Papers - Obi, Shinnosuke

単一傾斜型熱線風速計による二次元混合層の乱流計測

小形俊夫， 前鶴昭徳， 小尾晋之介， 益田重明

年会一般講演 17, 183-184  1998

2・2 境界層 (2. 非圧縮性流れ)(流体工学機械工学年鑑 (1997 年))

小尾晋之介

日本機械学會論文集. B 編 64 (624), 2368  1998

チャネル乱流の壁面せん断応力統計量に関する実験的研究

小尾晋之介

日本流体力学会誌 「ながれ」 17 (2), 74-79  1998

二次元非対称ディフューザ内乱流のはく離予測について

冲永佳史， 小尾晋之介

年会一般講演 17, 179-180  1998

The mechanism of momemtum transfer enhancement in the periodically perturbed turbulent separated flow

Obi, S. Ishibashi, N. Masuda, S.

2nd Int. Symp. Turbulence, Heat and Mass Transfer    835-844 1997.06

Research paper (conference, symposium, etc.), Joint Work

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はく離乱流に加えられた周期的変動により運動量輸送が促進される様子を詳細なレーザ計測に基づく実験解析により定量化した。(１０頁)

周期的外乱によるディフューザ内乱流はく離流の制御 (制御効果と速度場の変化)

石橋 信正、青木 謙太、小尾 晋之介、益田 重明

日本機械学会論文集B編 63巻 ( 605号 )  1997.01

Research paper (conference, symposium, etc.), Joint Work

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二次元非対称ディフューザ内はく離乱流の制御において周期的な変動がもたらす効果について、レーザ流速計を用いた詳細に実験解析を行った。(7頁)

Control of turbulent separated flow in a plane diffuser using periodic perturbation (control effects and response of velocity field)

Ishibashi N., Aoki K., Obi S., Masuda S.

Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B (Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B)  63 ( 605 ) 62 - 68 1997.01

ISSN  03875016

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The effects of periodic perturbation on turbulent separated flow in a two-dimensional asymmetric diffuser were investigated. Measurements of velocity fields were undertaken using a LDV, and data reduction was conducted on a time-averaged as well as ensemble-averaged manner that made the mean-periodic-turbulent decomposition possible. Effects of imposed perturbation on the velocity field strongly depend on the frequency of the perturbation, and the optimum frequency ranges between 0.01≤St≤0.04, with St being the perturbation frequency normalized by the channel height at the diffuser inlet and the maximum inlet velocity. At the optimum frequency, the effect of perturbation appears as an organized velocity fluctuation along a separated shear flow, resulting in the enhancement of momentum transport, which is the primary effect of imposed perturbation. An increase in the turbulent Reynolds stress component in the recirculation region is also observed, indicating the secondary effect of the organized fluid motion due to periodic perturbation.

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周期的外乱に対するバックステップ流の応答特性

枡川高久， 吉岡修哉， 斎藤武， 小尾晋之介， 益田重明

年会一般講演 16, 281-282  1997

周期的外乱によるディフユーザ内乱流はく離流の制御

石橋信正， 青木謙太， 小尾晋之介， 益田重明

日本機械学会論文集 B 編 63 (605), 62-68  1997

二次元混合層における乱流エネルギー収支の測定

小形俊夫， 伊藤健二， 小尾晋之介， 益田重明

年会一般講演 16, 107-108  1997

周期的外乱によるディフユーザ内乱流はく離流の制御 制御効果と速度場の変化

石橋信正， 青木謙太， 小尾晋之介， 益田重明

日本機械学会論文集 B 編 63 (605), 62-68  1997

レイノルズ応力の乱流輸送モデル (速度変動三次モーメントの輸送方程式による検討)

原 英統、小尾 晋之介

日本機械学会論文集B編 62巻 ( 600号 )  1996.08

Research paper (conference, symposium, etc.), Joint Work

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変動速度の三次モーメントの輸送方程式を簡略化することで導かれる代数方程式を用いて、レイノルズ応力方程式モデルの予測性能向上を試みた。(8頁)

Model of the turbulent transport of Reynolds stress (Study on the transport equation of triple velocity moment)

Hara H., Obi S.

Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B (Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B)  62 ( 600 ) 2986 - 2993 1996.08

ISSN  03875016

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An algebraic model of the turbulent transport of Reynolds stress is proposed, based on an examination of the budget of the transport equation for the third-moment of fluctuating velocity. Combined with a basic version of the second-moment closure, the new model is applied to the calculation of a two-dimensional free mixing layer. The results show a slight modification of the conventional gradient transport model for the turbulent diffusion, and yield a better agreement with experimental results in terms of the amplitude of the third-moment. The inclusion of a simple model for the pressure diffusion term indicates the possibility of further improvement of the turbulent transfer process in free flows.

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二次元混合層における乱流エネルギ収支の測定 (第一報，局所等方性を仮定した乱流エネルギ消散率)

長谷川 善行、小尾 晋之介、益田 重明

日本機械学会論文集B編 62巻 ( 598号 )  1996.06

Research paper (conference, symposium, etc.), Joint Work

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速度差のある流動場に特有の乱流場の性質を論じるために、熱線風速計による詳細な計測を通じて輸送方程式の収支を定量化した。(7頁)

Experimental study on the statistics of wall shear stress in turbulent channel flows

Obi, S., Inoue, K., Furukawa, T., Masuda, S.

Int. J. Heat and Fluid Flow Vol. 17 1996.06

Joint Work

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壁面せん断応力の計測法としてレーザ光を用いたLGM法を実現し、チャネル乱流における計測を通じてその性能を明らかにした。(6頁)

Measurement of turbulent energy budget of the two-dimensional mixing layer (1st report, evaluation of the dissipation rate assuming local isotropy)

Hasegawa Y., Obi S., Masuda S.

Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B (Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B)  62 ( 598 ) 2187 - 2193 1996.06

ISSN  03875016

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Measurement of the turbulent velocity field have been performed in a newly designed low-speed two-dimensional mixing layer facility. Mean and fluctuating velocity in the streamwise direction are measured by an I-type hot-wire anemometer, and the dissipation rate is evaluated from the time derivative of the fluctuating velocity signal based on the Taylor hypothesis and under the assumption of local isotropy of turbulence. The moments of velocity fluctuation up to the third order agree well with previous experiments and DNS, when normalized by the local turbulence velocity scale; the region of self-similarity in terms of the relative turbulence structure is found to be larger than the conventional definition of the global self similarity region where the turbulence velocity scale no longer varies in the streamwise direction. The dissipation rate can also be well correlated with the recent DNS result, when the Taylor micro length scale and local turbulence velocity scale are chosen as the characteristic length and velocity scales, respectively.

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遠心羽根なしディフューザに発生する旋回失速の能動制御

廣瀬則仁， 金井剛， 小尾晋之介， 有賀一郎

日本機械学会論文集 B 編 62 (593), 218-223 62巻 ( 593号 )  1996.01

Research paper (conference, symposium, etc.), Joint Work

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旋回失速の予兆現象を現わす壁面の微小な圧力変動を感知し、それをDSPでデジタル処理した信号にしてフィードバックすることではく離の制御効果を得ることができた。(6頁)

Active control of the rotating stall in a radial vaneless diffuser

Hirose N., Kanai T., Obi S., Ariga I.

Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B (Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B)  62 ( 593 ) 218 - 223 1996.01

ISSN  03875016

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An active control method for suppression of the rotating stall in a radial vaneless diffuser is proposed. The activator is driven by the prestall pressure fluctuation detected at the shroud wall of the diffuser. In order to extract the characteristic frequency of the prestall signal, an analogue bandpass filter system as well as a digital signal processor (DSP) system based on an auto-regressive model are adopted and the results obtained using the two systems are compared. The latter realizes a real-time response to the varying frequency of the pressure fluctuation of the prestall. It is confirmed that the critical flow rate is decreased by 12% by the DSP method, yielding a further extension of the operation range of the vaneless diffuser as compared to that of the filter system. The phase angle is found to be an important parameter for the optimum operation of the present control system.

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第 23 回乱流シンポジウム講演論文集第 23 回乱流シンポジウム講演論文集, 254-260, 1991

長谷川善幸， 小尾晋之介， 益田重明

日本機械学会論文集. B 編 62 (00598), 2187-2193  1996

回転する積層ディスク間流れの乱流構造

小野孝朗， 雨宮健一郎， 小尾晋之介， 益田重明

年会一般講演 15, 133-134  1996