論文 - 小尾　晋之介

An attempt to measure fluctuating local pressure in free turbulent flow in water

河田 卓也、前田 星透、小尾 晋之介

Journal of Fluid Science and Technology （Japan Society of Mechanical Engineers）  9 （ 2 ）  2014年07月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

We developed a technique for the measurement of fluctuating hydraulic-pressure at an arbitrary point in turbulent
flow. A pressure-measuring system was composed of a miniature static-pressure probe (SP-probe), a strain-gagetype
pressure transducer, and a tube connecting them. A model equation of dynamic response of the pressuremeasuring
system was introduced, and a calibration technique for determining parameters in the model equation
was developed. Effects of the size of the SP-probe, length of the tube, and sensitivity of the pressure sensor were
systematically investigated using several SP-probes, tubes, and pressure transducers with different sizes, lengths,
and sensitivities, and fluctuating hydraulic-pressure measurement was performed in a wake of a circular cylinder

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Velocity-pressure correlation measurement based on planar PIV and miniature static pressure probes

河田 卓也、小尾 晋之介

Experiments in Fluids （Experiments in Fluids）  55 （ 7 ） 1776 2014年06月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  07234864

　概要を見る

This study aimed to measure pressure-related turbulence statistics such as the velocity-pressure or the pressure-strain correlations. To do so, the pressure field evaluation based on the velocity data measured by particle image velocimetry (PIV) was combined with direct single-point-measurement by miniature static pressure probes (SP-probe). The instantaneous pressure field was derived from the measurement results by PIV, and the pressure fluctuations associated with the large-scale vortex motion were extracted using the instantaneous pressure directly measured by the SP-probe as a reference signal. The measurement was taken in a turbulent near wake of a circular cylinder. After the validity of the instantaneous pressure evaluated from the PIV data was addressed, the velocity-pressure correlation and the pressure-strain correlation were investigated. © 2014 Springer-Verlag Berlin Heidelberg.

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Simultaneous measurement of fluctuating velocity and pressure in the near wake of a circular cylinder

小尾 晋之介

Experiments in Fluids （Experiments in Fluids）  55 （ 5 ） 1731 2014年05月

研究論文（学術雑誌）, 共著,  ISSN  07234864

　概要を見る

Simultaneous measurement of fluctuating velocity and pressure by a static-pressure probe and a hot-wire probe was performed in the near wake of a circular cylinder, in order to strengthen reliability of the measurement technique. Effect of geometry of the static-pressure probe was systematically investigated, and validity of the measurement results was addressed by quantitative comparison with reference data by a large-eddy simulation. Interference between the probes was found to mainly depend on the diameter of the pressure probe and only weakly on the length. A certain time lag between the velocity and pressure signals was detected in the experiment, and the measurement results of velocity-pressure correlation up ̄ and vp ̄ obtained with the correction of the time lag were in good agreement with the computational results. It was also found that the measurement of vp ̄ is extremely sensitive to a small time lag between the velocity and pressure signals, while that of up ̄ is not. © 2014 Springer-Verlag Berlin Heidelberg.

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S0550302 ナノ秒パルスプラズマアクチュエータによる矩形翼, 後退翼上における流体制御 ([S055-03] プラズマアクチュエータ (3))

加藤賢太郎， 小尾晋之介

年次大会 2014, _S0550302--_S0550302- 2014年

7・3 乱流 (7. 流体工学,< 特集> 機械工学年鑑)

小尾晋之介

日本機械学会誌 117 (1149), 521 2014年

LES study of flow between shrouded co-rotating disks

鷲津 智哉、ルービッシュ フローリアン、小尾 晋之介

Flow, Turbulence and Combustion （Flow, Turbulence and Combustion）  91 （ 3 ） 607 - 621 2013年10月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  1386-6184

　概要を見る

Large eddy simulations of turbulent flow between shrouded co-rotating disks, representing a simplified model of a hard disk drive, are performed. The computation domain surrounds a complete disk and is bounded at top and bottom by half a disk. Therefore, it is possible to compute the fluctuating pressure field surrounding the middle disk. Also, the influence of the shroud geometry is taken into account by comparing a flat shroud wall and a wall with rib chambers. In the flat shroud case, the fluctuating pressure on the upper- and lower-surface of a disk indicates a strong correlation with fluid motion travelling across the disk-tip clearance region. However, in the ribbed shroud case the organized flow structure that is observed in the flat shroud case disappears and the fluctuating pressure acting on the surface of the disk is remarkably diminished. © 2013 Springer Science+Business Media Dordrecht.

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An experimental study on the flow behavior near the read-and-write arm in a hard disk drive model with a shroud opening

白井 克明、ラース ビュットナー、小尾 晋之介、ユルゲン チャルスケ

Microsystem Technologies （Microsystem Technologies）  19 （ 9-10 ） 1519 - 1527 2013年09月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  0946-7076

　概要を見る

Complex flow inside a hard disk drive (HDD) was investigated using a simplified 3.5″ model for clarifying the mechanism causing flow-induced vibration. In contrast to the authors' related study in the past, our model had a non-axisymmetric geometry equipped with a shroud opening and a read/write arm (RWA). The model is designed to serve as a benchmark to study HDD flows both in experiments and in numerical simulations. The complex flow behavior in the disk-to-disk space was investigated with the RWA inserted into the inter-disk space. Flow measurements were carried out with a test rig which consisted of transparent disks, RWA and covers. The measurements were performed at the disk Reynolds number Re d = 1.2 × 105 which corresponds to the rotation speed of 7,700 rpm of a real 3.5″ HDD. Two sets of the flow measurements were performed - the first Reynolds stress components measured along four different lines with the RWA inserted at a shallow angle (experiment I), and the other mean and rms velocity statistics along several selected lines with two different RWA insertion angles (experiment II). The mean velocity and velocity variance were obtained at a spatial resolution of 30 μm along eight different lines perpendicular to the disk surfaces. The high spatial resolution of the results was achieved using a laser Doppler velocity profile sensor with a physical resolution in micrometers and a velocity uncertainty of 0.2 %. In the experiment I, the mean velocity and velocity variance statistics were mostly consistent with the common findings in other studies using axisymmetric models except for the flow behavior in the radial direction at the shroud opening. The secondary flow behavior was likely caused by the shroud opening which was not included in most of the models in the past. In experiment II, the mean velocity and velocity variance were successfully measured through examination of the flow above and below the RWA in the space between the rotating disks. The resulting velocity statistics exhibit turbulent Couette-like flow in the narrow 1 mm space between the disks and the RWA. © 2013 Springer-Verlag Berlin Heidelberg.

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Simulation and PIV experiment of the ducted water current turbine and extremely low had helical turbine

ソンティサック　ポマチャン、小尾 晋之介、プリヨノ スティノ、アリャディ　ソエウォノ

ASEAN Engineering Journal Part A （AUN/SEED-Net）  3 （ 2 ） 54-69 2013年09月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  2229-127X

　概要を見る

The paper introduced a ducted water curent turbine triple helix with very low head less than 2 m and water current at river or in the ocean. The expected power is between 100 kW and 1000 kW. The differ-like passage was installed in a water tunnel and its effect was investigated both experimentally and numerically. The PIV measurement provided a useful information to evaluate the relationship between the power coefficient and flow field behind the turbine.

0617 時間分解 PIV と小型静圧プローブを用いた速度・圧力相関計測 (OS6-4 噴流, 後流およびはく離流れ現象の探求と先端的応用, OS6 噴流, 後流およびはく離流れ現象の探求と先端的応用)

河田卓也， 前田星秀， 小尾晋之介

流体工学部門講演会講演論文集 2013, _0617-01_-_0617-02_ 2013年

0639 自由せん断乱流中の局所圧力変動の計測 (OS6-8 噴流, 後流およびはく離流れ現象の探求と先端的応用, OS6 噴流, 後流およびはく離流れ現象の探求と先端的応用)

前田星透， 河田卓也， 小尾晋之介

流体工学部門講演会講演論文集 2013, _0639-01_-_0639-02_ 2013年

1102 円筒容器内回転積層円盤間乱流における圧力変動とディスク振動の同時計測 (OS11-1 流体関連振動・騒音, OS11 流体関連振動・騒音)

高橋昌之， 小尾晋之介， 河田卓也

流体工学部門講演会講演論文集 2013, _1102-01_-_1102-02_ 2013年

Simultaneous measurment of fluctuating velocity and pressure using time-resolved PIV and miniature static-pressure probes

Kawata T., Obi S.

International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013 （International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2013）  2 2013年

ISSN  9780000000002

　概要を見る

Simultaneous measurement of the fluctuating velocity and pressure is performed combining a miniature staticpressure probe and a time-resolved PIV aiming at further improvement in evaluation of the velocity-pressure correlation. Two static-pressure probes were placed in the measurement domain of the time-resolved PIV and the instantaneous velocity field and the fluctuating velocity are measured simultaneously. The instantaneous pressure filed is estimated from the measured velocity field by numerically solving a discrete Poisson equation for pressure. The values of the estimated pressure are corrected based on the pressure values which are directly measured by the static-pressure probe.

An attempt to evaluate pressure force on a flapping rigid plate using velocity data of PIV measurements

アレクサンドル スリァディ、小尾 晋之介

ASEAN Engineering Journal 2 （ 1 ） 30-44 2012年06月

研究論文（学術雑誌）, 共著

　概要を見る

The flow field generated by a sinusoidally flapping rigid flat plate was measured using stereo particle image velocimetry to estimate the pressure field on two cross sections of the flapping plate. The pressure field was estimated by integrating the three–dimensional Poisson equation derived from the Euler equation. The solution of this Poisson equation is obtained as a function of the measured phase-averaged velocity field. Simultaneous to PIV measurements, the torque on the flapping axis, which depicts the forces acting on the wing, was measured using strain gauges. The maximum torque coefficients, observed from both methods, of each cycle are delayed from the maximum acceleration of the plate. One of the factors of the phase delay is attributed to the separation of vortex structure along the edges of the plate. After the separation point the increase of pressure drag is delayed relative to the flapping motion. At the same phase, vortex structure is generated on the leeward side of the plate at the free end. Low pressure region was observed on the leeward side of the plate which further add to the pressure drag.

1009 移動壁面を有する密閉容器内流れの渦法解析 (OS10 渦流れのダイナミクス, オーガナイズドセッション)

宮内新喜， 小尾晋之介

流体工学部門講演会講演論文集 2012, 389-390 2012年

Experimental and numerical investigation on a fully developed turbulent pipe flow over a semicircle orifice

Okuda S., Lepeut C.H., Rasti M., Kawata T., Obi S.

Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer （Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer）  2012-September   2504 - 2512 2012年

　概要を見る

The internal separated flow associated with remarkable mean secondary flow is investigated both experimentally and computationally. The computational investigation indicates that the commercially available RANS model group and LES provide obvious difference in terms of the prediction of the flow reattachment and recovery. On the other hand, some over-proportional magnitude of the velocity fluctuation across the mean flow direction is found by velocity measurement by stereo PIV. The recirculation region in either side of the orifice seems to be the source of the streamwise vortex that governs the development of the flow near the flow reattachment point. The considered flow serves as a useful test case for both RANS modeling and LES.

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Simultaneous measurement of fluctuating velocity and pressure using stereo-PIV and static-pressure probe in a turbulent wing-tip vortex

Kawata T., Obi S.

Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer （Proceedings of the International Symposium on Turbulence, Heat and Mass Transfer）  2012-September   2311 - 2320 2012年

　概要を見る

Simultaneous measurement of the fluctuating pressure and velocity field is performed combining a miniature static-pressure probe and a stereo-PIV. The static-pressure probe is placed just behind the velocity measuring plane illuminated by the laser sheet, and the instantaneous velocity field and the fluctuating pressure are measured simultaneously in a turbulent wing-tip vortex flow. The instantaneous pressure field is estimated by numerically solving a discrete two-dimensional Poisson equation for pressure. The result is compared with directly measured pressure for validation.

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The estimation of pressure on the surface of a flapping rigid plate by stereo PIV

Suryadi A., Obi S.

Experiments in Fluids （Experiments in Fluids）  51 （ 5 ） 1403 - 1416 2011年11月

ISSN  07234864

　概要を見る

The method to estimate the dynamic load of a flapping wing by the integration of pressure on the wing's surface is discussed. The flapping wing was modeled as a plate flapping sinusoidally in hovering condition. The flow around the flapping plate was measured using stereo PIV on multiple measurement planes along the out-of-plane direction. The phase-averaged velocity field of each measurement plane was calculated so that three-dimensional analyses could be applied. The phase-averaged pressure field was obtained from the integration of the three-dimensional Poisson equation for pressure using the available information acquired from stereo PIV measurements. The pressure field is visualized on the measurement planes. In this study, the estimated load was the torque of the axis of rotation. This torque was compared with the result from strain gauge measurements. The torque estimation, although only on a partial surface of the plate, is within reasonable agreement with the measured torque. The integration of the Poisson equation based on stereo PIV measurements and estimations of the torque shows that an increase in the torque at the start of a flapping stroke is caused by the stagnation on the surface of the plate from the flow that is induced by the leading-edge vortices. © 2011 Springer-Verlag.

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Estimation of pressure on the surface of a flapping rigid plate by stereo PIV

スルヤディ アレクサンドレ、小尾 晋之介

Experiments in Fluids （Springer）  51 （ 5 ） 1403-1416 2011年10月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

The method to estimate the dynamic load of a flapping wing by the integration of pressure on the wing's surface is discussed. The flapping wing was modeled as a plate flapping sinusoidally in hovering condition. The phase-averaged pressure field was obtained from the integration of the three-dimensional Poisson equation for pressure using the available information acquired from stereo PIV measurements. The torque estimation, although only on a partial surface of the plate, is within reasonable agreement with the measured torque.

Simultaneous measurements of disk vibration and pressure fluctuation in turbulent flow developing in a model hard disk drive

倉島 大輔、中 吉嗣、深潟 康二、小尾 晋之介

International Journal of Heat and Fluid Flow （International Journal of Heat and Fluid Flow）  32 （ 3 ） 567–574 - 574 2011年05月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  0142727X

　概要を見る

The complex flow features inside hard disk drive models are investigated in an axisymmetric and a semi-open shroud configurations. For the axisymmetric case, we have employed both experimental and computational approaches. The experiment focuses on both flow dynamics and the disk vibration, where measurements of the fluctuating pressure and velocity are undertaken at some representative points. The correlation between the disk vibration and the fluctuating pressure in the turbulent flow between disks is evident from the spectral analysis. The experimentally observed fluctuating pressure and velocity are partly due to the disk vibration and its contribution could be estimated by comparing the experiment with the results of a large eddy simulation. For the semi-open shroud case, although the characteristic peaks attributable to the large-scale vortical structure are still observed in the power spectra, the pressure fluctuation and the disk vibration are suppressed when the arm is inserted. © 2011 Elsevier Inc.

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Simultaneous measurement of velocity and fluctuating pressure in a turbulent wing-tip vortex using triple hot-film sensor and miniature total pressure probe

Kawata Takuya, Naka Yoshitsugu, Fukagata Koji, Obi Shinnosuke

Flow, Turbulence and Combustion 86 （ 3-4 ） 419 - 437 2011年04月

ISSN  1386-6184

　概要を見る

<p>We have developed a probe-system for simultaneous measurement of three velocity components and pressure in turbulent flows. A miniature total pressure probe is placed adjacent to the sensors of a triple hot-film probe in order to achieve the spatial resolution which is equivalent to that of the triple hot-film probe itself. The instantaneous static pressure is calculated from measured velocity and total pressure by means of a newly developed processing method based on the Bernoulli equation for unsteady flows. The measurements were undertaken in a turbulent wing-tip vortex flow. The look-up table method is employed for the calibration of the hot-film probe so accurate velocity data could be obtained over a wide range of the flow-attack angles. It is also demonstrated that the present probe-system is capable of measuring fluctuations in both velocity and pressure in the 20-650 Hz frequency range. The distribution of the fluctuating pressure obtained by this indirect method is in good agreement with the results from direct measurements of static pressure, demonstrating the promising performance of the present method. Furthermore, an improvement in the ability to make measurements of the velocity-pressure correlation across the wing-tip vortex is achieved. This improvement is possible because the effects of lateral velocity components are properly taken into account in the present formulation. The investigation regarding the transport equation budget for turbulent kinetic energy shows an anomalous structure of turbulence in this flow, mainly due to the meandering of the vortex, and the measurement of pressure diffusion is found to play an important role in the characterization of this kind of flow. © 2010 Springer Science+Business Media B.V.</p>

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