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Morii, Youhi
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Ignition Experiments by Nanosecond Repetitively Pulsed Discharges in Intense Turbulence for Super Lean Burn at Engine Condition

Institute of Fluid Science, Tohoku University-Kodai Uesugi, Youhi Morii, Taichi Mukoyama, Takuya Tezuka, Susumu Hasegawa, Hisashi Nakamura, Hidemasa Takana
Institute of Fluid Science, Tohoku University / ICE Lab. Far-Kaoru Maruta
  • Technical Paper
  • 2019-01-2160
Published 2019-12-19 by SAE International in United States
Ignition by Nanosecond Repetitively Pulsed Discharges (NRPD) at EXponential Increase of Minimum Ignition Energy (MIE-EXI) region under super lean SI engine conditions was studied. Fundamental experiments were conducted with a turbulent ignition test chamber with twin counter-rotating fans. The MIE-EXI region by arc discharge appeared over 6500 rpm of fan speed. In the MIE-EXI region (7000 rpm), successful ignition was achieved by establishing coupled ignition kernels with NRPD at 15 kHz although ignition was unsuccessful at 1 kHz. Results show that ignition by NRPD has potential advantages for lean burn applications. Preliminary engine test results with NRPD were also demonstrated.
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Numerical Simulation on Soot Formation in Diesel Combustion by Using a CFD Code Combined with a Parallelized Explicit ODE Solver

Japan Aerospace Exploration Agency-Youhi Morii
Mazda Motor Corp.-Kiyotaka Sato, Hidefumi Fujimoto
Published 2014-10-13 by SAE International in United States
The objective of the present study is to analyze soot formation in diesel engine combustion by using multi-dimensional combustion simulations with a parallelized explicit ODE solver. Parallelized CHEMEQ2 was used to perform detailed chemical kinetics in KIVA-4 code. CHEMEQ2 is an explicit stiff ODE solver developed by Mott et al. which is known to be faster than traditional implicit ODE solvers, e.g., DVODE. In the present study, about eight times faster computation was achieved with CHEMEQ2 compared to DVODE when using a single thread. Further, by parallelizing CHEMEQ2 using OpenMP, the simulations could be run not only on calculation servers but also on desktop machines. The computation time decreases with the number of threads used. The parallelized CHEMEQ2 enabled combustion and emission characteristics, including detailed soot formation processes, to be predicted using KIVA-4 code with detailed chemical kinetics without the need for reducing the reaction mechanism.After validating the code, diesel engine combustion was simulated to investigate combustion and emission characteristics, focusing on soot formation, growth and oxidation at different EGR ratios. To predict soot formation,…
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