研究者詳細 - 坪井　伸幸

論文 - 坪井　伸幸

分割表示254 件中 161 - 180 件目／全件表示 >>

Detailed Shock Configuration of Cylindrical Cellular Detonation 査読有り

Makoto Asahara, Nobuyuki Tsuboi, A.Koichi Hayashi

23rd International Colloquium on the Dynamics of Explosions and Reactive Systems, Oral 324 2011年07月

Numerical Simulation on Two-Dimensional Detonation including Boundary Layer Effects 査読有り

Nobuyuki Tsuboi, A.Koichi Hayashi, Youhi Morii, Mitsuo Koshi

23rd International Colloquium on the Dynamics of Explosions and Reactive Systems, Oral 187 2011年07月

Physics of Detonation Propagation in Rotating Detonation Engine 査読有り

Takayuki Yamada, Nobuyuki Tsuboi, Yuho Uemura, A.Koichi Hayashi, Eisuke Yamada

23rd International Colloquium on the Dynamics of Explosions and Reactive Systems, Poster 173 2011年07月

Fast Deflagration in the Smooth Tube in Hydrogen-Oxygen Mixture 査読有り

Edyta Dzieminska, Nobuyuki Tsuboi, A.Koichi Hayashi, Eisuke Yamada, Motoki Fukuda

23rd International Colloquium on the Dynamics of Explosions and Reactive Systems, Poster 185 2011年07月

Two-dimensional　analysis of Hydrogen/Oxygen cylindrical detonation using AUSMDV scheme 査読有り

Makoto Asahara, Nobuyuki Tsuboi, A. Koichi Hayashi, and Eisuke Yamada

Archivum　Combustions 30 ( 3 ) 177 - 186 2011年04月

Transition to detonation after a ‘volume explosion’ - Oppenheim’s experiment validation with a numerical calculation 査読有り

Edyta Dzieminska, Motoki Fukuda, A. Koichi Hayashi, Nobuyuki Tsuboi

Archivum　Combustions 30 ( 3 ) 187 - 195 2011年04月

Updated kinetic mechanism for high-pressure hydrogen combustion 査読有り

Shimizu K., Hibi A., Koshi M., Morii Y., Tsuboi N.

Journal of Propulsion and Power 27 ( 2 ) 383 - 395 2011年03月

記述言語：英語掲載種別：研究論文（学術雑誌）

A chemical kinetic model for high-pressure combustion of H 2=O2 mixtures has ben developed by updating some of the rate constants important under high-pressure conditions without any diluent. The revised mechanism is validated against experimental shock-tube ignition delay times and laminar flame speeds. Predictions of the present model are also compared with those by several other kinetic models proposed recently. Although predictions of those models (including the present model) agree quite well with each other and with the experimental data of ignition delay times and flame speeds at pressures lower than 10 atm, substantial differences are observed between recent experimental data of high-pressure mass burning rates and model predictions, as well as among the model predictions themselves. Different pressure dependencies of mass burning rates above 10 atm in different kinetic models result from using different rate constants in these models for HO 2 reactions, especially for H + HO2 and OH + HO 2 reactions. The rate constants for the reaction H + HO2 involving different product channels were found to be very important for the prediction of high-pressure combustion characteristics. An updated choice of rate constants for those reactions is presented on the basis of recent experimental and theoretical studies. The role of O(1D), which can be produced by the H + HO2 reaction, in the high-pressure combustion of H2 is discussed. © 2010 by the American Institute of Aeronautics and Astronautics, Inc.

DOI： 10.2514/1.48553

Scopus

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Mechanism of high-pressure hydrogen auto-ignition when spouting into air 査読有り

Yamada E., Kitabayashi N., Hayashi A., Tsuboi N.

International Journal of Hydrogen Energy 36 ( 3 ) 2560 - 2566 2011年02月

記述言語：英語掲載種別：研究論文（学術雑誌）

High-pressure hydrogen leak is one of the top safety issues presently. This study elucidates numerically the physics and mechanism of high-pressure hydrogen jet ignition when the hydrogen suddenly spouts into the air through a tube. The direct numerical simulation based on the compressible fluid dynamics was carried out. When high-pressure hydrogen is passing through the tube filled by atmospheric air, a strong shock wave is formed and heats up hydrogen behind the shock wave by compression effect. The leading shock wave is expanded widely after the tube exit, auto-ignitions of hydrogen occur. When the tube becomes longer, the tendency of auto-ignition is increased. Other type of auto-ignitions is also predicted. An explosion is also occurred in the tube under a certain condition. Vortices are generated behind the shock wave in a long tube. There is a possibility of an auto-ignition induced by vortices. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2010.05.011

Scopus

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Numerical Study and Performance Evaluation for Pulse Detonation Engine with an Aerospike Nozzle 査読有り

N. Tsuboi, Y. Kawakami, K. Ezure, A. Hayashi, E. Yamada

AIAA-2011-800, 49th AIAA Aerospace Sciences Meeting 2011年01月

Numerical Study on Detonation Characteristics Using a Bio-Fuel 査読有り

A. Hayashi, T.Shimada, E. Yamada, N. Tsuboi

AIAA-2011-582, 49th AIAA Aerospace Sciences Meeting 2011年01月

Numerical analysis of threshold of limit detonation in Rotating Detonation Engine 査読有り

Yamada T., Hayashi A., Yamada E., Tsuboi N., Tangirala V., Fujiwara T.

48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition 2010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）

Rotating Detonation Engine (RDE) is a new kind of detonation engine, which may provide a high performance with a smaller and simpler system than the traditional ones. In order to optimize RDE system, the threshold of detonation limit must be studied for its best design and its best run. In this paper, the following four aspects are discussed: (1) what will be happen to the rotating detonation limit when the computational area is doubled; (2) what will be happen to rotating detonation when the ignition energy is increased; (3) what will be happen to specific impulse (Isp) when the ignition energy is increased. The results show that the lower detonation limit gets the computational area effct, but the upper one does not. The max specific impulse of Ispf is about 4000 s and that of Ispm is about 450 s. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc.

Scopus

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Combustion characteristics of hydroxylammonium nitrate aqueous solutions 査読有り

Katsumi T., Matsuda R., Inoue T., Tsuboi N., Ogawa H., Sawai S., Hori K.

International Journal of Energetic Materials and Chemical Propulsion 9 ( 3 ) 219 - 231 2010年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

Hydroxylammonium nitrate (HAN) based liquid propellant has been investigated as a candidate for the monopropellant to be utilized in the reaction control system of satellites as an alternative to hydrazine. This propellant, which consists of ammonium nitrate, methanol, and water, has moderate burning characteristics, sufficiently low freezing temperature, high density, low toxicity, and its density x Isp is 70% higher than hydrazine. In a previous study, the combustion characteristics of the propellants were obtained and found to be very complex. In this paper, the research was focused on the combustion characteristics of HAN aqueous solution. Sample solutions of several concentrations, 95-50 mass %, were prepared. The measurement of linear burning rates, the temperature measurement of the combustion wave, and the observation of combustion phenomena were included in the study. The linear burning rate does not increase monotonically with increasing HAN concentration. The burning rates increase as the HAN concentration increases up to 80 mass %, and decrease as the concentration increases from 80 to 95 mass %. The burning rate peaks at around 80 mass % of HAN concentration. The combustion mode is very complex and is dependent upon composition and pressure. Temperature measurements indicate that the role of the two-phase region is very important, and the boiling of water caused by superheat is responsible for the high burning rate. The relationship between the rate of nucleation of bubbles and the linear burning rate is discussed. © 2010 by Begell House, Inc.

DOI： 10.1615/IntJEnergeticMaterialsChemProp.v9.i3.30

Scopus

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Numerical investigations of film cooling effect on sub-scale rocket engine performance 査読有り

Ito T., Tsuboiy N., Miyajima H.

Transactions of the Japan Society for Aeronautical and Space Sciences 53 ( 179 ) 63 - 70 2010年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

LOX/LH 2 subscale rocket nozzle flow fields are simulated computationally using the 3D compressible Navier- Stokes equations. The area ratio of the nozzle is 140 and the film coolant hydrogen gases are injected from 30 film cooling holes distributed circumferentially at an area ratio of 13. The experimental nozzle throat Reynolds number indicates that the boundary layer of the nozzle is in its transition region as the size of the nozzle is small. A clear difference in effective specific impulses of the secondary flow between the laminar and turbulent conditions is also shown. The nozzle wall temperature also influences the nozzle performance and the experimental performances were in better agreement with the laminar computations when the wall temperature is set to 300 K, which is closer to the experimental conditions. Both turbulent and laminar computations are carried out to investigate the effect of the boundary layer conditions on the nozzle performance. The computed results show that the structure of the separated flow downstream of the film cooling injection significantly changes between the turbulent and laminar conditions. © 2010 The Japan Society for Aeronautical and Space Sciences.

DOI： 10.2322/tjsass.53.63

Scopus

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Mechanism of High Pressure Hydrogen Auto-ignition When Spouting into Air 査読有り

E.Yamada,Naoki Kitabayashi,A. Koichi Hayashi,Nobuyuki Tsuboi

International Journal of Hydrogen Energy 36 ( 2560-2566 ) 2010年04月

Advanced Computer Science on Internal Ballistics of Solid Rocket Motors 査読有り

Toru SHIMADA,Kazushige KATO,Nobuhiro SEKINO,Nobuyuki TSUBOI,Yoshio SEIKE,Mihoko FUKUNAGA,Yu DAIMON,Hiroshi HASEGAWA,Hiroya ASAKAWA

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 8 ( ists27 ) Pa_29 - Pa_37 2010年04月

Detonation Limit Thresholds in H2/O2 Rotating Detonation Engine 査読有り

Takayuki Yamada,A.Koichi Hayashi,Eisuke Yamada,Nobuyuki Tsuboi,Venkat E. Tangirala,Toshi Fujiwara

Combustion Science and Technology 182 ( 11-12 ) 1901 - 1914 2010年04月

90°曲管におけるH2/O2デトネーションの流体力学的効果に関する数値解析査読有り

坪井伸幸,阿達聡,林光一,山田英助,内田正宏,藤森俊郎,須田俊之

日本燃焼学会誌論文集 52 ( 161 ) 213 - 223 2010年04月

ノーズコーンをもつ超音速機の壁面圧力を用いた機体姿勢およびマッハ数計測に関する数値解析査読有り

吹場活佳,坪井伸幸,小林弘明

日本航空宇宙学会論文集 58 ( 676 ) 130 - 137 2010年04月

Numerical Investigations of the Film Cooling Effect on Sub-Scale Rocket Engine Performance 査読有り

Takashi ITO,Nobuyuki TSUBOI,Hiroshi MIYAJIMA

Transactions of the Japan Society for Aeronautical and Space Sciences 53 ( 179 ) 63 - 70 2010年04月

排気ノズルを有するパルスデトネーションエンジンの数値解析による推力性能評価（第1報：詳細反応モデルによる基本性能の評価）査読有り

木村勇一朗，坪井伸幸，林光一，山田英助

日本航空宇宙学会論文集 58 ( 675 ) 91 - 99 2010年04月

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