研究者詳細 - 坪井　伸幸

論文 - 坪井　伸幸

分割表示254 件中 141 - 160 件目／全件表示 >>

102 数値計算によるローティングデトネーションエンジンの推進性能評価 : 回転デトネーションの数及び燃焼器サイズによる影響

原野孝也, 渡辺裕介, 坪井伸幸, 小島孝之, 林光一

日本機械学会九州支部講演論文集 ( 一般社団法人日本機械学会 ) 2014 ( 0 ) _102 - 1_-_102-2_ 2014年01月

101 煤膜法による円管内でのメタン/酸素デトネーションのセル模様に関する実験的研究

吉田啓祐, 元永孝英, 森井雄飛, 村上清人, 須佐秋生, 坪井伸幸, 林光一

日本機械学会九州支部講演論文集 ( 一般社団法人日本機械学会 ) 2014 ( 0 ) _101 - 1_-_101-2_ 2014年01月

A molecular dynamics analysis of quantum effect on the thermodynamic properties of liquid hydrogen 査読有り

Nagashima H., Tsuda S., Tsuboi N., Koshi M., Hayashi A., Tokumasu T.

ASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013 2013年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Liquid Hydrogen plays an important role in hydrogen energy society. Therefore it is important to understand its thermal and transport properties accurately. However cryogenic hydrogen has unusual thermodynamic properties because of its quantum nature. The thermal de Broglie wavelength of cryogenic hydrogen molecule becomes the same order as molecular diameter. Therefore, each molecular position and its momentum cannot be defined classically. Because of this nature, hydrogen molecules show higher diffusivity than classical counterpart. Until now, the effects of quantum nature of hydrogen and its mechanism on the thermodynamic properties have not been clarified in detail. Especially, how the quantum nature would effect on the energy transfer in molecular scale has not been clarified. An accurate understanding of the effect and mechanism of quantum nature is important for hydrogen storage method and energy devices which use hydrogen as a fuel. In this study, therefore, we investigated the effect of this quantum nature and its mechanism on the thermodynamic and transport properties of cryogenic hydrogen using classical Molecular Dynamics (MD) method and quantum molecular dynamics method. We applied path integral Centroid Molecular Dynamics (CMD) method for the analysis. First, we have conducted thermodynamic estimation of cryogenic hydrogen using the MD methods. This simulation was performed across a wide density-temperature range. Using these results, equations of state (EOS) were obtained by Kataoka's method, and these were compared with experimental data according to the principle of corresponding states. As a result, it was confirmed that both quantitative and qualitative effect of the quantum nature on the thermodynamic properties of hydrogen are large. It was also found that taking account the quantum nature makes larger virial pressure and weaker intermolecular interaction energy. Second, we have calculated the diffusion coefficient of liquid hydrogen to clarify the effect of the quantum nature on the transport properties. We used Green-Kubo form for the calculation using velocity autocorrelation function. The simulation was performed across a wide temperature range. CMD simulation results were compared with classical simulation results and experimental data. We clarified the effect of quantum nature on the transport properties of liquid hydrogen. Copyright © 2013 by ASME.

DOI： 10.1115/ICNMM2013-73161

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An analysis of quantum effect on the p-V-T relation of cryogenic hydrogen using centroid molecular dynamics method 査読有り

Nagashima H., Tsuda S., Tsuboi N., Koshi M., Koichi Hayashi A., Tokumasu T.

Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B 79 ( 805 ) 1848 - 1857 2013年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

In this paper, we conducted analysis of p-V-T relation of cryogenic hydrogen using classical Molecular Dynamics (MD) and path integral Centroid MD (CMD) method to understand an effect of quantum nature of hydrogen molecules. We performed NVE constant MD simulation across a wide density-temperature region to obtain an Equation Of State (EOS). Simulation results were compared with experimental data. As a result, it was confirmed that classical MD cannot reproduce the experimental data at the high density region. On the other hand, CMD well reproduces the thermodynamic properties of liquid hydrogen. Moreover, it was clarified that taking the quantum effect into account makes repulsion force larger and the potential well smaller. Because of this mechanism, the intermolecular interaction of hydrogen diminishes and the virial pressure increases. ©2013 The Japan Society of Mechanical Engineers.

DOI： 10.1299/kikaib.79.1848

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Strong and Mild Ignition Mechanism behind Reflected Shock Waves in Hydrogen Mixture 査読有り

Asahara, M., Shirakawa, Y., Hayashi, A.K. , Tsuboi, N.

5th International Conference on Hydrogen Safety No: 167 2013年09月

Numerical analysis of spinning detonation dependency on initial pressure using AUSMDV scheme 査読有り

Nagao T., Asahara M., Koichi Hayashi A., Tsuboi N., Yamada E.

51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013 2013年08月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In order to investigate the fundamental characteristics of spinning detonation propagating tubes, this present study shows a numerical simulation using AUSMDV scheme which is more capable to capture detonation phenomenon clearly than TVD scheme and a detailed chemical kinetic model of H2/O2 by Petersen and Hanson. By analyzing the lower limit of spinning detonation propagation, disclosing the detonation propagation limit and the feature is the present purpose. In the numerical results, the lower limit of spinning detonation propagating in a rectangular tube has partially analyzed. The numerical results indicated the differences of the propagation limit of spinning detonation propagating in between a circular tube and a rectangular tube. Because of the number of transverse wave, spinning detonation propagating in rectangular tube is able to maintain more than circular tube's one. © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

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Numerical Study on Shock Wave Interaction over Compression Corner with 30 deg. in Hypersonic Flow 査読有り

T.Kuramoto, D.Muto, N.Tsuboi, H.Nagai, K.Asai

29th International Symposium on Shock Waves #0246-000035 2013年07月

Numerical Analysis of 3D-Rotating Detonation Engine Concerning Propagation Mechanism in Combustor Thickness Direction and Effect on its Performance 査読有り

Zusai K., Uemura Y., Asahara M., Yamada E., Hayashi A.K., Tsuboi N.

24th International Colloquium on the Dynamics of Explosions and Reactive Systems #251 2013年07月

Detailed Hydrodynamic Instability Structure at Hydrogen/Air Detonation Front Using WCNS Scheme 査読有り

Iida R., Asahara M., Tsuboi N., Nonomura T., Hayashi A.K.

24th International Colloquium on the Dynamics of Explosions and Reactive Systems #234 2013年07月

Thrust Performance Estimation on Rotating Detonation Engine Using Two-Dimensional Numerical Simulations Isp under Low-Pressure Environment 査読有り

Watanabe Y., Tsuboi N., Kojima T., Hayashi A.K.

24th International Colloquium on the Dynamics of Explosions and Reactive Systems #117 2013年07月

Experimental Study on CH4/O2 Detonation Characteristics near Propagation Limit: Influence of Initial Pressure and Equivalence Ratio on Cellular Structure 査読有り

Motonaga T., Yoshida K., Morii Y., Murakami K., Susa A., Tsuboi N., Hayashi A.K.

24th International Colloquium on the Dynamics of Explosions and Reactive Systems #237 2013年07月

Numerical Simulations on Propagating Process of H2/O2/H2O Cylindrical Detonation with Detailed Reaction Model 査読有り

Sugiyasu T., Morii Y., Tsuboi N., Asahara M., Hayashi A.K.

24th International Colloquium on the Dynamics of Explosions and Reactive Systems #158 2013年07月

Three-Dimensional Simulation on Deflagration to Detonation Transition with a Detailed Chemical Reaction 査読有り

Machida T., Fukuda M., Asahara M., Yamada E., Hayashi A.K., Tsuboi N.

24th International Colloquium on the Dynamics of Explosions and Reactive Systems #252 2013年07月

Evaluation of Chemical Reaction Models and Numerical Simulations of Detonations in C2H4/O2 Mixtures 査読有り

Araki T., Morii Y., Tsuboi N., Hayashi A.K.

24th International Colloquium on the Dynamics of Explosions and Reactive Systems #57 2013年07月

Numerical Analysis on Ignition Problem behind Reflected Shock Waves in Reactive Mixture 査読有り

Asahara M., Koyama T., Hayashi A.K., Tsuboi N.

24th International Colloquium on the Dynamics of Explosions and Reactive Systems #256 2013年07月

Numerical approach to one-dimensional CH<inf>4</inf>/O<inf>2</inf> detonation with the reduced chemical kinetic model DRG30 査読有り

Morii Y., Tsuboi N., Ogawa H., Tokudome S., Koichi Hayashi A.

Science and Technology of Energetic Materials 73 ( 5-6 ) 169 - 174 2012年09月

記述言語：英語掲載種別：研究論文（学術雑誌）

In order to understand the effect of the CH4/O2 chemical kinetic models for detonation phenomena, the numerical calculations use one detailed chemical kinetic model k311 and four reduced chemical kinetic models such as DRG30 model, DRG23 model, Petersen & Hanson model, and Soetrisno model. At first, the calculations of laminar flame velocity and onedimensional ZND model are performed to compare with k311 model. Then, it is shown that DRG30 model is the most reliable reduced chemical kinetic model in four reduced kinetic models in these conditions. Next, the one-dimensional Euler simulations are performed with k311 model, DRG30 model, Petersen & Hanson model, and Soetrisno model. The results are discussed about detonation velocity history, and instantaneous pressure and temperature profiles. The detonations using k311, DRG30, and Petersen & Hanson models can propagate unstably, but Soetrisno model cannot reproduce a detonation. As a result, the similar features appear between the results with k311 model and DRG30 model.

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Numerical study and performance evaluation for a pulse detonation engine with an exhaust nozzle (1st report: Estimation on performance using a detailed reaction model) 査読有り

Kimura Y., Tsuboi N., Tsuboi N., Hayashi A., Yamada E.

Transactions of the Japan Society for Aeronautical and Space Sciences 55 ( 1 ) 51 - 59 2012年02月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

This paper presents a propulsive performance evaluation for a H 2/Air pulse detonation engine (PDE) equipped with a converging-diverging exhaust nozzle. The evaluation was conducted using system-level modeling and multi-cycle numerical simulations. This study discusses two-dimensional and axisymmetric compressible Euler equations with a detailed chemical reaction model. First, the single-shot propulsive performance of a simplified-PDE (i.e., no exhaust nozzle) is evaluated to show the validity of the numerical and performance evaluation method. The influences of the initial conditions, ignition energy, grid resolution and scale effects on the propulsive performance are studied using multi-cycle simulations. The present results are compared with the results calculated by Ma et al. and Harris et al. The differences between their results and the present simulations are approximately 2-3% because their chemical reactions use a one-step model with a single-γ model. The effects of the specific heat ratio should be estimated for various nozzle configurations and flight conditions. © 2012 The Japan Society for Aeronautical and Space Sciences.

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An estimation of thermodynamic and transport properties of cryogenic hydrogen using classical molecular simulation 査読有り

Nagashima H., Tokumasu T., Tsuda S., Tsuboi N., Koshi M., Hayashi A.

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference, AJK 2011 2 289 - 299 2011年12月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In this paper, we estimated the thermodynamic and transport properties of cryogenic hydrogen using classical molecular simulation to clarify the limit of classical method on the estimation of those properties of cryogenic hydrogen. Three empirical potentials, the Lennard-Jones (LJ) potential, two-center Lennard-Jones (2CLJ) potential, and modified Buckingham (exp-6) potential, and an ab initio potential model derived by the molecular orbital (MO) calculation were applied. Molecular dynamics (MD) simulations were performed across a wide density-temperature range. Using these data, the equation of state (EOS) was obtained by Kataoka's method, and these were compared with NIST (National Institute of Standards and Technology) data according to the principle of corresponding states. Moreover, we investigated transport coefficients (viscosity coefficient, diffusion coefficient and thermal conductivity) using time correlation function. As a result, it was confirmed that the potential model has a large effect on the estimated thermodynamic and transport properties of cryogenic hydrogen. On the other hand, from the viewpoint of the principle of corresponding states, we obtained the same results from the empirical potential models as from the ab initio potential, showing that the potential model has only a small effect on the reduced EOS: the classical MD results could not reproduce the NIST data in the high-density region. This difference is thought to arise from the quantum effect in actual liquid hydrogen. Copyright © 2011 by ASME.

DOI： 10.1115/AJK2011-36005

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Dependency of Equivalence Ratio on Hydrogen Cylindrical Detonation Induced by Direct Initiation 査読有り

Asahara, M., Tsuboi, N. Hayashi, A.K. and Yamada, E.

The 4th International Conference on Hydrogen Safety (ICHS) 2011, paper no.224 2011年09月

Oscillating propagation of near-limit detonations of CH4/O2 system in a small diameter tubes 査読有り

2) Akio Susa, Nobuyuki Tsuboi, Takuma Endo, Youhi Morii, Hiroyuki Yokoyama, Syunsuke HASEGAWA, Yosuke OGAWA

23rd International Colloquium on the Dynamics of Explosions and Reactive Systems, Oral 131 2011年07月

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