Yaga Minoru

写真a

Researcher Number(JSPS Kakenhi)

60220117

Laboratory Address

1 Senbaru,Nishihara,Okinawa

Mail Address

E-mail address

Laboratory Phone number

-9529

Laboratory Fax number

-9529
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Current Affiliation Organization 【 display / non-display 】

  • Concurrently   University of the Ryukyus   Graduate School of Engineering and Science   Professor  

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Study abroad experiences 【 display / non-display 】

  • 1994.04
    -
    1995.03

    Visiting associate  

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Academic degree 【 display / non-display 】

  • Kyushu University -  Doctor of Engineering

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External Career 【 display / non-display 】

  • 1989.04
    　
    　

    University of the Ryukyus, Faculty of Engineering, Professor  

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Research Interests 【 display / non-display 】

  • 高速空気力学,伝熱工学,数値流体力学(CFD),衝撃波工学

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Research Areas 【 display / non-display 】

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Fluid engineering

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Research Theme 【 display / non-display 】

  • Study of high performance submerged water jet

  • Supersonic Mixing Enhancements

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Published Papers 【 display / non-display 】

  • Extraction of Pressure Wave from Transonic Diffuser by Applying Ceramic Actuator at Throat

    Minoru Yaga, Hayato Goya, Wang Yihe, Heuy Dong Kim

    15th International Symposium on Experimental Computational Aerothermodynamics on Internal Flows     1 - 8   2023.10 [ Peer Review Accepted ]

    Type of publication: Research paper (international conference proceedings)

  • Pressure Variation behind Interaction between Droplet and Unsteady Compressible Flow

    Takahito Kamoshida, Minoru Yaga, Tasuku Azama, Junya Tomita, Masaaki Ishikawa

    The 34th International Symposium on Shock Waves   34   2023.07 [ Peer Review Accepted ]

    Type of publication: Research paper (international conference proceedings)

    　View Summary

    Liquid atomization is the process of reducing the particle size and increasing the number of particles by reducing the liquid mass into a group of microparticles. The process of droplet collapse has been studied in detail by high-speed photography and simulations that take surface tension into account, including changes in shape. In this study, we attempted to clarify the unsteady pressure change in the interference between a droplet and a high-speed fluid by studying the pressure change downstream of the droplet and to construct quantitative data for comparison with calculation results. By using a straight small-volume shock tube, the pressure fluctuation was observed in synchronization with a high-speed camera image taken by an interfering droplet with a high-speed flow that occurs in a very short period of time. The results showed that the droplet was hardly affected by the shock wave but was affected by the high-speed jet following the shock wave. The larger the pressure ratio, the larger the difference in the pressure peak values with and without droplet, and the longer the time interval between the shock wave and the high-velocity jet. These quantitative results indicate that atomization of droplet in unsteady flow fields involves a drop in downstream pressure that cannot be obtained only by image processing of droplet shape change.

  • Significant removal of bacterial biofilm induced by multiple-Short ranges of electric interventions

    Hiroyuki Taira, Minoru Yaga, Satoshi Nakasone, Kotaro Nishida, Tetsu Yamashiro

    Journal of Orthopaedic Science ( Elsevier )  29 ( 1 ) 341 - 348   2023.02 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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    Biofilm-related infections are serious problems in the Orthopedics field, and Staphylococcus aureus are the most popular causative agents of bacterial infections associated with arthroplasty. Several studies demonstrated a synergistic effect of the electric intervention (EI) and the antibiotic administration in killing bacteria in biofilm; however, a constant, long-time EI was needed. In the present study, the effective removal of biofilm formed with S. aureus on a titanium ring by multiple times of one minute-EI was observed and described.

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  • Mixing of laser‑induced plumes colliding in a background gas

    Keita Katayama, Toshiki Kinoshita, Ren Okada, Hiroshi Fukuoka, Takehito Yoshida, Minoru Yaga, Tamao Aoki‑Matsumoto, Ikurou Umezu

    Applied Physics A , Material Science & Processing ( Springer )  128 ( 1007 ) 1 - 10   2022.10 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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    We collided silicon and germanium laser-induced plumes in helium background gas to clarify the behavior of the plumes after the collision. The expansion of the silicon and germanium species in the mixed plume after the collision was observed separately by spectroscopic measurements and the degree of mixing was evaluated by the experimental results. When the pressure of the background gas was 2000 Pa, the plumes moved backward after the collision with the counter-propagating shock wave, and no mixing of the plumes was observed. The efect of the counter-propagating shock wave was discussed by comparing with the results of numerical calculations based on the compressible Euler equations. At 300 Pa, the plumes concentrated at about 1 mm around the central region just after the collision and almost 100% mixing occurred in this region. The concentration and mixing of the plumes in the central region is a key to forming well-mixed plume. Stagnation and partial mixing of the plumes were observed at intermediate pressures. By decreasing the background helium gas pressure from 2000 to 300 Pa, the degree of mixing increased from 0 to about 100%. The results are compared with those in argon background gas to discuss efects of mean free path. The efects of counter-propagating shock wave, mean free path and the onset time of the collision on the backward movement and mixing of the plumes are discussed

  • Effect of Coaxial Air Stream on High-Pressure Submerged Water Jet

    M. Yaga, T. Wakuta, R.V. Reji , H.D. Kim

    Recent Researc on Thermal and Fluid Science ( Springer )    2020 [ Peer Review Accepted ]

    Type of publication: Research paper (international conference proceedings)

    　View Summary

    The effect of coaxial air stream on a high-pressure water jet is studies by measuring the stagnation pressure on the impinging target and by the optical observations of the water jets. The water jet is pressurized at 12.7MPa and discharged into atmosphere and still water, which correspond to non-submerged and submerged water jets. The coaxial air is also pressurized at various pressure po/pb = 1.0 to 3.0, where po and pb are the stagnation air pressure and the atmospheric pressure. And the distance between the water jet nozzle and the normal target plate L divided by the nozzle diameter D is changed from 1.0 to 15. As a result, according to the optical observation for non-submerged case, the spreading angle of the non-submerged water jet is found to be the minimum angle in case of the coaxial air jet pressure ratio of 1.4. The recovery factor decreases both for the case of non-submerged and submerged one decrease as L/D increases. However, the recovery factor in case of submerged water jet is greatly increased by the coaxial air flow by 70% of that for no air stream.. Comparison of the recovery factors between the case of submerged and non-submerged conditions reveals that the coaxial air stream seems to achieve the atmospheric environment for the submerged water jet, even in the submerged conditions.

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Other Papers 【 display / non-display 】

  • Noise Reduction Device with High speed flow and FPGA

        2020.07

     

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Presentations 【 display / non-display 】

  • Study of Unsteady Supersonic Jet using Shock Tube with Small High-Pressure Chamber with Elliptical Cell

    M. Sakamoto, M. Matsui, H. Fukuoka, M. Yaga and T. Takiya

    Proc. Of International Symposium on Explosion Shock wave and High-energy reaction Phenomena  2013.03  -  2013.03 

  • Experimental Study of Interaction between Supersonic Duct Flow and Jets and Rods surrounded by the Porous Cavity

    Nao Kuniyoshi, Minoru Yaga, Isao Teruya, Masaaki Ishikawa

    5th BSME International Conference on Thermal Engineering  2012.12  -  2012.12 

  • Study on Underexpanded Impinging Jet issued from Rectangular Nozzle

    Ruhul Azam, Hiroaki Ozono, Minoru Yaga, Isao Teruya and Masaaki Ishikawa

    5th BSME International Conference on Thermal Engineering  2012.12  -  2012.12 

  • Effect of Water Droplets on Underexpanded Impinging Jets

    Hiroaki Ozono, Iihoshi Takahiro1, Minoru Yaga, Isao Teruya and Masaaki Ishikawa

    4th Asian Joint Workshop on Thermophysics and Fluid Science  2012.10  -  2012.10 

  • Study of Interaction between Supersonic Flow and Rods or Jets surrounded by Porous Cavity

    Nao Kuniyoshi, Minoru Yaga, Akito Koda, Isao Teruya, Masaaki ishikawa

    4th Asian Joint Workshop on Thermophysics and Fluid Science  2012.10  -  2012.10 

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Industrial Property 【 display / non-display 】

  • Control mechanism for air bearing

    Industrial Property No 特願2021-148045  (2021.09.10)

    Unexpectedly No 特願2021-148045  (2022.03.10)

    Minoru Yaga

  • The method to control to oscillation in a transonic diffuser

    Industrial Property No 特開2009-092003  (2007.10.10)

    Unexpectedly No 特開2009-092003  (2009.04.30)

    Minoru Yaga

  • The method and device to mixing enhanacement for SCRAM jet engines

    Industrial Property No 　  (2000.08.11)

    Unexpectedly No P2002-54504A  (2002.02.20)

    Minoru Yaga, Kenyu Oyakawa

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Preferred joint research theme 【 display / non-display 】

  • high speed flow, shock wave, heat transfer, CFD

    Fluid dynamics

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