The SAE MOBILUS platform will continue to be accessible and populated with high quality technical content during the coronavirus (COVID-19) pandemic. x

Your Selections

Teraji, Atsushi
Show Only

Collections

File Formats

Content Types

Dates

Sectors

Topics

Authors

Publishers

Affiliations

Events

   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

In-cylinder flow design based on the representative scales of turbulence and premixed combustion

Nissan Motor Co., Ltd.-Yuko Mito, Taisuke Shiraishi, Atsushi Teraji
  • Technical Paper
  • 2019-01-2210
Published 2019-12-19 by SAE International in United States
Dilution combustion with exhaust gas recirculation (EGR) has been applied for the improvement of thermal efficiency. In order to stabilize the high diluted combustion, it is important to form an appropriate turbulence in the combustion cylinder. Turbulent intensity needs to be strengthened to increase the combustion speed, while too strong turbulence causes ignition instability. In this study, the factor of combustion instability under high diluted conditions was analyzed by using single cylinder engine test, optical engine test and 3D CFD simulation. Finally, methodology of in-cylinder flow design is attempted to build without any function by taking into account the representative scales of turbulence and premixed combustion.
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Mechanism Analysis on LSPI Occurrence in Boosted S. I. Engines

Nissan Motor Co., Ltd.-Masaharu Kassai, Hiroki Hashimoto, Taisuke Shiraishi, Atsushi Teraji, Toru Noda
Published 2015-09-01 by SAE International in United States
Mechanism of suddenly occurring behavior of low speed pre-ignition (LSPI) in boosted spark ignition (SI) engines was analyzed with various experimental methodologies.Endoscope-visualized 1st cycle of LSPI showed droplet-like luminous flame kernels as the origin of flame propagation before spark ignition. With the oil lubricated visualization engine, droplets flying were observed only after enough accumulation of fuel at piston crevice. Also, it was confirmed that subsequent cycles of LSPI occur only after enough operation time.These results indicated that local accumulation of liner adhered fuel and saturation of oil dilution can be a contributing factor to the sudden occurrence of LSPI.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

The Effects of Ignition Environment and Discharge Waveform Characteristics on Spark Channel Formation and Relationship between the Discharge Parameters and the EGR Combustion Limit

SAE International Journal of Engines

Chiba University-Yasuo Moriyoshi
Nissan Motor. Co., Ltd.-Taisuke Shiraishi, Atsushi Teraji
  • Journal Article
  • 2015-01-1895
Published 2015-09-01 by SAE International in United States
In order to realize the high compression ratio and high dilution combustion toward improvement in thermal efficiency, the improvement in stability of ignition and initial phase of combustion under the high gas flow field is the major challenge. In terms of the shift on the higher power side of the operating point by downsizing and improvement of real world fuel consumption, the improvement of ignitability is increasingly expected in the wide operating range also including high load and high engine speed region. In this study, the effects of the gas pressure, gas flow velocity near the spark gap at ignition timing, and discharge current characteristics on spark channel formation were analyzed, focusing on restrike event and spark channel stretching in the spark channel formation process. And the relationship between the average discharge current until 1 ms and the EGR combustion limit was considered.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

TEM Analysis of Soot Particles Sampled from Gasoline Direction Injection Engine Exhaust at Different Fuel Injection Timings

Meiji University-Kazuya Miyashita, Yusei Fukuda, Yushun Shiozaki, Katsufumi Kondo, Tetsuya Aizawa
Nissan Motor Co., Ltd.-Dai Yoshikawa, Daisuke Tanaka, Atsushi Teraji
Published 2015-09-01 by SAE International in United States
For better understanding of in-cylinder soot formation processes and governing factors of the number of emitted soot particles of Gasoline Direct Injection (GDI) engines, Transmission Electron Microscope (TEM) analysis of morphology and nanostructure of the soot particles sampled in the exhaust should provide useful information. However, the number concentration of the soot particles emitted from GDI engines is relatively low, which was impeding reliable morphological analysis of the soot particles based on a sufficient number of sampled particles. Therefore, in the present study, a water-cooled thermophoretic sampler for simple and direct sampling of exhaust soot particles was developed and employed, which enabled to obtain a sufficient number of particle samples from the exhaust with Particulate Number (PN) 105 #/cc level for quantitative morphology analysis. Using the developed sampler, soot particles were sampled from the exhaust of a single-cylinder GDI test engine operated with three different fuel injection timings (advanced, normal, retarded) and their morphology and nanostructure were quantitatively analyzed. Number concentration and size distribution of the emitted particles were simultaneously measured with Scanning Mobility Particle…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A Comprehensive Model to Predict the Initial Stage of Combustion in SI Engines

Nissan-Atsushi Teraji, Taisuke Shiraishi
Politecnico di Milano-Tommaso Lucchini, Luca Cornolti, Gianluca Montenegro, Gianluca D'Errico, Marco Fiocco
Published 2013-04-08 by SAE International in United States
A correct prediction of the initial stages of the combustion process in SI engines is of great importance to understand how local flow conditions, fuel properties, mixture stratification and ignition affect the in-cylinder pressure development and pollutant formation. However, flame kernel growth is governed by many interacting processes including energy transfer from the electrical circuit to the gas phase, interaction between the plasma channel and the flow field, transition between different combustion regimes and gas expansion at very high temperatures.In this work, the authors intend to present a comprehensive, multi-dimensional model that can be used to predict the initial combustion stages in SI engines. In particular, the spark channel is represented by a set of Lagrangian particles where each one of them acts as a single flame kernel. Each particle is convected by the gas flow and its growth is governed by flame speed and thermal expansion due to the energy transfer from the electrical circuit. From particle positions and size it is then possible to reconstruct the flame surface density distribution, that is then…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Improvement of Combustion Stability under Cold Ambient Condition by Mixture Control

SAE International Journal of Engines

Nissan Motor Co., Ltd.-Manabu Hasegawa, Toru Nishizawa, Yoshihiro Imaoka, Keiji Kawamoto, Atsushi Teraji, Shuichi Iio
  • Journal Article
  • 2013-01-1303
Published 2013-04-08 by SAE International in United States
For diesel engine, lower compression ratio has been demanded to improve fuel consumption, exhaust emission and maximum power recently. However, low compression ratio engine might have combustion instability issues under cold temperature condition, especially just after engine started.As a first step of this study, cold temperature combustion was investigated by in-cylinder pressure analysis and it found out that higher heat release around top dead center, which was mainly contributed by pilot injection, was the key factor to improve engine speed fluctuation.For further understanding of combustion in cold condition, particularly mixture formation near a glow plug, 3D CFD simulation was applied. Specifically for this purpose, TI (Time-scale Interaction) combustion model has been developed for simulating combustion phenomena. This model was based on a reasonable combustion mode, taking into account the characteristic time scale of chemical reactions and turbulence eddy break-up. In addition, parameters of the ignition model and computational grids near glow plug were improved to apply under cold start conditions.As a result, the result of this study reveal that controlling an equivalence ratio and temperature…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Study of Improvement for Combustion Stability Under Cold Start Condition of DI Diesel Engine (2nd Rep.): Application of TI (Time-Scale Interaction) Combustion Model for Cold Start Condition

Nissan-Yoshihiro Imaoka, Toru Nishizawa, Shuichi Iio, Atsushi Teraji, Manabu Hasegawa, Keiji Kawamoto
  • Technical Paper
  • 2012-08-0603
Published 2012-10-03 by Society of Automotive Engineers of Japan in Japan
Diesel engines of low compression ratio have issues of white smoke and combustion instability under cold start conditions. TI (Time-scale Interaction) combustion model applied cold start conditions in order to resolve those issues. TI combustion model has been developed for simulating combustion phenomena with high accuracy from premixed charged combustion to diffusion combustion. This model is based on a reasonable combustion mode, taking into account the characteristic time scale of chemical reactions and turbulence eddy break-up. In addition, parameters of the ignition model and computational grids near glow-plug were improved to apply under cold start conditions. Comparisons of measured and calculated heat release patterns show good agreement under cold conditions. It was shown by application of TI combustion model under cold start conditions that the fuel reaction near the glow plug is significant for ignition.
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A Study of Rich Flame Propagation in Gasoline SI Engine Based on 3-D Numerical Simulations

Nissan Motor Co. Ltd.-Atsushi Teraji
Renault-Nissan Technology and Business Center-Anand Gurupatham
Published 2011-10-06 by The Automotive Research Association of India in India
The objective of this work was to improve the accuracy of the combustion speed estimation in rich fuel condition (φ ≻ 1.2) as in case of Gasoline Direct Injection (GDI) engine. During rich fuel mixture combustion, the accuracy of calculation of laminar burning velocity deteriorates because of not considering the flame stretch. In the present study, the unstable flame due to the imbalance of the mass diffusion and the temperature diffusion of the fuel (Lewis Number (Le) ≺ 1.0) was modeled. The laminar burning speed model was developed by considering the stretch. It was applied with three-dimensional combustion simulation tools together with the Universal Coherent Flamelet Model (UCFM), a flame propagation model. The model has shown the capability to reproduce the heat generation (heat release rate) at high accuracy in comparison with experimental data. The simulation was carried out for both homogeneous and the stratification combustion (includes GDI) and validated with experimental data.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Development of Flame Propagation Model considering Lewis Number Effect for Fast Idle Condition

Nissan Motor Co. Ltd.-Atsushi Teraji
Renault-Nissan Technology and Business Center-Anand Gurupatham
Published 2011-08-30 by SAE International in United States
The objective of this work was to improve the accuracy of the combustion speed estimation in rich fuel condition (φ ≻ 1.2) as in case of Gasoline Direct Injection (GDI) engine. During rich fuel mixture combustion, the accuracy of calculation of laminar burning velocity deteriorates due to not considering the flame stretch. In the present study, the unstable flame was formed due to the imbalance of the mass diffusion and the temperature diffusion of the fuel (Lewis Number (Le) ≺1.0) was modeled. The laminar burning speed model was developed by considering the stretch. It was applied with three-dimensional combustion simulation tools together with the Universal Coherent Flamelet Model (UCFM), a flame propagation model. The model has shown the capability to reproduce the heat generation (heat release rate) at high accuracy in comparison with experimental data. The simulation was carried out for both homogeneous and the stratification combustion (includes GDI) and validated with experimental data.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Transient Analysis of the Piston Temperature with Consideration of In-cylinder Phenomena Using Engine Measurement and Heat Transfer Simulation Coupled with Three-dimensional Combustion Simulation

SAE International Journal of Engines

NISSAN MOTOR CO., LTD.-Hideaki Mizuno, Koichi Ashida, Atsushi Teraji, Kenshi Ushijima, Shinichi Takemura
  • Journal Article
  • 2009-01-0187
Published 2009-04-20 by SAE International in United States
This study examined a method of predicting the piston temperature in reciprocating internal combustion engines with the aim of developing lightweight pistons. Since the piston temperature is strongly affected by the in-cylinder temperature distribution and turbulence, it is necessary to consider the effects of flame propagation, cooling by the intake air, temperature rise due to combustion, in-cylinder flow and the combustion chamber shape. A three-dimensional combustion simulation that can take these effects into consideration was run to calculate the heat transfer coefficient from the piston crown surface and the gas temperature. The results were used as the boundary conditions for an analysis of heat transfer from the piston, and a method was thus developed for analyzing the piston temperature. The hardness method was used to obtain the piston temperature distribution and maximum temperature during engine operation, and a comparison was made with the analytical results to examine the effects of flame propagation.
Annotation ability available