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Chemical Reaction Processes of Fuel Reformation by Diesel Engine Piston Compression of Rich Homogeneous Air-Fuel Mixture

SAE International Journal of Engines

Hokkaido University-Yusuke Watanabe, Shuntaro Ishiguro, Gen Shibata, Hideyuki Ogawa, Yoshimitsu Kobashi
YANMAR Co., Ltd.-Go Asai
  • Journal Article
  • 2017-32-0120
Published 2017-11-15 by Society of Automotive Engineers of Japan in Japan
To extend the operational range of premixed diesel combustion, fuel reformation by piston induced compression of rich homogeneous air-fuel mixtures was conducted in this study. Reformed gas compositions and chemical processes were first simulated with the chemistry dynamics simulation, CHEMKIN Pro, by changing the intake oxygen content, intake air temperature, and compression ratio. A single cylinder diesel engine was utilized to verify the simulation results. With the simulation and experiments, the characteristics of the reformed gas with respect to the reformer cylinder operating condition were obtained. Further, the thermal decomposition and partial oxidation reaction mechanisms of the fuel in extremely low oxygen concentrations were obtained with the characteristics of the gas production at the various reaction temperatures.The main reformed products were hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), and ethylene (C2H4) and the results indicated that the reforming depends on the maximum temperature in the cylinder, however, the amount of reformed gas is lower than the values predicted by the CHEMKIN simulation.
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Analysis of Interaction between Autoignition and Strong Pressure Wave Formation during Knock in a Supercharged SI Engine Based on High Speed Photography of the End Gas

SAE International Journal of Engines

Nihon University-Akira Iijima, Takuya Izako, Takahiro Ishikawa, Takahiro Yamashita, Shuhei Takahata, Hiroki Kudo, Kento Shimizu, Mitsuaki Tanabe, Hideo Shoji
  • Journal Article
  • 2017-32-0119
Published 2017-11-15 by Society of Automotive Engineers of Japan in Japan
Engine knock is the one of the main issues to be addressed in developing high-efficiency spark-ignition (SI) engines. In order to improve the thermal efficiency of SI engines, it is necessary to develop effective means of suppressing knock. For that purpose, it is necessary to clarify the mechanism generating pressure waves in the end-gas region. This study examined the mechanism producing pressure waves in the end-gas autoignition process during SI engine knock by using an optically accessible engine. Occurrence of local autoignition and its development process to the generation of pressures waves were analyzed under several levels of knock intensity. The results made the following points clear. It was observed that end-gas autoignition seemingly progressed in a manner resembling propagation due to the temperature distribution that naturally formed in the combustion chamber. Stronger knock tended to occur as the apparent propagation speed of autoignition increased. It is particularly notable that a condition was observed in which the apparent propagation speed of autoignition through the end gas clearly exceeded the speed of sound. Exceptionally strong knock…
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Data Analysis of Off-Road Motorcycles in an Enduro Race

Yamaha Motor Co., Ltd-Akinori Shinagawa
Yamaha Motor Engineering Co., Ltd-Hisayuki Nozawa, Yutaro Uchiyama
  • Technical Paper
  • 2017-32-0033
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
Two-wheeled off-road vehicles are mainly ridden on slippery dirt roads that include steep slopes and rough, uneven surfaces. An analysis method for the driving state and the vehicle movement limits that would be suitable for analyzing the movement of such two-wheeled off-road vehicles under these conditions was examined. These movement limits were then formulated by taking into consideration the coefficient of friction and the road surface gradient in accordance with the basic laws of physics and also by focusing on the vehicle movement in the longitudinal direction. Measurements were also taken during actual off-road riding by top-class Japanese off-road motorcycle riders. It was confirmed that this measurement data was distributed within the range of the assumed vehicle movement limits. Consequently, it was confirmed that it is possible to use such measurements to accurately grasp the vehicle movement limits and the associated driving state for two-wheeled off-road vehicles.
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Practicability and Influencing Factors of a Lean Burn Mode for Two-Stroke Engines in Hand-Held Powertools

Andreas Stihl AG & Co KG-Florian Schumann, Tim Gegg
Graz University of Technology-Pascal Piecha, Christoph Ninaus, Stephan Schmidt, Roland Kirchberger
  • Technical Paper
  • 2017-32-0043
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
For many applications, such as scooters, hand-held power tools and many off-road vehicles, two-stroke engines are used as a preferred propulsion unit. These engines convince by a good power to weight ratio, a high durability and low maintenance technology and are therefore the first choice in this field of application. In general, already much development effort has been expended to improve those systems. However, an increasing environmental awareness, the protection of health and the shortage of fossil resources are the driving factors to further enhance the internal combustion process of those adapted two-stroke engines. The current focus here is on the reduction of emissions and fuel consumption with an at least constant power output.An approach to address an improvement of engine efficiency can be covered by applying a lean combustion burn mode. In almost all combustion technology sectors, including furnaces, gas turbines and many internal combustion engines, a lean combustion is utilized. Possible advantages of a combustion process under lean conditions are low pollutant emissions and high efficiencies, because flame temperatures are typically low. Nevertheless,…
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Improvement of Spray and Combustion Process by Applying CO2 Gas Dissolved Fuel

Doshisha University-Tomoyuki Mukayama, Ryota Nishigami, Annisa Bhikuning, Eriko Matsumura, Jiro Senda
YANMAR CO., LTD.-Go Asai, Masaki Kuribayashi
  • Technical Paper
  • 2017-32-0046
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
The CO2 gas dissolved fuel for the diesel combustion is effective to reduce the NOx emissions to achieve the internal EGR (Exhaust Gas Recirculation) effect by fuel. This method has supplied EGR gas to the fuel side instead of supply EGR gas to the intake gas side. The fuel has followed specific characteristics for the diesel combustion. When the fuel is injected into the chamber in low pressure, this CO2 gas is separated from the fuel spray. The distribution characteristics of the spray are improved and the improvement of the thermal efficiency by reduction heat loss in the combustion chamber wall, and reduce soot emissions by the lean combustion is expected. Furthermore, this CO2 gas decreases the flame temperature. Further, it is anticipated to reduce NOx emissions by the spray internal EGR effect.In this paper, the n-tridecane and CO2 gas were used as a basic fuel spray research, and shadowgraph photography and luminescence flame photography were conducted to measure the evaporation characteristics and flame characteristics of the fuel spray. In addition, chemiluminescence photography and luminous…
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Heat Transfer Analysis in a Diesel Engine Based on a Heat Flux Measurement Using a Rapid Compression and Expansion Machine

Chiba University-Tatsuya Kuboyama, Yasuo Moriyoshi
Tokyo Institute of Technology-Hidenori Kosaka
  • Technical Paper
  • 2017-32-0115
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
To investigate the heat transfer phenomena inside the combustion chamber of a diesel engine, a correlation for the heat transfer coefficient in a combustion chamber of a diesel engine was investigated based on heat flux measured by the authors in the previous study(8) using the rapid compression and expansion machine. In the correlation defined in the present study, thermodynamically estimated two-zone temperatures in the burned zone and the unburned zone are applied. The characteristic velocity given in the correlation is related to the speed of spray flame impinging on the wall during the fuel injection period. After the fuel injection period, the velocity term of the Woschni’s equation is applied. It was shown that the proposed correlation well expresses heat transfer phenomena in diesel engines.
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Spectroscopic Investigation of Initial Combustion Stages in a SI Engine Fuelled with Ethanol and Gasoline

Istituto Motori - CNR-S. Di Iorio, A. Irimescu, S.S. Merola, P. Sementa, B. M. Vaglieco
  • Technical Paper
  • 2017-32-0092
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
It is well known that ethanol can be used in spark-ignition (SI) engines as a pure fuel or blended with gasoline. High enthalpy of vaporization of alcohols can affect air-fuel mixture formation prior to ignition and may form thicker liquid films around the intake valves, on the cylinder wall and piston crown. These liquid films can result in mixture non-homogeneities inside the combustion chamber and hence strongly influence the cyclic variability of early combustion stages. Starting from these considerations, the paper reports an experimental study of the initial phases of the combustion process in a single cylinder SI engine fueled with commercial gasoline and anhydrous ethanol, as well as their blend (50%vol alcohol). The engine was optically accessible and equipped with the cylinder head of a commercial power unit for two-wheel applications, with the same geometrical specifications (bore, stroke, compression ratio). Ultra-violet (UV) natural emission spectroscopy measurements ranging from 250nm to 470nm wavelength and simultaneous thermodynamic analysis were used to better understand the effect of ethanol content on flame kernel inception and development. All experiments…
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Precise Measurement of Propagating Flame in 2-Stroke Gasoline Engine by Multiple Ion-Probes

Hiroshima Institute of Technology-Tomoaki Yatsufusa, Kentaro Takatani, Keigo Kii, Shinsuke Miyata
  • Technical Paper
  • 2017-32-0048
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
Multiple ion-probes method provides fine measurement on propagating flame by using multiple ion-probes installed tow-dimensionally on the wall surface of confined chamber. Each ion-probe detects the arrival of propagating flame and the detecting time is recorded. The data set of flame detecting times is able to re-generate the temporary and spatially detailed behavior of flame propagation. Because ion-probe itself generally has physical and thermal strength, multiple ion-probe method is suitable method for detailed measurement of the combustion resulting pulsatile high pressure such as in reciprocating piston engines.In the present study, flame measurement technic by multiple ion-probes has been experimentally introduced for measuring the combustion in 2-stroke gasoline engine. The present paper reports the detailed results of measurement on propagating flame in the engine. In addition, newly clarified technical issues of this technic is also mentioned. Experimental results shows that this technic is able to capture the flame even in IDLE operation, which usually results weak combustion and very small flame signal. This is realized by high-speed and high-amplification gain by spatially designed amplification circuit. Finally,…
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Investigation and Model-Based Compensation of the Pitch Dynamic Impact on Longitudinal Acceleration Measurement on Motorcycles

University of Applied Sciences Upper Austria-Alexander Winkler, Gernot Grabmair
  • Technical Paper
  • 2017-32-0053
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
In this study we focus on systematic disturbances caused by the motorcycle pitch dynamic when measuring longitudinal acceleration on motorcycles using low-cost acceleration sensors. Major systematic influences in the sensor measurement like gravitational acceleration, suspension dynamics and the road slope are addressed. During acceleration phases the motorcycle pitch angle changes according to the suspension setting. As a result the longitudinal sensing axis of the accelerometer includes parts of the gravitational acceleration and lags parts of the longitudinal acceleration. Gravitational acceleration has also significant influence on inclined roads. To obtain correct values of the effective longitudinal acceleration, the disturbances in the measured signal are analyzed and in further consequence compensated. For this purpose a linearized in-plane-dynamics model of the motorcycle is derived from a comprehensive multibody simulation. The mathematical description of the motorcycle behavior includes the systematic influences and serves as a basis for the model-based compensation. A state observer for pitch angle estimation and road slope reconstruction is designed. As a result the measured acceleration can be corrected with the estimated quantities. In the course…
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Influence of Engine Speed on Autoignition and Combustion Characteristics in a Supercharged HCCI Engine

Nihon University-Akira Iijima, Hideo Shoji
Nihon University Graduate School-Hiroto Tanaka, Tatsuya Sato, Shuntaro Takano, Yuya Motoki, Hyota Hoshino, Yuya Higuchi
  • Technical Paper
  • 2017-32-0090
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
Homogeneous Charge Compression Ignition (HCCI) combustion has attracted widespread interest because it achieves high efficiency and can reduce particulate matter (PM) and nitrogen oxide (NOx) emissions simultaneously. However, because HCCI engines lack a physical means of initiating ignition, it is difficult to control the ignition timing. Another issue of HCCI engines is that the combustion process causes the cylinder pressure to rise rapidly. The time scale is also important in HCCI combustion because ignition depends on the chemical reactions of the mixture. Therefore, we investigated the influence of the engine speed on autoignition and combustion characteristics in an HCCI engine. A four-stroke single-cylinder engine equipped with a mechanically driven supercharger was used in this study to examine HCCI combustion characteristics under different engine speeds and boost pressures. The results revealed that the engine speed range can be expanded by a mechanically driven supercharger. It was also found that there was no change in the ignition delay time under conditions of a constant equivalence ratio even at different engine speeds. The findings of this study provide…
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