研究者詳細 - 坪井　伸幸

論文 - 坪井　伸幸

分割表示254 件中 41 - 60 件目／全件表示 >>

Recent experimental and numerical study on disc-type rdes 査読有り

Hayashi K., Tsuboi N., Ozawa K., Watanabe T., Jourdaine N.H., Ishii K., Kawana H., Kuwata W., Ohno K., Obara T., Maeda S., Dzieminska E., Tang X., Mizukaki T.

AIAA Scitech 2020 Forum 1 PartF 2020年01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）

The present study discusses disc-type rotating detonation engine (DTRDE) experimental ly and numerically. The experimental work is performed using hydrogen and air and measuring pressure records together with taking a high speed movie to see a direction of rotating detonation. Especially the relation between mass flow rate and operation frequency and that between equivalence ratio and operation frequency. The number of detonation head is figured out from the maximum operation frequency. Then the 3D numerical analysis of DTRDE will provide the flow structure in the DTRDE combustion chamber, high pressure profile, and low mach number profiles.

DOI： 10.2514/6.2020-1169

Scopus

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Numerical study on JP-10/air detonation and rotating detonation engine 査読有り国際誌

Hayashi A.K., Tsuboi N., Dzieminska E.

AIAA Journal 58 ( 12 ) 5078 - 5094 2020年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

JP-10/air two-phase detonation and rotating detonation engine (RDE) are numerically studied to find out their limits of physical values as a function of equivalence ratio, prevaporization, fuel concentration, droplet diameter, and initial pressure and temperature. To find such limits, the JP-10/air two-step chemical reaction mechanism is used and the Eulerian–Eulerian two-phase governing system is developed to simulate those limits. Especially the JP-10/air two-phase detonation velocity and cell size are investigated in detail and the generation of nonreacted region and quenching mechanism of JP-10/air two-phase RDE are simulated. The findings from those studies are that 1) the JP-10/air two-phase detonation and RDE codes are developed and validated to calculate detonation and RDE; 2) the JP-10/air detonation cell size is calculated by the developed code to show a good agreement with the experimental data; and 3) the JP-10/air RDE simulation shows a detonation quenching at the condition when the droplet diameter is larger than 4 μm and the prevaporization factor is smaller than 20%.

DOI： 10.2514/1.J058167

Scopus

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Accuracy of real-time fuel regression measurement function of a 3d printed solid fuel 査読有り

Ozawa K., Wang H.W., Inenaga T., Tsuboi N.

AIAA Propulsion and Energy 2020 Forum 1 - 15 2020年01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）

The accuracy of a real-time fuel regression measurement by an additive manufactured solid fuel was discussed by comparing with optically measured regression acquired in firing experiments for the conceptual demonstration. The solid fuels that succeeded in fuel regression measurement were manufactured by a multi-material 3D printer and had the ladder-shaped resistor structure with the 0.15 mm thickness rungs. The fuel regression is detected by the voltage change in the reference resistor due to the break of rungs. For all experiments, the initial resistance of the ladder-shaped resistor structure was estimated to be as expected, and all rung break was successfully detected by the steep voltage change. The acquired measurement values by the two methods had errors like an offset for all runs. The major factors of these errors were the distribution of the fuel regression in the fuel width direction and the resolution of the high-speed video camera. As a result, it was found that the time histories of the values optically measured for comparison had relatively large uncertainties. The remaining errors that cannot be explained by these major error factors were estimated to be less than ±0.15 mm, which corresponds to two layers of the solid fuels manufactured in this study.

DOI： 10.2514/6.2020-3741

Scopus

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Real-time regression rate measurement of an additive-manufactured functional hybrid rocket fuel 査読有り国際誌

Ozawa, K, Wang, H.-W., Yoshino, T., Tsuboi, N.

70th International Astronautical Congress, IAC 2019 2019年10月

Boundary-layer combustion of wax-based fuels at various chamber pressures under two static acceleration environments 査読有り国際誌

Ozawa, K., Yoshino, T., Wang, H.-W., Tsuboi, N.

AIAA Propulsion and Energy Forum and Exposition 2019 AIAA-2019-4100 2019年08月

A Study on Operating Conditions of Disk-Type Rotating Detonation Engine 査読有り国際誌

H. Kawana, W. Kurata, K. Ohno, K. Ishii, A. K. Hayashi, N. Tsuboi, K. Ozawa, T. Obara, S. Maeda, E. Dzieminska, T. Mizukaki

27th International Colloquium on the Dynamics of Explosions and Reactive System 415 2019年08月

Gradient Mechanism on the Onset of Detonation in the Deflagration to Detonation Transition 査読有り国際誌

X. M. Tang, E. Dzieminska, A.K. Hayashi, N. Tsuboi

27th International Colloquium on the Dynamics of Explosions and Reactive System 247 2019年08月

Simulation of detonation propagation in a two-phase gas/liquid cross flow injection 査読有り国際誌

Nicolas Jourdaine, Nobuyuki Tsuboi, A. Koichi Hayashi, Xinmeng Tang, Kohei Ozawa

27th International Colloquium on the Dynamics of Explosions and Reactive System 435 2019年08月

Two-dimensional Numerical Simulations on Unstable Propagation of Propane/Oxygen Detonation Using Detailed Chemical Mechanism 査読有り国際誌

Naomi Takeshima, Kohei Ozawa, Nobuyuki Tsuboi, Youhi Morii, A. Koichi Hayashi

27th International Colloquium on the Dynamics of Explosions and Reactive System 268 2019年08月

Two-dimensional Numerical Simulation of Flame Acceleration and Deflagration-to-Detonation Transition in Channels with Obstacles: Effects of Blockage Ratio and Channel Size 査読有り国際誌

Kanta Iwasaki, Ayu Ago, Nobuyuki Tsuboi, Kohei Ozawa, A. Koichi Hayashi

27th International Colloquium on the Dynamics of Explosions and Reactive System 267 2019年08月

Mixing characteristics of the slit-shaped hydrogen jet in supersonic crossflow 査読有り国際誌

Toshihiro Iwasa, Nobuyuki Tsuboi

32nd International Symposium on Shock Waves OR-21-0357 2019年07月

Feasibility Study of a Real-time Fuel Regression Rate Measurement using an Electrostatic Capacitive Probe for Hybrid Rocket Engine 査読有り

Han-Wei Wang, Kohei Ozawa, Nobuyuki Tsuboi

32nd International Symposium on Space Technology and Science 2019 a91363 2019年06月

Numerical Study on Cryogenic Jet/Crossflow Interaction Structures under a Supercritical Pressure 査読有り

Taishi Amano, Takahide Araki, Hiroshi Terashima, Daiki Muto, Kohei Ozawa, Nobuyuki Tsuboi

32nd International Symposium on Space Technology and Science (ISTS) a91387 2019年06月

Validation of classical mixing rule coupled with van der Waals type equation of state for sound speed of non-ideal gas mixture

Ryuji Takahashi, Nobuyuki Tsuboi, Takashi Tokumasu, Satoshi Watanabe and Shin-ichi Tsuda

American Physical Society March Meeting 2019 R18.00010 2019年03月

Three-dimensional numerical thrust performance analysis of hydrogen fuel mixture rotating detonation engine with aerospike nozzle 査読有り

Jourdaine N., Tsuboi N., Ozawa K., Kojima T., Koichi Hayashi A.

Proceedings of the Combustion Institute 37 ( 3 ) 3443 - 3451 2019年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

The propulsive performance for an H 2 /O 2 and H 2 /Air rotating detonation engine (RDE) with conic aerospike nozzle has been estimated using three-dimensional numerical simulation with detailed chemical reaction model. The present paper provides the evaluation of the specific impulse (I sp ), pressure gain and the thrust coefficient for different micro-nozzle stagnation pressures and for two configurations of conic aerospike nozzle, open and choked aerospike. The simulations show that regardless of the nozzle, increase the micro-nozzles stagnation pressure increases the mass flow rate, the pre-detonation gases pressure and consequently the post-detonation pressure. This gain of pressure in the combustion chamber leads to a higher pressure thrust through the nozzle, improving the I sp . It was also found that the choked nozzle increases the chamber time-averaged static pressure by 50-60% compared with the open nozzle, inducing higher performance for the same reason explained before.

DOI： 10.1016/j.proci.2018.09.024

Scopus

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Three-dimensional numerical simulation of disk rotating detonation engine: Unsteady flow structure 査読有り

Watanabe T., Jourdaine N., Ozawa K., Tsuboi N., Kojima T., Hayashi A.

AIAA Scitech 2019 Forum 2019年01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）

© 2019 by Timothy K. Minton. Published by the American Institute of Aeronautics and Astronautics, Inc. Disk Rotating Detonation Engine (DRDE) simulation using a mixture of hydrogen and oxygen was performed by three-dimensional numerical analysis with detailed chemical reaction model. The computational grid is created based on the DRDE combustor shape designed by Huff et al. and this grid system use three regions. In zone 1 and 2, the inside of the combustor is simulated and in zone 3, the flow behind the nozzle exit is simulated. The combination of coarse and fine computational grids can calculate the propagation of rotating detonation wave inside the DRDE with small computational resources. The present results show that the detonation wave front is not normal to the outer circular wall but has approximately 60 degrees. The maximum pressure near the detonation head on the outer wall has approximately 10 MPa. The Mach number of the exhaust flow becomes approximately 2.5 in this condition.

DOI： 10.2514/6.2019-1498

Scopus

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Development of a high efficiency system with a rotating detonation engine for a gas turbine engine (RDE-GTE) using pressure gain combustion 査読有り

Koichi Hayashi A., Tsuboi N., Ozawa K., Ishii K., Obara T., Maeda S., Dzieminska E., Mizukaki T.

AIAA Scitech 2019 Forum 2019年01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）

© 2019 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. The present study will show a new development of a gasturbine engine with rotating detonation engine. Five universities and a venture company will study characteristics of rotating detonation engines to develop a gasturbine engine with RDE system in order to improve its performance of gas turbine engine, especially its efficiency. We have three teams; the experimental team, numerical team, and gasturbine team. The experimental team will perform several categories; concentric as well as disk type RDE development and measurement of its stable conditions and controlabilities as well as its efficiency; the cooling system of RDE; injection and ignition system; and DDT performance. The numerical group will simulate above experimental categories by real size calculations with both DNS and AMR base. And a micro-gasturbine engine will be run together with RDE system in a near future. We prefer to choose a disc type RDE instead of concentric cylinder type one. Hence the midterm report like presentation will be given at the SciTech meeting, Jan 2019 and 2020.

DOI： 10.2514/6.2019-1509

Scopus

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Effects of a recess on supercritical co-flowing planar jets 査読有り

Muto D., Terashima H., Tsuboi N.

Transactions of the Japan Society for Aeronautical and Space Sciences 62 ( 4 ) 203 - 212 2019年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 The Japan Society for Aeronautical and Space Sciences. The effects of a recess on co-flowing planar jets under supercritical pressure are numerically studied. Two-dimensional hybrid LES/RANS simulations are performed in a wide range of recess lengths and injection momentum flux ratios, which are important design parameters for liquid rocket engine injectors. The present study showed that confinement effects of the near-injector flowfield by applying a recess, suppress outer jet spreading and thus enhances the penetration of the outer jet flow into the inner jet. The enhanced penetration of the outer jet flow results in the appearance of flapping motions in the inner jet. Low-frequency oscillations corresponding to the flapping motions clearly appear in the case of recessed injectors. Moreover, the confinement effects promote interactions between vortex structures resulting in vortex breakdown. Consequently, the inner-jet length is shortened, indicating an improvement in mixing when a recess is applied. The present results also show that the inner-jet length deceases as the recess length increases, and the effects of a recess remarkably appear at higher momentum flux ratios. This is explained by the vortices generated behind the post lip that is strengthened as the result of increased velocity ratio.

DOI： 10.2322/tjsass.62.203

Scopus

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障害物を有する管内での酸水素デトネーション遷移の2次元数値解析：実験との比較

岩﨑幹太, 吾郷愛由, 坪井伸幸, 小澤晃平, 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 ) 2019 ( 0 ) 2019年01月

記述言語：日本語掲載種別：研究論文（研究会，シンポジウム資料等）

<p>Detonation is a type of premixed combustion, which propagates interacting with shock waves and combustion flames at supersonic speed. It is known in the early researches that DDT (Deflagration to Detonation Transition) in a channel is promoted by installing obstacles. This research investigates flame propagation and local explosions in channels filled with hydrogen/oxygen stoichiometric mixture and installed ten obstacles by using the two-dimensional simulation with a detailed reaction model. Furthermore, we estimate differences between the three-dimensional experiments performed in a past study and the present two-dimensional simulations. The simulations performed by changing the scale of the channel, grid width, and obstacle height. As a result, the flames did not transit to detonation under any conditions of the obstacle heights and channel sizes, unlike the experiments. Higher obstacles disturbed the flame propagation and induced the shock waves crossing the channel, which lead to the enhancement and acceleration of the combustion reaction. A small local explosion was observed near the eighth obstacle at one-tenth the size. The flame acceleration was faster in the experiment than in the numerical analysis.</p>

DOI： 10.1299/jsmekyushu.2019.72.B14

CiNii Article

その他リンク： https://ci.nii.ac.jp/naid/130007801915

超臨界圧下における主流と直交干渉する極低温噴流構造について：3-D LES/RANSハイブリッド解析

天野泰嗣, 荒木天秀, 寺島洋史, 武藤大貴, 坪井伸幸

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 ) 2019 ( 0 ) 2019年01月

記述言語：日本語掲載種別：研究論文（研究会，シンポジウム資料等）

<p>The engine cycle of a Japanese next flagship liquid rocket applies an expander bleed cycle and it has a component called mixer. In the mixer, cryogenic hydrogen is vertically injected through the perforated plate into the high temperature hydrogen flow under supercritical pressures. It is important to complete mixing efficiently in the mixer because insufficient mixing may lead to non-uniform temperature distribution and thereby cause combustion instabilities in the chamber. The objective of this study is to investigate flow structures and mixing of a cryogenic jet injected into the crossflow under a supercritical pressure using a three-dimensional LES/RANS hybrid model. The results found that periodic vortex structures are formed around the jet and they have dominant role on near jet mixing processes. The shedding vortices penetrate into a region behind the jet, establishing a recirculation region. There are some differences in the jet height and the recirculation region, compared with those in a two-dimensional calculation.</p>

DOI： 10.1299/jsmekyushu.2019.72.D12

CiNii Article

その他リンク： https://ci.nii.ac.jp/naid/130007801950

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