Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

PREMIER (PREmixed Mixture Ignition in the End-gas Region) combustion occurs with auto-ignition in the end-gas region when the main combustion flame propagation is nearly finished. Auto-ignition is triggered by the increases in pressure and temperature induced by the main combustion flame. Similarly to engine knocking, heat is released in two stages when engines undergo this type of combustion. This pattern of heat release does not occur during normal combustion. However, engine knocking induces pressure oscillations that cause fatal damage to engines, whereas PREMIER combustion does not. The purpose of this study was to elucidate PREMIER combustion in natural gas spark-ignition engines, and differentiate the causes of knocking and PREMIER combustion. We applied combustion visualization and in-cylinder pressure analysis using a compression-expansion machine (CEM) to investigate the auto-ignition characteristics in the end-gas region of a natural gas spark-ignition engine. We occasionally observed knocking accompanied by pressure oscillations under the spark timings and initial gas conditions used to generate PREMIER combustion. No pressure oscillations were observed during normal and PREMIER combustion. Auto-ignition in the end-gas region was found to induce a secondary increase in pressure before the combustion flame reached the cylinder wall, during both knocking and PREMIER combustion. The auto-ignited flame area spread faster during knocking than during PREMIER combustion. This caused a sudden pressure difference and imbalance between the flame propagation region and the end-gas region, followed by a pressure oscillation. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

DOI： 10.1016/j.proci.2018.08.055

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The effects of split pilot fuel injection on engine performance and PREmixed Mixture Ignition in the End Gas Region (PREMIER) combustion characteristics were investigated in a single-cylinder dual-fuel natural gas engine ignited with diesel fuel. In particular, the effect of second spray timing on combustion mode was examined. PREMIER combustion was observed in a wider range of operating conditions with split injection strategy compared to single injection strategy. We determined that it was possible to both decelerate heat release and suppress knocking to PREMIER combustion, and accelerate heat release and promote normal combustion to PREMIER combustion, with suitable second injection timing. The maximum of thermal efficiency of PREMIER combustion operation with split injection was close to the results obtained with knocking operation. In-cylinder images showed that split injection strategy advances or retards the progress of combustion by controlling the size and rate of growth of flame kernels, depending on the timing of the second injection. The combustion progress is earlier when the pilot fuel delivered during the first injection autoignites during the second injection. Kernel growth and the final size were adversely affected when the second injection was initiated after pilot fuel autoignition. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.fuel.2016.07.120

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Biogas is a renewable alternative fuel for internal combustion engines that has several advantages over conventional fuels, including lower costs and reduced levels of harmful emissions. In particular, it exhibits a neutral recirculation loop for carbon dioxide (CO2), which is one of the main causes of global warming. In this study, we investigated biogas fuels with various compositions using a micro co-generation engine system. The ratio of methane to CO2 and engine load were varied, and the intake air and fuel flow rates were controlled to change the equivalence ratio. The results show that for a given engine load, the ignition delay and combustion period increased with CO2 content, and the combustion speed decreased. The fuel consumption increased slightly with CO2 content; however, the thermal efficiency improved using a lean burn strategy, resulting in lower nitrogen oxide (NOx) emission, and moreover, the use of biogas with the stoichiometric air-fuel ratio appears effective in reducing NOx emissions and can improve the fuel economy at higher loads. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apenergy.2016.08.152

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Ethanol is a particularly promising bio-fuel, which is already widely used in the transportation sector. Much research has focused on laser ignition in internal combustion engines, because it offers a number of significant advantages. The motivation of this study is to reduce the higher cost of anhydrous ethanol by enabling the direct use of wet ethanol for combustion applications. This study reports the effects of water content on the laser ignition characteristics of air-ethanol flames with 0-40% water by volume added to the ethanol. Laser-induced breakdown was generated by focusing a 532-nm nanosecond pulse from a Q-switched Nd:YAG laser. High-speed visualisation of the combustion was achieved, together with analyses of the in-chamber pressure history, mass fraction burned, and ignition delay over a range of equivalence ratios. Removing the final 20% of water from ethanol is particularly energy intensive. The results of this investigation revealed that the flame growth rate and flame propagation velocity are both increased by adding up to 20% water (by volume) to ethanol, indicating a positive effect of the water at relatively low concentrations. It was also found that the ignition delay was shorter as the water content was increased up to a volume fraction of 20%. Therefore, it can be hypothesised that the presence of water enhances the ionisation process and increases the rate of radical generation during laser-induced breakdown of wet ethanol. Numerical analysis using the commercial software package CHEMKIN-PRO revealed a reduction in adiabatic flame temperature and laminar burning velocity due to the addition of water to ethanol. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.fuel.2015.10.067

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2015.53._1009-1_

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Laser ignition of wet ethanol was carried out at equivalence ratio of 0.8. Additions of water in ethanol up to 20% (v/v) accelerated the combustion rate with shorter laser ignition delay compared to dehydrated ethanol.

DOI： 10.1364/lic.2015.w3a.2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

We report an investigation of the effects of the ambient pressure on fuel concentration measurements of an injected jet of hydrogen using spark-induced breakdown spectroscopy (SIBS) in a constant-volume vessel. Measurements were carried out using hydrogen injected into a nitrogen environment with different ambient pressures, and the local concentrations were measured at various spark locations. The optical emission from the spark discharge at 501 nm (corresponding to nitrogen) and 656 nm (corresponding to hydrogen) was observed using SIBS. Spectrally resolved emission from the plasma was detected simultaneously using a spectrometer. The potential to determine the hydrogen/nitrogen ratio in the spark gap using was demonstrated. Spectral calibration was carried out using a hydrogen/nitrogen mixture, and hydrogen was injected at a pressure of 5.0 MPa into nitrogen with ambient pressures in the range 0.5-1.5 MPa. The results show an increase in the background radiation, as well as of the peaks corresponding to hydrogen and nitrogen atomic emission lines, as the ambient pressure increased. An increase in the density of nitrogen inside the chamber influenced the structure of the hydrogen jet, slowing the spray and reducing penetration, which altered the equivalence ratio at the location of the spark. When the spark occurred during injection, the behavior of the hydrogen jet was quasi-steady state; when the spark timing followed the injection, however, an unsteady state was observed. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2015.01.121

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In this work, spark-induced breakdown spectroscopy (SIBS) was employed to investigate the mixing process of a hydrogen jet in a constant-volume vessel. The local fuel concentration of the hydrogen jet was measured at several locations, using a SIBS sensor. A high-speed camera was used to visualize spark discharge fluctuations, and hydrogen jet concentration measurements were conducted simultaneously. Spectrally resolved atomic emissions from the plasma generated by the spark plug were examined to determine the local equivalence ratio. Direct visualization of the spark discharge provided useful information about the influence of spark discharge characteristics related to the spark timing. Using the developed SIBS sensor, atomic emission spectra were obtained from hydrogen H-alpha at 656 nm and nitrogen N (I) at 501 nm. Comparison of the intensity peaks of atomic emissions from hydrogen and nitrogen allows the local hydrogen concentration in a measured volume to be determined, and hence also the local equivalence ratio. The measurement results demonstrate the local variation in the equivalence ratio throughout the jet and along its axis. From the results, the spatial structure of the hydrogen jet affects the hydrogen/nitrogen mixing and could be clarified with SIBS technique when the spark is discharged. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2014.08.146

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DOI： 10.4236/ojfd.2014.43021

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DOI： 10.4236/ojfd.2014.43022

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DOI： 10.4236/ns.2014.612093

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OPTICAL SOC AMER  

The behaviors of laser-induced plasma and fuel spray were investigated by visualizing images with an ultra-high-speed camera. Timeseries images of laser-induced plasma in a transient spray were visualized using a high-speed color camera. The effects of a shockwave generated from the laser-induced plasma on the evaporated spray behavior were investigated. The interaction between a single droplet and the laser-induced plasma was investigated using a single droplet levitated by an ultrasonic levitator. Two main conclusions were drawn from these experiments: (1) the fuel droplets in the spray were dispersed by the shockwave generated from the laser-induced plasma; and (2) the plasma position may have shifted due to breakdown of the droplet surface and the lens effect of droplets. (C) 2013 Optical Society of America

DOI： 10.1364/OE.22.000A44

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A multidimensional computational fluid dynamics (CFD) simulation of a constructed syngas chemical kinetic mechanism was performed to evaluate the combustion of syngas in a supercharged dual-fuel engine for various syngas initial compositions under lean conditions. The modelled results were validated by comparing predictions against corresponding experimental data for a supercharged dual-fuel engine. The predicted and measured in-cylinder pressure, temperature, and rate of heat release (ROHR) data were in good agreement. The effect of the hydrogen peroxide chain-propagation reaction on the progress of combustion under supercharged conditions was examined for different types of syngas using various initial H-2 concentrations. The effect of the main syngas kinetic mechanism reactions on the combustion progress was analysed in terms of their contribution to the total heat of the reaction. The best results compared with experimental data were obtained in the range of equivalence ratios below about 0.8 for all types of syngas considered in this paper. As the equivalence ratio increased above 0.8, the results deviated from the experiment data. The spatial distribution of the in-cylinder temperature and OH center dot within this equivalence-ratio range showed the completeness of the combustion. The present CFD model captured the overall combustion process well and could be further developed into a useful tool for syngas-engine combustion simulations. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2011.07.140

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER SOC MECHANICAL ENGINEERS  

To investigate the relationship between local burning velocity and flame displacement speed with different density ratio, a numerical analysis was performed using DNS databases of statistically steady and fully developed turbulent premixed flames. The local burning velocity based on fuel consumption rate is considered to be most appropriate as the definition of burning rate because combustion is a kind of chemical reactions. Since it is impossible, however, that the local burning velocity is obtained experimentally by using any present measurement technology, the numerical results using the local burning velocity cannot be compared with any experimental data. Hence the flame displacement speed, which can be obtained and compared easily with experiments, has previously been used for numerical analyses. Thus, to realize comparison of numerical results using the local burning velocity with some experimental ones, it is necessary to reveal the relationship between the local burning velocity and the flame displacement speed.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

The interaction of spray and combustion processes forms a complex system of physical phenomena undergoing in IC engines. Studying this interaction is important to determine strategies for simultaneously reducing soot and NOx emissions from diesel engines. Spray combustion interactions are evaluated by the flame lift-off length - the distance from the injector orifice to the location of hydroxyl luminescence closest to the injector in the flame jet. Various works have been dedicated to successful simulations of lifted flames of a diesel jet by use of various combustion modeling approaches. In this work, flame surface density and flamelet concepts were used to model the diesel lift-off length. Numerical studies have been performed with the ECFM3Z model and n-Heptane fuel to determine the flame lift-off length under quiescent conditions. The numerical results showed good agreement with experimental data, which were obtained from an optically accessible constant volume chamber and presented at the Engine Combustion Network (ECN) of Sandia National Laboratories. It was shown that at a certain distance downstream from the injector orifice, stoichiometric scalar dissipation rate matched the extinction scalar dissipation rate. This computed extinction scalar dissipation rate correlated well with the flame lift-off length. For the range of conditions investigated, adequate quantitative agreement was obtained with the experimental measurements of lift-off length under various ambient gas O-2 concentrations and ambient gas densities.

DOI： 10.1299/jtst.5.238

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To investigate the effect of Lewis number on local burning velocity and stretch rate, a numerical analysis was performed using DNS databases of statistically steady and fully developed turbulent premixed flames. In our previous study, it was found that a probability density function (pdf) of local burning velocity is affected by Lewis number and especially the pdf for lower Lewis number had a wide distribution. To explain the above results, the present work focused on the correlation between local burning velocity and each of local stretch rate, local tangential strain rate and local flame curvature.

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The interaction between turbulence and reactive scalar fields is discussed for the wrinkled flamelets regime of turbulent premixed combustion. Emphasis is placed on the effects associated with the turbulent straining term. In the regime of turbulent combustion under consideration, which corresponds to Karlovitz and Damkohler numbers such that Ka < 1 and Da > 1, a clear and simple formulation is proposed to explain and to model the influence of the correlation between velocity and reactive scalar gradients. This formulation is based on the conservative variables budget across one-dimensional premixed laminar flamelets. The analysis firmly confirms the dependence on both the Damkohler number and the expansion factor, a feature already foreseen in recent studies. Nevertheless, in contrast with previous work, (i) the scaling arguments used in the present contribution are different from those used in other recent proposals, and (ii) the proposed closures are not only deduced from dimensional arguments but also from the consideration of conservative variable budgets across laminar flamelets. The resulting functional dependence on the expansion factor is found to be influenced by the underlying one-dimensional flamelet representation and two possible closures are put forward to take this dependence into account. (iii) The two closures do not exhibit a proportionality to the mean scalar dissipation rate (epsilon) over tilde (Y) as suggested in previous studies but to the square of this quantity. This results in the presence of a second contribution proportional to (epsilon) over tilde (2)(Y) in the modelled transport equation for the mean scalar dissipation rate, in addition to the modelled molecular dissipation term. (iv) Since previous Direct Numerical Simulation (DNS) studies have been essentially devoted to the influence of the Damkohler number, the present DNS validation step is focused on the effects of the expansion rate. To this purpose, the proposed models are validated against three available DNS databases obtained for turbulent premixed flames with different values of the density ratio between unburned and fully burned gases.

DOI： 10.1080/13647830801975154

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

A numerical analysis was performed using DNS (Direct Numerical Simulation) databases of statistically steady and fully developed turbulent premixed flames with different density ratios and with different Lewis numbers. Firstly, local flame surfaces at a prescribed progress variable were identified as local three-dimensional polygons. And then the polygon was divided into some triangles and local flame areas were evaluated. The turbulent burning velocity was evaluated using the ratio of the area of a turbulent flame to that of a planar flame and compared with the turbulent burning velocity obtained by the reaction rate. As a result, for unity Lewis number, the turbulent burning velocity evaluated by the flame area agrees with that by the reaction rate independent of the density ratio, while for non-unity Lewis number, the turbulent burning velocity obtained by the reaction rate increases or decreases by the extent which the Lewis number contributes. Secondary, local burning velocities over the flame surface were evaluated, and then the probability density functions (pdfs) of local burning velocities were obtained. For Le = 0.8, 1.0, the peak of the pdf is located at a higher value than the unstretched local burning velocity, while for Le = 1.2, it is located at a lower value than the unstretched local burning velocity.

DOI： 10.1299/jtst.3.103

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER SOC MECHANICAL ENGINEERS  

An analysis of local flame area was performed using DNS (Direct Numerical Simulation) databases of turbulent premixed flames with different density ratios and with different Lewis numbers. Firstly, a local flame surface at a prescribed progress variable was identified as a local three-dimensional polygon. And then the polygon was divided into some triangles and local flame area was evaluated. The turbulent burning velocity was evaluated using the ratio of the area of turbulent flame to that of planar flame and compared with the turbulent burning velocity obtained by the reaction rate.

DOI： 10.1115/HT2007-32794

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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An analysis of local flame area was performed using DNS databases of turbulent premixed flames with different density ratios and with different Lewis numbers. A local flame surface at a prescribed progress variable was identified as a local three-dimensional polygon. The polygon was divided into some triangles and local flame area was evaluated. The turbulent burning velocity was evaluated using the ratio of the area of turbulent flame to that of planar flame and compared with the turbulent burning velocity obtained by the reaction rate.

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SOUTHEAST UNIV PRESS  

Direct numerical simulations were implemented and studied for the intrinsic instabilities of two dimensional premixed planar hydrogen/air flames. The 6th-order compact finite difference scheme was used for the spatial discretization, and the 3rd-order Runge-Kutta method for the time advancement. The boundary conditions were based on the Navier-Stokes characteristic boundary conditions. The hydrogen/air detailed kinetics, which contains 9 species and 35 elementary reactions, was used. Small perturbation was imposed at the upstream boundary of calculation domain (a rectangle), the evolution of a flame was investigated. The flame became unstable due to the Darrieus-Landau instability. After-wards, a cusp, which was a concave part towards the unburned gas, appeared, and then was closing. These are considered to be due to the diffusive-thermal instability. Furthermore in order to investigate the effect of the size of computation domain on the evolution of flames, calculations were conducted in the different sizes.

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Combustion Society of Japan  

<p>Direct numerical simulations were implemented and studied for the intrinsic instabilities of two-dimensional hydrogen/air premixed planar flames. The 6th-order compact finite difference scheme was used for the spatial discretization, and the 3rd-order Runge-Kutta method for the time advancement. The boundary conditions were based on the Navier-Stokes characteristic boundary conditions. The hydrogen/air detailed kinetics, which contains 9 species and 35 elementary reactions, was used. Small perturbation was imposed at the upstream boundary of the calculation domain (a rectangle), and then the perturbation grew up when it reached a planar flame. The flame became unstable due to the intrinsic instabilities. Afterwards, a cusp, which was a concave part towards the unburned gas, appeared, and developed rapidly. It is considered to be due to the diffusive-thermal instability. And then, the cusp was closing, while a convex part towards the unburned gas appeared. This is considered as a cellular structure. The dispersion relation between the wave number and the growth rate of the perturbation was obtained and compared with a theoretical prediction. The behaviour of the flame was qualitatively similar to one obtained in past experiments. Furthermore the results with the perturbation imposed continuously and in a limited time were compared.</p>

DOI： 10.20619/jcombsj.45.133_184

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Language：English   Publisher：Springer Singapore  

Current energy and emission regulations set the requirements to increase the use of natural gas in engines for transportation and power generation. The characteristics of natural gas are high octane number, less amount of carbon in the molecule, suitable to lean combustion, less ignitibility, etc. There are some advantages of using natural gas for engine combustion. First, less carbon dioxide is emitted due to its molecular characteristics. Second, higher thermal efficiency is achieved owing to the high compression ratio compared to that of gasoline engines. Natural gas has higher octane number so that knock is hard to occur even at high compression ratios. However, this becomes a disadvantage in homogeneous charge compression ignition (HCCI) engines or compression ignition engines because the initial auto-ignition is difficult to be achieved. When natural gas is used in a diesel engine, primary natural gas–air mixture is ignited with small amount of diesel fuel. It was found that under high pressure, lean conditions, and with the control of certain parameters, the end gas is auto-ignited without knock and improves the engine combustion efficiency. Recently, some new fuel ignition technologies have been developed to be applied to natural gas engines. These are the laser-assisted and plasma-assisted ignition systems with high energy and compact size.

DOI： 10.1007/978-981-13-3307-1_8

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2015.53._1011-1_

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It is necessary for the control of turbulent combustion to investigate the local flame structure and combustion properties. However, the detailed local flame structure has yet to be elucidated. Local flow velocity are necessary to evaluate flame stretch rate and strain rate in relation to the flame structure. The evaluation methods of these properties are different in numerical and experimental analyses: in the numerical analyses, direct numerical simulation (DNS) is used, while in the experimental analyses, visualization techniques are needed. Therefore, it is difficult to compare the results obtained from both techniques and to evaluate quantitative relationships. In this study, the differences between the experimental and numerical analyses on local flow velocity were investigated. The Particle Image Velocimetry (PIV) analysis was performed with the DNS data of hydrogen/air turbulent premixed flames. As a result, the vector map and probability density function (PDF) of the local flow velocity obtained from simulated PIV system is in good agreement with those from DNS.

DOI： 10.1299/jsmemecj.2015._J0550401-

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

DOI： 10.1299/jsmemag.117.1148_479

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DOI： 10.1299/jsmecmd.2013.26._213-1_

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The relation of the flame displacement speeds of turbulent premixed flame obtained by both of an experimental analysis method and a numerical calculation was researched using the three-dimensional DNS database of the turbulent premixed flame. The two-dimensional flame displacement speed is experimentally evaluated by a laser sheet imaging approach. In this study, firstly, the flame displacement speeds were obtained by the numerical calculation using both the three-dimensional set and the two-dimensional component of DNS data, and were compared. It was found that negative flame displacement speed appeared only in the two-dimensional calculation. Secondly, the flame displacement speed was evaluated by the analysis method imitated experimental imaging approach, and was compared with the two-dimensional flame displacement speed obtained by the numerical calculation. As a result, it was found that the statistics of the flame displacement speed differed depending on the way to consider the local velocity in experimental analyses.

DOI： 10.1299/jsmemecj.2013._G061055-1

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Various turbulent combustion models are currently used with RANS (Reynolds-Averaged Navier-Stokes Simulation) or LES (Large Eddy Simulation) for the analyses and developments of IC (internal combustion) engines. Their models are, however, insufficient for their analyses and developments because the models are constructed by considering only the combustion in the gas phase without considering the chemical process on the internal surface of engine cylinder. In actual IC engines, the effects of chemical process on solid surfaces on the combustion should not be negligible because the combustion takes place in a very small volume surrounded by cylinder liner, cylinder head and piston. In this study, DNS (Direct Numerical Simulation) of premixed flames with a detailed chemical kinetics of hydrogen/air including the chemical processes in the bulk and on the solid surface were implemented. It was found that heat release rate near the wall increased temporally in the case of both a turbulent flame and a planar flame. This may be due to the Lewis number effect or adiabatic wall condition.

DOI： 10.1299/jsmeted.2012.75

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Various turbulent combustion models are currently used with RANS (Reynolds-Averaged Navier-Stokes Simulation) or LES (Large Eddy Simulation) for the analyses and developments of IC (internal combustion) engines. Their models are, however, insufficient for their analyses and developments because the models are constructed by considering only the combustion in the gas phase without considering the chemical process on the internal surface of engine cylinder. In actual IC engines, the effects of chemical process on solid surfaces on the combustion should not be negligible because the combustion takes place in a very small volume surrounded by cylinder liner, cylinder head and piston. In this study, DNS (Direct Numerical Smilation) of premixed flames with a detailed chemical kinetics of hydrogen/air including the chemical processes in the bulk and on the solid surface were implemented. It was found that under the adiabatic wall conditions the flame adjacent to the adiabatic walls as solid surface quenches due to almost no existence of adsorbates.

DOI： 10.1299/jsmemecj.2012._G060011-1

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DOI： 10.1299/jsmecs.2011.49.393

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DOI： 10.1299/jsmecs.2011.49.391

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To investigate the relationship between local burning velocity and flame displacement speed with different density ratio, a numerical analysis was performed using DNS database of turbulent premixed flames. Since it is impossible that the local burning velocity is obtained experimentally, the numerical results using the local burning velocity cannot be compared with any experimental data. The flame displacement speed can be obtained and compared easily with experiments. Thus, to realize comparison of numerical results using the local burning velocity with some experimental ones, it is necessary to reveal the relationship between the local burning velocity and the flame displacement speed.

DOI： 10.1299/jsmeted.2010.125

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To investigate the effects of Lewis number on local burning velocity and stretch rate, a numerical analysis was performed using DNS databases of statistically steady and fully developed turbulent premixed flames. In our previous study, it was found that a probability density function (pdf) of local burning velocity is affected by Lewis number and especially the pdf for lower Lewis number had a wide distribution. To explain the above results, the present work focused on the correlation between local burning velocity and each of local stretch rate, local tangential strain rate and local flame curvature and on the distribution of reaction rates.

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DOI： 10.1299/jsmetokai.2008.57.397

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An analysis of flame area was performed for DNS database of turbulent premixed flames. A local flame front at a prescribed progress variable was identified as a local three-dimensional polygon. The polygon was divided into some triangles and local flame area was evaluated. The turbulent burning velocity was evaluated using the ratio of the total turbulent flame area to the planar flame area and compared with that obtained by the reaction rate.

DOI： 10.1299/jsmemecjo.2006.3.0_351

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An analysis of flame area was performed for DNS database of turbulent premixed flames. A local flame front at a prescribed progress variable was identified as a local three-dimensional polygon. The polygon was divided into some triangles and local flame area was evaluated. The turbulent burning velocity was evaluated using the ratio of the total turbulent flame area to the planar flame area and compared with that obtained by the reaction rate.

DOI： 10.1299/jsmeted.2006.331

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Event date： 2022.9.11 - 2022.9.14

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Event date： 2022.3.4

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2021.11.22 - 2021.11.24

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：WEB（岐阜）  

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Event date： 2021.3

Language：Japanese  

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Event date： 2020.12.2 - 2020.12.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：WEB（松山）  

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Event date： 2020.3.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東広島  

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Event date： 2020.3.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東広島  

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Event date： 2019.11.20 - 2019.11.22

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌  

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Event date： 2019.10.2 - 2019.10.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：函館  

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Event date： 2019.7.1 - 2019.7.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka  

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Event date： 2019.6.10 - 2019.6.14

Language：English   Presentation type：Poster presentation  

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Event date： 2019.3.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：山口大学  

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Event date： 2018.11.14 - 2018.11.16

Language：English   Presentation type：Oral presentation (general)  

Venue：堺市産業振興センター  

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Event date： 2018.11.14 - 2018.11.16

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：堺市産業振興センター  

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Event date： 2018.10.29 - 2018.10.31

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山コンベンションセンター  

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Event date： 2018.10.29 - 2018.10.31

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山コンベンションセンター  

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Event date： 2018.10.20 - 2018.10.21

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：富山大学  

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Event date： 2018.3.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島  

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Event date： 2018.3.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島  

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Event date： 2017.11.13 - 2017.11.15

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：仙台  

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Event date： 2017.3.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島  

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Event date： 2016.11.23 - 2016.11.25

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：仙台  

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Event date： 2016.3.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：松山  

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Event date： 2015.11.16 - 2015.11.18

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：つくば  

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Event date： 2015.9.13 - 2015.9.16

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌  

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Event date： 2015.3.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東広島  

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Event date： 2015.3.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東広島  

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Event date： 2015.2.27

Language：Japanese  

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Event date： 2014.12.3 - 2014.12.5

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2014.12.3 - 2014.12.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山  

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Event date： 2014.12.3 - 2014.12.5

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2014.8.3 - 2014.8.8

Language：English   Presentation type：Poster presentation  

Venue：San Francisco  

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Event date： 2014.8.3 - 2014.8.8

Language：English   Presentation type：Poster presentation  

Venue：San Francisco  

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Event date： 2014.3.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鳥取  

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Event date： 2013.12.4 - 2013.12.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

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Event date： 2013.12.4 - 2013.12.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

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Event date： 2013.11.26 - 2013.11.28

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：神戸  

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Event date： 2013.11.2 - 2013.11.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀  

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Event date： 2013.11.2

Language：Japanese  

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Event date： 2013.9.8 - 2013.9.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山  

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Event date： 2013.9.8

Language：Japanese  

The relation of the flame displacement speeds of turbulent premixed flame obtained by both of an experimental analysis method and a numerical calculation was researched using the three-dimensional DNS database of the turbulent premixed flame. The two-dimensional flame displacement speed is experimentally evaluated by a laser sheet imaging approach. In this study, firstly, the flame displacement speeds were obtained by the numerical calculation using both the three-dimensional set and the two-dimensional component of DNS data, and were compared. It was found that negative flame displacement speed appeared only in the two-dimensional calculation. Secondly, the flame displacement speed was evaluated by the analysis method imitated experimental imaging approach, and was compared with the two-dimensional flame displacement speed obtained by the numerical calculation. As a result, it was found that the statistics of the flame displacement speed differed depending on the way to consider the local velocity in experimental analyses.

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Event date： 2012.12.5 - 2012.12.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Event date： 2012.11.17 - 2012.11.18

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本  

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Event date： 2012.11.16

Language：Japanese  

Various turbulent combustion models are currently used with RANS (Reynolds-Averaged Navier-Stokes Simulation) or LES (Large Eddy Simulation) for the analyses and developments of IC (internal combustion) engines. Their models are, however, insufficient for their analyses and developments because the models are constructed by considering only the combustion in the gas phase without considering the chemical process on the internal surface of engine cylinder. In actual IC engines, the effects of chemical process on solid surfaces on the combustion should not be negligible because the combustion takes place in a very small volume surrounded by cylinder liner, cylinder head and piston. In this study, DNS (Direct Numerical Simulation) of premixed flames with a detailed chemical kinetics of hydrogen/air including the chemical processes in the bulk and on the solid surface were implemented. It was found that heat release rate near the wall increased temporally in the case of both a turbulent flame and a planar flame. This may be due to the Lewis number effect or adiabatic wall condition.

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Event date： 2012.10.31 - 2012.11.2

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌  

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Event date： 2012.9.9 - 2012.9.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢  

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Event date： 2012.9.9

Language：Japanese  

Various turbulent combustion models are currently used with RANS (Reynolds-Averaged Navier-Stokes Simulation) or LES (Large Eddy Simulation) for the analyses and developments of IC (internal combustion) engines. Their models are, however, insufficient for their analyses and developments because the models are constructed by considering only the combustion in the gas phase without considering the chemical process on the internal surface of engine cylinder. In actual IC engines, the effects of chemical process on solid surfaces on the combustion should not be negligible because the combustion takes place in a very small volume surrounded by cylinder liner, cylinder head and piston. In this study, DNS (Direct Numerical Smilation) of premixed flames with a detailed chemical kinetics of hydrogen/air including the chemical processes in the bulk and on the solid surface were implemented. It was found that under the adiabatic wall conditions the flame adjacent to the adiabatic walls as solid surface quenches due to almost no existence of adsorbates.

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Event date： 2012.7.29 - 2012.8.3

Language：English   Presentation type：Poster presentation  

Venue：Warsaw  

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Event date： 2012.3.18 - 2012.3.21

Language：English   Presentation type：Oral presentation (general)  

Venue：Incheon  

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Event date： 2011.12.5 - 2011.12.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：横浜  

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Event date： 2011.12.5 - 2011.12.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：横浜  

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Event date： 2011.12.5 - 2011.12.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：横浜  

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Event date： 2011.4.27 - 2011.4.29

Language：English   Presentation type：Oral presentation (general)  

Venue：Corfu  

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Event date： 2011.3.13 - 2011.3.17

Language：English   Presentation type：Oral presentation (general)  

Venue：Honolulu  

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Event date： 2011.3.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山  

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Event date： 2011.3.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岡山  

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Event date： 2011.2.23

Language：Japanese  

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Event date： 2011.2.23

Language：Japanese  

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Event date： 2010.12.10 - 2010.12.13

Language：English   Presentation type：Oral presentation (general)  

Venue：Hyderabad  

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Event date： 2010.12.1 - 2010.12.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡  

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Event date： 2010.10.30 - 2010.10.31

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長岡  

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Event date： 2009.12.2 - 2009.12.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：札幌  

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Event date： 2009.11.13

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：豊田  

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Event date： 2009.9.2 - 2009.9.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

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Event date： 2009.5.24 - 2009.5.27

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2008.12.3 - 2008.12.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都  

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Event date： 2008.10.22 - 2008.10.24

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2008.10.13 - 2008.10.16

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2008.9.4 - 2008.9.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：神戸  

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Event date： 2008.8.9 - 2008.8.10

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2008.8.3 - 2008.8.8

Language：English   Presentation type：Poster presentation  

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Event date： 2008.6.4

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2008.3.10 - 2008.3.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Event date： 2008.3.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

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Event date： 2007.12.5 - 2007.12.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：仙台  

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Event date： 2007.11.23 - 2007.11.25

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2007.11.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Event date： 2007.7.23 - 2007.7.27

Language：English   Presentation type：Poster presentation  

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Event date： 2007.7.23 - 2007.7.27

Language：English   Presentation type：Poster presentation  

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Event date： 2007.7.8 - 2007.7.12

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2007.5.20 - 2007.5.23

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2007.3.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

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Event date： 2006.12.18 - 2006.12.20

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Event date： 2006.12.6 - 2006.12.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島  

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Event date： 2006.11.24 - 2006.11.25

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：横浜  

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Event date： 2006.11.17

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Event date： 2006.9.18 - 2006.9.22

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本  

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Event date： 2006.5.31 - 2006.6.2

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名古屋  

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Event date： 2005.12.5 - 2005.12.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京  

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Event date： 2005.11.25

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岐阜  

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Event date： 2004.12.1 - 2004.12.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：岐阜  

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Event date： 2004.11.11 - 2004.11.12

Language：English   Presentation type：Poster presentation  

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Event date： 2003.12.3 - 2003.12.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：つくば  

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Event date： 2003.11.23 - 2003.11.26

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2003.9.28 - 2003.9.29

Language：English  

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Event date： 2002.12.4 - 2002.12.6

Language：Japanese   Presentation type：Poster presentation  

Venue：大阪  

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Event date： 2002.8.25 - 2002.8.27

Language：English  

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Event date： 2002.7.21 - 2002.7.26

Language：English   Presentation type：Poster presentation  

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Event date： 2002.3.12 - 2002.3.13

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：仙台  

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Event date： 1997.3.21 - 1997.3.22

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪  

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