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Technical Paper

Propagation Processes of Newly Developed Plasma Jet Igniter

2000-06-12
2000-05-0014
In plasma jet ignition, combustion enhancement effects occur toward the plasma jet issuing direction. Therefore, when the igniter is attached at the center of cylindrically shaped combustion chamber, plasma jet should issue toward the round combustion chamber wall. The plasma jet igniter that had an annular circular orifice has been developed. The purpose of this study is to elucidate the relationship between the newly developed plasma jet igniter configuration and the combustion enhancement effects. In this newly developed plasma jet igniter, the fine scale turbulence appears on the flame front and flame propagates very rapidly. Plasma jet influences on the flame propagation for long period when the plasma jet igniter has issuing angle 90 [deg.] and large cavity volume. However, in the early stage of combustion, flame front area of issuing angle 45 [deg.] is larger than that of 90 [deg.], because the initial flame kernel is formed by the plasma jet.
Technical Paper

Improvement of Engine Performance With Lean Mixture Ignited By Diesel Fuel Injection and Internal Egr

2000-06-12
2000-05-0076
The uniform lean methanol-air mixture was provided to the diesel engine and was ignited by the direct diesel fuel injection. The internal EGR is added to this ignition method in order to activate the fuel in the mixture and to increase the mixture temperature. The test engine was a 4-stroke, single- cylinder direct-injection diesel engine. The cooling system was forced-air cooling and displacement volume was about 211 (cm3). The compression ratio was about 19.9:1. The experiment was made under constant engine speed of 3000 (r/min). The boost pressure was maintained at 101.3 (kPa). Five values of mass flow rate of diesel fuel injection were selected from 0.060 (g/s) to 0.167 (g/s) and five levels of back pressure: 0), 26.7, 53.3, 80.0 and 106.6 (kPa) were selected for the experiment. The effect of internal EGR is varied by the back pressure level.
Technical Paper

Study on Combustion and Exhaust Gas Emission Characteristics of Lean Gasoline-Air Mixture Ignited by Diesel Fuel Direct Injection

1998-10-19
982482
The uniform lean gasoline-air mixture was provided to diesel engine and was ignited by direct diesel fuel injection. The mixing region that is formed by diesel fuel penetration and entrainment of ambient mixture is regarded as combustible turbulent jet. The ignition occurs in this region and the ambient lean mixture is burned by flame propagation. The lean mixture of air-fuel ratio between 150 and 35 could be ignited and burned by this ignition method. An increase of diesel fuel injection is effective to ensure combustion and ignition. As diesel fuel injection increases, HC concentration decreases, and NOx and CO concentration increases.
Technical Paper

Relationship between Plasma Jet and Newly Developed Plasma Jet Igniter

1998-10-19
982564
In plasma jet ignition, combustion enhancement effects are caused toward the plasma jet issuing direction. Therefore, when the igniter is attached at the center of cylindrically shaped combustion chamber, the plasma jet should issues toward the round combustion chamber wall. The plasma jet igniter that had a concentric circular orifice has been developed. It is expected that the plasma jet is issued and is diffused from concentric circular orifice toward the combustion chamber wall. Relationship between plasma jet and igniter configuration was experimentally clarified. Plasma jet can issue from the entire concentric circular orifice for some igniter. Plasma jet is extended with increasing concentric circular orifice area. Plasma jet penetration increases with increasing concentric circular orifice width.
Technical Paper

Spectroscopic Measurement of Radical Behavior Under Knocking Operation, 1996

1996-10-01
962104
Emission intensity was measured at a wavelength of 395 2 nm (corresponding to the characteristic spectrum of the HCHO radical) and absorbance was measured at 306 4 nm (corresponding to that of the OH radical). The emission intensity and absorbance waveforms recorded during engine operation on n-heptane show behavior indicative of the passage and degeneracy of cool flame in the preflame reaction interval. As the combustion chamber wall temperature approached an overheated state in the transition from normal combustion to knocking operation different preflame reaction behavior was observed which is thought to correspond to the presence of a negative temperature coefficient region related to the ignition delay time.
Technical Paper

Radical Behavior in Preflame Reactions Under Knocking Operation in a Spark Ignition Engine

1994-10-01
942061
Using absorption spectroscopy, simultaneous measurements were made of the behavior of the OH (characteristic spectrum of 306.4 nm), CH (431.5 nm) and C2(516.5 nm) radicals in the end-gas region and center of the combustion chamber of a spark-ignition engine during preflame reactions with four types of fuel having different octane numbers. The results of this research show that the behavior of the OH, CH and C2 radicals in preflame reactions differed significantly in both the center and end-gas region of the combustion chamber depending on the octane number of the fuel and also between normal and knocking combustion conditions.
Technical Paper

Spectroscopic Measurement of OH Radical Emission Behavior Using a 2-Cycle Engine

1997-10-27
978515
The aim of this research was to investigate the mechanism causing autoignition and the effect of exhaust gas recirculation (EGR) on combustion by detecting the behavior of the OH radical and other excited molecules present in the flame in a spark ignition engine. The test equipment used was a 2-cycle engine equipped with a Schnürle scavenging system. Using emission spectroscopy, the behavior of the OH radical was measured at four locations in the end zone of the combustion chamber. The OH radical plays an important role in the elemental reactions of hydrocarbon fuels. When a certain level of EGR was applied according to the engine operating conditions, the unburned gas became active owing to heat transfer from residual gas near the measurement positions on the exhaust port side and the influence of excited species in the residual gas, and autoignition tended to occur.
Technical Paper

Analysis of Intermediate Combustion Products in Preflame Reactions in a Spark-Ignition Engine

1997-10-27
978516
The use of a higher compression ratio is desirable for improving the thermal efficiency and specific power of spark-ignition engines, but it gives rise to a problem of engine knock. In the present research, an investigation was made of the role of the preflame reaction region of a spark-ignition engine in the occurrence of autoignition. Emission spectroscopy was used to measure the behavior of formaldehyde (HCHO) in a cool flame. In addition, measure the behavior of the faint light attributed to the HCO radical in a blue flame with the concurrent measurement of the OH radical. The emission waveforms measurements obtained for HCHO when n-heptane (ORON) was used as the fuel, It is thought that these tendencies correspond to the passage and degeneracy of a cool flame. Further, the emission waveforms measured for the HCO radical when blended fuels (6ORON, 8ORON) were correspond to that of a blue flame.
Technical Paper

Combustion Characteristic of Lean Mixture Ignited by Gas-Oil Injection in High Compression Engine

1997-10-27
978496
We have investigated combustion characteristics of lean gasoline-air pre-mixture ignited by gas-oil injection using a high compression D.I. diesel engine. Gasoline was supplied as an uniform lean mixture by using carburetors, and gas-oil was directly injected into the cylinder. Two different types of combustion chamber were attempted. It was confirmed that the lean mixture of air-fuel ratio between 150 and 35 could be ignited and burned by this ignition method. An engine with the re-entrant type combustion chamber had an advantage for combustion and ignition. The brake mean effective pressure increased when relatively rich mixture was provided with a small amount of the gas-oil injection. As the gas-oil injection increased, HC concentration decreased, and NO and CO concentration increased. The exhaust gas emission of pollutants could be reduced when lean mixture was ignited by an optimum gas-oil injection.
Technical Paper

Influence of the Characteristic Length on Performance of Plasma Jet Igniters

1994-10-01
942051
The investigation regarding performance of plasma jet igniters was explored by using a constant volume vessel. This study focused on investigating the relationship between the jet effect, the hot gas jet issued from the igniter, and combustion enhancement. The hot gas penetration was visualized by the schlieren system with CCD camera and image intensifier. In the cases of small energies, 0.63 and 0.90 J, the combustion enhancement effect is similar to that of combustion jet igniter. In cases of supplied energies, 2.45 and 5.00 J, the jet effect influences on the combustion enhancement effect for small characteristic length of the igniter.
Technical Paper

Influence of Electrical Supplied Energy and Characteristic Length on the Plasma Jet Ignition

1993-10-01
932750
The investigation regarding the plasma jet ignition was explored by using a combustion vessel. The first purpose is to elucidate the issuing duration and the penetration of hydrogen plasma jet. A temporal change of local electron temperature was measured along the central axis of plasma jet. A small characteristic length of igniter seems favorable with regard to the plasma jet penetration and the generation of high temperature, as compared with the case of the igniter that has the excessive cavity volume. The second purpose is to elucidate relationship between the characteristic length and the combustion enhancement effect, when the excessive volume of cavity and the excessive supplied electrical energy were used. The influence of the characteristic length on the plasma jet penetration and the combustion enhancement differs with the supplied energy. The combustion enhancement seems to be caused by the plasma jet in case of excessive supplied energy.
Technical Paper

Application of Newly Developed Cellulosic Liquefaction Fuel for Diesel Engine

2009-11-03
2009-32-0132
A new bio-fuel i.e. the cellulosic liquefaction fuel (CLF) was developed for diesel engines. CLF was made from woods by direct liquefaction process. When neat CLF was supplied to diesel engine, the compression ignition did not occur, so that blend of CLF and diesel fuel was used. The engine could be operated when the mixing ratio of CLF was up to 35 wt%. CO, HC and NOx emissions were almost the same as those of diesel fuel when the mixing ratio of CLF was less than 20 wt% whereas the thermal efficiency slightly decreases with increase in CLF mixing ratio.
Technical Paper

The Diffusion Combustion Induced by the High Voltage Electrical Discharge - The Influence of Fuel Property on Combustion Behavior -

2009-11-03
2009-32-0144
A new diffusion combustion method characterized by plasma jet ignition is proposed. In this new diffusion combustion, the fuel is injected and ignited by the high-voltage electrical discharge, so this combustion method can be applied for various fuels which have different ignitability. Tests were carried out with seven fuels by using a combustion bomb. When a small orifice was used, fuels which had branched chain molecular structure were hardly ignited. In case of large orifice, all test fuels were surely ignited, and the maximum combustion pressures of branched chain structure molecular fuels were higher than those of straight chain structure molecular fuel.
Technical Paper

Influence of Various Biodiesel Fuels on Diesel Engine Performance

2009-11-03
2009-32-0100
The composition ratio of saturated and unsaturated fatty acid methyl esters (FAME) is depended on feedstock. Three FAMEs: soybean (SME), palm (PME) and coconut oil (CME) methyl esters were mixed to make fuels which have different composition ratio. The ignitability of fuel which mainly consisted of unsaturated FAME was inferior. Power was slightly reduced with increasing of mixing ratio of CME; however exhaust gas emissions were improved because CME contained a lot of oxygen atoms. Fuel which was equal mixture SME and CME indicated almost the same ignition characteristic as that of PME because they have same composition ratio.
Technical Paper

The Effect of Corona Discharge on Pre-Mixed Combustion

2009-11-03
2009-32-0095
The flame propagation behavior of hydrogen-air and propane-air mixtures under application of high-voltage non-uniform electric field was explored by using combustion vessel. Both mixtures were ignited by laser-induced breakdown of Nd:YAG laser. In a case of propane-air mixture, top of flame front was drawn to the electrode and bottom of flame front was expanded. In a case of hydrogen-air mixture, the wrinkle caused by the preferential diffusion was enhanced by corona discharge, however the entire flame front was merely moved toward downward by corona wind. Therefore, the non-uniform electric field strongly influences charged particles originated in hydrocarbon of propane-air mixture.
Technical Paper

A Study of IDI 2-Stroke Cycle Compression Ignition Engine with DME

2009-11-03
2009-32-0063
DME is alternate fuel for diesel engines, however DME has defects such as small lower calorific value, inferior lubricity and weak fuel penetration. To compensate disadvantages, In-direct injection 2-stroke diesel engine with low pressure fuel injection system was proposed. The fuel injection timing near TDC gave good performance because the heat loss of low temperature oxidation reaction reduced. The brake torque and brake thermal efficiency of 2-stroke IDI diesel engine were lower than those of 4-stroke engine. However, the exhaust gas emissions were very low level because the intake air leaked through the exhaust port and the exhaust gas was diluted.
Technical Paper

Light Emission and Absorption Spectroscopic Study of HCCI Combustion

2009-06-15
2009-01-1846
In this study, light emission and absorption spectroscopic measurement techniques were used to investigate the Homogeneous Charge Compression Ignition (HCCI) combustion process in detail, about which there have been many unclear points heretofore. The results made clear the formation behavior and wavelength bands of the chemical species produced during low-temperature reactions. Specifically, with a low level of residual gas, a light emission band was observed from a cool flame in a wavelength range of 370–470 nm. That is attributed to the light emission of formaldehyde (HCHO) produced in the cool-flame reactions. Additionally, it was found that these light emission spectra were no longer observable when residual gas was applied. The light emission spectra of the combustion flame thus indicated that residual gas has the effect of moderating cool-flame reactions.
Technical Paper

Analysis of Knocking in an SI Engine based on In-cylinder: Spectroscopic Measurements and Visualization

2010-09-28
2010-32-0092
There are strong demands today to further improve the thermal efficiency of internal combustion engines against a backdrop of various environmental issues, including rising carbon dioxide (CO2) emissions and global warming. One factor that impedes efforts to improve the thermal efficiency of spark ignition engines is the occurrence of knocking. The aim of this study was to elucidate the details of knocking based on spectroscopic measurements and visualization of phenomena in the combustion chamber of a test engine that was operated on three primary reference fuels with different octane ratings (0 RON, 30 RON, and 50 RON). The ignition timing was retarded in the experiments to delay the progress of flame propagation, making it easier to capture the behavior of low-temperature oxidation reactions at the time knocking occurred.
Technical Paper

The Effects of Electric Fields on Flame Propagation of Homogeneous Hydrogen-Air Mixture

2011-11-08
2011-32-0577
The flame propagation behavior of homogeneous hydrogen-air mixture under application of high-voltage uniform or non-uniform electric field was explored by using combustion vessel. When a uniform electric field was applied, two plate electrodes were attached to ceiling and bottom of combustion chamber and, to apply a non-uniform electric field, an electrode in ceiling was needle-shaped and an electrode in bottom was plate-shaped. The positive or negative polarity DC high voltage was applied for an electrode in ceiling. When a positive polarity non-uniform electric field was applied to the mixture at any equivalence ratios and the input voltage was higher than 12 kV, the flame propagation was enhanced in the downward direction. This is because the corona wind was generated from the tip of needle-shaped electrode to grounded electrode by the brush corona.
Technical Paper

Performance of Air Motor with Regenerating System Designed for Propulsion of Bicycle

2011-11-08
2011-32-0615
An air motor with regenerating system for propulsion of a bicycle was newly developed. An air motor was driven by the compressed air and the bicycle was propelled. When the bicycle was decelerating, the air motor was acted as a compressor and the kinetic energy of bicycle was regenerated as compressed air. The purpose of this study is to elucidate the performance of air motor and driving characteristic of bicycle. The air motor in this study was the reciprocating piston type like an internal combustion engine, and cylinder arrangement was in-line two-cylinder. The output power increased with an increase of supply air pressure although the maximum cylinder pressure was less than the supply air pressure. The output power decreased as the revolution increased due to friction loss. The maximum cylinder pressure reduced as the rotational frequency increased because the inlet valve opening duration was decreased.
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