Updated on 2025/08/19

 
OZAWA Kohei
 
Scopus Paper Info  
Total Paper Count: 0  Total Citation Count: 0  h-index: 9

Citation count denotes the number of citations in papers published for a particular year.

Affiliation
Faculty of Engineering Department of Mechanical and Control Engineering
Job
Associate Professor
External link

Research Interests

  • Fluid Dynamics

  • Combustion

  • Rocket Engineering

Research Areas

  • Frontier Technology (Aerospace Engineering, Marine and Maritime Engineering) / Aerospace engineering

Degree

  • The University of Tokyo  -  Doctor of Engineering   2017.03

Biography in Kyutech

  • 2022.02
     

    Kyushu Institute of Technology   Faculty of Engineering   Department of Mechanical and Control Engineering   Associate Professor  

  • 2017.03
    -
    2022.01
     

    Kyushu Institute of Technology   Faculty of Engineering   Department of Mechanical and Control Engineering   Assistant Professor  

Biography before Kyutech

  • 2015.04 - 2017.03   The University of Tokyo   School of Engineering   Special researcher of the Japan Society for the Promotion of Science   Japan

  • 2024.02 - 2027.02   University of Michigan, Ann Arbor   Department of Aerospace Engineering   Visiting Scholar   Visiting Scholar   United States

  • 2022.02 - 2024.02   University of Michigan   JSPS Overseas Research Fellowships   Visiting Research Scholar   United States

Academic Society Memberships

  • 2020.07   Japan Explosives Society   Japan

  • 2020.06   宇宙工学委員会   Japan

  • 2018.03   JSME   Japan

  • 2014.06   AIAA   United States

  • 2013.06   The Japan Society for Aeronautical and Space Sciences   Japan

Research Career

  • 液化ガス燃料を用いた革新的爆轟推進の研究

    回転デトネーションエンジン、パルスデトネーションエンジン

    研究期間: 2024.04  - 

  • Real-time regression rate measurement of an additive-manufactured functional hybrid rocket fuel

    Hybrid rocket, real-time regression rate measurement, functional solid fuel, additive manufacturing, engine feedback control

    研究期間: 2019.04  - 

  • R&D of reaction control system using pulse detonation engines

    detonation, reaction control system

    研究期間: 2018.09  - 

  • 低粘性液化燃料を生ずる境界層燃焼の加速度環境下における燃焼機構解明

    加速度環境, 境界層燃焼, 混相流, 超臨界流体

    研究期間: 2018.04  - 

Papers

  • 3D Numerical Simulation on Disk Type RDE Used Hydrogen-Air Premixed Gas and Non-Premixed Gas With Multi-Ports Injection International journal

    Takumi Ito, Nobuyuki Tsuboi, Kohei Ozawa and A Koichi Hayashi

    AIAA SCITECH 2025 Forum ( AIAA )   2025.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2025-1974

  • Difference between 2D and 3D NS calculations for RDE pressure gain International journal

    A Koichi Hayashi, Takumi Ito, Nobuyuki Tsuboi, Kohei Ozawa, Yuta Otsuka and Kazuhiro Ishii

    AIAA SCITECH 2025 Forum ( AIAA )   2025.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

  • Two-dimensional detailed numerical simulation of ammonia/hydrogen/air detonation: hydrogen concentration effects and transverse detonation wave structure Reviewed International journal

    Kohama S., Ito T., Tsuboi N., Ozawa K., Hayashi A.K.

    Shock Waves   34 ( 2 )   139 - 154   2024.04

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    Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.1007/s00193-024-01181-6

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85196712978&origin=inward

  • Visualization of the physical destruction process of additive-manufactured regression sensor structures Reviewed

    Kohei Ozawa, Tomoya Neki, Nobuyuki Tsuboi

    Science and Technology of Energetic Materials   84 ( 2 )   24 - 31   2023.05

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.34571/stem.84.2_24

    DOI: 10.34571/stem.84.2_24

  • Numerical Simulation on Rotating Detonation Engine: Effect of Number of Injection Ports in Non-Premixed H2-O2 Gases International journal

    Yoshidomi K., Kurita N., Ozawa K., Tsuboi N., Hayashi A.K., Kawashima H.

    AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022   2022.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2022-1112

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85123582558&origin=inward

  • Experimental and Numerical Study on Disc-RDE: Relation between Number of Detonation Wave and Pressure International journal

    Koichi Hayashi A., Ohno K., Ishii K., Shimomura K., Tsuboi N., Ozawa K., Jourdaine N.H., Dzieminska E., Obara T., Maeda S., Mizukaki T.

    AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022   2022.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2022-0837

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85123355591&origin=inward

  • Attempts of Time-Resolved Fuel Regression Measurements of an Altering-Swirling-Oxidizer-Flow-Type Hybrid Rocket Motor International journal

    Ozawa K., Omiya K., Tsuboi N., Ishii K.

    AIAA AVIATION 2022 Forum   2022.01

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2022-3565

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85135041692&origin=inward

  • Regression behavior of polylactic acid manufactured by fused filament fabrication for hybrid rocket propulsion Reviewed

    Kohei Ozawa, Han-wei Wang, Takefumi Inenaga, Nobuyuki Tsuboi

    Science and Technology of Energetic Materials ( Japan Explosives Society )   82 ( 6 )   170 - 177   2021.12

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)

    Advanced closed-loop control of thrust and mixture ratio of hybrid rockets is planned by combing a fuel mass flow rate control technique with a real-time fuel regression measurement. The latter technique is enabled by a multi-materialadditive-manufactured solid fuel with an integrated sensor probe structure. This work investigated the fuel regression behavior of polylactic acid (PLA) fuel used for the main material of this type of solid fuels. Rectangular slab fuels and cylindrical fuel grains were manufactured by Fused Filament Fabrication (FFF) and fired in an optically accessible slab burner and a lab-scale motor, respectively. The cylindrical fuel grains had more than 2 times larger regression rates than rectangular slab fuels even with the same PLA filament. One of the main factors causing this large difference can be an anisotropy in the fuel regression rate behavior of the solid fuels manufactured by FFF.

    DOI: 10.34571/stem.82.6_170

    Kyutacar

    CiNii Article

    CiNii Research

    Other Link: http://hdl.handle.net/10228/00008705

  • ハイブリッドロケットの推力 - 混合比制御のノミナル性能向上を詳細に評価

    小澤 晃平

    宇宙航空研究開発機構宇宙科学研究所年次要覧2020年度 ( 国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 )   23 - 23   2021.11

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    Authorship:Lead author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (bulletin of university, research institution)

  • Time-resolved fuel regression measurement function of a hybrid rocket solid fuel integrated by multi-material additive manufacturing Reviewed International journal

    Ozawa K., Wang H.w., Yoshino T., Tsuboi N.

    Acta Astronautica   187   89 - 100   2021.06

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.1016/j.actaastro.2021.06.031

    Kyutacar

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85108881693&origin=inward

  • Experimental and numerical study on disc-rde: Flow structure and its performances International journal

    Hayashi A.K., Ishii K., Watanabe T., Tsuboi N., Ozawa K., Jourdaine N.H., Dzieminska E., Tang X., Obara T., Maeda S., Mizukaki T.

    AIAA Scitech 2021 Forum   1 PartF   1 - 12   2021.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85100319111&origin=inward

  • 3D numerical study on flow field in disc-RDE International journal

    Hayashi A.K., Shimomura K., Tsuboi N., Ozawa K., Jourdaine N.H., Ishii K., Dzieminska E., Obara T., Maeda S., Mizukaki T.

    AIAA Propulsion and Energy Forum, 2021   2021.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2021-3665

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85123365877&origin=inward

  • Numerical simulations on propane/oxygen detonation in a narrow channel using a detailed chemical mechanism: formation and detailed structure of irregular cells Reviewed International journal

    Takeshima Naomi, Ozawa Kohei, Tsuboi Nobuyuki, Hayashi Koichi A., Morii Yuhi

    Shock Waves ( Springer )   30 ( 7-8 )   809 - 824   2020.12

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    Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.1007/s00193-020-00978-5

    Scopus

    Other Link: https://link.springer.com/article/10.1007/s00193-020-00978-5

  • Performance of Mixture-Ratio-Controlled Hybrid Rockets under Uncertainties in Fuel Regression Reviewed International journal

    Kohei Ozawa, Toru Shimada

    Journal of Propulsion and Power ( American Institute of Aeronautics and Astronautics )   37 ( 1 )   86 - 99   2020.10

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.2514/1.B37970

    Kyutacar

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85098688616&origin=inward

  • Performance of mixture-ratio-controlled hybrid rockets for nominal fuel regression Reviewed International journal

    Ozawa K., Shimada T.

    Journal of Propulsion and Power   36 ( 3 )   400 - 414   2020.03

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.2514/1.B37665

    Kyutacar

    Scopus

    Other Link: https://arc.aiaa.org/doi/abs/10.2514/1.B37665

  • Accuracy of real-time fuel regression measurement function of a 3d printed solid fuel International journal

    Ozawa K., Wang H.W., Inenaga T., Tsuboi N.

    AIAA Propulsion and Energy 2020 Forum   1 - 15   2020.01

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2020-3741

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85091296741&origin=inward

  • Recent experimental and numerical study on disc-type rdes International journal

    Hayashi K., Tsuboi N., Ozawa K., Watanabe T., Jourdaine N.H., Ishii K., Kawana H., Kuwata W., Ohno K., Obara T., Maeda S., Dzieminska E., Tang X., Mizukaki T.

    AIAA Scitech 2020 Forum   1 PartF   2020.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2020-1169

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85091925389&origin=inward

  • Numerical simulation on disk rotating detonation engine: Influence of internal flow field structure on performance International journal

    Watanabe T., Shimomura K., Jourdaine N.H., Ozawa K., Tsuboi N., Kojima T., Ishii K., Hayashi A.K.

    AIAA Scitech 2020 Forum   1 PartF   1 - 7   2020.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2020-2160

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85092418617&origin=inward

  • Three-dimensional numerical simulation on hydrogen/air rotating detonation engine with aerospike nozzle: Effects of nozzle geometries International journal

    Kurita N., Jourdaine N., Tsuboi N., Ozawa K., Hayashi A.K., Kojima T.

    AIAA Scitech 2020 Forum   1 PartF   2020.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2020-0688

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85091953963&origin=inward

  • Real-time regression rate measurement of an additive-manufactured functional hybrid rocket fuel International journal

    Ozawa K., Wang H.W., Yoshino T., Tsuboi N.

    Proceedings of the International Astronautical Congress, IAC   2019-October   2019.01

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (international conference proceedings)

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85079135960&origin=inward

  • Boundary-layer combustion of wax-based fuels at various chamber pressures under two static acceleration environments International journal

    Ozawa K., Yoshino T., Wang H.W., Tsuboi N.

    AIAA Propulsion and Energy Forum and Exposition, 2019   2019.01

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2019-4100

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85095974363&origin=inward

  • Three-dimensional numerical simulation of disk rotating detonation engine: Unsteady flow structure International journal

    Watanabe T., Jourdaine N.H., Ozawa K., Tsuboi N., Kojima T., Hayashi A.K.

    AIAA Scitech 2019 Forum   2019.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2019-1498

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85083943692&origin=inward

  • Investigation of graphite nozzle erosion in hybrid rockets using N2O/HDPE International journal

    Kamps L., Sakurai K., Ozawa K., Nagata H.

    AIAA Propulsion and Energy Forum and Exposition, 2019   2019.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2019-4264

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  • Development of a high efficiency system with a rotating detonation engine for a gas turbine engine (RDE-GTE) using pressure gain combustion International journal

    Koichi Hayashi A., Tsuboi N., Ozawa K., Ishii K., Obara T., Maeda S., Dzieminska E., Mizukaki T.

    AIAA Scitech 2019 Forum   2019.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2019-1509

    Scopus

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  • A Theoretical Study on Throttle Ranges of O/F Controllable Hybrid Rocket Propulsion Systems, jointly worked Reviewed International journal

    Kohei OZAWA, Toru SHIMADA

    Journal of Fluid Science and Technology   13 ( 4 )   1 - 18   2018.11

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.1299/jfst.2018jfst0031

    Kyutacar

    Scopus

    Other Link: https://www.jstage.jst.go.jp/browse/jfst/-char/en

  • Three-dimensional numerical thrust performance analysis of hydrogen fuel mixture rotating detonation engine with aerospike nozzle, jointly worked Reviewed

    Nicolas Jourdaine, Nobuyuki Tsuboi, Kohei Ozawa, Takayuki Kojima, A.Koichi Hayashi

    Proceedings of the Combustion Institute   2018.10

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    Language:English   Publishing type:Research paper (international conference proceedings)

    UK   Dublin   2018.07.29  -  2018.08.03

    DOI: 10.1016/j.proci.2018.09.024

    Other Link: https://www.sciencedirect.com/science/article/pii/S1540748918306291

  • Hybrid Rocket Firing Experiments at Various Axial-Tangential Oxidizer-Flow-Rate Ratios, jointly worked Reviewed International journal

    Kohei OZAWA, Koki KITAGAWA, Shigeru ASO, Toru SHIMADA

    Journal of Propulsion and Power   35 ( 1 )   94 - 108   2018.09

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.2514/1.B36889

    Kyutacar

    Scopus

    Other Link: https://arc.aiaa.org/doi/abs/10.2514/1.B36889

  • Experimental Investigation of Fuel Regression Rate of Low-Melting-Point Thermoplastic Fuels in the Altering-Intensity Swirling-Oxidizer-Flow-Type Hybrid Rocket Engine, "jointly worked" Reviewed

    Yo KAWABATA, Ayana BANNO, Yutaka WADA, Kohei OZAWA, Toru SHIMADA, Nobuji KATO, Keiichi HORI, Ryo NAGASE

    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN ( THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES )   16 ( 3 )   267 - 273   2018.05

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    Language:English   Publishing type:Research paper (scientific journal)

    <p>In this study, we developed a high-performance and high-thrust hybrid rocket motor using low-melting-point thermoplastic (LT) fuel and swirling oxidizer flow. LT fuel has excellent mechanical and adhesive properties, as well as a high regression rate compared to conventional hybrid rocket fuel. In this study, we conducted several firing tests using swirling oxidizer flow to obtain the fuel regression rate and evaluate its effects on the geometric swirl number (<i>S<sub>g</sub></i>). We determined that the average regression rate of the LT fuel with <i>S<sub>g</sub></i> = 37.3 was ~2.9 times larger than the axial flow test value. The LT fuel was more susceptible to swirling flow than polypropylene, presumably due to the different physical properties of the fuels. In the swirl flow experiment, we confirmed that the local fuel regression rate behind the fuel is uniform, and it differs from the regression rate seen in the axial flow experiment. For the range of oxygen mass flux values <i>G<sub>oxlo</sub></i> = 30–72, <i>ṙ<sub>loave</sub></i> was fitted to a conventional formula. The results of this fit suggested that the local regression rate at the head region of low-melting-point fuel, such as the LT fuel, cannot be represented only by chemical reactions; therefore, the fluid dynamics of liquefied fuel must be included in the model.</p>

    DOI: 10.2322/tastj.16.267

    CiNii Article

    CiNii Research

    Other Link: https://www.jstage.jst.go.jp/article/tastj/16/3/16_267/_pdf

  • Visualization of boundary layer combustion of wax-based fuels in vertical and horizontal configurations International journal

    Ozawa K., Yoshino T., Tsuboi N.

    2018 Joint Propulsion Conference   2018.01

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2018-4928

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85066478484&origin=inward

  • Effects of O/F shifts on flight performances of vertically launched hybrid sounding rockets International journal

    Ozawa K., Shimada T.

    53rd AIAA/SAE/ASEE Joint Propulsion Conference, 2017   2017.01

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.2514/6.2017-5051

    Scopus

    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85082546786&origin=inward

  • Online Magnetometer Calibration in Consideration of Geomagnetic Anomalies Using Kalman Filters in Nanosatellites and Microsatellites Reviewed

    Takaya Inamori, Ryuhei Hamaguchi, Kouhei Ozawa, Phongsatorn Saisutjarit, Nobutada Sako, Shinichi Nakasuka

    Journal of Aerospace Engineering   29 ( 6 )   2016.06

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    Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.1061/(ASCE)AS.1943-5525.0000612

    Other Link: https://ascelibrary.org/doi/pdf/10.1061/%28ASCE%29AS.1943-5525.0000612

  • Theoretical prediction of regression rates in swirl-injection hybrid rocket engines, "jointly worked" Reviewed

    K. Ozawa, T. Shimada

    Progress in Propulsion Physics   2016.06

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.1051/eucass/201608283

  • Flame emission spectroscopy in a paraffin-based hybrid rocket International journal

    Stober K.J., Leccese G., Narsai P., Ozawa K., Cantwell B.

    Proceedings of the International Astronautical Congress, IAC   0   2016.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

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  • Static burning tests on a bread board model of altering-intenisty swirling-oxidizer-flow-type hybrid rocket engine International journal

    Ozawa K., Usuki T., Mishima G., Kitagawa K., Yamashita M., Mizuchi M., Katakami K., Maji Y., Aso S., Tani Y., Wada Y., Shimada T.

    52nd AIAA/SAE/ASEE Joint Propulsion Conference, 2016   2016.01

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (international conference proceedings)

    Scopus

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  • A Theoretical Study of Combustion Stability in Vortex Injection Hybrid Rocket Engine, "jointly worked" Reviewed

    Kohei OZAWA, Toru SHIMADA

    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN   2014.07

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)

    DOI: 10.2322/tastj.12.Pa_53

    Other Link: https://www.jstage.jst.go.jp/browse/tastj/-char/en

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Publications (Books)

  • Hybrid Propulsion Technology Development in Japan for Economic Space Launch Reviewed

    Shimada T., Yuasa S., Nagata H., Aso S., Nakagawa I., Sawada K., Hori K., Kanazaki M., Chiba K., Sakurai T., Morita T., Kitagawa K., Wada Y., Nakata D., Motoe M., Funami Y., Ozawa K., Usuki T.(Joint author)

    Springer Aerospace Technology  2017.01 

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  • Chemical Rocket Propulsion: A Comprehensive Survey of Energetic Materials

    De Luca, L.T., Shimada, T., Sinditskii, V.P., Calabro, M. (Eds.), Ozawa, K.

    Springer  2016.08  ( ISBN:978-3319277462

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    Language:English

Conference Prsentations (Oral, Poster)

  • Accuracy of real-time fuel regression measurement function of a 3d printed solid fuel

    Ozawa K., Wang H.W., Inenaga T., Tsuboi N.

    AIAA Propulsion and Energy 2020 Forum  American Institute of Aeronautics and Astronautics

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    Event date: 2020.08.24 - 2020.08.26   Language:English  

  • Real-time Regression Rate Measurement of an Additive-manufactured Functional Hybrid Rocket Fuel

    Kohei Ozawa, Han Wei Wang, Takuro Yoshino, Nobuyuki Tsuboi

    70th International Astronautical Congress 

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    Event date: 2019.10.21 - 2019.10.25   Language:English  

  • Investigation of Graphite Nozzle Erosion in Hybrid Rockets Using N2O/HDPE

    Kohei Ozawa

    AIAA Propulsion and Energy 2019 Forum 

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    Event date: 2019.08.19 - 2019.08.22   Language:English  

  • Boundary-Layer Combustion of Wax-based Fuels at Various Chamber Pressures under Two Static Acceleration Environments

    Kohei Ozawa

    AIAA Propulsion and Energy 2019 Forum 

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    Event date: 2019.08.19 - 2019.08.22   Language:English  

  • Simulation of a Detonation Propagation in a Two-phase Gas/liquid Cross Flow Injection

    Nicolas Jourdaine

    27th International Colloquium on the Dynamics of Explosions and Reactive Systems 

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    Event date: 2019.07.28 - 2019.08.02   Language:English  

  • Two-dimensional Numerical Simulations on Unstable Propagation of Propane/Oxygen Detonation Using a Detailed Chemical Mechanism

    Naomi Takeshima

    27th International Colloquium on the Dynamics of Explosions and Reactive Systems 

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    Event date: 2019.07.28 - 2019.08.02   Language:English  

  • Two-Dimensional Numerical Simulation of Flame Acceleration and Deflagration-to-Detonation Transition in Channels with Obstacles: Effects of Blockage Ratio and Chanel Size

    Kanta Iwasaki

    27th International Colloquium on the Dynamics of Explosions and Reactive Systems 

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    Event date: 2019.07.28 - 2019.08.02   Language:English  

  • Numerical Study on Cryogenic Jet/Crossflow Interaction Structures under a Supercritical Pressure

    Taishi AMANO

    International Symposium on Space Technology and Science  The Japan Society for Aeronautical and Space Sciences

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    Event date: 2019.06.15 - 2019.06.21   Language:English  

  • Feasibility Study of a Real-time Fuel Regression Rate Measurement using an Electrostatic Capacitive Probe for Hybrid Rocket Engines

    Han Weig WANG

    International Symposium on Space Technology and Science  The Japan Society for Aeronautical and Space Sciences

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    Event date: 2019.06.15 - 2019.06.21   Language:English  

  • Visualization of Boundary Layer Combustion of Wax-Based Fuels in Horizontal and Vertical Chamber Configurations

    Kohei OZAWA

    International Symposium on Space Technology and Science  The Japan Society for Aeronautical and Space Sciences

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    Event date: 2019.06.15 - 2019.06.21   Language:English  

  • カーボンブラックを用いたメタン/酸素予混合気におけるデ トネーションセル構造の可視化とギャッロッピングデトネーシ ョンの速度振動の詳細計測

    久門昂平

    日本機械学会九州支部 第72期総会講演会 講演論文集 

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    Event date: 2019.03.14   Language:Japanese  

  • Development of a high efficiency system with a rotating detonation engine for a gas turbine engine (RDE-GTE) using pressure gain combustion

    Koichi Hayashi A., Tsuboi N., Ozawa K., Ishii K., Obara T., Maeda S., Dzieminska E., Mizukaki T.

    AIAA Scitech 2019 Forum 

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    Event date: 2019.01.01   Language:English  

  • Three-dimensional numerical simulation of disk rotating detonation engine: Unsteady flow structure

    Watanabe T., Jourdaine N., Ozawa K., Tsuboi N., Kojima T., Hayashi A.

    AIAA Scitech 2019 Forum 

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    Event date: 2019.01.01   Language:English  

  • ハイブリットロケットの推力・酸燃比制御に向けた新しい瞬時後 退速度計測手法

    王 瀚緯

    第62回宇宙科学技術連合講演会 

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    Event date: 2018.10.24 - 2018.10.26   Language:Japanese  

  • 数値解析及び風洞試験によるオービター搭載Waveriderの空力 特性調査

    宇崎友規

    第62回宇宙科学技術連合講演会 

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    Event date: 2018.10.24 - 2018.10.26   Language:Japanese  

  • 加速度環境におけるハイブリッドロケット用ワックス燃料の境界層燃焼可視化に関する研究

    吉野 拓郎

    第62回宇宙科学技術連合講演会 

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    Event date: 2018.10.24 - 2018.10.26   Language:Japanese  

  • 軸・接線噴射を用いたハイブリッドロケットエンジンのインジェクタ特性解析

    吉野 拓郎

    第62回宇宙科学技術連合講演会 

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    Event date: 2018.10.24 - 2018.10.26   Language:Japanese  

  • Visualization of boundary layer combustion of wax-based fuels in vertical and horizontal configurations

    Ozawa K., Yoshino T., Tsuboi N.

    2018 Joint Propulsion Conference 

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    Event date: 2018.07.09 - 2018.07.11   Language:English  

  • Study of ignition method for firing experiments to visualize boundary layer combustion of paraffin fuel in acceleration environments

    The Proceedings of Conference of Kyushu Branch 

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    Event date: 2018.01   Language:Japanese  

    CiNii Article

  • Unsteady Numerical Simulation on Axial and Tangential Oxidizer Injection in Altering-intensity Swirling Oxidizer Flow Type Hybrid Rocket Engine

    The Proceedings of Conference of Kyushu Branch 

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    Event date: 2018.01   Language:Japanese  

    CiNii Article

  • Monitoring of natural disaster based on Synthetic Aperture Radar (SAR) satellite in Southeast Asia

    Seo S., Nomura S., Ariu K., Yoshihara Y., Kumse K., Funabiki N., Ozawa K., Tanaka E., Yuki T.

    Proceedings of the International Astronautical Congress, IAC 

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    Event date: 2017.09.25 - 2017.09.29   Language:English  

    Southeast Asia is a region that is severely affected by a variety of natural disasters, such as typhoons, heavy rain, earthquakes, and volcanic eruptions. Synthetic-Aperture Radar (SAR) has a large advantage in speed of data acquisition and observation because it can observe in the night or through clouds. SAR has been implemented only on large satellites so far. However, recently, a new concept of SAR and a high-speed downlink system using single small satellites has been developed. This technology can drastically decrease development costs of SAR satellites, increase the frequency of observations using a constellation of SAR satellites, and enable many developing countries to have SAR satellites. Moreover, this technology enables Southeast Asian countries to construct a shared rapid disaster observation system internationally. In this paper, a possible business model from the viewpoints of Japanese manufacturer and governments that utilize a feasible SAR satellite system based on MicroXSAR is described. A cost-benefit analysis is conducted and presented from the perspective of the manufacturer. Besides, the price of the whole observation systems is also calculated using a cost-estimation method of satellites, and is evaluated from the aspects of economic powers of Southeast Asian countries.

  • Effects of O/F shifts on flight performances of vertically launched hybrid sounding rockets

    Ozawa K., Shimada T.

    53rd AIAA/SAE/ASEE Joint Propulsion Conference, 2017 

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    Event date: 2017.01.01   Language:English  

    Impacts of various types of O/F shifts on flight performances of a single stage sounding rocket with a scale of S-520 sounding rocket series were comprehensively evaluated by flight simulations of O/F controlled and uncontrolled hybrid rockets. Before the simulation, sources of O/F shifts and factors affected by O/F shifts were classified and discussed in order to clarify the respective sets of simulations. O/F shifts along with the median fuel regression rate behaviors, systematic errors of the behaviors, and random errors of fuel regression rates were statistically modelled using multiple regression theroy. Shifts of thermodynamic states of productive gases after combustion, shifts of c ∗ efficiency, and nozzle throat erosion were modelled as factors affected by O/F shifts. Operations of propulsion systems were assumed to include throttling. In the presence of O/F shifts along with a median regression rate equation, shifts of thermodynamic states of productive gases were the dominant factor causing performance losses of O/F uncontrolled rockets. In the presence of systematic or random errors of fuel regression rates, residuals of propellants were the other dominant factor to decrease flight performances. Especially in the random error cases, as a result of 3000 times of flight performances, the guaranteed highest altitude of the O/F controlled rocket was 5.2% higher than that of uncontrolled rocket within ±3σ. This result shows that the O/F controlled hybrid rockets have about 2.6% higher acceleration than the O/F uncontrolled rockets. Accuracy of acceleration of the O/F controlled hybrid rocket was 10 times higher than that of the O/F uncontrolled hybrid rocket. These results indicate that the significance of O/F shifts elimination of hybrid rockets from both the aspects of expectancy and accuracy of flight performances.

  • Flame emission spectroscopy in a paraffin-based hybrid rocket

    Stober K., Leccese G., Narsai P., Ozawa K., Cantwell B.

    Proceedings of the International Astronautical Congress, IAC 

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    Event date: 2016.01.01   Language:English  

    Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved. A spectrometer was used to measure the emissions emanating from the plume and combustion chamber of a paraffin-based hybrid rocket. Flame emissions were captured between 200-900 nm at numerous points during the 3-7 second ground tests. Time-resolved blackbody emissions were obtained, as well as emission and absorption peaks associated with combustion products, emanating from the plume and combustion chamber. Plume measurements were taken seven inches aft of the nozzle exit plane at the center of the plume. The rocket is described in Narsai et al. [1] and utilizes paraffin and additives as fuel along with gaseous oxygen as the oxidizer. Chamber pressure and oxidizer flow rates were varied in order to validate results over a wide range of operating conditions. The blackbody emissions were fit to Planck's law in order to estimate flame temperature. The observed temperatures matched well with simulations run via a chemical equilibrium solver [2] . Further validation of the algorithm used to estimate flame temperature was provided by capturing emissions from a tungsten filament. Additionally, numerous species of interest were identified, including igniter materials and combustion products which contributed to erosion of the nozzle. Two other techniques for estimating flame temperature were investigated: (1) the analysis of OH emission bands near 315 nm and (2) the analysis of the sodium D-lines around 590 nm. Trace amounts of sodium chloride were added to the melted paraffin wax prior to spin-casting in order to attempt to produce D-line emissions. Absorption spectroscopy was conducted on paraffin and a blackener dye used to improve the absorption of thermal radiation at the exposed surface of the fuel grain. Absorption spectra were acquired between 0.2 and 22 microns. These absorption spectra were compared with flame emission spectra within the combustion chamber in order to gain insight into how heat is transferred from the flame to the fuel surface.

  • Static burning tests on a bread board model of altering-intenisty swirling-oxidizer-flow-type hybrid rocket engine

    Ozawa K., Usuki T., Mishima G., Kitagawa K., Yamashita M., Mizuchi M., Katakami K., Maji Y., Aso S., Tani Y., Wada Y., Shimada T.

    52nd AIAA/SAE/ASEE Joint Propulsion Conference, 2016 

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    Event date: 2016.01.01   Language:English  

    © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. A bread board model of Altering-number Swirling Flow Type (A-SOFT) hybrid rocket engine has been newly developed and the static burning tests have been conducted. A-SOFT hybrid rocket engines have controllability of both thrust and O/F without any replacement of components in the engine. This advantage is acquired by controlling oxidizer mass flow rate and effective swirl number. The purpose of this set of experiments is to confirm the continuity, monotonousness and predictability of the performances of A-SOFTs. The A-SOFT BBM showed a favorable fuel regression behavior. The fuel regression averaged along spatial direction fit the shape of regression rate function proposed before the experiments within ±3.5% errors, and the fuel regression rates are continuous and monotonous along swirl number and oxidizer mass flux. The O/F and thrust data also respectively fit the prediction formulas within ±4.2% and ±4.7% errors. c* efficiency is evaluated with the Isp efficiency - nozzle efficiency ratio η Isp / η C F in order to compensate the pressure sensing errors caused by the centrifugal forces of swirling flows. Though η Isp / η C F in the cases of weak swirl injection was clearly larger than in the cases of axial injection, its dependence on effective geometric swirl number was not clear in strong swirl conditions.

  • Flight performance simulations of vertical launched sounding rockets using altering-intensity swirling-oxidizer-flow-type hybrid motors

    Ozawa K., Shimada T.

    51st AIAA/SAE/ASEE Joint Propulsion Conference 

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    Event date: 2015.01.01   Language:English  

    © 2015, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. In practical usage of conventional hybrid rocket engines, the oxidizer-to-fuel ratio (O/F) shift occurs by either the fuel port diameter increase or throttling because the fuel regression rate is not proportional to the oxidizer mass flux. As a promising technique to eliminate the O/F shift in a wide throttling range, Altering-intensity-Swirling-Oxidizer-Flow-Type (A-SOFT) hybrid rocket engines are proposed. A-SOFTs control O/F, independently of thrust, with the swirl intensity of oxidizer from the injector, as well as the mass flow rate of the oxidizer. In this paper, the increase rates of engine performance caused by O/F shift eliminating technique are evaluated with a vertical launch simulation for single stage sounding rockets. This simulation includes the throat erosion and c* efficiency models which can be affected by O/F shifts. The statistical uncertainty of fuel regression model is also included to evaluate the robustness of A-SOFTs and SOFTs. The increase rates of total impulse and maximum altitude of A-SOFTs compared to SOFTs depends on maximum oxidizer mass flow rate and are about 2% and 4% respectively. The most effective indicators in this evaluation to the flight performance are residuals of propellants and c* efficiency. Owing to the sensitivity of the flight performances to residuals, the fuel regression errors can cause risks of large losses of the highest altitude in SOFTs, and it is found that the feedback control of A-SOFTs have robustness to the fuel regression errors to some extent. c* efficiency dependent on L* is also sensitive to O/F shifts because O/F shifts affect combustion chamber volume and increase of throat area.

  • Performance calculations and burning tests on altering-intensity swirling oxidizer flow type hybrid rocket engines

    Ozawa K., Kitagawa K., Shimada T.

    Proceedings of the International Astronautical Congress, IAC 

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    Event date: 2015.01.01   Language:English  

    As a technique to eliminate O/F shifts, Altering-intensity Swirling Oxidizer Flow Type (A-SOFT) hybrid rocket is proposed using the combination axial and tangential oxidizer injection. In this paper, the possible geometric design point of the motor is considered about 2-tons class single stage A-SOFT hybrid rockets, and the nominal performance increase by eliminating O/F shifts is evaluated. The highest altitude of the A-SOFT is 450 [km] and the averaged ISP is 284[s] with 100[kg] payload, and this performance is several percent higher than the ones of S-520 with 95[kg] payload, Japanese 2-tons class solid sounding rocket. Though A-SOFTs increase the nominal flight performance by 1% from Swirling Oxidizer Flow Type hybrid rockets, which cannot O/F shift, their feedback control prevents the large performance losses caused by fuel regression errors and residuals, and this function is not found in the conventional hybrid rockets. In this paper, a planning of steady state burning tests of A-SOFT bread board model is also explained. The purpose of the burning tests are to demonstrate the concept of A-SOFTs. The test motor is 250[N] scale and uses polypropylene and GOX and its burning duration is 5[s] . In more than 10 times steady state tests, 50% throttling conditions with effective geometric swirl intensity between 0 and 37.3 are inculded.

  • Linear stability analysis of uni-directional vortex injection hybrid rocket engines

    Ozawa K., Shimada T.

    50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference 2014 

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    Event date: 2014.01.01   Language:English  

    © 2014 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. In this paper, first, a theoretical prediction method of regression rates and heat flux to solid fuels of uni-directional vortex injection hybrid rocket engines is developed by introducing a new swirl intensity decline model toward axial direction. Next, a linear propagative relation of heat flux to solid fuels with disturbances of oxidizer mass flux, fuel regression, and initial swirl intensity is derived. The couple of this response model and another unteady response model of solid fuel gasification amplifies oxidizer mass flux disturbance in the form of regression rate oscillation. This is the basic mechanism of low frequency instability unique to hybrid rocket engines. The linear stability analysis for uni-directional vortex types simulating both ILFI amplification source and main stream model is conducted. The result of this analysis shows that uni-directional vortex injection hybrid rocket engines have the same linear unstable mode as axial hybrid rocket engines.

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Industrial Property

  • A manufacturing method of solid fuels for hybrid rocket engines with a real-time regression rate measurement function

    Kohei Ozawa, Han-wei Wang, Takuro Yoshino

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    Application no:2019-190285  Date applied:2019.10.17

Lectures

  • Combustion Flow of Wax-based Hybrid Rockets in Various Acceleration Environments

    JST さくらサイエンスプラン 2019 年度 熱流体工学分野に関する国際共同セミナー  2019.08  九州工業大学

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    Presentation type:Keynote lecture   Venue:九州工業大学戸畑キャンパス  

Press

  • CLOSE-UP JKA   Newspaper, magazine

    Kohei Ozawa

    Nishinippon Shimbun  2021.08.06

Honors and Awards

  • Incentive Award of Japan Explosives Society

    Japan Explosives Society   Research on Multi-Material Additive-Manufactured Solid Fuels for Hybrid Rockets   2022.05.24

    Kohei OZAWA

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    Country:Japan

  • JAICI Award

    Japan Association for International Chemical Information   2022.05.24

    Kohei OZAWA

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    Country:Japan

  • AIAA Hybrid Rocket Best Student Paper

    2016.07.27

    Kohei Ozawa, Toru Shimada

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    Country:United States

  • Japanese Rocket Society Award

    2013.06.09

    Kohei Ozawa

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    Country:Japan

Grants-in-Aid for Scientific Research

  • 低粘性液化燃料を生ずる境界層燃焼の加速度環境下における燃焼機構解明

    Grant number:18K13926  2018.04 - 2022.03   若手研究

  • Simultaneous Control of Optimal Mixture Ratio and Thrust Using Oxidizer Swirling Flow for Hybrid Rockets

    Grant number:15J08028  2015.04 - 2017.03   Grant-in-Aid for JSPS Fellows

Contracts

  • Research and Development of Reaction Control System using Pulse Detonation Engine

    2018.09

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    Grant type:Consigned research

    A prototype pulse detonation engines are developed to be applied for the green reaction control systems for upper stages of small satellite launchers. This contract research is aimed at the conceptual demonstration of a new semi-valveless pulse detonation engine using a liquid fuel as well as the identification of challenges of this type of engines.

Other External Funds

  • Study on Determination Mechanism of Detonation Wave Properties under the Presence of Deflagration and Gaseous Hydrogen-Air Mixing Process

    2022.02 - 2024.02

    Japan Society for the Promotion of Science Overseas Fellowship  

  • Investigation on Boundary Layer Combustion of Liquefying Fuel with Low Viscosity in Acceleration Environment

    2021.04 - 2022.03

    AY2021 Linear Hyper G Public Offering Joint Research  

  • Study of Conductive Resin Mixed with Graphene for Upgrade of Solid Fuels Capable of Flow Rate Measurement

    2020.04 - 2021.03

    Grant-in-Aid for High-Energy Materials  

  • Investigation on Boundary Layer Combustion of Liquefying Fuel with Low Viscosity in Acceleration Environment

    2020.04 - 2021.03

    Linear Hyper G Public Offering Joint Research  

  • Demonstration of Advanced Closed-Loop Thrust Control of Hybrid Rockets Using Additively-manufactured Solid Fuels

    2020.04 - 2021.03

    Grant-in-Aid for Young Scientists, Promotion of Mechanical Engineering  

  • Upgrade of Thruster for Nano-satellites Using Functional Solid Fuels Manufactured by a 3D Printer

    2019.10 - 2021.03

    Grant-in-Aid for Young Scientists, Promotion of Mechanical Engineering  

  • Boundary-Layer Combustion of Blacken Wax-based Fuels at Various Chamber Pressures under Two Steady Acceleration Environments

    2019.08

    Travel Grant for International Conferences, Society for Promotion of Space Science  

  • Study on Non-toxic RCS for Upper Stages of Rockets using Detonation Waves

    2019.04 - 2020.03

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    A prototype pulse detonation engines are developed to be applied for the green reaction control systems for upper stages of small satellite launchers. This contract research is aimed at the conceptual demonstration of a new semi-valveless pulse detonation engine using a liquid fuel as well as the identification of challenges of this type of engines.

  • Real-time regression rate measurement of an additive-manufactured functional hybrid rocket fuel

    2019.04 - 2020.03

    Grant-in-Aid for High-Energy Materials  

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Career of Research abroad

  • Study on Determination Mechanism of Detonation Wave Properties under the Presence of Deflagration and Gaseous Hydrogen-Air Mixing Process

    University of Michigan, Ann Arbor  Project Year:  2022.02.28

  • Parametric study and visualization of combustion flow in small hybrid rocket engines

    Stanford University  Project Year:  2016.07.03 - 2016.10.02

Award for Educational Activities

  • ミスミ学生ものづくり支援

    株式会社ミスミグループ本社   2018.12.26

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    学生のものづくり・研究に対する支援

Activities of Academic societies and Committees

  • The Japan Society for Aeronautical and Space Sciences West Branch   Executive Secretary  

    2020.03 - 2021.02

Social activity outside the university

  • NHK高専ロボコン 九州沖縄地区大会 主審

    2017.10.20 - 2017.10.21

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    Type:Other