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Experimental Study of Aerodynamic Drag Control on Bluff Body using Synthetic Jets

Utsunomiya University-Naoto Kato, Shunsuke Watanabe, Hiroaki Hasegawa
  • Technical Paper
  • 2019-32-0538
Published 2020-01-24 by Society of Automotive Engineers of Japan in Japan
Since flow separation causes increase of the drag on bluff bodies, its control method has been studied for many years. Active control methods are currently focused as an alternative to passive ones because they impose a larger drag penalty under certain conditions. Although the effectiveness of a steady jet using suction, blowing or pulsed jets has been demonstrated, it is difficult to obtain an effect commensurate with weight increase because the mechanism is complicated.One method of solving this problem is a synthetic jet. Synthetic jets are produced by periodic ejection and suction of fluid from an orifice induced by oscillation of a diaphragm inside a cavity. Small engine powered vehicles demand less drag, a compact package and light weight because the drivers expect fuel efficiency, load capacity and economy. Synthetic jets can supply them because they contribute drag reduction and require only simple components.In this study, the influence of synthetic jets on the drag of a simple bluff body representing a road vehicle is measured. Drag measurement was performed by varying synthetic jet parameters: jet…
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Two-Degree-of-Freedom Controller Design for Diesel Engine Airpath System Considering Dynamics of Turbocharger and Manifolds

Utsunomiya University-Mitsuo Hirata, Tomofumi Hayashi, Teruhiko Asahi
University of Tokyo-Motoki Takahashi, Yudai Yamazaki, Shigehiko Kaneko
  • Technical Paper
  • 2019-01-2321
Published 2019-12-19 by SAE International in United States
We developed a two-degree-of-freedom (2-DOF) control system for a diesel engine airpath system. First, a physical airpath model of the diesel engine was developed, followed by a nonlinear feedforward controller developed based on the inverse characteristics of the developed physical model. The dynamics of turbocharger and manifolds were considered in the feedforward controller to improve the transient response. The feedback controller was designed by H∞ control theory considering plant nonlinearities as uncertainties. The feedforward and feedback controllers were implemented as a 2-DOF freedom control scheme. The effectiveness of the proposed method was evaluated by conducting simulation and experiment.
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Study on Lubricating Oil Consumption from Evaporation of Oil-Film on Cylinder Wall for Diesel Engine

SAE International Journal of Fuels and Lubricants

Utsunomiya University-Yasuo Harigaya
Kyushu Sangyo University-Mitsuhiro Soejima
  • Journal Article
  • 2017-01-0883
Published 2017-03-28 by SAE International in United States
It is effective in engine fuel economy to reduce the viscous friction by applying lubricating oil with low viscosity. The lower viscosity such as SAE0W20, however, increase lubricating oil consumption, LOC. In addition, it has become urgent to reduce the LOC because the emission of the sulfide ash, phosphorous and sulfur contents degrades the diesel particulate filter and the de-NOx catalyst, in addition to which the emission of metal oxide contents from oil additives can cause pre-ignition in highly supercharged spark ignition engines.In order to clarify the LOC mechanism of low viscosity oils, the LOC rates were measured with a supercharged diesel engine under various operating conditions when lubricated with SAE30 or SAE10W30 test oil, and the resulting data have been compared with the rates of the evaporation from the oil-film on the cylinder wall, LOE, as predicted by the devised analysis method for multi-species component oils.Results obtained show that the change of LOC with the test oil is mostly equal to that of LOE under the same engine operating conditions concerning the gas pressure,…
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Development of a Slip Speed Control System for a Lockup Clutch (Part III)

SAE International Journal of Engines

Utsunomiya University-Fumiyo Iino, Mitsuo Hirata
Nissan Motor Co., Ltd.-Yutaka Kaneko, Kazutaka Adachi
  • Journal Article
  • 2009-01-0955
Published 2009-04-20 by SAE International in United States
It is difficult for a conventional robust control algorithm to assure the performance of a slip speed control system, because the plant (lockup system) includes the nonlinear characteristics of the hydraulic system and large changes in the parameters of the slip model at low vehicle speed. The purpose of this study is to reduce the fuel consumption and improve the drivability of vehicles at takeoff by using a slip speed control system.Providing a large feedback gain is effective in reducing the influence of nonlinearity. However, since the operating parameters of the lockup clutch change depending on the driving conditions, that is not possible. A feedback compensator with a gain-scheduled H∞ control method was used in this study to solve these problems. The effectiveness of the slip speed control system was demonstrated in driving tests. Using this control system, the slip speed can be controlled with high accuracy, thereby reducing unnecessary revving of the engine. The system is expected to contribute to improved fuel economy.
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An Experimental Study on Relationship between Lubricating Oil Consumption and Cylinder Bore Deformation in Conventional Gasoline Engine

SAE International Journal of Engines

Utsunomiya University-Yasuo Harigaya
Musashi Institute of Technology-Naoki Iijima, Takeo Sakurai, Masaaki Takiguchi
  • Journal Article
  • 2009-01-0195
Published 2009-04-20 by SAE International in United States
It is well known that lubricating oil consumption (LOC) is much affected by the cylinder bore deformation occurring within internal combustion engines. There are few analytical reports, however, of this relationship within internal combustion engines in operation.This study was aimed at clarifying the relationship between cylinder bore deformation and LOC, using a conventional in-line four-cylinder gasoline engine. The rotary piston method developed by the author et al. was used to measure the cylinder bore deformation of the engine’s cylinder #3 and cylinder #4. In addition, the sulfur tracer method was applied to measure LOC of each cylinder. LOC was also measured by changing ring tension with a view to taking up for discussion how piston ring conforms to cylinder, and how such conformability affects LOC. Their measured results were such that the cylinder bore deformation was small in the low engine load area and large in the high engine load area. In particular, it was shown that there was a different tendency in deformation between cylinder #3 and cylinder #4 around the top dead center.…
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