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In order to investigate the soot formation process in a diesel spray flame, simultaneous imaging of soot precursor and soot particles in a transient spray flame achieved in a rapid compression machine was conducted by laser-induced fluorescence (LIF) and by laser-induced incandescence (LII) techniques. The 3rd harmonic (355nm) and the fundamental (1064nm) laser pulses from an Nd:YAG laser, between which a delay of 44ns was imposed by 13.3m of optical path difference, were used to excite LIF from soot precursor and LII from soot particles in the spray flame. The LIF and the LII were separately imaged by two image-intensified CCD cameras with identical detection wavelength of 400nm and bandwidth of 80nm. The LIF from soot precursor was mainly located in the central region of the spray flame between 40 and 55mm (270 to 370 times nozzle orifice diameter d0) from the nozzle orifice. The LII from soot particles was observed to surround the soot precursor LIF region and to extend downstream.

The two-dimensional distribution of a soot cloud in an unsteady spray flame in a rapid compression machine(RCM) was visualized using the laser sheet scattering technique. A 40 mm x 50 mm cross section on the flame axis was illuminated by a thin laser sheet from a single pulsed Nd:YAG laser(wavelength 532 nm). Scattered light from soot particles was taken by a CCD camera via a high speed gated image intensifier. The temporal variation of the scattered light images were presented with the injection pressure as a parameter. The results showed that scattered light was intense near the periphery of the flame tip and that the scattered light becomes weaker significantly and disappears fast after the end of injection as injection pressure is increased. This technique was also applied to the visualization of the two-dimensional distribution of liquid droplets in the non-evaporating spray to correlate it with the soot concentration distribution.

IMEP can be generally calculated by numerical integration on the PV diagram. However, this method requires a great number of sampled data per cycle, in order to ensure high accuracy in calculation. The present method is a to use only the primary and secondary components of engine speed from the pressure diagram based on the Fourier series. Owing to this method, calculation errors have become smaller than conventional method even though the number of samples is reduced, and calculation time is also reduced by the conventional method. Using present method, a Fourier series type combustion analyzing system has been developed. Real-time IMEP measurement is allowed in this system owing to the characteristic features described above, and the validity of calculated results is confirmed by comparing the results with the IMEP values obtained by batch processing through the numerical integration.

To adhere to stringent environmental regulations, SI (spark ignition) engines are required to achieve higher thermal efficiency. In recent years, EGR (exhaust gas recirculation) systems and lean-burn operation has been recognized as key technologies. Under such operating conditions, reducing CCV (cycle-to-cycle variation) in combustion is critical to the enhancement of overall engine performance. Flow-field CCV is one of the considerable factors affecting combustion in engines. Conventionally, in research on flow fields in SI engines, the ensemble average is used to separate the measured velocity field into a mean component and a fluctuation component, the latter of which contains a CCV component and a turbulent component. To extract the CCV of the flow field, previous studies employed spatial filter, temporal filter, and POD (proper orthogonal decomposition) methods.

Three-dimensional direct numerical simulations of methane-air turbulent premixed flame propagating in homogenous isotropic turbulence are conducted to investigate local and global flame structure in thin reaction zones. GRI-Mech 3.0 is used to represent methane-air reactions. The equivalence ratio of unburned mixture is 0.6 and 1.0. For a better understanding of the local flame structure in thin reaction zones, distributions of mass fractions of major species, heat release rate and temperature are investigated. To clarify effects of turbulence on the local and global flame structures, the statistical characteristics of flame elements are also revealed.

The concentrations of soot, NO and the other combustion products were measured by incylinder gas sampling in a DI diesel engine. The effects of injection timing, swirl ratio, and combustion chamber geometry on the formation and emission processes of soot and NO were studied. The following results were obtained: (1) Soot is promptly formed in the flame during the early combustion period where the equivalence ratio in the flame is high over 1.0. Thereafter almost all the formed soot is swiftly burnd up by oxidation during the middle combustion period. This process mainly determines the exhaust soot concentration. (2) NO is formed in the flame during the early and middle combustion period where the flame temperature is high over 2000 K. The highest NO concentration is observed at the flame tip swept by the air swirl. Though the concentration of the formed NO decreases by dilusion it nearly constant during the later combustion period.

A mixed timescale subgrid model of a large eddy simulation was used to simulate the turbulence regime in diesel engine combustion. The combustion model used the direct integration approach with a diesel oil surrogate mechanism (developed at Chalmers University of Technology and consisting of 70 species and 309 reactions). Additional reactions for the generation and consumption of OH*, CO2*, and CH* species were added from recent kinetic studies. Collisional quenching and spontaneous emission resulted in de-excitation of the excited state radical. A phenomenological soot formation model (developed at Waseda University) was combined with the LES code. The following important steps were considered in the soot model: particle inception where naphthalene grows irreversibly to form soot, surface growth with the addition of C2H2, surface oxidation (induced by OH radicals and O2 attack), and particle coagulation.

A diesel spray and flame in a quiescent atmosphere were realized without interference with combustion chamber walls in a newly constructed rapid compression machine. High speed shadow photography and pressure measurement were employed to obtain data for calculating the amount of air entrainment into the the flame and spray. From a comparison of air entrainment between the flame and spray, it turned out that when ignition delay becomes longer air entrainment into flames is promoted by the thermal expansion of multi-points ignition sources in the central region of the spray.

The 4th Workshop of the Engine Combustion Network (ECN) was held September 5-6, 2015 in Kyoto, Japan. This manuscript presents a summary of the progress in experiments and modeling among ECN contributors leading to a better understanding of soot formation under the ECN “Spray A” configuration and some parametric variants. Relevant published and unpublished work from prior ECN workshops is reviewed. Experiments measuring soot particle size and morphology, soot volume fraction (fv), and transient soot mass have been conducted at various international institutions providing target data for improvements to computational models. Multiple modeling contributions using both the Reynolds Averaged Navier-Stokes (RANS) Equations approach and the Large-Eddy Simulation (LES) approach have been submitted. Among these, various chemical mechanisms, soot models, and turbulence-chemistry interaction (TCI) methodologies have been considered.

Development of the diesel particulate filter (DPF) aims to attain fast oxidation of accumulated soot at low temperature. Numerous researchers have explored the characteristics of soot oxidation under ambient conditions of simulated exhaust gas using thermogravimetric analysis or a flow reactor. In this study, temperature programmed oxidation (TPO) experiments were carried out for soot entrapped in miniaturized DPFs, cut-out from practical particulate filters, yielding wall-flow features typically encountered in real-world DPFs. Furthermore, when using the miniaturized samples, highly accurate lab-scale measurements and investigations can be facilitated. Examining different temperature ramping rates used for the TPO experiments, we propose a rate of 10°C/min as the most effective in analyzing soot oxidation in the practical filter substrates.

In this study, the combustion characteristics of diesel flame achieved in a rapid compression and expansion machine (RCEM) at various patterns of oxygen distribution in the chamber are investigated in order to clarify the effect of heterogeneity of oxygen distribution in diesel engines induced by EGR on the soot and NOx emissions. To make the heterogeneous distribution of oxygen in a combustion chamber, the mixtures with different oxygen concentrations are injected through the each different port located on the cylinder wall. Results indicate that the amount of oxygen entrained into the spray upstream the luminous flame region affects the NO emission from diesel flame strongly.

A thermodynamic two-zone model which assumes a stoichiornetric burned gas region and unburned air region is presented in an attempt to calculate more precise rate of heat release of diesel combustion. A comparison is made of the rate of heat release obtained by the two-zone model with that obtained by the conventional single-zone model. It shows around 10 % increase in the rate of heat release with the two-zone model. The effect of state equation of gas is also examined with the single-zone model and the use of a real gas law in stead of the perfect gas law is found to yield minor difference in the rate of heat release at a high boost operating condition.

A multi-functional membrane filter was developed through deposition of agglomerated Three-Way Catalyst particles with a size of 1 ~ 2 microns on the conventional bare particulate filter. The filtration efficiency reaches almost 100 % from the beginning of soot trapping with a low pressure drop and both reductions of NO and CO emission were achieved.

Hydraulically damped rubber engine mounts (HDM) are an effective means of providing sufficient isolation from engine vibration while also providing significant damping to control the rigid body motions of the engine during normal driving conditions. This results in a system which exhibits a high degree of non-linearity in terms of both frequency and amplitude. The numerical simulation of vibration isolation characteristics of HDM is difficult due to the fluid-structure interaction between the main supporting rubber and fluid in chambers, the nonlinear material properties, the large deformation of rubber parts, structure contact problems among the inner parts, and the turbulent flow in the inertia track. In this paper an integrated numerical simulation analysis based on structural FEM and a lumped-parameter model of HDM is carried out.

This paper concerns the Direct System Identification Method (hereafter referred to as DSIM) which allows accurate and quick determination of two groups of properties which exercise dominant effects on low frequency vibration of a vehicle body. The first group is the rigid body properties of an engine. The second group is the properties of each engine mount. Under the assumption that the engine/mount system is a rigid body, this paper makes theoretical discussion for using the DSIM to induce the parameters of an engine/mount system, and makes improvements for better correlation with experiments. Also mentioned is a comparison of this study with the experimental results and verification of consistency on those parameters obtained from DSIM to predict the accurate vehicle characteristics, along with the role this method will play in upgrading the technology of prediction analysis.

Energy optimal control theory (EOC) is applied to the energy flow control of a hybrid electric vehicle. Since the differential equation is solved analytically, the control law can be easily implemented in real time. Because the objective function is described in power form that permits negative value, not only the energy consumption is minimized but also the energy regeneration by the motor is maximized. In the simulation for the 10-mode driving, it is shown that the fuel cost of EOC is 15% lower than the rule based control (RBC).

In order to examine the effect of aromatic addition to Fischer-Tropsch Diesel (FTD) fuel on formation and oxidation processes of soot particles in diesel spray flame, small amount of naphthalene (0 to 65,000 ppm) was added to the FTD fuel and variation of soot morphology and nanostructure of primary soot particles directly sampled in a diesel spray flame were investigated via High-Resolution Transmission Electron Microscopy (HRTEM). A single-shot diesel spray flame was achieved in a constant volume combustion chamber under a diesel-like condition (Ta=1000K, Pa=2.7MPa) and a grid for HRTEM observation was directly exposed to the spray flame to thermophoretically sample soot particles onto the grid surface. The primary particle diameter, aggregate gyration radius, lattice fringe length, lattice fringe tortuosity and lattice fringe separation of soot particles sampled at different locations (from 60 to 90mm from nozzle tip) in the spray flame were analyzed.

Robust performance control of an autocruise system for a heavy-duty truck is described. The controller design is carried out employing a loopshaping method, considering dynamics variation caused by the gear shift, the load changes, the vehicle speed and also the vibrational characteristics of the propulsion system as the plant uncertainty. Thereby a robust-stable controller is obtained without sacrificing the response to disturbances. Finally, nonlinear simulations and real vehicle experiments prove that the steady-state performance and its robustness excel the conventional PID's.

As well-known, the diesel engine has the highest thermal efficiency at the same load as compared with internal combustion engine but its disadvantage is particulate matter (PM) emitted to the atmosphere. The studies of this paper were divided into two parts. The first part studied the quantity of PM from the both diesel and biodiesel fuels at 80% load (2400 rpm) by the trapping process on diesel particulate filter (DPF) used in a partial flow dilution tunnel. The second part studied the regeneration process of PM under the flow rate of oxygen and nitrogen gas of 13.5 L/min with 10%, 15%, and 21% of oxygen gas. The result showed that amount of PM from biodiesel fuel was lower around two times than PM from diesel fuel. The duration in regeneration process of biodiesel's PM was shorter than diesel while increasing of oxygen percentage can reduce regeneration time.

CI engines provide higher thermal efficiency compared to other internal combustion engines. On the other hand large amounts of smoke and NOx are produced during combustion. Smoke and NOx can be reduced by applying Premixed Charge Compression Ignition (PCCI) combustion. Unfortunately, the problems of PCCI combustion include unstable start of combustion and limited operating range. The multi-pulse ultrahigh pressure injection allows fuel to control PCCI combustion. The objective of offset orifice nozzle is to improve mixture formation and shorten spray penetration in order to increase thermal efficiency and control PCCI combustion. The offset orifice nozzle was designed by shift orifice aliment from into the sac center to edge of sac follow swirl direction. Counter bore design was applied to offset orifice nozzle in order to keep the constant orifice length as standard nozzle.