JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES
Online ISSN : 2432-3691
Print ISSN : 1344-6460
ISSN-L : 1344-6460
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Paper
  • Yuki Mando, Ichiro Shiota, Sunao Hasegawa, Koji Tanaka
    2020 Volume 68 Issue 4 Pages 133-141
    Published: 2020
    Released: August 05, 2020
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    Ejecta from hypervelocity impact includes not only fragments but also luminous vapor cloud with plasma. The plasma (i.e. plasma density) is an important parameter for estimating the risk of discharge on solar array paddle or power harness of spacecraft. We carried out hypervelocity impact experiments using a two-stage light gas gun to analyze luminous vapor cloud and plasma from impacts of the different projectile and target materials. We measured luminous vapor cloud and plasma by using a high-speed video camera and a streak camera spectroscopy, which gives time-resolved spectra and a plasma probe. From the time-resolved spectra, the temperature of the luminous vapor cloud was calculated by fitting the black body radiation from a continuous spectrum of the luminous vapor cloud. Also, we compared and investigated the temporal change of each emission line spectrum from impacts of different target and projectile materials.

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  • Natsuki Tsushima, Masato Tamayama, Tomohiro Yokozeki
    2020 Volume 68 Issue 4 Pages 142-147
    Published: 2020
    Released: August 05, 2020
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    In this paper, a new multi-fidelity aeroelastic framework for highly flexible wings is proposed. A corotational approach with a shell finite element is used to consider the geometrical nonlinearity produced by flexible wings. An unsteady vortex-lattice aerodynamic method and a fast unstructured CFD code are coupled with the structural model subject to the large deformations, providing different fidelity solutions. The developed geometrically nonlinear aeroelastic solutions with different fidelities are compared to evaluate accuracies and computational efficiencies.

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  • Sayaka Kanata, Daiki Nakanishi, Takashi Shimomura
    2020 Volume 68 Issue 4 Pages 148-155
    Published: 2020
    Released: August 05, 2020
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    In recent years, vibration of flexible structures such as solar battery paddles is a problem in attitude control of satellites. Input Shaping (IS) is an effective technique to suppress such vibration, in which multiple input signals are created to cancel its own vibration. This paper analytically describes the influence of the IS-signals upon the attitude of spacecraft, which realizes the vibration control and attitude control of spacecraft at the same time. Numerical simulation is conducted to verify the efficiency of the proposed method.

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  • Junichi Akatsuka, Hideyuki Obata, Hajime Miki, Atsushi Ueno, Yasushi W ...
    2020 Volume 68 Issue 4 Pages 156-162
    Published: 2020
    Released: August 05, 2020
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    This paper describes effects of nozzle geometry and a jet plume on the near-field signature and the thrust performance to explore concepts of aft-boom mitigation for future supersonic transport. Numerical analyses of four kinds of convergent-divergent nozzles were conducted to investigate the sensitivity of the near-field signature and the thrust. The results showed that reducing expansion region at the boat-tail is important to reduce both the peak pressure of near-field signature and the nacelle drag. A nozzle shape, which has an inclined exit shape without a boat-tail portion at lower side, demonstrated a good potential to reduce aft-boom. Supersonic wind tunnel tests using a jet with high-pressure air were also performed to validate the numerical analyses and the results showed good agreement with numerical analyses.

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  • Hideaki Sugawara, Yasutada Tanabe, Masaharu Kameda
    2020 Volume 68 Issue 4 Pages 163-171
    Published: 2020
    Released: August 05, 2020
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    Download due to aerodynamic interaction between a rotor and a wing/body of a winged compound helicopter is analyzed at hover condition. At first, the experimental data available in the literature are examined to find effective wing design parameters which describe the correlation of the download with the rotor thrust. The examination indicates that the projected areas of the wing and body on the rotor disk are the most effective parameters. The ratios of download to the rotor thrust in the experiments are correlated well with the ratio of the sum of these projected areas to the rotor disk area. Secondly, the influence of the arrangement of the fixed di-/anhedral wings on the download is investigated numerically using a rotorcraft CFD tool, rFlow3D. The numerical results show that the download of the anhedral wing with the high-wing arrangement is reduced 4% smaller than other configurations. The small reduction ratio implies that the di-/anhedral angle is a minor parameter in the aerodynamic design of the winged compound helicopter.

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