著者

秋山 修 加藤 千幸 河手 大輔

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集B編 (ISSN:18848346)

巻号頁・発行日

vol.78, no.795, pp.1903-1918, 2012 (Released:2012-11-25)

参考文献数

21

被引用文献数

3 4

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Mechanism of particle separation in a cylindrical cyclone separator has been fully clarified by a combined numerical method of large eddy simulation and a particle tracking method. The former resolves all the important vortical structures in the separator while the latter inputs the instantaneous flow fields computed by the LES and computes trajectory of each particle by considering Stokes drag as well as gravity force. Particle collection efficiency predicted by the proposed method has been compared with the experimental data measured for two cylindrical cyclone separators with several sets of particle diameters. The results showed that the collection efficiency has been quantitatively predicted by the proposed method, which confirms that the method can be used for the engineering design of such a cyclone separator. Detailed investigation of the particle trajectories predicted by the present method has clarified the mechanism of particle separation of a cylindrical cyclone separator. Those particles that are successfully collected by the separator move outward in the swirl flow and are collected when the swirl flow changes its direction at the bottom of the separator. The essential mechanism of this particle separation is due to the centrifugal forces acting on the particles. Three types of particle trajectories have been identified for those particles that are exhausted from the cyclone separator together with the swirl flow. More than half of the uncollected particles are trapped by longitudinal vortexes. The unsteady longitudinal vortexes and vortex rope drastically decrease collection efficiency.

著者

加藤 千幸

出版者

東京大学生産技術研究所

雑誌

生産研究 (ISSN:0037105X)

巻号頁・発行日

vol.54, no.4, pp.278-286, 2002 (Released:2007-09-26)

著者

加藤 千幸

出版者

一般社団法人 ターボ機械協会

雑誌

ターボ機械 (ISSN:03858839)

巻号頁・発行日

vol.32, no.5, pp.267-273, 2004 (Released:2005-08-12)

参考文献数

7

被引用文献数

1

著者

飯田 明由 小久保 あゆみ 塚本 裕一 本田 拓 横山 博史 貴島 敬 加藤 千幸

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 B編 (ISSN:03875016)

巻号頁・発行日

vol.73, no.732, pp.1637-1646, 2007-08-25 (Released:2011-03-03)

参考文献数

10

被引用文献数

4 1 7

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The aim of this investigation is to understand the generation mechanism of aero-acoustic feedback noise radiated from rear-view mirrors. In order to clarify the relationship between the velocity fluctuation and radiated noise, correlation in terms of aerodynamic noise and velocity fluctuations were measured in a low-noise wind tunnel. The experimental results showed that noise level of the tonal-noise depended on the ratio of the height of the bump to the thickness of the boundary layer. Strong tonal-noise was generated when the height of the bump was almost equal to 40% of the height of the boundary layer. The tonal-noise level also depended on the length between the trailing-edge of the bump and the edge of rear-view mirror. The frequency of the tonal noise can be calculated by modified Rossiter equation. The tonal-noise was disappeared in the case of the bump was placed at separated boundary layer. It revealed that the seed of the tonal noise was small disturbances generated by the bump on the surface of the rear-view mirror.

著者

内田 孝紀 小野 謙二 飯田 明由 吉村 忍 加藤 千幸 山出 吉伸 今村 博 植田 祐子

出版者

一般社団法人 日本風力エネルギー学会

雑誌

風力エネルギー学会 論文集 (ISSN:24363952)

巻号頁・発行日

vol.45, no.4, pp.71-82, 2021 (Released:2022-03-30)

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In the current project, the first author and the second author play a central role in conducting high-speed tuning and wind turbine wake analysis of the supercomputer version of RIAM-COMPACT. In this report, we applied the supercomputer version RIAM-COMPACT to the wind turbine wake simulation from the wind tunnel scale to the utility-scale wind turbine wakes. As a result, we clarified unsteady wake aerodynamics of wind turbines including multiple wake interactions with high precision and high reality.

著者

加藤 千幸 Kato Chisachi

出版者

宇宙航空研究開発機構(JAXA)

雑誌

宇宙航空研究開発機構特別資料: 風洞技術の開発と応用シンポジウム講演集: 第1回-第4回 = JAXA Special Publication: Proceedings of the Symposium on Developments and Applications of Wind Tunnel Technologies: 1st meeting - 4th meeting (ISSN:1349113X)

巻号頁・発行日

vol.JAXA-SP-15-021, pp.59-64, 2016-03-01

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第3回風洞技術の開発と応用シンポジウム: 風洞シンポジウム2014 (2014年10月24日. 日産自動車株式会社テクニカルセンター), 厚木市, 神奈川県

著者

郭 陽 加藤 千幸 山出 吉伸 トバグス ノーファル ハエダル 高山 務

出版者

一般社団法人 日本機械学会

雑誌

流体工学部門講演会講演論文集

巻号頁・発行日

vol.2012, pp.251-252, 2012

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The internal flow in a simplified heating,ventilation,and air conditioning(HVAC) model was calculated by large-eddy simulation(LES).The acoustic field generated from the flow in the HVAC model was computed by solving the Lighthill equation in the frequency domain,using the LES results to calculate the sound sources.The computed sound pressure level(SPL) agrees reasonably well with the experimental data of Wakahara et al.A maximum difference of about 7 dB at the frequency 800 Hz between the computed SPL and the experimental data was found.The reason of the difference will be investigated in detail in the next stage.

著者

山出 吉伸 加藤 千幸 山田 和豊 大西 順也 今野 彰

出版者

Institute of Industrial Science The University of Tokyo

雑誌

生産研究 (ISSN:0037105X)

巻号頁・発行日

vol.70, no.1, pp.43-48, 2018-01-01 (Released:2018-01-30)

参考文献数

18

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乱流の高精度予測および自動メッシュ作成を特長とする格子ボルツマン法(Lattice Boltzmann Method,LBM)ベースの流体解析システムFrontFlowX(FFX)を開発している.FFX のプロトタイプに対し,計算精度,計算性能およびメッシュ作成機能に関するベンチマークテストを実施した.計算精度に関しては,Cavity 流れおよび一様等方性乱流に関するベンチマークテストを実施した.計算性能に関しては京のほぼフルノードを用いた2.2 兆グリッド規模のメッシュを用いたweak-scale ベンチマークテストを実施した.最後に,複雑形状に対するメッシュ作成ソフトの性能を評価するためイルカモデルまわり流れを500 億グリッド規模のメッシュデータで解析した.

著者

水島 文夫 栗田 健 加藤 千幸

出版者

東京大学生産技術研究所

雑誌

生産研究 (ISSN:0037105X)

巻号頁・発行日

vol.58, no.1, pp.23-26, 2006 (Released:2006-11-15)

参考文献数

2

著者

鈴木 貴之 加藤 千幸

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集B編 (ISSN:18848346)

巻号頁・発行日

vol.79, no.808, pp.2743-2758, 2013 (Released:2013-12-25)

参考文献数

15

被引用文献数

1 2

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Over the past two decades, many types of homogeneous models have been proposed for the numerical simulation of cavitating flows. Homogeneous models represent cavitation by the media whose density continuously varies from the value corresponding to liquid to that to gas. Recent studies have, however, revealed that the present homogenous models are unable to predict the breakdown characteristics of cavitating hydrofoils. The objective of this study is to clarify causes of such inability of homogeneous models to predict breakdown characteristics of cavitating hydrofoil accurately. Theoretical analysis shows that the present cavitation models inevitably cause kinetic energy loss through expansion and contraction of the media. To illustrate this fact, we computed cavitating flows in a venturi and around a hydrofoil (NACA0015) with a homogeneous model and investigated the computed flow field in detail. It is shown that the expansion and contraction of the media based on the homogeneous model do in fact cause kinetic energy loss and as a result, a region of low velocity appears downstream of the cavity. This results in a decrease of lift force in a partial cavitation condition, which is not observed in the corresponding measurements.

著者

飯田 明由 小久保 あゆみ 塚本 裕一 本田 拓 横山 博史 貴島 敬 加藤 千幸

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.73, no.732, pp.1637-1646, 2007-08-25

被引用文献数

6

---

The aim of this investigation is to understand the generation mechanism of aero-acoustic feedback noise radiated from rear-view mirrors. In order to clarify the relationship between the velocity fluctuation and radiated noise, correlation in terms of aerodynamic noise and velocity fluctuations were measured in a low-noise wind tunnel. The experimental results showed that noise level of the tonal-noise depended on the ratio of the height of the bump to the thickness of the boundary layer. Strong tonal-noise was generated when the height of the bump was almost equal to 40% of the height of the boundary layer. The tonal-noise level also depended on the length between the trailing-edge of the bump and the edge of rear-view mirror. The frequency of the tonal noise can be calculated by modified Rossiter equation. The tonal-noise was disappeared in the case of the bump was placed at separated boundary layer. It revealed that the seed of the tonal noise was small disturbances generated by the bump on the surface of the rear-view mirror.