Search Results 1-20 of 1913

  • A new framework for design and validation of complex heat transfer surfaces based on adjoint optimization and rapid prototyping technologies

    KAMETANI Yukinori , FUKUDA Yutaka , OSAWA Takayuki , HASEGAWA Yosuke

    … Investigation of numerical results reveals that the pressure drop of the optimal shape is significantly reduced by the suppression of vortex shedding behind the fin, whereas the heat transfer performance is maintained by the extended surface. …

    Journal of Thermal Science and Technology 15(2), JTST0016-JTST0016, 2020

    J-STAGE 

  • Study on the relation between secondary vortex at trailing edge and motion-induced vortex vibration in heaving mode for rectangular cross sections with side ratios of <i>B/D</i>=0.50-6.0

    Cao Nade , Matsuda Kazutoshi , Kato Kusuo

    … <p>In general, motion-induced vortex vibration is considered to be caused by the unification of separated vortex from leading edge and secondary vortex at trailing edge. … However, the results of wind tunnel tests for the cross sections with side ratios of 1.18 reveal that motion-induced vortex in heaving mode might occur without the formation of secondary vortex at trailing edge. …

    Journal of Structural Engineering, A 66A(0), 303-316, 2020

    J-STAGE 

  • Mechanism of momentum transportation in the intermediate wake of a heated cylinder  [in Japanese]

    WATANABE Hideaki , MAKITA Hideharu , TAGO Makoto

    … The causes of antisymmetric configuration in the horizontal heated cylinder wake are the downward motion of the vortex streets in upstream sections, and in downstream sections, the upward stretching of upper side vortices due to buoyancy. … In the upstream sections, velocity fluctuation at the vortex shedding frequency <i>f<sub>c</sub></i> …

    Transactions of the JSME (in Japanese) 86(883), 19-00367-19-00367, 2020

    J-STAGE 

  • An Application of Spectral Proper Orthogonal Decomposition to the Flow Field around a Rectangular Prism Building Model  [in Japanese]

    ZHANG Bingchao , OOKA Ryozo , KIKUMOTO Hideki

    <p>本研究は,スペクトル固有直交分解(SPOD)を用いて,角柱建物モデルの周辺における地表面に近い平面の風速場の乱流構造を解明することを目的としている.SPOD は,固有直交分解(POD)と離散フーリエ変換(DFT)の組み合わせで,最大の運動エネルギーを持っている物理現象を抽出することができる.研究の結果,計算から得られた固有関数は,カルマン渦を含み,色んな渦の時空間構造を示した.ま …

    SEISAN KENKYU 72(1), 65-70, 2020

    J-STAGE 

  • STUDY ON UNSTEADY WIND FORCE AND FLOW FIELD AROUND AN OSCILLATING FLAT-PLATE ROOF  [in Japanese]

    NAKAMURA Ryohei , TANIGUCHI Tetsuro

    … Aerodynamic instabilities such as vortex-induced vibrations can arise depending on the shape and dynamic characteristics of the structure. … This analysis shows that the harmonic components of the unsteady wind force are caused by two-dimensional vortex shedding from windward edge of the roof when the non-dimensional frequency of the roof is relatively high. …

    Journal of Structural and Construction Engineering (Transactions of AIJ) (763), 1153-1163, 2019-09

    J-STAGE  AIJ 

  • Combustion Instabilities in Hybrid Rockets Induced by Acoustic Triggering

    Carmicino Carmine

    第2回ハイブリッドロケットシンポジウム(2019年7月11日-12日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県資料番号: SA6000143014

    第2回ハイブリッドロケットシンポジウム 講演集 = Proceedings of the 2nd Hybrid Rocket Symposium, 2019-07

    IR 

  • Feature extraction technique for large time-series data and its application to wake flow analysis of a re-entry capsule  [in Japanese]

    大道 勇哉 , 小林 憲司 , 金崎 雅博 , Omichi Yuya , Kobayashi Kenji , Kanazaki Masahiro

    第50回流体力学講演会/第36回航空宇宙数値シミュレーション技術シンポジウム (2018年7月4日-6日. 宮崎市民プラザ), 宮崎市, 宮崎形態: カラー図版あり資料番号: AA1830029004

    宇宙航空研究開発機構特別資料: 第50回流体力学講演会/第36回航空宇宙数値シミュレーション技術シンポジウム論文集 = JAXA Special Publication: Proceedings of the 50th Fluid Dynamics Conference / the 36th Aerospace Numerical Simulation Symposium (JAXA-SP-18-005), 83-90, 2019-02-25

    IR 

  • Effect of cylindrical ring configuration attached to a circular cylinder on aeroacoustic noise reduction  [in Japanese]

    SANO Hidetoshi , NAKAMURA Hajime , YAMADA Shunsuke , FUNAMI Yuki

    … <p>Large aeroacoustic noise is generated by the vortex shedding from a circular cylinder. … The suppression of the vortex shedding is one of the important issues in engineering. … The instullation of cylindrical rings on a circular cylinder has been proposed as a method to suppress the vortex shedding. …

    The Proceedings of the Fluids engineering conference 2019(0), OS5-17, 2019

    J-STAGE 

  • Effects of relaxation time of surfactant solutions on turbulence statistics in two-dimensional turbulemt flow  [in Japanese]

    FUKUSHIMA Kengo , HIDEMA Ruri , SUZUKI Hiroshi

    … Cationic surfactant and counter ion supplier were added to 2D turbulent flow, and the flow field and vortex shedding in the flow were visualized using interference patterns and particle image velocimetry (PIV). … We considered the relationship between vortex shedding and drag reduction properties of the fluid.</p> …

    The Proceedings of the Fluids engineering conference 2019(0), OS7-01, 2019

    J-STAGE 

  • Autocorrelation Characteristics of Karman Vortex from a Circular Cylinder Supported by End Walls  [in Japanese]

    INAGAKI Ayumu , MIZOBE Ryohei , YAMADA Hidemi

    … <p>In this research, the relationship between the laminar boundary layer thickness on the end wall and the Karman vortex frequency characteristics is investigated using the autocorrelation coefficient. … In the case of thick boundary layer thickness 0.82, the vortex shedding has fluctuations and autocorrelation coefficient decays faster than the thin boundary layer thickness 0.37.</p> …

    The Proceedings of the Fluids engineering conference 2019(0), OS3-49, 2019

    J-STAGE 

  • Flow control around an oscillating square cylinder by using plasma actuators  [in Japanese]

    ONAHA Chihiro , YOSHINAGA Tsukasa , IIDA Akiyoshi

    … The vortex shedding frequency associated with the oscillation can be halved and the velocity fluctuation intensity can be suppressed by 24%.</p> …

    The Proceedings of the Fluids engineering conference 2019(0), OS1-22, 2019

    J-STAGE 

  • Study on structural design of the power generation flag using piezoelectric films  [in Japanese]

    Oda Chisuzu , Nishigaki Tsutomu

    … In order to overcome the low power generation of the piezoelectric wind energy harvesting method at small wind speeds, vortex-induced vibrations (VIVs) of the flexible cylinder excited by the Karman vortex generated downstream of PCSWEHFs was used and it was shown in the preliminary experiment that more than ten times larger power was generated by PCSWEHFs compared with the conventional planar-type piezoelectric energy harvesting flags. …

    The Proceedings of the Symposium on the Motion and Vibration Control 2019.16(0), A207, 2019

    J-STAGE 

  • Investigation of downstream separation structure in turbulent flow over a forward-facing step by using PIV measurement and POD analysis  [in Japanese]

    HIOKI Ryota , OGAWA Takuya , YAMADA Toru , TAMANO Shinji , MORINISHI Yohei

    … <p>We investigated the mechanism of downstream vortex shedding in turbulent flows over a forward-facing step between lower-movable and upper-step-side walls. … In this study, the region containing downstream separation and vortex shedding is visualized with a high-speed camera. … The large-scale vortex structures are shed around reattachment point by means of the ejection event Q2. …

    The Proceedings of Mechanical Engineering Congress, Japan 2019(0), S05127P, 2019

    J-STAGE 

  • The Research on Source of Aerodynamic Noise from Ventilating Perforated Metal Plate  [in Japanese]

    UMINO Masaki , MATSUMOTO Hiroki

    <p>This study deals with aerodynamic noise generated from perforated metal plate. Perforated metal plate has two flow direction and the aerodynamic noise are varied by flow direction. At the exp …

    The Proceedings of the Dynamics & Design Conference 2019(0), 626, 2019

    J-STAGE 

  • A 3-D LES/RANS Simulation of Cryogenic-Jet/Crossflow Interactions under a Supercritical Pressure  [in Japanese]

    AMANO Taishi , ARAKI Takahide , TERASHIMA Hiroshi , MUTO Daiki , TSUBOI Nobuyuki

    … 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. …

    The Proceedings of Conference of Kyushu Branch 2019.72(0), D12, 2019

    J-STAGE 

  • Robustness of Savonius turbine for inflow of isotropic turbulence  [in Japanese]

    MURAI Yuichi , Otomo Shuji , TASAKA Yuji , Denissenko Petr

    … Hot-wire anemometer measurement of the flow behind the turbine revealed that periodic vortex-shedding due to the blade-passing frequency was suppressed with strong turbulence in the inflow. …

    The Proceedings of the National Symposium on Power and Energy Systems 2019.24(0), C211, 2019

    J-STAGE 

  • Experimental Study on the Flow Phenomena behind Two Parallel Flat Plates  [in Japanese]

    SHIN B. , ARATAKE Hiroki , KONDO Masamune , OZONO Shigehira

    … 2.0, the switching of the biased gap flow was observed due to the vortex interaction behind the plates, while at G/D ≥ … At gap ratios less than 2.0, two Strouhal numbers indicating the bi-stable state exist, and the vortex shedding frequency from the plate on the biased side decreases with the gap ratio. …

    Journal of Wind Engineering 44(1), 1-10, 2019

    J-STAGE 

  • Noise increase phenomenon of the air flow through a perforated metal plate  [in Japanese]

    MATSUMOTO Hiroki , IGARASHI Sou , UMINO Masaki

    … The expansion type perforated metal plate generates orderly vortex shedding and it brings the vibration of perforated metal plate. … That phenomenon is predicted as lock-in phenomenon between vortex and vibration of the plate.</p> …

    Transactions of the JSME (in Japanese) 85(873), 18-00456-18-00456, 2019

    IR  J-STAGE 

  • Numerical study of flow past a transversely oscillating wavy cylinder at Re=5000

    Zhang Kai , Katsuchi Hiroshi , Zhou Dai , Yamada Hitoshi , Bao Yan , Han Zhaolong , Zhu Hongbo

    … Even though the wavy cylinder is optimally designed to annihilate the Kármán vortex shedding in the fixed configuration, the Strouhal frequency is found to resurrect in the forced vibration cases, leading to very similar responses between the normal and wavy cylinders, especially at high forcing frequencies. …

    Ocean Engineering (169), 539-550, 2018-12-01

    IR 

  • Numerical Investigation of Terrain-induced Turbulence in Complex Terrain by Large-eddy Simulation (LES) Technique

    Uchida Takanori

    … It was suggested that the terrain-induced turbulence which caused the wind turbine blade damage accident on Shiratakiyama Wind Farm was attributable to rapid wind speed and direction fluctuations which were caused by vortex shedding from Tenjogadake (elevation: 691.1 m) located upstream of the wind farm. …

    Energies 11(10), 2638-1-2638-15, 2018-10-02

    IR 

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