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Technical Paper

Effect of ADOIL TAC Additive on Diesel Combustion

1991-11-01
912555
Some papers on the combustion in a diesel engine have been already presented to discuss the effect of the additive called ADOIL TAC. A bottom view DI diesel engine driven at 980rpm with no load was used in the experiment presented here, in order to make clear this effect. JIS second class light diesel fuel oil was injected through a hole nozzle at the normal test run. The additive was intermixed 0.01 vol. % in this fuel oil, in the experiments to compare with the normal combustion. The flame was taken by direct high-speed photography. Profiles of flame temperature and KL were detected on the film by image processing, applying the two-color method. Soot was visualized by high-speed laser shadowgraphy, and the heat release rate was calculated using the cylinder pressure diagram. Discussion on the effect of the additive on the combustion phenomena was made by using all the data.
Technical Paper

Distribution of Vapor Concentration in a Diesel Spray Impinging on a Flat Wall by Means of Exciplex Fluorescence Method -In Case of High Injection Pressure-

1997-10-01
972916
Diesel sprays injected into a combustion chamber of a small sized high-speed CI engine impinge surely on a piston surface and a cylinder wall. As a consequence, their vaporization, mixture formation and combustion processes are affected by impingement phenomena. And the other important factors affecting on the processes is the injection pressure. Then, the distribution of the vapor concentration in a single diesel spray impinging on a flat and hot wall was experimented by the exciplex fluorescence method, as a simple case. The injection pressure was varied in the range from 55 MPa to 120 MPa. It is found that the distribution of the vapor concentration in this case is much leaner than that in the case of the low injection pressure of 17.8MPa.
Technical Paper

Study on Characteristics of Auto-Ignition and Combustion of Unsteady Synthetic Gas Jet

2007-04-16
2007-01-0629
It is thought that the synthetic gas, including hydrogen and carbon monoxide, has a potential to be an alternative fuel for internal combustion engines, because a heating value of the synthetic gas is higher than one of hydrogen or natural gas. A purpose of this study is to acquire stable auto-ignition and combustion of the synthetic gas which is supposed to be applied into a direct-injection compression ignition engine. In this study, the effects of ambient gas temperatures and oxygen concentrations on auto-ignition characteristics of the synthetic gas with changing percentage of hydrogen (H2) or carbon monoxide (CO) concentrations in the synthetic gas. An electronically-controlled, hydraulically-actuated gas injector was used to control a precise injection timing and period of gaseous fuels, and the experiments were conducted in an optically accessible, constant-volume combustion chamber under simulated quiescent diesel engine conditions.
Technical Paper

NO Formation in Transient Premixed Combustion Field by LIF

2000-06-12
2000-05-0120
In the internal combustion engines, combustion characteristics relating to HC & NO emission are affected remarkably by the spatial distribution of fuel concentration, temperature and turbulence properties. Especially, No formation process inside the combustion chamber affected by the mixture concentration field should be focused relating to the flame field temperature distribution. As the first step of NO formation study in premixed combustion field, NO formation process in the chamber was examined by considering OH radical property and flame temperature in homogeneous mixture conditions. In this study, in order to clarify NO formation process inside the transient premixed combustion field, relative concentration fields of OH radical and NO and temperature fields were measured by laser induced fluorescence technique(LIF) in the constant volume vessel for methane-air homogeneous mixture with the variation of equivalent ratio of the mixture.
Technical Paper

Soot formation/oxidation and fuel-vapor concentration in a DI diesel engine using laser-sheet imaging method

2000-06-12
2000-05-0078
Four kinds of optical measurements were performed to investigate the process of soot formation and oxidation in a direct-injection (DI) diesel engine. Measurements were carried out in an optically accessible DI diesel engine that allows planar laser sheet for combustion diagnostics to enter the combustion chamber either horizontally or along the axis of the fuel jet. The temporal and spatial distribution of soot particles has been investigated using the laser- induced incandescence (LII) and high-speed direct photography. Fuel vapor concentration, which is directly linked to the soot formation process in diesel combustion, has been deduced from the images obtained by the measurements of laser shadowgraph and elastic Mie scattering. According to the experimental results, soot formation begins to occur near the injector nozzle in which a fuel-rich mixture is distributed with a homogeneous condition. LII signal is dominated by the fuel vapor concentration in initial combustion period.
Technical Paper

Mechanism of Combined Combustion of Premixed Gas and Droplets

2002-10-21
2002-01-2843
In an SI engine with direct injection of gasoline (DGI), many small droplets disperse in premixed gas in the cylinder. In a CI engine, diesel spray is injected a cylinder, thus, the situation at the spray periphery is almost the same as that of DGI SI engine. From the standpoint it is useful for understanding the combustion phenomena in both engines to experiment the combined combustion of premixed gas where many small droplets exist. This paper describes this kind of combustion and it seems to be able to apply the results to the simulation of combustion in these engines.
Technical Paper

Experimental Analysis on Soot Formation Process In DI Diesel Combustion Chamber by Use of Optical Diagnostics

2002-03-04
2002-01-0893
Soot formation process inside the combustion chamber of an DI diesel engine is focused as a phenomenological basic scheme by using several optical diagnostics technique for the improvement of diesel exhaust emission. We have conducted the series of optical measurement research for the clarification of combustion field in an DI diesel engine. Then, this paper is a kind of review by adding the fuel vapor properties and particle image velocimetry (PIV) analysis with focusing the soot formation process. The experiments were carried out in a small sized high-speed DI diesel engine installed with an optical access view. The spray characteristics and its flow field in 2-D field were measured by laser sheet scattering (LIS) method and PIV scheme.
Technical Paper

Vizualization of Evaporative Diesel Spray Impinging Upon Wall Surface by Exciplex Fluorescence Method

1992-02-01
920578
A single diesel spray of n-decane which was miscible with a small quantity of exciplex dopants was injected from a hole nozzle into a quiescent high-temperature and high-pressure atmosphere of nitrogen, and was impinged in a normaldirection upon a flat wall with elevated temperature. This experiment was to serve as a simplified model of the actual state in a combustion chamber of diesel engines. When a thin sheet of laser light from Nd:YAG laser is passing through the cross section of this spray containing its central axis, it is able to generate fluorescent emissions from vapor and liquid phases in this evaporating spray. Then, clear 2-dimensional images concerning the concentration distributions of vapor and liquid phases were obtained simultaneously, by an exciplex fluorescence method using an image-intensifier and a CCD camera system. The dispersion processes of vapor and liquid phases in this impinging spray near the wall were analyzed with an image analyzer.
Technical Paper

Combustion in a Small DI Diesel Engine at Starting

1992-02-01
920697
It is unavoidable that a DI diesel engine exhausts a blue and white smoke at starting, especially in the cold atmosphere. In the experiments presented here, a small DI diesel engine started under the conditions of coolant and suction air whose minimum temperatures were 255 K and 268 K, respectively. The flame was photographed by high-speed photography, the temperature of flame and the soot concentration were measured by two-color method, and CO2 concentration was detected by luminous method. The engine cannot be started over several cycles when the coolant temperature is 255 K and suction air temperature is 268 K. As the temperature of coolant and suction air are decreasing, the maxima of the cylinder pressure, the flame temperature, the soot concentration and CO2 concentration are decreasing. Luminous small dots or small lumps of flame become scattered in the piston cavity.
Technical Paper

Characteristics of Combustion in an IDI Diesel Engine with a Swirl Chamber Made of Ceramics

1992-02-01
920696
There is a concept that the increase in the temperature of charge in a combustion chamber and the shield of heat transferred through a chamber wall can facilitate the oxidation of soot and reduce the discharge of soot from the engine. In the experiments presented here in, an IDI diesel engine was used to inspect the concept. The engine was installed a bigger sized cylindrical swirl chamber which was equipped with two flat quarts windows, in order to observe the combustion phenomena and to apply the optical measurement. The experiments were carried out using two types of divided chambers, that is, the swirl chamber made of ceramics and that made of steel, to examine the the effects mentioned above.
Technical Paper

Knocking Phenomena in a Rapid Compression and Expansion Machine

1992-02-01
920064
In this study, a rapid compression and expansion machine(RCEM) with a pancake combustion chamber was designed to investigate fundamentally on the knocking phenomena in spark ignition(S.I) engines. This RCEM is intended to simulate combustion in an actual engine. The homogeneous pre-mixture of n-pentane and air was charged into a quiescent atmosphere of the chamber. Then, the combustion field become simpler in this machine than it in a real S.I. engine. Also, the combustion phenomena, that is a cylinder pressure history, the behavior of flame propagation and so on, with high reproducibility are realized in this machine. The phenomena caught in this experiment were so-called low speed knocking. And, this knocking characteristics such as a knock intensity and a knock mass fraction were revealed by the cylinder pressure analysis varying the charge pressure and the equivalence ratio of the mixture, a compression ratio and an ignition timing.
Technical Paper

Modelling of Atomization Process in Flash Boiling Spray

1994-10-01
941925
This paper presents the analysis of atomization and vaporization processes in a flash boiling spray based on experimental results obtained from injection systems in the suction manifold of a gasoline engine. Two kinds of liquid fuel, n-Pentane and n-Hexane, were injected into quiescent atmosphere at room-temperature and low-pressure through a pintle type injector with electronic control. The spray characteristics of both fuels below various atmospheric pressures were investigated in detail by taking photography. Then, in the region of flash boiling, where the back pressure was below the saturated vapor pressure of fuel, the bubble nucleation process due to the flash boiling was modelled by both the measurement results of bubble and the nucleation rate equation using the degree of superheat of the liquid fuel.
Technical Paper

Analysis of Knocking Mechanism Applying the Chemical Luminescence Method

1995-02-01
951005
One of the most effective means of improving the thermal efficiency and the specific fuel consumption in spark ignition engines is the increase of the compression ratio. However, there is a limit to it because of the generation of knocking combustion due to the rise of temperature and pressure in the unburnt mixture. Also in turbo charged spark ignition engines, the ignition timing cannot be advanced until MBT in order to avoid the knocking phenomena. Generally speaking, it is very difficult to investigate the phenomena in an actual engine, because there are many restriction and the phenomena are too complex and too fast. According-ly, it is advantageous to reveal the phenomena fundamentally, including the autoignition process of the end-gas by using simplified model equipment. Therefore, a rapid compression and expansion machine (RCEM) with a pan-cake combustion chamber was designed and developed for the experiments presented here.
Technical Paper

Detection of Luminescence from Pre-Autoignition Reaction Zone in S.I. Engine

1997-02-24
970508
Knocking phenomenon in a spark ignition engine breaks out due to autoignition in the unburned gas region. Investigation on the pre-autoignition reaction, that is, the reaction of cool and blue flames happening before autoignition must be carried out in detail to control knocking. The reactions appear in an extremely short time before autoignition, so, much difficulties accompany an attempt to grasp the situation. In the experiments presented hear, progress situation of pre-autoignition reaction was made clear by visualized phenomena in a rapid compression and expansion machine (R.C.E.M), which had good reproducibility. Taken by two ultra high-speed video cameras. We determined the ignition delay time was caught by analyzing the emission of light from the combustion chamber before knocking occurrence.
Technical Paper

Characterization of Fuel Vapor Concentration Inside a Flash Boiling Spray

1997-02-24
970871
For current passenger vehicles, multi-point injection (MPI) systems are extensively employed for gasoline engines due to ease of control and rapid response. In these systems, the pressure within the intake manifold to which the injectors are installed can fall below the saturated vapor pressure of some hydrocarbon components present in the fuel. Such a condition leads to an atomization process in which flash boiling occurs. In the present work, the atomization process under flash boiling conditions has been characterized both experimentally and theoretically. The experimental investigation has been carried out with a spray test facility consisting of a variable pressure chamber equipped with a pintle type fuel nozzle. Infrared Extinction/Scattering (IRES) is utilized to provide temporal and spatially resolved distribution of the fuel vapor concentration within the spray.
Technical Paper

Characteristics of Free and Impinging Gas Jets by Means of Image Processing

1997-02-24
970045
A transient gas jet seems to be a model of a diesel spray because it has no vaporization process. Recently, CNG is utilized in a diesel engine. In the case of diesel engine, sprays or jets have the free state in some cases, and they are impinging surely on the piston surface in the other cases. The 2-D image of acetylene gas with tracer particles was taken by high-speed photography. In both jets, the outer shape was measured on the images and the characteristics of the internal flow was obtained by particle image velocimetry. Then, the physical models of these jets were constructed by use of experimental results.
Technical Paper

CO2 Mixed Fuel Combustion System for Reduction of NO and Soot Emission in Diesel Engine

1997-02-24
970319
We propose a new concept on simultaneous reduction of NO and soot emissions in Diesel engine exhaust by the diesel fuel oil (n-Tridecane) with liquefied CO2 dissolved. The CO2 dissolved fuel is expected to undergo flash boiling or gas separation when being injected into the combustion chamber and improve spray atomization and mixing process both of which are primary factors to govern soot formation. Also the internal EGR effect caused by CO2 injected with the fuel is expected to NO formation. In order to assess this concept, combustion experiments were carried out using a rapid compression and expansion machine. Thus, flame characteristics and heat release rate were analyzed for the combustion process of diesel fuel and CO2 mixed fuel. And, it is revealed that the diesel fuel-liquefied CO2 mixed fuel can successfully reduce NO emission in a diesel combustion system.
Technical Paper

Characteristics of Intermediate Products Generated During Diesel Combustion by Means of Total Gas Sampling

2004-10-25
2004-01-2923
It is very significant to take the intermediate products in diesel combustion for understanding the generation of exhaust emissions like SOF, dry soot and so on. The products generated in a constant volume combustion chamber were sampled by pricking a sheet of polyester film installed in the chamber to freeze the chemical reaction. The gas was analyzed by a gas chromatography. The fuel used was n-heptane. It is able to explain the generation of exhaust emissions by the experimental results. The other objective is to simulate the intermediate products. It is capable of explaining the relation between the simulated and experimental results.
Technical Paper

Modeling and Measurement on Evaporation Process of Multicomponent Fuels

2000-03-06
2000-01-0280
In previous multi-dimensional modeling on spray dynamics and vapor formation, single component fuel with pure substance has been analyzed to assess the mixture formation. Then it should be expected that the evaporation process could be performed for the multicomponent fuel such as actual Gasoline and Diesel gas oil. In this study, vapor-liquid equilibrium prediction was conducted for multicomponent fuels such as 3 and 10 components mixed solution with ideal solution analysis and non-ideal solution analysis. And the computation of distillation characteristics was conducted for the steady state fuel condition fuel condition to understand the evaporation process. As a result, calculated distillation characteristics are consistent well with experiment results. And the evaporation process of a multicomponent droplet in the combustion chamber has been calculated with the variation of ambient pressure and temperature.
Technical Paper

Low Emission Diesel Combustion System by Use of Reformulated Fuel with Liquefied CO2 and n-Tridecane

1999-03-01
1999-01-1136
We propose a new concept on simultaneous reduction of NO and soot emissions in Diesel engine exhaust by use of the diesel fuel oil (n-Tridecane) with liquefied CO2 dissolved. The CO2 dissolved component is expected to undergo flash boiling or gas separation when being injected into the combustion chamber, and improve spray atomization and mixing process both of which are primary factors to govern soot formation. Further, the internal EGR effect caused by CO2 component injected with the fuel is expected for NO formation. In order to assess this concept, spray dynamics measurement was conducted in the constant volume vessel with a variation of ambient pressure and temperature. Further, combustion experiments were carried out by using a rapid compression and expansion machine. Here, characteristics of the evaporative mixed fuel spray were examined by shadowgraph photography.
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