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Computational Fluid Dynamics (CFD) simulation is widely used in the development and validation of automotive engine performance. In engine simulation, spray breakup submodels are important because spray atomization has a significant influence on mixture formation and the combustion process. However, no breakup models have been developed for the fuel spray with plate-type multi-hole nozzle installed in port fuel injection spark ignition (SI) engines. Therefore, the purpose of this study is to simulate spray formation in port fuel injection precisely. The authors proposed the heterogeneous sheet breakup model for gasoline spray injected from plate type multi-hole nozzle. The novel breakup model was developed by clarifying the phenomenological mechanism of the spray atomization process. In this paper, this model was improved in dispersion characteristics and evaluated by the comparison of the model calculation results with experimental data.

The purpose of this study is to reduce cooling loss in gas engines using hydrogen. In this report, the effect of different hydrogen-CNG supply methods on combustion and exhaust characteristics of SI engine were investigated. As a result, the 13A-port-injection caused sharp heat release at hydrogen addition ratio (RH) of 20 %, with a maximum brake thermal efficiency of 27.5 %. Also, the hydrogen-port-injection promotes combustion above RH=40 % and reduces cooling loss, resulting in a maximum brake thermal efficiency of 31.0 % at RH=80 %, 1.8 pt higher than that of the 13A-port-injection.

In recent years, internal combustion engine using hydrogen gas, has attracted attention as one solution to the problem of global warming. Hydrogen gas has excellent combustion characteristics such as wide limits of inflammability and fast burning velocity because of high diffusion rate. Therefore, it has been made to obtain stable ignition and combustion by adding hydrogen with lean mixture in spark ignition engines using hydrocarbon fuels and to be attempted efficient operation by engine researchers. The purpose of this study is to reduce cooling loss in a gas engine using hydrogen gas and hydrogen Mixer system (Mixer) engine was remodeled to hydrogen Port Injection (PI) system engine. In this report, the heterogeneity of hydrogen mixture is clarified by comparing the combustion characteristics of the Mixer and the PI, and the effect of the difference in hydrogen supply systems on cooling loss is system. Ignition delay of the PI system is shorter than that of the Mixer.

Research on alternative fuels is necessary to reduce CO2 emissions. Hydrotreated Vegetable Oil (HVO) of light fuel physically improves spray and combustion characteristics. Fatty Acid Methyl Ester (FAME) is an oxygenated fuel and its combustion characteristics are chemically improved, although its spray characteristics such as penetration and atomization are deteriorated. The purpose of this study is to understand the effects of blending HVO, which has carbon neutral (CN) characteristics, with FAME, which also has CN characteristics, on spray and combustion characteristics, and to further improve emission such as THC and Smoke. This report presents the effect of the combination of improved spray characteristics and oxygenated fuel on emissions. Spray characteristics such as penetration, spray angle and spray volume were investigated by shadowgraph photography.

Fuel design concept has been proposed for low emission and combustion control in engine systems. In this concept, the multicomponent fuels, which are mixed with a high volatility fuel (gasoline or gaseous fuel components) and a low volatility fuel (gas oil or fuel oil components), are used for artificial control of fuel properties. In addition, these multicomponent fuels can easily lead to flash boiling which promote atomization and vaporization in the spray process. In order to understand atomization and vaporization process of multicomponent fuels in detail, the model for flash boiling spray of multicomponent fuel have been constructed and implemented into KIVA3V rel.2. This model considers the detailed physical properties and evaporation process of multicomponent fuel and the bubble nucleation, growth and disruption in a nozzle orifice and injected fuel droplets.

We have proposed the application of Exhaust Gas Recirculation (EGR) gas dissolved fuel which might improve spray atomization through effervescent atomization instead of high injection pressure. Since EGR gas is included in the spray of EGR gas dissolved fuel, it directly contributes to combustion, and the further reduction of NOx emissions is expected rather than the conventional external EGR. In our research, since highly contained in the exhaust gas and highly soluble in the fuel, CO2 was selected as the dissolved gas to simulate EGR gas dissolved. In this paper, the purpose is to evaluate the influence of the application of CO2 gas dissolved fuel on the combustion characteristics and emission characteristics inside the single cylinder, direct injection diesel engine. As a result, by use of the fuel, smoke was reduced by about 50 to 70%, but NOx reduction does not have enough effect.

In recent years, depletion of energy resources and increasing CO2 emission have been concerned. As this solution, the use of biofuels from garbage is focused. In this research, higher efficiency and lower emissions in the gas engine for power generation using biomass gas are aimed. However, the biomass gas is low caloric value and the output is low and the combustion is unstable. Therefore, a turbocharged spark ignition gas engine is used as the test institution. As a result, it is found that combustion stability and high efficiency of biomass gas can be realized.

The purpose of this study is to achieve thermal efficiency improvement and cooling loss reduction of a diesel engine with a combustion concept of earlier evaporation, higher entrainment, and compact spray flame. In order to realize this concept, the paper focused on two-component fuel (nC5H12/nC10H22) with high evaporation. In this paper, the effects of two-component fuel on thermal efficiency and exhaust characteristics are examined by using single cylinder diesel engine. In addition, spray characteristics are revealed in an optically accessible chamber and combustion characteristics are revealed by using RCEM.

We have proposed the application of EGR gas dissolved fuel which might improve spray atomization through effervescent atomization instead of high injection pressure. In this paper, the purpose is to evaluate the influence of the application of CO2 gas dissolved fuel on the combustion characteristics and emissions inside the single cylinder, direct injection diesel engine. As a result, by use of the fuel, smoke was reduced by about 50 to 70%. The amount of NOx was reduced at IMEP=0.3 MPa, but it was increased at IMEP=0.9 MPa.

The CO2 gas dissolved fuel for the diesel combustion is effective to reduce the NOx emissions to achieve the internal EGR (Exhaust Gas Recirculation) effect by fuel. This method has supplied EGR gas to the fuel side instead of supply EGR gas to the intake gas side. The fuel has followed specific characteristics for the diesel combustion. When the fuel is injected into the chamber in low pressure, this CO2 gas is separated from the fuel spray. The distribution characteristics of the spray are improved and the improvement of the thermal efficiency by reduction heat loss in the combustion chamber wall, and reduce soot emissions by the lean combustion is expected. Furthermore, this CO2 gas decreases the flame temperature. Further, it is anticipated to reduce NOx emissions by the spray internal EGR effect.

Diesel Particulate filter (DPF) is installed as after treatment device of exhaust gas in diesel engine, and collects the Particulate Matter (PM). However, as the operation time of engine increases, PM is accumulated in the DPF, resulting in deterioration of PM collection efficiency and increasing in pressure loss. Therefore, Post injection has been attracted attention as DPF regeneration method for burning and removing PM in DPF. However, Post injection causes oil dilution when fuel is injected at the middle to late stage of expansion stroke. Oil dilution are concerned to deteriorate the sliding property of piston and the thermal efficiency. For this reason, it is necessary to elucidate the mechanism and the behavior that spray impinges lubricating oil film. Therefore, in this study, we aimed to construct model of Computational Fluid Dynamics (CFD) that predicts amount of oil dilution which is concern for post injection in diesel engine, with high accuracy.

n-Tridecane is a low boiling point component of gas oil, and has been used as a single-component fuel for diesel spray and combustion experiments. However, no reduced chemical kinetic mechanisms for n-tridecane have been presented for three-dimensional modeling. A detailed mechanism developed by KUCRS (Knowledge-basing Utilities for Complex Reaction Systems), contains 1493 chemical species and 3641 reactions. Reaction paths during ignition process for n-tridecane in air computed using the detailed mechanism, were analyzed with the equivalence ratio of 0.75 and the initial temperatures of 650 K, 850 K, and 1100 K, which are located in the cool-flame dominant, negative-temperature coefficient, and blue-flame dominant regions, respectively.

Fuel design approach has been proposed as the control technique of spray and combustion processes in diesel engine to improve thermal efficiency and reduce exhaust emissions. In order to kwow if this approach is capable of controlling spray flame structure and interaction between the flame and a combustion chamber wall, the present study investigated ignition and flame characteristics of dual-component fuels, while varying mixing fraction, fuel temperature and ambient conditions. Those characteristics were evaluated through chemiluminescence photography and luminous flame photography. OH radical images and visible luminous flame images were analyzed to reveal flame shape aspect ratio and its fractal dimension.

In direct injection spark ignition (DISI), spray characteristics such as the penetration, spatial dispersion, droplet size distribution and the spray wall interaction process are extremely important to control the combustion process through the mixture formation process. Furthermore, the spray basic feature including the spatial and temporal changes is the key issue to reduce the Particulate Matter (PM) & HC emissions. In this study, we reveal both of the macroscopic and microscopic structures of the spray dynamics by Super High Spatial Resolution Photography (SHSRP). Furthermore, it is found that the simulated spray structure such as the penetration and droplet size distribution using Computational Fluid Dynamics (CFD) code is well consistent with the experimental results.

The compressible Large-Eddy Simulation (LES) for the diesel spray with OpenFOAM is presented to reduce CPU time by massively parallel computing of the scalar type supercomputer (CRAY XE6) and simulate the development of the non-evaporative and the evaporative spray. The maximum computational speeds are 14 times (128 cores) and 43 times (128 cores) for of the non-evaporative spray and the spray flame with one-step reaction, respectively, compared to the one core simulation. In the spray flame simulation with the reduced reaction mechanism (29 species, 52 reactions), the maximum computational speed is 149 times (512 cores). Then LES of the non-evaporative and the evaporative spray (Spray A) are calculated. The results indicate that the spray tip penetration is well predicted, although the size of the computational domain must be set equal to that of the experiment.

Researches for automation of hydraulic excavators have been conducted for laborsaving, improved efficiency of operations and increased worker's safety improvement. Authors' final goal is to develop automatic digging system which can realize the high efficiency. Therefore, it is thought that appropriate digging control algorithm is important for the automation. For this goal, this paper shows a dynamics model of the backhoe excavator and simulations using such models. Detailed dynamic models are needed from the point of view of the control engineering. Authors evaluate effectiveness of automatic digging algorithm by simulation models. In this research, the linkage mechanism which contains the closed loops is modeled based on the Newton-Euler formulation, where motion equation is derived. Moreover, we apply a soil model for simulation, based on the two dimensional distinct element method (DEM), in order to reproduce reaction force from grounds.

Ignition, combustion and emissions characteristics of dual-component fuel spray were examined for ranges of injection timing and intake-air oxygen concentration. Fuels used were binary mixtures of gasoline-like component i-octane (cetane number 12, boiling point 372 K) and diesel fuel-like component n-tridecane (cetane number 88, boiling point 510 K). Mass fraction of i-octane was also changed as the experimental variable. The experimental study was carried out in a single cylinder compression ignition engine equipped with a common-rail injection system and an exhaust gas recirculation system. The results demonstrated that the increase of the i-octane mass fraction with optimizations of injection timing and intake oxygen concentration reduced pressure rise rate and soot and NOx emissions without deterioration of indicated thermal efficiency.

In order to reduce CO₂, Electric Vehicles (EV) and Hybrid Vehicles (HV) are effective. Those types of vehicles have powertrains from conventional vehicles. Those new powertrains drastically improve their efficiency from conventional vehicles keeping the same or superior power performance. On the other hand, those vehicles have an issue for thermal energy shortage during warming up process. The thermal energy is very large, and seriously affects the fuel economy for HV and the mileage for EV. In this paper, we propose VHDL-AMS multi-domain simulation technique for the estimation of the vehicle performance at the concept planning stage. The VHDL-AMS is IEEE and IEC standardized language, which supports not only multi-domain (physics) but also encryption. The common modeling language and encryption standard is indispensable for full-vehicle simulation.

Auto-ignition and combustion processes of dual-component fuel spray were numerically studied. A source code of SUPERTRAPP (developed by NIST), which is capable of predicting thermodynamic and transportation properties of pure fluids and fluid mixtures containing up to 20 components, was incorporated into KIVA3V to provide physical fuel properties and vapor-liquid equilibrium calculations. Low temperature oxidation reaction, which is of importance in ignition process of hydrocarbon fuels, as well as negative temperature coefficient behavior was taken into account using the multistep kinetics ignition prediction based on Shell model, while a global single-step mechanism was employed to account for high temperature oxidation reaction. Computational results with the present multi-component fuel model were validated by comparing with experimental data of spray combustion obtained in a constant volume vessel.

A high performance digging algorithm for a hydraulic excavator has not been established because the relationship between digging parameters and digging performance is complex. An examination process for a high-performance digging algorithm is proposed. In this paper, the digging efficiency is defined as the soil volume derived by the applied energy to drive the bucket in order to evaluate digging performance. The digging algorithm, which we study for high digging efficiency, decreases the reaction force to the bucket from the soil by moving the bucket upward when the reaction force exceeds a threshold during digging. Digging tests are performed with a miniature test device and a simulation model by two-dimensional distinct element methods (2D-DEM). The device and the simulation assess the effectiveness of the digging algorithm. It is quantitatively shown that the digging performance obtained by the feedback digging system is improved to prevent growing of reaction force.