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The Influence of Connecting-Rod Specifications on the Combustion-Noise Generation from a Diesel Engine

Yamaguchi University-Hitoshi Oguchi, Koki Minato, Takehiko Seo, Masato Mikami
Published 2019-06-05 by SAE International in United States
We experimentally investigated the influence of shifting natural frequencies of the internal transmission system depending on the connecting-rod specifications on the characteristics of noise radiated from a single-cylinder diesel engine. We used FFT analysis to investigate the influence of shifting natural frequencies of the internal transmission system on the radiated noise characteristics. By changing the thinned portion of the connecting-rod, we confirmed that the natural frequency of the piston-connecting-rod-coupled vibration differed from another natural frequency of the engine structure, and thus the engine noise was reduced. This research studied the time-frequency characteristics of combustion impact and engine noise by wavelet analysis of in-cylinder pressure and sound pressure. We examined the vibration-transmission characteristics through the relationship between the maximum engine noise power and the maximum combustion energy in the same cycle for the main frequencies of combustion noise. Two types of connecting-rods were used: the original connecting-rod and a connecting rod that has a short-thinned portion (STP). By shortening the thinned portion of the connecting-rod, the natural frequency of the piston-connecting-rod-coupled vibration became around 2800 Hz…
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Group Combustion Excitation in Randomly Distributed Droplet Clouds Based on Flame-spread Characteristics with Two-droplet Interaction in Microgravity

Yamaguchi University-Masato Mikami
Sebelas Maret University-Herman Saputro, Laila fitriana
  • Technical Paper
  • 2017-32-0077
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
Experiments of flame-spread of fuel droplets have been performed in microgravity actively. However, the experiment has limitation in the number of droplets due to relatively short microgravity durations in the ground based facilities. It is difficult to conduct flame spread experiments of large scale droplet clouds in microgravity. This study conducted simulation of flame-spread behavior in randomly distributed large-scale droplet clouds by using a percolation approach, in order to make a theoretical link the gap between droplet combustion experiments and spray combustion phenomenon with considering two-droplet interaction. Droplets are arranged at lattice points in 2D lattice. The occurrence probability of group combustion (OPGC) is calculated as a function of the mean droplet spacing (S/d0)m. The (S/d0)m for 0.5 OPGC is defined as the critical mean droplet spacing (S/d0)critical, which separates the droplet cloud into two groups if the lattice size becomes infinity; relatively dense droplet clouds in which the group combustion is excited through flame spread and dilute droplet clouds in which the group combustion in is never excited. The results show that in 2D…
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Combustion and Noise Characteristics in a Diesel Engine with Hydrogen Addition and Pilot Injection

Yamaguchi University-Ryota Sakane, Toshiki Fujimura, Takehiko Seo, Masato Mikami
Published 2015-09-01 by SAE International in United States
We experimentally investigated effects of pilot diesel-fuel injection on ignition timing variation and noise reduction in a diesel engine with hydrogen addition to the intake pipe. The pilot diesel-fuel injection suppressed ignition timing variation which was significant under hydrogen addition conditions. The heat release by the pilot diesel-fuel injection stably acted as an ignition source of the hydrogen-air mixture. The maximum in-cylinder pressure rise rate increased with the hydrogen fraction. However, the sound pressure level attained minimum around a specific hydrogen fraction.
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Effect of Hydrogen Fraction in Intake Mixture on Combustion and Exhaust Emission Characteristics of a Diesel Engine

Yamaguchi University-Toru Miyamoto, Masato Mikami, Naoya Kojima
Honda R&D Co., Ltd.-Hajime Kabashima, Yasuhiro Urata
Published 2009-09-13 by Consiglio Nazionale delle Ricerche in Italy
The present study experimentally investigated the performance and emission characteristics of the diesel engine with hydrogen added to the intake air at late diesel-fuel injection timings. The diesel-fuel injection timing and the hydrogen fraction in the intake mixture were varied while the gross heating value per second of diesel fuel and hydrogen was kept constant at a certain value. NO showed minimum at specific hydrogen fraction. The maximum rate of incylinder pressure rise also showed minimum at 10 vol% hydrogen fraction. The indicated thermal efficiency was almost constant or slightly increased with small amount of hydrogen. A combination of hydrogen addition and late diesel-fuel injection timing contributed to low temperature combustion, in which NO decreased without the increase in unburned fuel.
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Effects of Fuel Volatility on Combustion Characteristics of PCCI Diesel Engine

Yamaguchi University-Bansei Kobayashi, Shinji Najima, Masato Mikami, Naoya Kojima
Honda R&D Co., Ltd.-Tomohiro Kanda
Published 2007-07-23 by SAE International in United States
In PCCI diesel engine, the fuel is injected much earlier than the injection timing of conventional diesel engines. Exhaust-emission improvements are attained by the lean-premixed combustion. It is expected that fuel properties influence mixture formation and combustion characteristics. In this research, experiments were carried out using a single-cylinder PCCI diesel engine operating on pure fuels with different volatilities. The injection timing and overall equivalence ratio of the premixed spray were varied. The results showed that the maximum heat release rate was smaller for lower-volatility fuel while ISFC was maintained smaller. So the combustion of a lower-volatility fuel would moderately make progress.
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Experimental Study on Intake Noise Generation in Marine Outboard Motors

Yamaguchi University-Takeshi ICHII, Masato MIKAMI, Naoya KOJIMA
YAMAHA MARINE Co., Ltd.-Yuji HORI
  • Technical Paper
  • 2005-32-0076
Published 2005-10-12 by Society of Automotive Engineers of Japan in Japan
Noise reduction is the needs of the time even for (demanded even from) the outboard motors which are typically used under heavy load and in higher engine speed for an extended period of time. For the sound emitted by an outboard motor, the acoustic impression to human ears largely depends on the high frequency intake noise. The high frequency intake noise is generated by the air flow that passes through the intake pipes at high speed. The test performed with a flow stand bench demonstrated that the sound pressure increment relative to the increasing flow velocity is definitely larger in high frequency band compared with that in low frequency band. Pressure wave form inside the intake pipe was measured relative to the crank angle. The measurement revealed that the high frequency sound is generated in the later part of the intake stroke when the flow velocity within the intake pipe becomes the highest.
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Noise Generating Mechanism at Idling for a Four-cylinder In-line Diesel Engine

Yamaguchi University-Naoya Kojima
Hino Motors, Ltd.-Yasuo Miura
Published 2003-05-05 by SAE International in United States
The separation of combustion noise and mechanical noise from the total noise of a four-cylinder in-line diesel engine at idling was carried out with high accuracy by changing the fuel injection timing. The mechanical noise, which accounts for the major share at 93%, was then separated into noises from the typical mechanical causes, and the valve train was found to be the major noise source. From analysis of the noise generating mechanism for the valve train, it was clarified that the noise was caused mainly by the gear rattling owing to the variation in the camshaft drive torque.
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19 Separation of Combustion Noise using Transient Noise Generation Model

Yamaguchi University-Masato MIKAMI, Naoya KOJIMA
Graduate School of Yamaguchi University-Masato KOMORI, Yasuo MIURA
  • Technical Paper
  • 2002-32-1788
Published 2002-10-29 by Society of Automotive Engineers of Japan in Japan
In a running engine, various impacts are excitation sources for structural vibrations and engine noises. Engine noises are classified, depending on their excitation sources, into the combustion noise, the combustion induced mechanical noise and the mechanical noise. It is difficult to measure such noises separately because some impacts occur closely in time and space. In this paper, a transient noise generation model of an engine was proposed considering vibration and its damping of engine structure. The present model was verified through the single explosion excitation experiment for a stationary engine. Using the noise generation model, the combustion noise was separated from the total noise radiating from a running four-stroke gasoline engine for motorcycles. It was found that the combustion noise had larger power at lower frequencies than higher frequencies. However, its contribution to the total engine noise was relatively small.
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