SIP, Innovative Combustion Technology,  "Gasoline Combustion Team

The Reserch and Development System

Research and Development Title: Research and Development of Super-Lean Burn Combustion for High Efficiency Gasoline Engines

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Affiliates Position Name Person in Charge ◎
Primary Co-researchers ○
Research Duration
Leader University Keio University Project Professor Norimasa Iida Oct. 2014 ~
Professor Toshihisa Ueda Oct. 2014 ~
Associate Professor Takeshi Yokomori Oct. 2014 ~
Fomer Assistant Professor (Non-Tenured) Mina Nishi Oct. 2014 ~ March. 2016
Reserch topics
・Management and coordination of the SIP “Gasoline Combustion Team”, management and operations of the SIP laboratory
・Investigation of wall heat transfer process by measuring instantanious heat flux under the condition of super-lean with high intensity turbulence
Objectives
As a leader of the SIP “Gasoline Combustion Team,” Keio University manages and coordinates all research activities at the SIP-Keio engine laboratory. Keio University also designs and develops the prototype of the common engine for SIP, validates a thermal efficiency, and obtains and provides data for verification from models. Further, an investigation for the heat transfer process between an in-cylinder gas and wall surfaces is conducted to reduce the cooling loss. A heat flux through the walls and an in-cylinder gas temperature near the walls are respectively measured by a wall-embedded heat flux sensor and a laser induced phosphor thermometry in order to clarify the heat transfer characteristics such as the heat flux swing during an engine cycle. Flame propagation and temperature distribution in thermal boundary layers aound the engine wall surfaces are measured by a non-contact thermometer using a temperature dependency of phosphor particles in the gas flow. Knowledge from these experiments are provided to Cluster universities as boundary conditions for a temperature and flow field analysis using a numerical analysis such as DNS. Based on the feedback from Cluster universities, models of the engine wall heat transfer can be developed for a further cooling loss reduction.
University:1 University of Tokyo Professor Mitsuhiro Tsue October, 2014~
Associate Professor Shinji Nakaya October, 2014~
Reserch topics
Detailed investigation of spark ignition mechanisms and development of a numerical simuration method on igntion process
Objectives
Ignition experiments of lean mixtures in stationary and flow fields are conducted using a constant volume sealed chamber in order to elucidate detailed ignition mechanisms and develop a numerical simulation method for the spark-ignition process. Fundamental ignition characteristics such as minimum ignition energy and ignition limit are investigated by experiments, and a spectrum is measured with high temporal resolution to confirm spark discharge characteristics.Two-color near-infrared thermometry is also used for measurements of the initial flame kernel temperature. Based on the experiment results, an one-dimensional ignition model is developed. This model is verified and will be modified for the improvement. Further, with discharge voltage, electrodes distance and discharge duration as a parameter, effects of discharge characteristics are elucidated by experiments in order to obtain the useful information for the development of the high performance ignition system.
University:2 Nihon University Professor Kazuhiro Akihama Oct. 2104~
Associate Professor Osamu Imamura Oct. 2104~
Research Associate Kazuya Iwata Apr. 2017~
Reserch topics
Effects of flow fields on spark ignition characteristics
Objectives
In supercharged lean-burn engines, the flame kernel may blow out due to the strong flow field to improve a burning velocity. It is necessary to stabilize the ignition in high-speed and strong turbulence flow field including high EGR environments. This study investigates effects of flow fields on the discharge voltages and energy, discharge channel deformation and ignition characteristics using constant-air flow apparatus and rapid compression machine. These experimental data contribute to the improvement of the discharge and ignition modesl in the flow fields.
University:3 Okayama University Associate Professor Nobuyuki Kawahara Oct. 2104~
Reserch topics
Elucidation of spark-ignition process under the condition of super-leanburn with high turbulence and modeling of spark ignition behaviors
Objectives
An ignition process of the spark discharge is elucidated, and sprak discharge behaviors in a ultra-lean burn spark-ignition engine is modeled. Simultaneouly, the spark discharge and a time series of emission spectra inside the spark-ignition engine are visualized in both a compression-expansion machine and an optically accesible spark-ignition engine. The spark discharge under the condition of higher turbulence and higher EGR is visualized using a high-speed color camera. A temperature of the spark discharge and the initial flame kernel are measured with a time series of spectra obtained using an EMCCD spectrometer coupled with a spark plug with an optical fiber to understand the energy transfer from the spark discharge to the combustible mixture in a spark-ignition engine. Effects of in-cylinder flow and turbulence around the spark plug on sprak discharge behaviors are examined using the spark-plug-in laser Doppler velocimetry (LDV) system.
University:4 Tokyo Institute of Technology Professor Mamoru Tanahashi Oct. 2104~
Associate Professor Masayasu Shimura Oct. 2104~
Assistant Professor Yuki Minamoto Sep.2015~
Reserch topics
Investigation and modeling of ignition, flame propagation and wall heat flux mechanisms under the condition of super-lean burn with forced induction and high EGR using direct numrical simulations and advanced laser diagnostics
Objectives
Turbulent eddies are expected to influence the flame inner structure under the condition of a high-pressure with the high Reynolds number; however, this combustion mechanism has not been identified. For advanced internal combustion engines, ignition and wall heat flux are likely to be based on more complex balance of multiple physical phenomena. The mechanisms with these combustion-related physics are yet unknown. Direct numerical simulations and advanced laser diagnostics technique on the single and multi-component fuel turbulent premixed combustion have been developed to study these phenomena over the years. With knowledge and expertise from the past study, required models are developed for the SIP project.
University:5 Yamaguchi University Professor Masato Mikami Oct. 2104~
Associate Professor Takehiko Seo Oct. 2104~
Reserch topics
Investigation of effects of the pressure and temperature on a laminar flame speed of the premixture of gasoline and gasoline surrogate and a flow movement around the spark plugs.
Objectives
A laminar flame speed of the lean premixture of gasoline and gasoline surrogate is measured under the condition of a high temperature and high pressure ( Max. 4.0MPa, Max. 400K) by a double kernel method to investigate effects of the pressure and the temperature of the laminar flame speed for the lean premixture of gasoline and gasoline surrogate. Based on findings from the laminar flame speed’s dependence on the pressure and experiment results from other Cluster universities, a mathmatical formula for the laminar flame speed is developed with a pressure, temperature and air ratio as a parameter. In addition, fuel properties, which increase a laminar flame speed are investigated, and effective fuel compositions are proposed to improve the laminar flame speed. Further, effects of the flow on ignition behaviors are investigated using an optically accessible engine capable of generating a strong tumble flow wiith PIV. This result is important to develop ignition models, which can be tools to realize the ignition under the unfavorable environment. The models are validated with a real engine, and spark ignition mechanisms are elucidated.
University:6-1 Kyushu University Professor Eichi Murase Oct. 2014 ~ March. 2017
Associate Professor Osamu Moriue Apr. 2015 ~ March. 2017
Part-time lecturer Hideki Hashimoto Oct. 2014 ~ March. 2017
Reserch topics
Proposal and verification of combustion enhancement tequnique under the condityion of super-lean with high EGR
Objectives
A combustion enhancement by turbulence is limited due to a local quenching by a flame stretch. Therefore, effects of a thermal efficiency improvement are examined by a single cylinder engine when changing a laminar flow speed by methods other than a turbulence enhancement, such as a method of increasing the oxygen concentration in the intake air by oxygen-enriched membranes. Furthermore, an average flow speed and the turbulent intensity are measured during the intake and compression strokes using a time series particle image velocimetry with an optically accessible engine, and the flame structure is measured by a laser induced fluorescence and a chemiluminescence spectroscopy. A methodology to enhance the combustion is verified, and effects of the thermal efficiency is evaluated under the the condition of super-lean with high EGR.
University:6-2 Kyushu University Professor Toshiaki Kitagawa Oct. 2104~
Associate Professor Hiruyuki Watanabe Apr. 2015~
Assistant Professor Yukihide Nagano Oct. 2104~
Reserch topics
Proposal of combustion enhancement with turbulance under the condition of super-lean with high EGR
Objectives
Intensity of the in-cylinder flow is required to enhance flame propagation for an engine. Intensity of the flow may change a flame structure to the “thin reaction zones” and/or “broken reaction zones”, which assumes to be taken place in high intensity flow fields. Effects on the turrbulence and the bulk flow on the combustion are evaluated, and an investigation of the flame structure in such regions are carried out with a constant volume combustion chamber and a rapid compression machine. A turbulent burning velocity model is developed, and the optimal in-cylinder flow is proposed based on the results of the investigation. Properties of lean combustion are acquired with a single cylinder engine and are used to verify the turbulent burining velocity model. Further, with a numerical simulation of turbulent flame propagation using the turbulent burining velocity model, a combustion enhancement methodology and the turbulent burning velocity model are verified, and a evaluation methodology of flame propagation characteristics is established.
University:7 Osaka Prefecture University Professor Daisuke Segawa Oct. 2104~
Assistant Professor Hidefumi Kataoka Oct. 2104~
Reserch topics
Measurement of laminar flame speeds and verification of combustion reaction mechanisms for super-lean combustion with high EGR combustion
Objectives
Experimental data sets of a laminar flame speed are obtained as validation data to improve a prediction accuracy of reduced combustion reaction mechanisms, which are needed for a numerical simulation of engine combustion under the condition of uper-lean with high EGR. Gasoline and gasoline equivalent fuels are the target fuels, and the dependency of the laminar flame speed on the equivalence ratio and EGR ratio is mainly examined. A microgravity environment by a free fall method is utilized for experiments. A numerical simulation of the laminar flame speed is performed using multi-purpose combustion simulation codes incorporated with typical combustion reaction mechanisms, and the results are compared with those from the experiments (including the results obtained by Kyushu Univ. and Yamaguchi Univ. ). The prediction accuracy with the typical reduced combustion reaction mechanisms is evaluated through the comparison, and issues are identified. The issues are shared as basic knowledge to develop new combustion reaction mechanisms.
University:8 Tokushima University Associate Professor Yuzuru Nada Oct. 2104~
Professor Yoshiyuki Kidoguchi Oct. 2104~
Reserch topics
Modeling of turbulent burning velocity of lean premixed flames under the condition of lean burn with high EGR and forced induction and investigation of flame propagation mechanisms around wall boudanry layers
Objectives
Numerical simulations (DNSs) for lean premixed flame propagating in homogeneous isotropic turbulence under the condition of lean burn with high EGR and forced induction is conducted to develop database including properties of turbulent premixed flames. Turbulent burning velocities are modeled based on the real engine condition using the database, and effects of enhanced tumble flow on flame propagation in cylinders are examined. In addition, DNSs for turbulent premixed flames propagating in an enclosed domain are conducted to develop the model, which is potential to predict the burning velocity of premixed flames in wall boundary layers and the heat flux to the walls. Based on the results by these 2 DNSs, a methodology is developed not only to reduce heat loss but also to enhance the operational limit of engines under the cndition of lean burn with high EGR and forced induction.
University:9 Chiba University Professor Yasuo Moriyoshi Oct. 2104~
Associate Professor Tatsuya Kuboyama Oct. 2104~
Research Professor Toshio Yamada Oct. 2104~
Research Professor Koji Morikawa Oct. 2104~
Reserch topics
Analysis of cycle-to-cycle variations of combusiton, knock occurrence and cooling loss for a lean-burn SI gasoline engine and development of a 1-D lean burn SI gasoline engine simulator
Objectives
Causes of cycle-to-cycle variations in SI lean burn combustion are clarified, and a methodology to reduce cycle-to-cycle variations is developed. A cycle by cycle combustion analysis based on cycle resolved measurements of in-cylinder pressure, visualization of combustion process, heat balance and exhaust emissions are conducted. Based on the cycle resolved combustion analyis, potential issues for the high efficiency super-lean burn engine are detected from the viewpoint on the engine combustion cycle, and a novel technique is developed to improve an operation stability of the SI lean burn gasoline engine from both experiments on a real engine and theory.
Further, a 1D SI gasoline engine simulator accurately predicting the engine performance under the super lean-burn condition is developed in cooperation with another Cluster universities and the Loss ReductionTeam.
University:10 Tokyo Iunstitute of Technology Professor Hidenori Kosaka Oct. 2104~
Associate Professor Susumu Sato Oct. 2104~
Reserch topics
Investigation of interactions between heat transfer on the wall and knock in spark ignition engine
Objectives
Ddistributions of a temperature, heat flux and velocity in boundary layers inside combustion chamber walls of the super lean burn SI engine are measured by laser based diagnostics in order to develop a heat transfer model for the engine. The interaction between the heat transfer and knock in the engine is modeled by identifying the time and location of knock occurrence. Further, a methodology of the cooling loss reduction is developed by a engine simulator, which includes the heat transfer model for the thermal efficiency improvement.
University:11 Tokyo University of Agriculture and Technology Associate Professor Kaoru Iwamoto Oct. 2104~
Reserch topics
Investigation of heat transfer mechanisms in the internal combustion engine to reduce heat loss and a reduction of heat transfer by optimization of the wall surface microstructure
Objectives
In order to investigate heat trasfer mechanisms of an internal combustion engine, a velocity distribution in boundary layers on the walls of the optically accessible single-cylinder super-lean-burn engine (shared engine) is measured. Various turbulence statistics are measured using a high-resolution LDV, and a difference from the similarity rule of steady turbulent boundary layers is quantitatively evaluated. Furthermore, unsteadiness of the boundary layers is measured, and dominant flow structures are quantitatively identified. Based on the result of the velocity field measurement, the original wall surface microstructure optimization and/or the wall shape to change the flow field in the entire engine are proposed to reduce a heat transfer rate.
University:12 Tokyo City University Professor Yuji Mihara Oct. 2104~
Reserch topics
Development of a thin-film instantaneous heat flux sensor and low noise measurement system
Objectives
In order to verify a structure of the heat flow inside wall boundary layers and a heat transfer model, and demonstrate effects of the combustion condition, wall materials and the fine structure on the cooling loss reduction, an instantaneous temperature sensor with a high accuracy and response is developed. Since the instantaneous heat flux is obtained from the combustion gas temperature and the instantaneous temperature of each wall surface, a high accuracy measurement system capable of measuring simultaneously at multiple locations is developed with a thin film type sensor with extremely small heat capacity to measure the instaneous temperature of each wall surface. As research activities, a sensor was designed for the prototye and a measurement system was developed in 2014. The sensor was applied to an experimental apparatus (RCEM) in 2015. A test to develop a heat transfer model was performed by the RCEM in 2016, and effects of cooling loss reduction technologies have been verified by experiments in 2017. In 2018, the cooling loss reduction technologies will be demonstrated in a single cylinder engine.
University:13 The University of Tokyo Professor Yuji Suzuki Oct. 2104~
Reserch topics
Development of a wireless MEMS Heat Flux Sensor for Engine Cylinders
Objectives
A novel MEMS wireless sensor is developed to estimate heat flux from the temperature gradient by mounting an independent wireless temperature sensor in the thickness direction of films. This small, thin-type sensor is capable of acquiring data using inductive coupling and measures a temperature wirelessly without any optical accessibility. Further, this sensor consists of only passive elements such as a capacitor and a coil and is applicable to the combustion field. A prototype of the wireless MEMS heat flux sensor is developed, and a methodology of measuring heat flux in the engine cylinder is established to realize the simultaneous multi-point measurement.
University:14 Meiji Univesrity Professor Osamu Nakabeppu Oct. 2104~
Reserch topics
Development of a high spatial resolution heat flux sensor with a MEMS technology
Objectives
Heat flux measurement technologies with a high spatial resolution are developed with a MEMS sensor mounted on the walls inside the gasoline engine to elucidate cooling loss mechanisms for lean burn with forced induction in order to develop cooling loss reduction technologies. A MEMS senosr based on the silicon technology has an excellent performance in the spatial resolution and response speed, but requires a delicated handling. Therefore, a thin film heat flux sensor on a metal substrate is initially developed and is advanced to a multi-point heat flux sensor for the engine application. The multi-point sensor is helpful to understand and mitigate the turbulent heat transfer in the engine. Cooling loss mechanisms are identified, and cooling loss reduction technologies are expected to be improved by combining the information of heat transfer to walls measured by this heat flux sensor with a detailed result of the optical measurement for the combustion, velocity and temperature field in the boundary layers by PIV and LIF. They are integrated to a DNS analysis.
University:15 Doshisha University Associate Professor Eriko Matsumura Oct. 2014 ~ March. 2016
Professor Jiro Senda Oct. 2014 ~ March. 2016
Reserch topics
Study on the cooling loss reduction with spatiotemporal changes in air-fuel mixture formation and temperature stratification
Objectives
In order to fundamentally analyze mechanisms of the heat transfer process to reduce a cooling loss in the combustion chamber, a correlation among a spatiotemporal change of the mixture concentration distribution using various spray forming methods, a flame temperature in the combustion chamber and a heat transfer process is investigated. How the various processes, such as spray formation, mixture concentration distribution and flame propagation of the thermal boundary layers on the wall surfaces affect the heat transfer process are also investegated. Finally, methods of forming the early spray vaporization by heating fuels, which leads to heat loss reduction and the flash boiling spray by overheating fuels are proposed, and experiments for the evaluation are carried out under real flow field conditions in the combustion chamber using the real engine in order to verify the ultimate potentiality of the heat loss reduction inside the SI engines from the viewpoint of the spray forming method.
University:16 Nihon University Professor Mitsuaki Tanabe Oct. 2104~
Associate Professor Akira Iijima Oct. 2104~
Assistant Professor Masanori Saito Apr. 2017 ~
Reserch topics
Development of a knocking supression concept and investigation of knock onset mechanisms using a real engine and a super rapid compression machine
Objectives
A methodology of knock occurrence elucidation and knock suppression control is developed to manage knock, which prevents gasoline engines from increasing the compression ratio. A super rapid compression machine, which can simulate fundamental phenomena and a single cylinder engine, which can demonstrate the combustion similar to a real engine are used concurrently to analyze fundamental characteristics of fuels separating from practical issues. Key technique for the knock suppression is discovered from a relationship among boost pressure, EGR, spatial distribution of the temperature, diluting gas species, turbulence and knock occurrence with spectroanalysis and reaction analysis.
University:17 Tohoku University Professor Kaoru Maruta Oct. 2104~
Associate Professor Hisashi Nakamura Oct. 2104~
Reserch topics
Investigation of ignition and combustion characteristics for practical fuels, surrogate fuels and a single component fuels and optimization of reaction mechanisms by a micro flow reactor with a controlled temperature profile.
Objectives
In order to elucidate knock mechanisms and attain knock controls at a high compression ratio, an extensive research collaboration is necessary between validation and modelling of ignition properties, especially to properly understand the multi-stage oxidation properties and elucidation of the mechanisms to control knock by computations with large-scale kinetics and a DNS with detailed chemical kinetics. As a unique method other than conventional, a micro flow reactor with a controlled temperature profile, which can be the substitution of the RCM and the shock tube is used to examine ignition and combustion properties of practical fuels, surrogate fuels and a single component fuels. Various detailed and reduced reaction mechanisms, which are used for computations, are validated and optimized. Further, fundamental combustion property data under the condition of super-lean, a high temperature and high pressure and for laminar flame speeds with a high EGR rate as well as ignition properties, which are difficult to obtain by the conventional experimental methods, are also provided by the micro flow reactor.
In addition, fundamental experiments are conducted, and research groups enhance the collaboration through the joint study events upon a result of the midterm project evaluation. Minimum ignition energy (MIE) transition phenomena observed under the SIP’s ultra lean condition are elucidated for the ignition to propagation transition process. Accordingly, new technologies to attain the robust ignition-to-propagation transition under the ultra-lean condition, which significantly contributes to increase the thermal efficiency of SI engines would be investigated. Elucidation of the mechanism significantly contribues to the development of new component-base models for SIP infrastructure software.
University:18 Ibaraki University Professor Mitsuru Konno Oct. 2104~
Associate Professor Kotaro Tanaka Oct. 2104~
Reserch topics
Study on ignition characteristics of practical gasoline at the low temperature and high pressure condition using a rapid compression machine and development of reduced reaction models
Objectives
In order to achieve a thermal efficiency of 50% in spark ignition engines, low temperature combustion technologies operated with ultra lean and highly diluted mixtures under high boost pressures are required. However, there are few studies regarding the ignition characteristics of gasoline under such conditions. Ignition delay times of gasoline (SIP standard gasoline) and gasoline surrogate fuels (SIP standard gasoline surrogate fuels) are measured using a rapid compression machine under the conditions of low temperatures, high pressures, lean fuel/air mixtures and EGR, which are similar to the in-cylinder conditions of spark ignition engines with a thermal efficiency of 50% in order to elucidate ignition characteristics of practical gasoline. In addition, quantitative measurements of intermediate species (formaldehyde etc.) formed in the oxidation of gasoline are performed using a mid-infrared laser absorption spectroscopy, and a chemical kinetic model for gasoline is validated using the obtained data.
University:19 Sophia University Associate Professor Kazuo Takahashi Oct. 2104~
Reserch topics
Measurements of ignition delay times for practical fuels by a heated high-pressure shock tube and development of new auto-ignition index by a real engine
Objectives
Reaction models for real fuels are necessary to prevent and control knock in real engines. In order to develop and optimize comprehensive reaction models for auto-ignition, experimental studies on high-pressure ignition are indispensable; however, there is still a lack of data for real fuels under the super-lean condition. High-pressure ignition data are created using a shock tube, which is a chemically and thermally ideal homogeneous reaction field. Further, effects of properties of each chemical component in gasoline on ignition characteristics under the lean condition are investigated on the basis of chemical kinetics, and an auto-ignition index alternative to the current octane number is developed.
University:20 Hokkaido University Associate Professor Hiroshi Terashima Oct. 2104~
Reserch topics
Research on mechanisms of pressure wave generation inducing end-gas auto-ignition and development of innovative knock suppression technique: A CFD study with detailed chemistry
Objectives
Innovative knock suppression methodologies are established to drastically increae a thermal efficiency of SI gasoline engines. A computational technique to efficiently introduce detailed chemical kinetics into the compressible Navier-Stokes equations has been applied in order to clarify effects of knock phenomena on heat transfer to walls and the engine, particularly the detailed mechanisms of pressure wave generation, which induces end-gas auto-ignition. A wide variety of computations with several parameters such as a pressure, temperature, equivalence ratio and various fuels, have been performed to establish innovative knock suppression methodologies.
University:21 Hiroshima University Professor Akira Miyoshi Oct. 2104~
Associate Professor Daisuke Shimokuri April 2017 ~
Reserch topics
Construction of the detailed kinetic mechanism for gasoline surrogate and elucidation of knock with chemical kinetics for SI engines
Objectives
A kinetic mechanism for gasoline surrogate is constructed by using quantum chemical calculations with ignition delay times measured by shock tubes as validated data. Ignition delay measurements under the in-cylinder condition by a RCM is emulated to elucidate knock occurrence under the conditions of super- lean, high supercharging performance, high EGR, high compression ratio and strong tumble as a R&D target. Further, technologies to elucidate the knock occurrence mechanism by low-dimensional models are developed, and kinetic interpretation is provided to CFD analysis results with reduced kinetic mechanism. A result of the analysis contributes to the creation of the proposal of knock-free combustion concept under the aforementioned conditions.
University:22 Osaka Institute of Technology Professor Kazunari Kuwahara Oct. 2104~
Reserch topics
Chemical kinetic analyses to elucidate knock mechanisms for gasoline surrogate fuels and to propose knock suppression strategies for super-lean burn
Objectives
By analyses of reaction paths for gasoline surrogate fuels and their components using a detailed reaction mechanism developed by Miyoshi (Hiroshima University) and Sakai (University of Fukui), factors determining ignition characteristics for Japanese regular and premium gasolines are investigated quantitatively, and chemical kinetics are incorporated to knock tendencies for the gasoline fuels under the condition of super-lean burn with a high compression ratio, high efficiency forced induction, high EGR, and strong tumble. Based on knowledge obtained from the analyses, a zero-dimensional knock prediction model is developed to accurately predict knock occurrence on a real engine, and knock suppression strategies for the super-lean burn is proposed.
University:23 University of Fukui Associate Professor Yasuyuki Sakai Oct. 2104~
Reserch topics
Chemical Mechanism Development and Reduction
Objectives
Detailed/reduced chemical mechanisms of gasoline surrogate fuels are developed in cooperation with a Miyoshi’s group (Hiroshima University). The mechanisms are validated for ignition delay times and laminar flame speeds under the equivalent engine conditions to other Cluster universities to elucidate knock occurrence. Both detailed and reduced mechanisms are used to analyze chemical and/or physical mechanisms of knock, and they contribute to a proposal of a novel gasoline engine concept.
University:24 Sophia University Professor Tielong Shen Oct. 2015 ~
Reserch topics
Modeling and Online Optimization Method for SI Engine Controls on Lean Combustion
Objectives
Developments of a control-oriented model and online optimization algorithms are conducted in order to improve a thermal efficiency and reduce cyclic variations and imbalance between cylinders for gasoline engines. Novel modeling and a controls methodology are proposed with an integration of the conventional dynamic system theory to stochastic modeling of cyclic transition behaviors of cylinders. Specifically, a lean burn boundary model is established based on knowledge of probability and statistic theory, and real-time efficiency optimization algorithms with some operation constraints are developed subsequently. Furthermore, spark timing, fuel injection quantity and valve timing for every cylinder are controlled to decrease both cyclic variances and cylinder-to-cylinder variances. The stochastic criteria are introduced as an evaluation for the performance of online control.
University:25 Nationaol Insititute of Advanced Industrial Science and Technology (AIST) Chief Senior Researcher Eiichi Takahashi April 2016~
Senior Researcher Takehiko Segawa April 2016~
Reserch topics
Combustion enhancement of premixed gas by dielectric barrier discharge
Objectives
In order to realize super-lean and diluted combustion, a technology to enhance combustion is developed by preprocessing the air/fuel mixture by dielectric barrier discharge (DBD) plasma. Chemical species generated by plasma in the premixture are investigated under various conditions, and ignition enhancement mechanisms and/or flame propagation are investigated as well. The DBD is installed in an engine cyliner and is expected to contribute to realizing the super-lean burn operation of gasoline engines.
University:26 Osaka Prefecture University Professor Kazuhiko Suga April, 2017~
Associate Professor Masayuki Kaneda April, 2017~
Assistant Professor Yusuke Kuwata April, 2017~
Reserch topics
Development of an analytical wall-function for a RANS-LES hybrid method
Objectives
A main mission is to contribute to the improvement of accuracy and usability of the HINOCA by develpeing a novel wall-function in collaboration with the other team members of the HINOCA working group. A new version for unsteady Reynolds-averaged Naiver-Stokes (RANS) equations simulation of IC engine cylinder flow is developed based on the analytical wall-function (AWF) for RANS equations(mainly steady flow) turbulence models. It allows the HINOKA RANS equations version to improve the accuracy and performance. Further, the AWF is developed for Large Eddy Simulation (LES) to improve the usability of the HINOCA bamboo version. By integrating the two versions of the AWF, a novel AWF applicable to a RANS-LES hybrid model is developed for the HINOCA final version.
University:27 Kyushu University Professor Ken-ichi Abe April 2017 ~
Assistant Professor Hisashi Kihara April 2017 ~
Reserch topics
Development of a hybrid LES/RANS equations model using a non-linear eddy-viscosity model and an anisotropy-resolving SGS model reflecting characteristics of a scale-similarity modeling concept
Objectives
A new high-performance turbulence model is developed to predict complex turbulence in flow fields of the engine-cylinder. In order to meet the objectives, a new switching function, which smoothly connects between Large Eddy Simulation(LES) and Reynolds-averaged Naiver-Stokes (RANS) equations regions depending on characteristics of near-wall turbulence as a LES/RANS equations hybrid model. This new model is capable of expanding a HINOCA to operate in a wide range.
University:28 Nagoya Institute of Technology Manager Hirofumi Hattori April 2017 ~
Nagoya Institute of Technology Associate Professor Tomoya Houra April 2017 ~
Reserch topics
Study for turbulent heat transfer model with multi-time scales
Objectives
In order to obtain highly-accurate predictions of near-wall heat transfer phenomena in an engine cylinder, existing turbulent heat transfer models on multi-time scales used in Reynolds-averaged Naiver-Stokes (RANS) equations simulation are evaluated and improved using a direct numerical simulation (DNS) database of turbulent boundary layers with various wall thermal boundary conditions while knowledge for the near-wall heat transfer phenomena from a DNS and experience is provided. Moreover, a study concerning RANS equations and Larger eddy simulation (LES) of the engine cylinder using a HINOCA is conducted in cooperation with groups using the HINOCA, and predictions are improved working as the HINOCA group.
University:29 Keio University Professor Koji Fukagata April 2017 ~
Reserch topics
Study on a DES and a Hybrid RANS equations/LES for the prediction of flow inside a cylinder of the engine
Objectives
In order to accurately predict turbulent behaviors near walls of the engine cylinder, Large Eddy Simulation (LES), Reynolds-averaged Navier-Stokes (RANS) equations simulation and Detached Eddy Simulation (DES) of turbulent flow in a circular pipe, which corresponds to canonical flow are performed. In addition to the validation of the developed code, knowledge based on physics and experience obtained from this study, such as a parameter adjustment is provided. Further, a prediction accuracy of a Hinoca is improved by research activities in collaboration with a group using a HINOCA, which conducts a research on hybrid wall function models and anisotropic subgrid-scale (SGS) models.