Faculty Profiles - KAWAHARA Nobuyuki

Papers - KAWAHARA Nobuyuki

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Effect of swirl flow on the main chamber combustion dynamics of methane in a passive pre-chamber spark ignition engine

MD. Tanvir Khan, Nobuyuki Kawahara, Yoshimitsu Kobashi, Isao Yamane, Towa Hirayama, Ayumi Shimizu, Sekai Miyamoto

Fuel 391 134735 - 134735 2025.7

Development of Ignitability Evaluation Index by Optical Combustion Analyzer

Nayuha Moriguchi, Yoshimitsu Kobashi, Nobuyuki Kawahara, Masahide Takagi, Satoshi Kawauchi

The 28th Small Powertrains and Energy Systems Technology Conference (SETC 2024), Poster 2024.11

Improvement of Lean Burn Characteristics with Ozone Addition in a Diesel Micro-Pilot Natural Gas Engine Reviewed

Yoshimitsu Kobashi, Shoki Miyata, Nobuyuki Kawahara, Ryuya Inagaki

The 28th Small Powertrains and Energy Systems Technology Conference (SETC 2024), JSAE 20249104/ SAE 2024-32-0104 2024.11

Hydrogen concentration measurements using spark induced breakdown spectroscopy in a real engine Reviewed

Dongchan Kim, Quancen Wan, Qing Nian Chan, Yoshimitsu Kobashi, Nobuyuki Kawahara, Sanghoon Kook

Proceedings of the Combustion Institute 40 ( 1-4 ) 105209 - 105209 2024.6

Droplet diameter and axial velocity measurements near a nozzle exit of an automotive fuel injector using PDA Invited

Nobuyuki Kawahara

2023.10

Visualization of Combustion and Flow Phenomena in a Methane-Fueled Passive Pre-Chamber Ignited Gas Engine Reviewed

MD Tanvir KHAN, Nobuyuki Kawahara, Yoshimitsu Kobashi, Towa Hirayama, Ayumi Shimizu, Sekai Miyamoto

2023 JSAE/SAE Powertrains, Energy and Lubricants Int. Meeting, JSAE 20239119, SAE 2023-32-0057 2023.8

PREMIER Combustion of Natural Gas Ignited with Diesel Fuel in a Dual Fuel Engine - Effects of EGR and Supercharging on End-gas Auto Ignition and Thermal Efficiency- Reviewed

Yoshimitsu Kobashi, Kengo Kishimoto, Nobuyuki Kawahara

2023 JSAE/SAE Powertrains, Energy and Lubricants Int. Meeting, JSAE 20239121, SAE 2023-32-0016 2023.8

Spatially and temporally resolved plasma formation on alumina target in microwave-enhanced laser-induced breakdown spectroscopy Reviewed

Yuji Ikeda, Joey Kim Soriano, Nobuyuki Kawahara, Ikuo Wakaida

Spectrochimica Acta Part B: Atomic Spectroscopy 197 106533 - 106533 2022.11

Evaluation of ignition characteristics of diesel spray using large eddy simulation Reviewed

Nobuyuki Kawahara

22nd Annual Conference on Liquid Atomization and Spray Systems-ILASS-Asia 2022, Paper No. 40 2022.10

Plasma formation and its sustainment in time and space in microwave enhanced laser induced breakdown spectroscopy Reviewed

Yuji Ikeda, Joey Kim Soriano, Nobuyuki Kawahara

20th Int. Symp. on the Application of Laser and Imaging Techniques on Fluid Mechanics (LISBON) 2022.7

Spark-induced breakdown spectroscopy in a direct-injected natural gas spark-ignition engine Reviewed

Nobuyuki Kawahara, Kohei Miyao

20th Int. Symp. on the Application of Laser and Imaging Techniques on Fluid Mechanics (LISBON) 2022.7

Visualization of End-gas Auto-ignition during PREMIER Combustion in a Dual-fuel Gas Engine Reviewed

Nobuyuki Kawahara, Eiji Tomita

The 10th International Conference on Modeling and Diagnostics for Advanced Engine Systems (COMODIA 2022), C9-3 2022.7

Measurement of Cyclic Variation of the Air-to-Fuel Ratio of Exhaust Gas in an SI Engine by Laser-Induced Breakdown Spectroscopy Reviewed

Yuji Ikeda, Nobuyuki Kawahara

Energies 15 ( 9 ) 3053 - 3053 2022.4

Authorship：Last author Publishing type：Research paper (scientific journal) Publisher：MDPI AG

Temporally and spatially resolved laser-induced breakdown spectroscopy (LIBS) was applied to a four-stroke, single-cylinder test engine’s cyclic exhaust gas to demonstrate engine performance. The LIBS technique provided quantitative air-to-fuel ratio (A/F) measurements by generating localized breakdown plasma during the compression and exhaust strokes. The results showed that the timing and duration settings of the emission energy ionization and molecular spectra affect the intensity peaks. Optimum measurements performed between 200 ns and 10 ms after breakdown resulted in observed atomic spectra of CI (248 nm), Hβ (485 nm), Hα (656 nm), NI (745, 824 nm), and OI (777, 844 nm). The intensities of CI (248 nm) and Hα (656 nm) decreased with increasing A/F, whereas the intensity ratios of NI and OI remained constant. A decrease in the intensity ratio of C/O and Hα/O was observed as the A/F increased. This study is a major step toward defining a means of using LIBS to control the A/F ratio in gasoline engines by focusing on the exhaust gas rather than the flame.

DOI： 10.3390/en15093053

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PREMIER combustion characteristics of a pilot fuel-ignited dual-fuel biogas engine with consideration of cycle-to-cycle variations Reviewed

Taku Imamoto, Nobuyuki Kawahara, Eiji Tomita

Fuel 314 123049 - 123049 2022.4

Fuel spray impingement and liquid film formation in a gasoline direct-injection spark-ignition engine Reviewed

Y. Tomomatsu, N. Kawahara, E. Tomita

International Journal of Environmental Science and Technology 20 ( 1 ) 477 - 488 2022.3

Droplet diameter measurement near a nozzle exit of a common-rail Diesel injector using PDA Reviewed International journal

Nobuyuki Kawahara, Rikuya Yamada, Eiji Tomita

15th International Conference on Liquid Atomization and Spray Systems, ICLASS2021, Paper No. 247 2021.8

Differences between PREMIER combustion in a dual-fuel gas engine and knocking with pressure oscillations Invited

Nobuyuki Kawahara

7th International Seminar on Motor Vehicle Environmental Protection 2021.7

Performance, emissions and end-gas autoignition characteristics of PREMIER combustion in a pilot fuel-ignited dual-fuel biogas engine with various CO2 ratios Reviewed International journal

Alireza Valipour Berenjestanaki, Nobuyuki Kawahara, Kazuya Tsuboi, Eiji Tomita

Fuel 286 119330 - 119330 2021.2

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier BV

Biogas, a renewable and alternative energy, has recently gained attention as an environmentally friendly fuel for power generation in internal combustion (IC) engines. This study aimed to investigate the effect of the carbon dioxide (CO2) to methane (CH4) ratio in a dual-fuel gas engine. It is known that gaseous fuel combustion at high loads is accompanied by knocking if an appropriate combustion controlling strategy is not applied. Therefore, premixed mixture ignition in the end-gas region (PREMIER) combustion was proposed under high load conditions. Experiments were carried out using a dual-fuel gas engine under supercharged conditions, with an intake pressure of 200 kPa. Simulated biogas consisting of CH4 and CO2 was used as a primary fuel and diesel was used as a pilot fuel. The pilot fuel injection timing was varied during the experiments. The indicated mean effective pressure (IMEP) and thermal efficiency increased as injection timing was advanced. With the addition of CO2, the thermal efficiency of PREMIER combustion was slightly increased, although the IMEP was slightly decreased. The unburned gas temperature for PREMIER combustion increases as a function of the CO2 content of the mixture. Due to compression by flame propagation, high unburned gas temperatures in dual-fuel gas engines are important for achieving autoignition inside the end-gas region under PREMIER combustion conditions.

DOI： 10.1016/j.fuel.2020.119330

Web of Science

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Multidimensional CFD Simulation of PAH Formation Process in Diesel Spray Combustion Reviewed

Nobuyuki Kawahara, Hirotomo Daido, Eiji Tomita

21st Annual Conference on Liquid Atomization and Spray Systems-ILASS-Asia 2020, ILASS-Asia2020-3-12 2020.10

Quantitative evaluation of liquid film formation process from DISI injector using LIF method Reviewed

Yasutaka Tomomatsu, Nobuyuki Kawahara, Eiji Tomita

21st Annual Conference on Liquid Atomization and Spray Systems-ILASS-Asia 2020, ILASS-Asia2020-3-11 2020.10

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Papers - KAWAHARA Nobuyuki