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The aim of the experiment is to observe the exhaust gas flow starting from the exhaust manifold to the catalytic converter at the 4 stroke engine of the passenger car to enhance the system's improvement. The manifold connects each exhaust pipe from the engine cylinders to the catalytic converter. The velocity pattern inside the exhaust manifold is measured using particle image velocimetry (PIV) meanwhile the time series velocity data is measured by Laser Doppler Anemometer (LDA). In the experiment, flow conditions with four pipes working simultaneously or single pipe working independently are tested. The initial velocity condition shown in the next is set at the upstream where the flow is inside the circular pipe. The initial velocity is 28m/s for the all pipes acting and 14m/s for each pipes acting. There are also 3 conditions of measurement: with catalytic converter, without catalytic converter and with hollow catalytic converter.

The lubrication mechanism is discussed by measuring the oil film behavior. The oil film behavior is evaluated by the oil film thickness and oil film velocity map. The combination method of laser induced fluorescence method (LIF) and particle image velocimetry (PIV) is applied to measure the oil film behavior. The oil film thickness is measured by LIF and its velocity distributions are measured by PIV. The combination method can provide both of the film thickness and velocities simultaneously. The first trial is performed in the model engine for checking the dynamics measurement of the oil film thickness by the LIF. The results show a difference of the oil film thickness distribution with crank angle. The combination method is tested in the engine with 4-cycle and 2-cylinder optical access engine with motoring condition. One cylinder of the engine is sapphire cylinder for observing oil film behavior on the piston skirt. Two clearances of the piston skirt of 30 µm and 100 µm is tested.

Air velocities in the cylinder of motored engine were measured by laser Doppler anemometer (LDA) and particle image velocimetry (PIV) to make the standard database that will be used for verification of the numerical simulation. A 4-stroke, 4-valve test engine with transparent cylinder was operated with engine speed of 600rpm. The velocities on that condition were measured individually in vertical- and swirl-direction. The distributions of mean- and RMS- velocities are obtained from the measured data. Flow velocity through the intake valve was also measured at the top of the cylinder. As the results, the flow structure by each crank angle can be clarified. The present data can be commonly used for some numerical research group of RC238 in JSME for verification of numerical simulation results. The effect of the tumble generation valve (TGV) is evaluated by velocity distributions.

HCCI (Homogeneous Charge Compression Ignition) combustion results in very low NOx emissions, however, it is not without problems. One of them is that the heavy load operation range is limited by knock, due to an exceptionally high heat release rate. Knock increases the heat loss to the cylinder walls and piston, reducing thermal efficiency. To help solve these problems, direct (in-cylinder) water injection has been suggested to lower the local temperatures that seem to cause knock in HCCI. Water injection was adapted in an HCCI engine fueled with DME and Propane. Results showed that the indicated thermal efficiency was improved by about 2% (λ = 3.0, NA), and the operation range was expanded from 460kPa to 700kPa (NA) maintaining a low NOx level.

One of the problems in HCCI combustion is a knocking in higher load conditions. It governs the high load limit, and it is suggested that the knock increases heat loss[1], because it breaks the thermal boundary layer. But it is not clear how much knock affects on heat loss in the HCCI combustion in various conditions, such as ignition timing and load. The motivation of this study is to clarify the ratio of heat loss caused by knock in HCCI engines. The heat loss from zero-dimensional calculations with modified heat transfer coefficient, which is considering the effect of knock by adding a term of cylinder pressure rising rate dp/dt, agreed well with the results from the thermodynamic analysis in various conditions. And the results show that it is possible to avoid heat loss by knock by controlling the ignition timing at appropriate timing after T.D.C. and it will be possible to expand the load range if knock can be avoided.

The effects of the spray impinging part on the in-cylinder airflow were numerically analyzed in the combustion chamber of the impinging diffusion direct injection diesel engine using KIVA-3 code. KIVA-3 code was enhanced to cater the impinging part as an internal obstacle by adopting the virtual droplet method, which is relatively easy to implement. Numerical result shows that the turbulence generation is promoted by the impinging part and is transformed by the squish flow into the piston cavity. The secondary flow is generated beneath the impinging part as well. The secondary flow area increases as the distance between top surface of the impinging part and bottom surface of the cylinder cover increases.

In a direct injection diesel engine, fuel spray was auto-ignited by an elevated temperature and pressure atmosphere in a combustion chamber. Since an ignition might appear in which a suitable mixture for exothermic reaction was prepared and flame might be developing to a combustible mixture, a settlement of ignition in time and space could control the entire combustion. The ignition position was usually investigated with photometric observations such as high-speed video systems. However plane observations could not inform the exact position of the ignition because spray had the 3D structure. In this paper, a new trial for the measurement of the ignition position was reported. A single shot diesel spray injected into a test chamber was ignited by elevated temperature and pressure atmosphere in the chamber. The chamber had an impingement plate so as to measure an ignition delay of a wall impingement diesel spray.

This paper presents the fuel atomization effect of a fuel supply system on the lean burn characteristics of a spark-ignition engine and its mechanism. The fuel supply system can realize extremely different two state of atomization, i.e., wall-film of fuel flow and ultra-fine spray (less than 7 um S.M.D. by Malvern measurement). For the first step of the study, the atomization effect is examined under steady operation; several operating parameters including cyclic variability are expressed against the A/F over the wide range of operating condition. Within the operation limits, the fuel atomization does not affect any parameters, while it gives pretty much influence on the lean operation limit. Furthermore, this influencing behavior strongly depends on the throttle valve position and its opening.

Among the emerging technologies in order to meet ever stringent emission and fuel consumption regulations, Exhaust Gas Recirculation (EGR) system is becoming one of the prerequisites particularly for diesel engines. Although EGR cooler is considered to be an effective measure for further performance enhancement, exhaust gas soot deposition may cause degradation of the cooling. To address this issue, the authors studied the visualization of the soot deposition and removal phenomena to understand its behavior. Based on thermophoresis theory, which indicates that the effect of thermophoresis depends on the temperature difference between the gas and the wall surface exposed to the gas, a visualization method using a heated glass window was developed. By using glass with the transparent conductive oxide: tin-doped indium oxide, temperature of the heated glass surface is raised.

Reduction of exhaust emissions and BSFC has been studied using a high boost, a wide range and high-rate EGR in a Super Clean Diesel, six-cylinder heavy duty engine. In the previous single-turbocharging system, the turbocharger was selected to yield maximum torque and power. The selected turbocharger was designed for high boosting, with maximum pressure of about twice that of the current one, using a titanium compressor. However, an important issue arose in this system: avoidance of high boosting at low engine speed. A sequential and series turbo system was proposed to improve the torque at low engine speeds. This turbo system has two turbochargers of different sizes with variable geometry turbines. At low engine speed, the small turbocharger performs most of the work. At medium engine speed, the small turbocharger and large turbocharger mainly work in series.

The effects of a multi-hole nozzle with throttle construction (NTC) on combustion and emissions were investigated at high pressure fuel injection conditions. The throttle area was larger than the total injector hole area, therefore its fuel flow quantity was about the same as the standard nozzle under steady flow conditions. But the initial fuel injection rate was lower under unsteady flow conditions and smoke emissions were improved with the NTC. It is postulated that these effects were due to fuel flow turbulence inside the nozzle during the time of needle valve lift.

By using an inside visible carburettor, effects of high voltage application to the injected fuel on its behaviour and engine performances are investigated. At first five electrode arrangements around the venturi are examined to clearify the charging mechanism on the injected fuel and its effect on the fuel atomization. The experimental results show that when induced charging, corona charging and electrostatic force are effectively applied to the injected fuel, its atomization is remarkably improved. The diameter of fuel droplets monotonously decreases with increase of applied voltage and the effect is more distinct when the induced air velocity is low. Firing engine test is also carried out and it is revealed that when the throttle valve opening is large, the application of voltage considerably spreads the combustible range toward leaner side. Cyclic variation is reduced and startability is improved by the charge under the severe operating condition.

Impingement of a spray flame on the periphery of the piston cavity strongly affects heat loss to the wall. The heat release rate history is also closely correlated with the indicated thermal efficiency. For further thermal efficiency improvement, it is thus necessary to understand such phenomena in state of the art diesel engines, by observation of the actual behavior of an impinging spray flame and measurement of the local temperature and flow velocity. A top-view optically accessible engine system, for which flame impingement to the cavity wall can be observed from the top (vertically), was equipped with a high speed digital camera for direct observation. Once the flame impinged on the wall, flame tip temperature decreased roughly 100K, compared to the temperature before impingement.

The combination method for measuring the oil film thickness and velocity is proposed. The oil film thickness is measured by laser induced fluorescence (LIF) method and its velocity is measured by particle image velocimetry (PIV). A model engine is employed in order to check the LIF measurement for oil film thickness, and an optical access engine based on production engine is utilized for both measurements of oil film thickness and velocity. In the combination method, LIF images are used in the PIV measurement instead of particle images. From the results, the oil film thickness and velocity can be measured simultaneously by the combination method utilizing only LIF dye. The oil film thickness and velocity are presented along with crank angle of the engine under the motoring operation. The oil film velocity is also measured under the firing operation.

This paper describes the evaluation of flow characteristics inside a model engine cylinder using particle image velocimetry (PIV), laser Doppler anemometry (LDA), and numerical simulation by Partial Cells in Cartesian coordinate (PCC) method. The main goal of the study is to clarify the differences in the velocity characteristics obtained by these methods. The model engine head has a four-valve system. Single- and dual- valve opening conditions of the model engine head were tested by a steady flow test rig. The flow structures were completely different for these valve opening conditions. The mean velocities and their distributions obtained by the three methods show satisfactory agreement. However, there were differences in the turbulence intensities under several conditions and measuring positions. Taylor's hypothesis in the integral length scale of turbulence was also compared with single LDA and PIV measurements.