研究者詳細 - 河内　俊憲

論文 - 河内　俊憲

分割表示 113 件中 41 - 60 件目／全件表示 >>

Extracting dominant turbulent structures in supersonic flow using two-dimensional Fourier transform 査読

Toshinori Kouchi, Goro Masuya, Shinichiro Yanase

Experiments in Fluids 58 ( 8 ) 2017年8月

Effect of Torsion on the Friction Factor of Helical Pipe Flow 査読

Datta Anup Kumer, Yanase Shinichiro, Hayamizu Yasutaka, Kouchi Toshinori, Nagata Yasunori, Yamamoto Kyoji

Journal of the Physical Society of Japan 86 ( 6 ) 064403 - 064403 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Physical Society of Japan

Three-dimensional direct numerical simulations of a viscous incompressible fluid flow through a helical pipe with a circular cross section were conducted for three Reynolds numbers, <italic>Re</italic>(= 80, 300, and 1000), and two nondimensional curvatures, δ (= 0.1 and 0.05), over a wide range of torsion parameters, β (= nondimensional torsion/<inline-formula><tex-math version="MathJax"><![CDATA[\(\sqrt{2\delta } \)]]></tex-math></inline-formula>), from 0.02 to 2.8. Well-developed axially invariant regions were obtained where the friction factors were calculated, in good agreement with the experimental data obtained by Yamamoto et al. [<ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1016/0169-5983(95)00022-6" xlink:type="simple">Fluid Dyn. Res. <bold>16</bold>, 237 (1995)</ext-link>]. It was found that the friction factor sharply increases as β increases from zero, then decreases after taking a maximum, and finally slowly approaches that of a straight pipe when β tends to infinity. It is interesting that a peak of the friction factor exists in the region 0.2 ≤ β ≤ 0.3 for all the Reynolds numbers and curvatures studied in the present paper, which manifests the importance of the torsion parameter in helical pipe flow.

DOI： 10.7566/jpsj.86.064403

Modified Lee’s Transonic Buffet Mechanism Inspired with Fast-framing Focusing-schlieren Visualization

Toshinori Kouchi, Shingo Yamaguchi, Yuki Yamashita, Shinichiro Yanase, Shunsuke Koike

55th AIAA Aerospace Sciences Meeting 2017年1月

Supersonic Combustion using Multiple Stinger-shaped Injectors 査読

KOUCHI Toshinori, TOMIOKA Sadatake, HIRANO Kohshi, MATSUO Akiko, MASUYA Goro

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 60 ( 1 ) 56 - 59 2017年

OpenFOAMを用いたポンプ水槽内に発生する空気吸込渦と水中渦の解析査読

山崎諒, 河内俊憲, 永田靖典, 柳瀬眞一郎

日本機械学会論文集 83 ( 853 ) 17 - 00181-17-00181 2017年

記述言語：日本語出版者・発行元：一般社団法人日本機械学会

<p>Numerical prediction of air-entraining and submerged vortices in pump sumps is important for engineering applications. The validation of pump sump simulations, however, still is not enough, because the simulations is very complicated; for examples, treatment of gas-liquid interface, detection method of the vortices and selection of turbulence model etc. We conducted numerical simulations of the benchmark experiments of the pump sump conducted by Matsui et al. (2006, 2016) and compared the simulation with the experimental data to investigate the effects of turbulence model, grid density and detection method of the vortices. We determined a threshold of the gas-liquid fraction function of VOF method (α) and the second invariant of velocity gradient tensor (Q₂) to detect the air-entraining and submerged vortices by using vorticity, respectively. This method well detected the vortices and well reproduced the experiments for the RANS simulation using SST k-ω model. Large eddy simulation using Smagorinsky model, however, was sensitive to the grid system and difficult to reproduce the experimental vortex structures even for the finest grid system having 3.7 million cells.</p>

DOI： 10.1299/transjsme.17-00181

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マイクロフォンアレイを用いた枚葉式半導体洗浄装置内に形成される大規模渦構造の検出査読

河内俊憲, 三好勇輝, 中野裕介, 永田靖典, 柳瀬眞一郎

日本機械学会論文集 83 ( 845 ) 16 - 00441 2017年

Application of the Modified Force-Coupling Method of Tracing the Trajectories of Spherical Bubbles with Solid-Like and Slip Surfaces 査読

Chao Guan, Shinichiro Yanase, Koji Matsuura, Toshinori Kouchi, Yasunori Nagata

Open Journal of Fluid Dynamics 07 ( 04 ) 657 - 672 2017年

Optimization of Focusing Schlieren System for an Axisymmetric Ejector 査読

Masato Nakaya, Toshinori Kouchi, Yasunori Nagata, Shinichiro Yanase

11th Pacific Symposium on Flow Visualization and Image Processing PSFVIP11-055 2017年

Combined Fast-framing Schlieren Imaging and Stereo PIV Measurements in a Supersonic Boundary-layer 査読

Mayu Mizoguchi, Kazuki Yamauchi, Toshinori Kouchi, Yasunori Nagata, Shinichiro Yanase

9th JSME-KSME Thermal and Fluids Engineering Conference TFEC9-1463 2017年

Wavelet analysis of transonic buffet on a two-dimensional airfoil with vortex generators 査読

Toshinori Kouchi, Shingo Yamaguchi, Shunske Koike, Tsutomu Nakajima, Mamoru Sato, Hiroshi Kanda, Shinichiro Yanase

Experiments in Fluids 57 ( 11 ) 2016年11月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

We visualized the shock buffets on a two-dimensional transonic airfoil with and without vortex generators (VGs) by using a fast-framing focusing schlieren imaging. The focusing schlieren visualization showed that the flow three-dimensionality around the airfoil became remarkable with installing the VGs. This implies that narrow depth of focus of imaging systems was a key to accurately capture the characteristics of the shock oscillation due to the buffet for the cases with VGs. The time-resolved imaging also revealed that non-periodic components were included in the shock oscillation due to the buffet for the cases with VGs. This prevented Fourier analysis from being applied. We used wavelet analysis to extract the characteristic of the shock oscillation for the cases with VGs. The wavelet spectrograms revealed that the low-frequency oscillation having the buffet frequency was still included intermittently in the shock oscillation even when VG controlled the buffet. The rate of appearing the low-frequency oscillation increased with increasing both the interval between VGs and the angle of attack.

DOI： 10.1007/s00348-016-2261-2

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その他リンク： http://link.springer.com/content/pdf/10.1007/s00348-016-2261-2.pdf

Wavelet Analysis of Unsteady Shock-wave Motion on Two-dimensional Airfoil with Vortex Generators

Toshinori Kouchi, Shingo Yamaguchi, Shunsuke Koike, Shinichiro Yanase, Tsutomu Nakajima, Mamoru Sato, Atsushi Kanda

54th AIAA Aerospace Sciences Meeting 2016年1月

Development of DEM–CFD Simulation of Combustion Flow in Incinerator with the Representative Particle Model 査読

Kenya Kuwagi, Toshihiro Takami, Azri Bin Alias, Degang Rong, Hiroshi Takeda, Shinichiro Yanase, Toshinori Kouchi, Toru Hyakutake, Kaoru Yokoyama, Yoshiyuki Ohara, Nobuo Takahashi, Noritake Sugitsue

Journal of Chemical Engineering of Japan 49 ( 5 ) 425 - 434 2016年

Turbulent diffusion flux of transverse jet into pseudo-shock wave

Taekjin Lee, Toshinori Kouchi, Yoshinori Oka, Goro Masuya

54th AIAA Aerospace Sciences Meeting AIAA 2016-0662 2016年

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）出版者・発行元：American Institute of Aeronautics and Astronautics

© 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All Rights Reserved. An experiment to investigate the effect of pseudo-shock wave (PSW) on turbulent diffusion of a transverse jet in a Mach 2.0 supersonic crossflow was conducted. The vertical jet from a 2.5 mm-diameter orifice was injected into pseudo-shock wave and jetto-crossflow momentum flux ratio was 2.2. To measure turbulent diffusion flux, stereoscopic particle image velocimetry (SPIV) and acetone planar laser-induced fluorescence (PLIF) system were combined and velocity and concentration fields were simultaneously measured. Measurement plane was a cross section at 10 mm downstream from the injection port. The position of PSW was controlled by a flow plug at the duct exit driven by a stepping motor. The front of PSW was set at 30 mm upstream from the orifice. Without PSW, turbulent diffusion flux (TDF) of the injectant was extended upward and the shape of injectant plume was deformed by a counter-rotating vortex pair (CVP) which was formed behind the injected gas. Under PSW, the CVP made horseshoe-shape concentration distribution. TDF directed from spur of concentration to both free stream side and lee side of the jet. Most of no-PSW condition and outward of under-PSW TDF was concentration-fluctuation-dominant, only inward TDF under PSW emerged as turbulent-dominant. The effect of PSW that enhances diffusion of injected gas was confirmed.

DOI： 10.2514/6.2016-0662

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超音速壁面噴射流れ場へ上流擾乱が及ぼす影響査読

浦本翔平, 河内俊憲, 升谷五郎

日本航空宇宙学会論文集 64 ( 4 ) 244 - 252 2016年

Focusing-schlieren visualization in a dual-mode scramjet 査読

Toshinori Kouchi, Christopher P. Goyne, Robert D. Rockwell, James C. McDaniel

Experiments in Fluids 56 ( 12 ) 2015年12月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

DOI： 10.1007/s00348-015-2081-9

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その他リンク： http://link.springer.com/article/10.1007/s00348-015-2081-9/fulltext.html

高速断層シュリーレンによる二次元翼バフェットの可視化査読

山口真伍, 河内俊憲, 小池俊輔, 中島努, 佐藤衛, 神田宏, 柳瀬眞一郎

日本航空宇宙学会論文集 63 ( 4 ) 166 - 174 2015年

担当区分：責任著者記述言語：日本語出版者・発行元：日本航空宇宙学会

We visualized two-dimensional wing buffet using fast-framing focusing schlieren method. A supercritical airfoil of NASA SC(2)-0518 was used in this study. Mach number of the freestream was 0.7, and Reynolds number based on the wing code (c) was 5×106. Angle of attack without corrections (α) was changed from 4° to 6°. The present focusing schlieren system had ±18mm depth of field, which was narrow than spanwise region where the two-dimensionality of the flow field was maintained. 8,345 successive images were captured by high speed CMOS camera with 7,000 frames per second with 20μs exposure time. The present imaging system well captured the shock wave motion on the airfoil. At α = 4°, the shock wave was positioned at x/c∼0.45. The shock wave was slightly fluctuated with a frequency of 585.5Hz. Above α = 5°, the wing buffet occurred. The buffet frequency increased as increasing α. The focusing schlieren movies revealed that the shock wave was bifurcated on the wing surface, as the shock traveling upstream. The boundary layer largely separated from the leading oblique foot of the bifurcated shock wave, whereas, the bifurcated shock wave changed into a normal shock and the flow separation disappeared, as the shock traveling downstream. For both cases, many pressure waves propagated from the downstream of the shock wave to the upstream. These waves merged with the shock wave, and seem to drive the shock oscillation.

DOI： 10.2322/jjsass.63.166

その他リンク： http://ousar.lib.okayama-u.ac.jp/56129

枚葉式半導体洗浄装置内に形成される渦の周期構造査読

河内俊憲, 福田修也, 中野裕介, 清水義也, 永田靖典, 柳瀬眞一郎

日本機械学会論文集 81 ( 829 ) 15 - 00273 2015年