研究者業績
基本情報
- 所属
- 千葉大学 大学院工学研究院 教授次世代モビリティパワーソース研究センター センター長
- 学位
- 工学博士工学修士
- J-GLOBAL ID
- 200901076796461220
- researchmap会員ID
- 1000010405
- 外部リンク
研究キーワード
8経歴
5-
2013年4月 - 現在
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2008年4月 - 現在
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1995年 - 2008年3月
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1994年 - 1995年
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1990年 - 1994年
学歴
4-
- 1990年
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- 1990年
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- 1985年
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- 1985年
委員歴
4-
2018年12月 - 2020年12月
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2015年1月
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2011年4月
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2008年4月
受賞
6-
2015年
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2011年12月
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2002年
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2001年
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1995年
論文
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Journal of Engineering for Gas Turbines and Power 146(10) 2024年8月21日 査読有りAbstract Although prechamber (PC) is regarded as a promising solution to enhance ignition in lean-burn gas engines, a lack of comprehensive understanding of PC jet penetration dynamics remains. This study proposed a zero-dimensional (0D) model for PC jet penetration, considering the mixing of combustion products and unburned gases in jets and the floating ejection pressure. A combustion completion degree was defined by employing fuel properties and heat release to estimate the time-varying jet density. Pressure differences between the PC and the main chamber (MC) were referred to as the ejection pressure. Then, this model was validated against experimental data from a constant volume chamber (CVC) and a rapid compression and expansion machine (RCEM) with CH4-H2 blends at different equivalent ratios. Results showed that the proposed model can provide a good prediction in stationary and turbulent fields with the calibrated model coefficient. The overall jet penetration exhibits a t0.5 dependence due to its single-phase characteristic and the relatively lower density compared to the ambient gas in MC. The flame propagation speed and heat release in PC influence the combustion completion degree at the start of jet ejection. The mass fraction of burned gas in the ejected jet grows in response to the mixture equivalent ratio. Jet penetration is primarily driven by ejection pressure, with tip dynamics barely affected by the pressure difference after peaks. Tip penetration intensity rises with increasing fuel equivalent ratio and H2 addition, owing to the faster flame propagation. These findings can offer useful suggestions for model-based design and combustion model development for gas engines.
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自動車技術会論文集 55(6) 1084-1090 2024年燃焼室を大小二つに分割することにより，予混合気圧縮着火燃焼を多段化することができる．本稿では冷却損失低減および高効率を狙い，小燃焼室をピストン内部に設けたときの本燃焼方式の実現可能性とポテンシャルを3D-CFDにより明らかにした．
MISC
255-
日本機械学会論文集. B編 65(632) 1479-1484 1999年Since the local inhomogeneity of mixture concentration inside a combustion chamber affects the combustion characteristics, a basic research on combustion phenomenon in stratified charge conditions is required. The authors have made experiments with a constant-volume chamber, which can simulate an idealized stratified charge field by using a removable partition, to obtain the combustion characteristics. As a result, it was found that pressure behavior strongly depends on flame propagation process and that the unburnt hydrocarbon amount can be reduced when a charge stratification of two combustible mixtures or that of a combustible mixture and air are made, while it increases due to a bulk quench when a combustible mixture and a too lean incombustible mixture are charge stratified.
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SAE Technical Papers (1999-01-3330) 598 1999年To survive the severe regulations for both the exhaust gas emissions and fuel economy, research on small two-stroke gasoline engines from both the experimental and theoretical viewpoints is quite necessary. In the present study, firstly, performance tests of a direct injection small two-stroke gasoline model engine were carried out. Based on these experimental results, three-dimensional flow calculations from scavenging pipe to exhaust pipe during the gas-exchange and piston compression processes were made with the same experimental conditions. As a result, the gas exchange process was investigated and some problems were clarified. Secondly, parametric calculations with changing just exhaust port timings were performed to solve the problems found in the above calculations. Copyright © 1999 Society of Automotive Engineers, Inc.
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SAE Technical Papers (1999-01-3322) 539 1999年The authors have experimentally produced a new type of Rotary Valve (ca11ed R.V.) which has a unique gas sealing mechanism. In this study, first, the mechanical loss in the valve train was measured comparing to that of the poppet valve drive train, and it was found that the mechanical loss of rotary valve train is much lower level. Secondary, three dimensional numerical calculation of the flow field from the intake-port to in-cylinder during the intake stroke was carried out. As a result, it was found that the flow field is very complicated due to the interaction between the moving piston and valve and that the profiles of "valve notch" and intake port affect the flow field and then, the modification of profile with a round edge form of the "notch" enables higher mass flow rate. Copyright © 1999 Society of Automotive Engineers, Inc.
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日本機械学会論文集. B編 64(621) 1566-1573 1998年5月25日A pilot flame ignition system, which has superior characteristics in the high ignition energy and the large flame contact area to a conventional spark ignition system, is experimentally examined by the indicated pressure analysis and the high speed direct photography. A model combustion chamber, which simulates a Wankel-type direct injection stratified charge rotary engine, was employed to test the ignition performance of both the pilot flame ignition and spark ignition systems. As a result, it was found that the pilot flame system successfully ignites the very lean charge stratified mixture which the spark system fails to ignite and that the combustion characteristic difference using different ignition systems becomes small as the overall equivalence ratio is increased.
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Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B 64(621) 1566-1573 1998年5月A pilot flame ignition system, which has superior characteristics in the high ignition energy and the large flame contact area to a conventional spark ignition system, is experimentally examined by the indicated pressure analysis and the high speed direct photography. A model combustion chamber, which simulates a Wankel-type direct injection stratified charge rotary engine, was employed to test the ignition performance of both the pilot flame ignition and spark ignition systems. As a result, it was found that the pilot flame system successfully ignites the very lean charge stratified mixture which the spark system fails to ignite and that the combustion characteristic difference using different ignition systems becomes small as the overall equivalence ratio is increased.
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神奈川工科大学研究報告 B 理工学編 22(22) 31-38 1998年3月Prototype rotary valve of newly designed for gas sealing have been developed and possibility of plactical use for this rotary valve was confirmed. Therefore mechanical driving loss in the valve train was measured comparing that of the poppet valve drive train, and it was found that mechanical loss of rotary valve was very lower level. Related with the air flows rate from inlet pipe to cylinder through rotary valve, the numerical analysis of static coefficient of discharge and also, the unsteady calculate with a rotating rotary valve during the intake stroke was made to the dynamic effect. As a result, the temporal variations of flow rate and the flow pattern inside the cylinder were influenced due to the inertial or dynamic effect.
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SAE Technical Papers (980152) 1998年A direct injection gasoline engine system which employs a unique combustion system with enhanced gas motion is evaluated. Enhanced gas motion is produced by employing both a moderately strong swirl flow and a cavity in the piston. Advantages of this system are that the injection timing or spark timing need not be controlled severely and that since the injection timing can be set at near the intake BDC, time for evaporation can be gained to reduce soot emissions. Problems to be improved are that the Nox emissions level is worse than other lean burn systems and full load operation is not evaluated. According to the numerical calculations, the problems may be solved by enhancing the in-cylinder gas motion with axial stratification of swirl intensity at intake BDC strong swirl near the cylinder head and weak swirl near the piston surface. Copyright © 1998 Society of Automotive Engineers, Inc.
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日本機械学会通常総会講演会講演論文集 75th(3) 113-120 1998年資料形態 : テキストデータ プレーンテキスト コレクション : 国立国会図書館デジタルコレクション > デジタル化資料 > 雑誌
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微粒化 = Atomization : journal of the ILASS-Japan 5(9) 2-11 1996年1月31日
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SAE Technical Papers (962087) 1-12 1996年Local inhomogeneity of mixture concentration affects combustion characteristics in the lean burn system and also in the stratified charge combustion system. To investigate such combustion systems, the effects of inhomogeneous mixtures were examined using a carefully controlled experimental system. In this study, a constant-volume chamber, which can simulate an idealized stratified charge by using a removable partition inside the chamber, was developed. Flow and combustion characteristics were examined by indicated pressure analysis, Schlieren photography, ion probe measurements and local equivalence ratios measurements while varying the combination of initial equivalence ratios on each side of the partition. As a result, combustion characteristics of charge stratified, very lean propane-air mixture were clarified. © 1996 Society of Automotive Engineers, Inc.
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SAE Technical Papers (962021) 1-15 1996年In order to enhance the reliability of a pilot flame ignition system, three kinds of subchambers in which a pilot injector and a glow plug were set up were tested with a model combustion chamber of DISC rotary engine. A two-stroke Diesel engine's cylinder head was replaced with this model combustion chamber to simulate temporal changes of air flow and pressure fields inside the chamber as an actual engine. The behavior of the pilot flame generated in the subchamber, ignition process of main fuel spray by the pilot flame, the most suitable mixture distribution between the main chamber and the subchamber, and the effect of nozzle diameter of main injector on combustion characteristics were studied by using a high-speed video camera and ion probes. The results are the following; (1)the pilot flame reliability was improved, comparing to the type without subchmber system, especially, when the pilot injection amount was little; (2) with the same total injection amount, changing the ratio of injection amount between the pilot and the main, it was found that a properly smaller subchamber made the optimum ratio of pilot to main injection amount fall, and resulted in more active combustion. (3) the combustion was enhanced when the diameter of the main nozzle orifice was small. © Copyright 1996 Society of Automotive Engineers, Inc.
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日本機械学会論文集. B編 61(590) 3484-3490 1995年The ignition mechanism of a pilot flame in a stratified charge mixture was examined using a model combustion chamber of a Wankel-type rotary engine. Experimental study such as LDV measurement, pressure data analysis, high-speed photography and image analysis provides detailed knowledge concerning the stratified charge combustion, which is complemented by theoretical study of the mixture formation process inside the combustion chamber. Characteristics of the pilot flame as an ignition source and the mixture formation inside the model chamber required for enhanced combustion are determined in this study.
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日本機械学会論文集. B編 61(590) 3446-3451 1995年A prediction model of the cycle-to-cycle variation and turbulence of the in-cylinder flow in reciprocating internal combustion engines that employs a modified k-ε turbulence model is applied to different types of combustion chamber namely ; square-stroke, short-stroke and long-stroke. Also the effect of the engine speed and compression ratio on the flow characteristics is estimated to have new implications for engine design. As a result, both the initial flow field with swirl and/or tumble and the combustion chamber profile are found to affect the cycle-to-cycle variation and turbulence inside the combustion chamber during the compression stroke.
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Transations of JSME B 61(590B) 3484-3490 1995年
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SAE Technical Papers (952455) 39-49 1995年A new idea for controlling the in-cylinder mixture formation in SI engines is proposed. This concept was developed by applying the results of numerical calculations. Fuel that is directly injected into the cylinder is transferred toward the cylinder head to form a mixture stratification by using the in-cylinder gas motion that is generated by the interaction between the swirl and squish flows inside a combustion chamber. At first, the flow characteristics were measured in the whole in-cylinder space using an LDV system. Also, numerical calculations of the in-cylinder flow were made using measured data as the initial conditions. Secondly, the local equivalence ratio at several points inside the combustion chamber was measured by using a fast gas sampling device. The results showed that this idea generates the desired stratified charge when the fuel is injected with a higher injection pressure (about 1.3 MPa) at near the intake-BDC timing than with a usual pressure of 0.2 MPa in the port-injection case. Further numerical calculations were performed to examine other factors that might enhance mixture stratification during the compression stroke. © Copyright 1995 Society of Automotive Engineers, Inc.
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SAE Technical Papers (941927) 1-17 1994年A new DISC combustion system with a pilot flame for ignition was analyzed by using a model combustion chamber of a Wankel type rotary engine. A two-stroke diesel engine's cylinder head was replaced with this combustion chamber to simulate temporal changes of air flow and pressure fields inside the chamber as in actual engines. Two types of fuel injection systems were tested to obtain combustion characteristics such as the heat release rate. Direct photographs of spray and combustion were analyzed to understand the mixture-formation process of the main spray and to see the flame temperature distribution and flame moving velocity vectors. In order to understand the mixture-formation process, numerical calculations were made using a gaseous fuel. Finally, the effect of the fuel characteristics on combustion was examined using diesel fuel and n-hexane. © Copyright 1994 Society of Automotive Engineers, Inc.
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Prof. of JSME International Symposium, COMODIA 94 553-558 1994年
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SAE Technical Papers (941028) 1-14 1994年A model combustion chamber of Wankel type rotary engine was employed to study the DISC RE system. A two-stroke Diesel engine's cylinder head was replaced with this combustion chamber to simulate temporal change of air flow and pressure fields inside the chamber as an actual engine. The base engine was motorized to operate as a continuous rapid compression and expansion machine. Pilot fuel spray was injected onto a glow plug to form a pilot flame and it ignites the main fuel spray. The ignitability of pilot fuel, mixture formation process, ignition process of main fuel by pilot flame and the effect of pilot and main injection timings on combustion characteristics were examined. © Copyright 1994 Society of Automotive Engineers, Inc.
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JSAE TRansactions 25(1) 22-27 1994年
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日本機械学会・自動車技術会内燃機関シンポジウム講演論文集 11th(2) 21-26 1993年
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SAE Technical Papers 930066,1-10 1993年A prediction model of the cycle-to-cycle variation of the in-cylinder flow in IC engines which employs the time averaged k-ε turbulence model is proposed. The concept is based on an assumption that the power spectrum of the cycle-to-cycle variation can be deduced from the power spectra of both the mean velocity and turbulence intensity. To validate this model, in-cylinder velocity measurement in a transparent cylinder engine with a 2-valve cylinder-head is made using an LDV system. Comparisons of in-cylinder flow fields between the calculation and measurement show a good agreement in the cycle-to-cycle variation as well as the turbulence intensity. Finally, this model is applied to three kinds of flow fields to examine how the cycle-to-cycle variation may be effected. As a result, it is found that the swirl flow is effective to reduce the cycle-to-cycle variation, while the tumbling flow enhances the turbulence generation around the compression TDC. © Copyright 1993 Society of Automotive Engineers, Inc.
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日本機械学会論文集 B編 58(552) p2617-2623 1992年8月Modeling of turbulence is one of the most important issues in calculating the in-cylinder flow of internal combustion engines. The authors have been engaged in evaluating the applicability of the k-ε turbulence model and also developing modified k-ε models, such as the C_D revised k-ε model which has the ability to reproduce turbulent characteristics in nearly isotropic fields, and another modified k-ε model which shows extensive multiplicity of predicting the mean velocity on any kind of turbulent field. This basic study has been made on axisymmertrical flow frields. In this report, detailed comparisons between the calculation and measurement are made to evaluate these turbulence models in an axisymmetrical field with a bowl-in piston. Also, a newly designed 3-D cylinder head that employs a variable swirl-intensity mechanism with a flat piston configuration is built for the test. Obtained conclusions in the 3-D case are fundamentally the same as those derived from the axisymmetrical cases.
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日本機械学会論文集 B編 58(551) 2314-2320 1992年The k-ε model has been widely used to calculate turbulent flows in engine cylinder ; however, it has not been evaluated adequately whether the k-ε model can be applied to anisotropic in-cylinder turbulent flows. In this paper, several modified k-ε models and the algebraic stress equation model are evaluated for an anisotropic in-cylinder flow by a comparison of predicted velocity field with experimental result. Based on the comparison, a modified k-ε model is newly proposed which can describe the mean and turbulent velocities of the flow in the pancake-shaped combustion chamber. The modified k-ε model, however, still lacks the ability to reproduce turbulence in the combustion bowl in a piston.
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Transactions of the Japan Society of Mechanical Engineers Series B 58(552) 2617-2623 1992年Modeling of turbulence is one of the most important issues in calculating the in-cylinder flow of internal combustion engines. The authors have been engaged in evaluating the applicability of the k-ε turbulence model and also developing modified k-ε models, such as the C revised k-ε model which has the ability to reproduce turbulent characteristics in nearly isotropic fields, and another modified k-ε model which shows extensive multiplicity of predicting the mean velocity on any kind of turbulent field. This basic study has been made on axisymmertrical flow frields. In this report, detailed comparisons between the calculation and measurement are made to evaluate these turbulence models in an axisymmetrical field with a bowl-in piston. Also, a newly designed 3-D cylinder head that employs a variable swirl-intensity mechanism with a flat piston configuration is built for the test. Obtained conclusions in the 3-D case are fundamentally the same as those derived from the axisymmetrical cases. © 1992, The Japan Society of Mechanical Engineers. All rights reserved. D
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SAE Technical Papers 1991年Control of turbulence during the compression stroke is suggested by both theoretical calculations and experimental results obtained with an LDV measurement in a motored engine. The authors have found experimentally that when an axial distribution of swirl intensity exists, a large-scale annular vortex is formed inside the cylinder during the compression stroke and this vortex generates and transports turbulence energy. A numerical calculation is adopted to elucidate this phenomenon. Then, an axial stratification of swirl intensity is found to generate a large-scale annular vortex during the compression stroke by an interaction between the piston motion and the axial pressure gradient. The initial swirl profile is parametrically varied to assess its effect on the turbulence parameters. Among calculated results, turbulence energy is enhanced strongest when the swirl intensity is highest at the piston top surface and lowest at the bottom surface of the cylinder head. © Copyright 1991 Society of Automotive Engineers, Inc.
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日本機械学会論文集 B編 56(530) 3173-3180 1990年The lateral turbulence integral length scales of the axial and tangential velocity components were measured using a two-point, single-probe-Volume, laser Doppler velocimetry system in a motored single-cylinder internal combustion engine. The measurements were carried out on an axisymmetric transparent cylinder engine with a pancake-shaped chamber during the period spanning the intake and expansion strokes at an engine speed of 320rpm for three different swirl ratios. The results obtained for this engine indicate that in the case of no swirl, the turbulence intensity and the integral length scale decrease monotonously from compression stroke to expansion stroke, while in the presence of swirl, they happen to increase during the compression stroke as affected by the vortex ring.
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Transactions of JSME 56(530) 1990年
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Proceedings of the International Centre for Heat and Mass Transfer 26 485-496 1989年To analyze in-cylinder air motion, animated studies were carried out from both the experimental and the theoretical aspects. Numerical calculation codes have been widely used. The appropriateness of the computational results obtained by these codes, however, should be verified experimentally, because these codes contain many assumptions. The authors carried out both an experiment and calculation under simple conditions to assess the κ-ε turbulence model and the wall functions used as the boundary condition. A transparent cylinder engine which has a pancake-type combustion chamber and is capable of giving an axi-symmetrical flow field was designed for the purpose.
書籍等出版物
4Works(作品等)
9共同研究・競争的資金等の研究課題
15-
日本学術振興会 科学研究費助成事業 2015年4月 - 2018年3月
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日本学術振興会 科学研究費助成事業 基盤研究(C) 2015年4月 - 2018年3月
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日本学術振興会 科学研究費助成事業 2011年 - 2013年
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日本学術振興会 科学研究費助成事業 2008年 - 2010年
産業財産権
3-
US 6,581,553 B2
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特開2002-004865