豊橋技術科学大学

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Yokoyama, Hiroshi

Affiliation Department of Mechanical Engineering
Title Associate Professor
Fields of Research Flow control, Computational fluid dynamics, Aeroacoustics
Degree Doctor of Philosophy in Engineering (The University of Tokyo)
Academic Societies Japan Society of Mechanical Engineers, Society of Automotive Engineers of Japan, The Visualization Society of Japan, The Japan Society of Fluid Mechanics, The American Institute of Aeronautics and Astronautics
E-mail h-yokoyama@me
Please append ".tut.ac.jp" to the end of the address above.
Laboratory website URL http://ec.me.tut.ac.jp/
Researcher information URL(researchmap) Researcher information

Research

研究概要

 流体機器および自動車や高速車両の高機能化(省エネルギー化, 低騒音化), 音響エネルギーの有効活用を目的とした熱音響現象の解明,リコーダーなど楽器からの発音機構に関連する研究を実施している. いずれも,流体, 音響, 熱, 電気など複数の分野の融合する現象・課題に興味をもっており研究を進めている. キャビティ音の直接計算に関する研究で東京大学博士 (工学) を取得. Southampton大学 (イギリス) に2015-2016年留学. 2010年より豊橋技科学大学 機械工学系の教員(東京大学リサーチフェロー兼務)として勤めている.

主な研究テーマ

  1. 省エネルギーを目的とし, ファンなど流体機械の研究,音響エネルギーの有効利用を目指した熱音響機器に関する研究に取り組んでいる. 藻の効率的な生成のためのバイオリアクターの開発も行ってきた.
  2. 流体機械や高速輸送機関からの空力音の発生機構の解明および低減手法の確立に向けた研究を, 風洞実験・スパコンを用いた大規模計算の両側面から実施している. 特にキャビティと呼ばれる溝部から発生する音の研究を行っている. プラズマアクチュエータなどを用いた能動的制御にも取り組んでいる.
  3. 流体力学・音響学・構造振動が連成するような現象の解明やそうした現象を再現できるプログラム開発に取り組んでいる.リコーダーやリード楽器内部の流れ・音場を明らかにしている.

キーワード

省エネルギー, 空力音, 流体機械, 乱流, 数値流体力学, キャビティ, ファン, プラズマアクチュエータ, 楽器, 高速輸送機関

主な業績

  1. H. Yokoyama, I. Tanimoto, A. Iida, "Experimental Tests and Aeroacoustic Simulations of the Control of Cavity Tone by Plasma Actuators", Applied Sciences, 7(8), 790, pp.1-15, 2017
  2. H. Yokoyama, Yuu Hirose, Akiyoshi Iida, "Effective mixing and aeration in a bioreactor with Taylor vortex flow", Mechanical Engineering Letters, 2, 16-00412, pp.1-9, 2016
  3. H.Yokoyama H, A. Miki, H. Onitsuka, A. Iida, "Direct numerical simulation of fluid-acoustic interactions in a recorder with tone holes", Journal of the Acoustical Society of America, 138(2), pp.858-873,2015
  4. H. Yokoyama, K. Kitamiya, A. Iida, "Flows around a cascade of flat plates with acoustic resonance", Physics of Fluids, 25(10), 106104-1-106104-22, 2013
  5. H. Yokoyama, C. Kato, "Fluid-acoustic interactions in self-sustained oscillations in turbulent cavity flows. I. Fluid-dynamic oscillations", Physics of Fluids, 21(10), 105103-1-105103-13, 2009
  6. H. Yokoyama, Y. Tsukamoto, C. Kato, A. Iida, "Self-sustained oscillations with acoustic feedback in flows over a backward-facing step with a small upstream step", Physics of Fluids, 19(10), 106104-1-106104-8, 2007

Academic networks: researchmap Google scholar ResearchGate ORCiD Scopus

解説・著書

  1. 遮音・吸音材料の開発、評価と騒音低減技術, 技術情報協会, 2018年7月
  2. 機械の研究, バイオリアクタ用撹拌器の開発, 養賢堂, 2016年5月
  3. 音響キーワードブック, 流体騒音, コロナ社, 2016年3月
  4. 音響・騒音(7.流体工学,<特集>機械工学年鑑), 日本機械学會誌 117(1149), pp.523-523, 2014年8月

Theme1:Aerodynamic noise generated from high-speed transports and fluid equipments

Overview
Voritices and pressure field in cavity flows

Aerodynamic noise increases in proportional to the high power of velocity. So, the noise is a sever problem for high-speed transport vehicles or flow-related machinery. For example, intense tonal sound radiates from cavity flow and flow around a cascade of flat plates, where the feedback loop due to fluid-acoustic interactions occurs. To clarify the mechanism of acoustic radiation and establish the methodologies for noise reduction, we perform wind tunnel experiments and aeroacoustic direct numerical simulation (AADNS). Also, to establish the prediction method of aerodynamic noise, decoupled simulations consisting of acoustic and flow simulations are focused on.

○Cavity tone
○Control of aerodynamic noise by plasma actuators
○Aerodynamic noise from flows around a cascade of flat plates with acoustic resonance
○Tonal sound from automobiles parts such as bonnet, door mirror and sunroof
○Decoupled simulations based on Lighthill analogy

Selected publications and works
  1. H. Yokoyama, K. Kitamiya, H. Yamamoto, and A. Iida, "Effects of distance between plates on flows around a cascade of flat plates with acoustic resonance", AIAA-2014-3197, Atlanta, 20th AIAA/CEAS Aeroacoustics Conference, 2014
  2. H. Yokoyama, K. Kitamiya, and A. Iida, "Flows around a cascade of flat plates with acoustics resonance", Physics of Fluids, 25(10), 106104, 2013.
  3. H. Yokoyama and A. Iida, "Acoustic Radiation from Flows around a Cascade of Flat Plates", Korea-Japan CFD workshop 2012, Busan, Korea, 2012, 11.
  4. H. Yokoyama and C. Kato, "Fluid-Acoustic Interactions in Acoustic Radiation in Turbulent Cavity Flows (Fluid-Dynamic Oscillations)", Journal of Environment and Engineering, 6 (1), (2011).
  5. H. Yokoyama and C. Kato, "Fluid-acoustic interactions in self-sustained oscillations in turbulent cavity flows. I. Fluid-dynamic oscillations", Physics of Fluids 21, 105103 (2009).
  6. H. Yokoyama, Y. Tsukamoto, C. Kato and A. Iida, "Self-Sustained Oscillations with Acoustic Feedback in Flow Over a Backward-Facing Step with a Small Upstream Step, Physics of Fluids19, 106104 (2007).

Keywords

Aeroacoustics, Direct simulation, Fluid-acoustic interactions, Wind tunnel experiments

Theme2:Coupled problems of fluid, acoustic, oscillations such as musical instruments

Overview
Visualized sound from musical instrument

 The computational methodology for prediction of phenomena related with coupling of fluid, acoustics and vibration has been developed.
In air-reed instruments such as a recorder, the flow velocity fluctuates by the blowing of performer. These fluctuations generate sound (pressure and density fluctuations). It had been known that a small change of the shape or material of instruments critically affects ease of playing or how a performer feels during performance. By the predicted results, we understand the way the sound is radiating from flows in the recorder.
Also, to increase lift of micro air vehicle and control aerodynamic noise, forced plate oscillation with constant frequency are applied for flow around the plate(s).

Selected publications and works
  1. Saya Sato, Hiroshi Yokoyama, Akiyoshi Iida, "Control of Flow around an Oscillating Plate for Lift Enhancement by Plasma Actuators", Applied Sciences, 9(4, applsci-428109) 776-1-776-19, 2019.
  2. Tanaka Y, Yokoyama H, Iida A., "Forced-oscillation control of sound radiated from the flow around a cascade of flat plates", Journal of Sound and Vibration, 431, pp.248-264, 2018
  3. M. Kobayashi, H. Yokoyama, A. iida, "Direct numerical simulation of flow and acoustic fields around woodwind instruments with reed oscillations", Inter-Noise 2017, Hong Kong, China.
  4. H. Yokoyama, M. Akira, R. Hamasuna, H. Onitsuka, A. Iida, “Direct aeroacoustic simulations and measurements of flow and acoustic fields around a recorder with tone holes”, The fifth joint ASA/ASJ meeting, 2016. [invited]
  5. H. Yokoyama, "Direct aeroacoustic simulation related with mode change in a recorder", Proceedings of ECCOMAS, 2016
  6. H. Yokoyama, A. Miki, H. Onitsuka, A. Iida, "Direct numerical simulation of fluid-acoustic interactions in a recorder with tone holes", Journal of the Acoustical Society of America, 138(2) 858-873, 2015
  7. H. Yokoyama, M. Kobayashi, H. Onitsuka, A. Miki, A. iida, "Direct numerical simulation of flow and acoustic fields around an air-reed instrument with tone holes",inter-noise 2014, Melbourne, Australia, (November 17,2014).

Keywords

Musical instrument, aeroacoustic direct simulation, Air-reed instrument, Reed instrument, Volume penalization, Immersed boundary method

Theme3:Research for conservation of energy (Thermoacoustic phenomena, Rotary fluid machinery)

Overview
Double-cylinder mixer for bioreactor

For conservation of energy, thermoacoustic device utilizing wasted heat and acoustic power, mixing device of bio-reactor, fan are developed. The thermoacoustic heat pump phenomena utilizing cavity tone due to self-sustained oscillations are clarified. Double-cylinder mixer for bio-reactor for the culture of algae is developed. The relationship between behavior of CO2 bubbles and culture of algae is focused on. We perform visualization of flow and simulation along with culture experiments. Regarding fan, objective is to establish both noise reduction and high performance. Moreover, to develop high-performance fluid-related machinery, flow control with various methods such as plasma actuators is developed.

Selected publications and works
    Katsutake Minowa, Hiroshi Yokoyama, Kohei Oriot, Akiyoshi Iida, "DIRECT AEROACOUSTIC SIMULATION OF FLOW AND NOISE AROUND AN AXIAL-FLOW FAN REGARDING EFFECTS OF SLITS IN A CASING", Proceedings of 26th International Congress on Sound and Vibration, 1-8, 2019.
  1. H. Yokoyama, I. Tanimoto, A. Iida, "Experimental Tests and Aeroacoustic simulations of the control of cavity tone by plasma actuators", Appl. Sci. 2017, 7(8), 790, pp.1-15; doi:10.3390/app7080790.(The figures of this paper was on cover page of this issue). Link (open access)
  2. H. Yokoyama, R. Adachi, T. Minato, A. Iida, "Experimental and Numerical Investigations on Control Methods of Cavity Tone by Blowing Jet in an Upstream Boundary Layer", SAE Int. J. Passeng. Cars - Mech. Syst. 10(3):2017, pp.13-21. doi:10.4271/2017-01-1786.
  3. T. Miyamoto, H. Yokoyama, A. Iida, "Suppression of Aerodynamic Tonal Noise from an Automobile Bonnet Using a Plasma Actuator", SAE Int. J. Passeng. Cars - Mech. Syst. 10(3):2017, pp.22-30. doi:10.4271/2017-01-1825.
  4. H. Yokoyama, Y. Hirose, A. Iida,"Effective mixing and aeration in a bioreactor with Taylor vortex flow", Mechanical Engineering Letters, 2(16-00412) 1-9, 2016
  5. S. Ullah, H. Yokoyama, A. Iida, Design and Fabrication of Two Stage Thermoacoustic Engine to Reduce the Onset Temperature,Proceedings of ECTE2016, 2016
  6. H. Yokoyama, R. Adachi, T. Minato, H. Odawara, H. Morishima and A. Iida, "Control of Cavity Tone by Spanwise Aligned Jets in Upstream Boundary Layer", European Drag Reduction and Flow Control Meeting 2015, (March, 2015)

Keywords

Bioreactor, Mixer, Double cylinder, Bubble flow, Thermoacoustic instruments, Fan, Control of flow

Title of class

○Fluid Mechanics (B11620110)
○Creative Experiment for Mechanical Engineering (B11610103)
○Computational Fluid Dynamics (M21624170)
○Advanced Environmental Enginnering (D51030080)

Others (Awards, Committees, Board members)

Awards

  1. Apr. 2019, The Commendation for Science and Technology by the Minister of Education, Culture, Sports, Science and Technology, The Young Scientists
  2. May 2018, The Asahara Science Award, Society of Automotive Engineers of Japan
  3. Apr. 2012, JSME Medal for Outstanding Paper, The Japan Society of Mechanical Engineers
  4. Apr. 2011, JSME Young Engineers Award, The Japan Society of Mechanical Engineers
  5. Mar. 2007, Society of Automotive Engineers of Japan, Prediction of tonal sound from side mirror, Best paper award

Press

  1. New Scientist, "See how sound radiates around a recorder", February 2015
  2. EurekAlert!, "Supercomputer simulations explore how an air-reed instrument generates air flow and sound", February 2015
  3. iSGTW (international science grid this week), "Simulating sound with supercomputers could lead to development of easy-to-play musical instruments", March 2015"
  4. The Visualization Society of Japan, "Today's Flash", July 2010"

Committees, Board members

  1. 2018- The Japan Society of Fluid Mechanics, Chubu, Acting committee
  2. 2018- JSME, Tokai, Gakuseikai, Adviser, 2018-
  3. 2017-2018 Experimental and Numerical Flow and Heat Transfer Scientific Committee member
  4. 2017 JSME Power&System Energy Division Symposium, Acting committee
  5. Apr. 2014 - Mar. 2017 JSME Fluids Engineering Division Committee on Public Information
  6. Apr. 2012 - Mar. 2015 JSME Fluids Engineering Division Acting committee
  7. Apr. 2010 - Jul. 2014 The Visualization Society of Japan Acting Committee of Symposium on Visualization

Research Grants and Projects

  1. MEXT: KAKENHI, KIBAN(C), Project Year: 2017 - 2020 (main)
  2. MEXT: KAKENHI, WAKATE(B), Project Year: 2014 - 2016 (main)
  3. MEXT: KAKENHI, KIBAN(B), Project Year: 2013 - 2015 (shared)
  4. MEXT: KAKENHI, WAKATE(B), Project Year: 2012 - 2013 (main)


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