well as comparison plots for in-cylinder pressures. Numerical predictions were compared to experiments for three metrics of main chamber combustion: gross indicated mean effective pressure, main chamber peak pressure, and main chamber phasing for the peak pressure. Predictions were within 5% of experimental data, with one exception of 6%. In addition, the absolute root mean square errors of in-cylinder pressures for both pre- and main-combustion chambers were below 0.35. The calibrated model was further studied to introduce a predictive and generalized model for dual-mode, turbulent jet ignition engines. Such a model can project engine behavior in a multi-cylinder configuration over the entire engine fuel map.

Homogeneous charge is a preferred operation mode of gasoline direct-injection (GDI) engines. However, a limited amount of work exists in the literature for combustion models of this mode of engine operation. Current work describes a model developed to study combustion in a homogeneous charge GDI engine. The model was validated using experimental data from a 1.6 L Ford EcoBoost® engine, tested at the U.S. EPA. The combustion heat release was approximated using a double-Wiebe function, to account for the rapid initial premixed combustion followed by a gradual diffusion-like state of combustion, as observed in this GDI engine. Variables of Wiebe correlations were adjusted into a semipredictive combustion model. The effectiveness of semipredictive combustion model was tested in prediction of in-cylinder pressures. The root-mean-square (RMS) errors between experiments and numerical results were within 2.5% of in-cylinder peak pressures during combustion. The semipredictive combustion model was further studied to develop a predictive combustion model. The performance of predictive combustion model was examined by regenerating the experimental cumulative heat release. The heat release analysis developed for the GDI engine was further applied to a dual mode, turbulent jet ignition (DM-TJI) engine. DM-TJI is a distributed combustion technology with the potential to provide diesel-like efficiencies and minimal engine-out emissions for spark-ignition engines. The DM-TJI engine was observed to offer a faster burn rate and lower in-cylinder heat transfer compared to the GDI engine.

Homogeneous charge is a preferred operation mode of gasoline direct-injection (GDI) engines. However, a limited amount of work exists in the literature for combustion models of this mode of engine operation. Current work describes a model developed and used to study combustion in a GDI engine having early intake fuel injection. The model was validated using experimental data obtained from a 1.6L Ford EcoBoost® four-cylinder engine, tested at the U.S. EPA. The start of combustion was determined from filtered cycle-averaged cylinder pressure measurements, based on the local maximum of third derivative with respect to crank angle. The subsequent heat release, meanwhile, was approximated using a double-Wiebe function, to account for the rapid initial pre-mixed combustion (stage 1) followed by a gradual diffusion-like state of combustion (stage 2) as observed in this GDI engine. A non-linear least-squares optimization was used to determine the tuning variables of Wiebe correlations, resulting in a semi-predictive combustion model. The effectiveness of the semi-predictive combustion model was tested by comparing the experimental in-cylinder pressures with results obtained from a model built using a one-dimensional engine simulation tool, GT-POWER (Gamma Technologies). Model comparisons were made for loads of 60, 120, and 180 N-m at speeds ranging from 1500 to 4500 rpm, in 500 rpm increments. The root-mean-square errors between predicted cylinder pressures and the experimental data were within 2.5% of in-cylinder peak pressure during combustion. The semi-predictive combustion model, verified using the GT-POWER simulation, was further studied to develop a predictive combustion model. The performance of the predictive combustion model was examined by regenerating the experimental cumulative heat release. The heat release analysis developed for the GDI engine was further applied to a dual mode, turbulent jet ignition (DM-TJI) engine. DM-TJI is an advanced combustion technology with a promising potential to extend the thermal efficiency of spark ignition engines with minimal engine-out emissions. The DM-TJI engine was observed to offer a faster burn rate and lower in-cylinder heat transfer when compared to the GDI engine under the same loads and speeds.

An incorrect version of Fig. 8 was published. The correct figure is given below. Fig. 8 Intercooler, intake manifold, coolant, and exhaust manifold temperature-all cases studied. The load and speed associated with each of these case numbers can be found in Table 2.