Refine Your Search

Search Results

Technical Paper

Mixture Formation Process in a Spark-Ignition Engine with Ethanol Blended Gasoline

2009-06-15
2009-01-1957
In this study, fuel concentration measurements in a spark-ignition (SI) engine with ethanol blended gasoline were carried out using an optical sensor installed in the spark plug with laser infrared absorption technique. The spark plug sensor for in-situ fuel concentration measurement was applied to a port injected SI engine. The molar absorption coefficients of ethanol blended gasoline were determined for various pressures and temperatures in advance using a constant volume vessel with electric heating system. Ethanol blended gasoline with high volumetric ratios shows lower molar absorption coefficients due to lower molar absorption coefficients of ethanol. The molar absorption coefficients of ethanol blended gasoline can be estimated by considering the molar fraction of each component.
Technical Paper

Effect of EGR on Combustion and Exhaust Emissions in Supercharged Dual-Fuel Natural Gas Engine Ignited with Diesel Fuel

2009-06-15
2009-01-1832
The combustion and exhaust emissions characteristics of a supercharged dual-fuel natural gas engine with a single cylinder were analyzed. We focused on EGR (Exhaust Gas Recirculation) to achieve higher thermal efficiency and lower exhaust emissions. The combustion of diesel fuel (gas oil) as ignition sources was visualized using a high-speed video camera from the bottom of a quartz piston. The luminous intensity and flame decreased as the EGR rate increased. Furthermore, the ignition delay became longer due to the EGR. Characteristics of the combustion and exhaust emissions were investigated with changing EGR rates under supercharged conditions. The indicated mean effective pressure and thermal efficiency decreased with increasing EGR rate. In addition, NOx emissions decreased due to the EGR. In this study two-stage combustion was observed.
Technical Paper

Effect of Fuel Injection Parameters on Engine Performance and Emissions of a Supercharged Producer Gas-Diesel Dual Fuel Engine

2009-06-15
2009-01-1848
This study investigated the effect of some pilot fuel injection parameters, like injection timing, injection pressure and injection quantity on engine performance and exhaust emissions of a supercharged producer gas-diesel dual fuel engine. The engine has been tested to be used as a co-generation engine and its power output is an important matter. Experiments have been done to optimize the injection timing, injection pressure and injection quantity for the maximization of engine power. At constant injection pressures, there is an optimum amount of pilot injection quantity for that maximum engine power is developed without knocking and within the limit of maximum cylinder pressure. Above or below of that amount engine power is decreased. Higher injection pressures generally show better results than lower ones. However, good results can also be obtained with lower injection pressure, if maximum power timings can be selected.
Technical Paper

Fuel Breakup Near Nozzle Exit of High-Pressure Swirl Injector for Gasoline Direct Injection Engine

2004-03-08
2004-01-0542
Experimental investigations of fuel breakup very close to nozzle of practical high-pressure swirl injector, which is used in gasoline direct injection (GDI) engine, were carried out. In GDI engines, fuel is directly injected into cylinder therefore the spray characteristics and mixture formation are of primary importance. In this research, visualizations of primary spray formation process were demonstrated using a high-speed video camera (maximum speed: 1Mfps) with a long-distance microscope. Initial state and development of the spray were discussed under the different injection pressure condition. During the injection period, the length and thickness of the liquid sheet, which is produced from the nozzle exit, were measured using Ar-ion laser sheet and high-speed camera. Primary spray structure and behavior of liquid sheet, especially surface wave of liquid sheet, at nozzle exit were discussed using obtained images.
Technical Paper

Gas Temperature Measurement in a DME-HCCI Engine using Heterodyne Interferometry with Spark-Plug-in Fiber-Optic Sensor

2007-07-23
2007-01-1848
Non-intrusive measurement of transient unburned gas temperatures was developed with a fiber-optic heterodyne interferometry system. Using the value of the Gladstone-Dale constant for DME gas and combustion pressure we can calculate the in-cylinder temperature inside unburned and burned region. In this experimental study, it was performed to set up a fiber-optic heterodyne interferometry technique to measure the temperature before and behind the combustion region in a DME-HCCI engine. At first, measured temperature was almost the same as the temperature history assuming that the process that changes of the unburned and the burned are polytropic. In addition, we measured the temperature after combustion which of condition was burned gas with DME-HCCI combustion. The developed heterodyne interferometry used the spark-plug-in fiber-optic sensor has a good feasibility to measure the unburned and burned temperature history.
Technical Paper

In-Situ Fuel Concentration Measurement near Spark Plug by 3.392 mm Infrared Absorption Method - Pressure and Temperature Dependence of the Gasoline Molar Absorption Coefficient

2006-04-03
2006-01-0182
This paper describes the development and application of a spark plug sensor using a 3.392 μm infrared absorption technique to quantify the instantaneous gasoline concentration near the spark plug. We developed an in situ laser infrared absorption method using a spark plug sensor and a 3.392 μm He-Ne laser as the light source; this wavelength coincides with the absorption line of hydrocarbons. First, we established a database of the molar absorption coefficients of premium gasoline at different pressures and temperatures, and determined that the coefficient decreased with increasing pressure above atmospheric pressure. We then demonstrated a procedure for measuring the gasoline concentration accurately using the infrared absorption technique. The history of the molar absorption coefficient of premium gasoline during the experiment was obtained from the established database using measured in-cylinder pressures and temperatures estimated by taking the residual gas into consideration.
Technical Paper

Transient Temperature Measurement of Gas Using Fiber Optic Heterodyne Interferometry

2001-05-07
2001-01-1922
A fiber optical heterodyne interferometry system was developed to obtain high temporal resolution temperature histories of unburned and burned gases non-intrusively. The effective optical path length of the test beam changes with the gas density and corresponding changes of the refractive index. Therefore, the temperature history of the gas can be determined from the pressure and phase shift of the interference signal. The resolution of the temperature measurement is approximately 0.5 K, and is dependent upon both the sampling clock speed of the A/D converter and the length of the test section. A polarization-preserving fiber is used to deliver the test beam to and from the test section, to improve the feasibility of the system as a sensor probe. This optical heterodyne interferometry system may also be used for other applications that require gas density and pressure measurements with a fast response time, or a transient temperature record.
Technical Paper

Effects of EGR and Early Injection of Diesel Fuel on Combustion Characteristics and Exhaust Emissions in a Methane Dual Fuel Engine

2002-10-21
2002-01-2723
A dual fuel engine fueled with methane from an inlet port and ignited with diesel fuel was prepared. This study focuses on the effects of early injection and exhaust gas recirculation (EGR) on the characteristics of combustion and exhaust emissions. The injection timing was changed between TDC and 50 degrees before the TDC. In the early injection timing, smoke was never seen and hydrocarbons were smaller compared with those at the normal injection timing. However, the combustion becomes too early to obtain an appropriate torque when the equivalence ratio increases. Then, moderate EGR was very effective to force the combustion to retard with lower NOx, higher thermal efficiency and almost the same hydrocarbons and carbon monoxide. The engine operated even under the condition of stoichiometric mixture.
Technical Paper

In-Situ Fuel Concentration Measurement Near Spark Plug by 3.392 μm Infrared Absorption Method-Application to Spark Ignition Engine

2003-03-03
2003-01-1109
This study measured the fuel concentration near a spark plug using a laser infrared absorption method. An IR spark plug sensor with a double-pass measurement length was developed. A He-Ne laser with a wavelength of 3.392 μm, which coincides with the absorption line of hydrocarbons, was used as the light source. In order to confirm the measurement accuracy, the concentrations of a methane-air mixture were measured in a compression-expansion engine. Then, the IR spark plug sensor was used for measurements in a 4-stroke spark-ignition engine fuelled with isooctane. The air/fuel ratio measured using this system clearly agreed with the mean air/fuel ratio.
Technical Paper

Measurement of Flame Propagation Characteristics in an SI Engine Using Micro-Local Chemiluminescence Technique

2005-04-11
2005-01-0645
A small Cassegrain optics sensor was developed to measure local chemiluminescence spectra and the local chemiluminescence intensities of OH*, CH*, and C2* in a four-stroke spark-ignition (SI) engine in order to investigate the propagation characteristics of the turbulent premixed flame. The small Cassegrain optics sensor was an M5 type that could be installed in place of a pressure transducer. The measurements could be used to estimate the flame propagation speed, burning zone thickness, and local air/fuel (A/F) ratio for each cycle. The specifications of the small Cassegrain optics sensor were the same as those used for previous engine measurements. In this paper, measurements were made of several A/F ratios using gasoline to fuel the model engine. The performances of two Cassegrain optics sensors were compared to demonstrate the advantages of the new small sensor by measuring the local chemiluminescence intensities of a turbulent premixed flame in the model engine.
Technical Paper

Visualization of Ambient Air Motion and Entrainment into a Transient Gas Jet Impinging on a Flat Wall

1995-10-01
952513
A turbulent gas jet impinging on a flat wall was visualized by a laser sheet method. Velocity fields were determined from the images with a high speed video system by processing them in terms of the cross correlation method for the jet and particle tracking method for the ambient air from the same images. The vortex flow near the transient jet tip impinging on the wall was visualized and analyzed successfully. The velocity field obtained from the above methods was compared to that determined with a laser Doppler anemometer. The path line of a certain period which was taken with a CCD camera with controlled shutter was analyzed and the mean rate of air entrainment was determined quantitatively. The spatial and temporal change of the entrainment rate was estimated and it was found that the entrainment rate near the upstream part of the jet tip region is larger because of the vortex.
Technical Paper

Combustion Diagnostics Using Time-Series Analysis of Radical Emissions in a Practical Engine

2015-11-17
2015-32-0748
The objective of this study is to investigate the initial flame propagation characteristics of turbulent flame in an engine cylinder through time-series analysis of radical emissions. A spark plug with optical fiber was developed in this study. The plug sensor is M12 type that makes it possible to mount in practical engine. The spark plug sensor can detect radical emissions in time-resolved spectra through time-series spectroscopic measurement. In this spectra, some kinds of radical emissions such as OH*(306nm), CH*(431nm) and C2*(517nm) based on principle of chemiluminescence are observed. In this study, the spark plug sensor was applied to both compression-expansion machine (CEM) and practical engine. As a result of CEM with bottom viewed high-speed camera, three kinds of spectra could be detected.
Technical Paper

Ion Current in a Homogeneous Charge Compression Ignition Engine

2007-10-29
2007-01-4052
Homogeneous charge compression ignition (HCCI), has the potential to improve the fuel economy and to reduce NOx emission significantly. Spark plug in SI engine and fuel injector in diesel engine can be used directly to control the start of combustion and the combustion period. However, the combustion of HCCI engine is controlled by the chemical kinetic mainly due to the temperature histories in the cylinder. Therefore the combustion process of HCCI engine cannot be directly controlled. Ion sensors such as a spark plug or a gasket are useful to detect the combustion information in production engines. In this study, the ion current was measured in an HCCI engine with the heated charge mixture of fuel and air without EGR when the charge temperature, equivalence ratio and fuel were varied. Simultaneously in-cylinder pressure was measured and the rate of heat release was calculated. The relationship between the rate of heat release and the ion current is mainly discussed.
Technical Paper

Measurement of Ambient Air Entrainment into Transient Free Gas Jet by Means of Flow Visualization

1995-02-01
950056
A path line method utilizing a CCD random shutter camera and a laser light sheet was applied for obtaining the air mass entrained into a transient gas jet. Large, light weight particles and fine particles were used for scattering the path lines of the surroundings and visualizing the approximate shape of the jet, respectively The jet configuration and the entrainment process could be visualized simultaneously, and this path line method was found to be very useful for estimating the air mass entrained because of the good agreement with the value obtained using LDA data. The spatial and temporal change of the ambient air entrainment into the jet was approximately clarified.
Technical Paper

Ambient Air Entrainment into Transient Hydrogen Jet and its Flame Jet

1997-02-24
970894
It is necessary to understand the entrainment process of ambient air into diesel sprays for the combustion process. This study focused on the entrainment process of non-combusting and combusting hydrogen jets instead of evaporated fuel sprays because of ease with measurement for fundamental research. Spatial and temporal changes of the air entrainment into the jets were obtained using flow visualization technique. The experimental results showed that the total air mass entrained into the flame jet is nearly equal to that into the cold jet. The rate of entrainment per unit area of the flame jet is smaller than that in the cold jet. When a transient jet is separated into side and front parts, the rate of air mass entrained from the front part of the jet decreases with time while the rate into the side of the jet per unit area is almost the same. The total air mass entrained into the jet can be approximately explained by the momentum theory.
Technical Paper

Detection of Flame Propagation Pattern in a Spark Ignition Engine Using Gasket Ion Sensor

2004-06-08
2004-01-1919
In order to reduce the exhaust emission and the fuel consumption in a spark ignition engine, the combustion diagnostics had been developed. However, there are few sensors which can detect the combustion quality for the individual cycle and cylinder in production engines. In previous study, the new technique using a gasket ion sensor for measuring the combustion quality has been proposed. In present study, the flame propagation pattern in a spark ignition engine was detected by using a gasket ion sensor with a circular electrode. The waveforms of ion current obtained from a circular ion sensor were compared with the flame propagation pattern obtained from multiple ion sensors. When the mixture was ignited in offset center of the cylinder, the flame propagation pattern was distorted from the spherical pattern. Then the waveforms of ion current from the circular ion sensor were varied from the waveform for a center ignition.
Technical Paper

A Study of Air-Fuel Mixture Formation in Direct-Injection SI Engines

2004-06-08
2004-01-1946
An investigation was made into two approaches to air-fuel mixture formation in direct injection SI engines in which charge stratification is controlled by swirl or tumble gas motions, respectively. Particle image velocimetry (PIV), laser-induced fluorescence (LIF) and air-fuel ratio measurement by infrared absorption were used to analyze fuel transport from the fuel injector to the spark plug and the fuel vaporization process. The results obtained were then compared with measured data as to combustion stability. As a result, the reason why the effects of injection timing on combustion stability were different between the two approaches was made clear from the standpoint of the mixture formation process.
Technical Paper

In-Situ Fuel Concentration Measurement Near Spark Plug by 3.392 μm Infrared Absorption Method-Application to a Port Injected Lean-Burn Engine

2004-03-08
2004-01-1353
In this study, a spark plug sensor for in-situ fuel concentration measurement was applied to a port injected lean-burn engine. Laser infrared absorption method was employed and a 3.392 μm He-Ne laser that coincides with the absorption line of hydrocarbons was used as a light source. In this engine, the secondary valve lift height of intake system was controlled to obtain appropriate swirl and tumble flow in order to achieve lean-burn with the characteristics of intake flow. For such in-cylinder stratified mixture distribution, the fuel concentration near the spark plug is very important factor that affects the combustion characteristics. Therefore, the mixture formation process near the spark plug was investigated with changing fuel injection timing. Under the intake stroke, the timing that fuel passed through near the spark plug depended largely on the fuel injection timing.
Technical Paper

Diagnostic of Knocking by Wavelet Transform Method Utilizing Real Signal as Mother Wavelet

2001-09-24
2001-01-3546
It is well known that the wavelet transform is a useful time-frequency analysis method for an unsteady signal and major attention has been focused on the selection of the mother wavelet (MW) because the MW plays an important role in the wavelet transform. In this study, we analyze the pressure signal in a spark-ignition engine and the vibration of the engine block measured by a knock sensor under the knocking conditions when knocking is caused. We then propose a new method of the knocking detection that utilizes the knocking signal measured with a knock sensor as a MW. We call this method the Instantaneous Correlation Method (ICM). The degree of similarity between the MW and the vibration of the engine block was judged and only the knocking signal from the vibration of the engine block was extracted. The results obtained here show that the method proposed in this study is useful for knocking detection even if the engine speed is very high of 6000rpm.
Technical Paper

Hydrogen Combustion and Exhaust Emissions Ignited with Diesel Oil in a Dual Fuel Engine

2001-09-24
2001-01-3503
Hydrogen is expected to be one of the most prominent fuels in the near future for solving greenhouse problem, protecting environment and saving petroleum. In this study, a dual fuel engine of hydrogen and diesel oil was investigated. Hydrogen was inducted in a intake port with air and diesel oil was injected into the cylinder. The injection timing was changed over extremely wide range. When the injection timing of diesel fuel into the cylinder is advanced, the diesel oil is well mixed with hydrogen-air mixture and the initial combustion becomes mild. NOx emissions decrease because of lean premixed combustion without the region of high temperature of burned gas. When hydrogen is mixed with inlet air, emissions of HC, CO and CO2 decrease without exhausting smoke while brake thermal efficiency is slightly smaller than that in ordinary diesel combustion.
X