日本航空宇宙学会論文集
Online ISSN : 2432-3691
Print ISSN : 1344-6460
ISSN-L : 1344-6460
66 巻 , 3 号
選択された号の論文の3件中1~3を表示しています
論文
  • 張 科寅, 渡邊 裕樹, 窪田 健一, 船木 一幸
    2018 年 66 巻 3 号 p. 61-68
    発行日: 2018年
    公開日: 2018/06/05
    ジャーナル 認証あり

    Facility backpressure effect remains to be an important unsolved problem for Hall thruster development making it difficult to predict the thruster on-orbit operation precisely. Measurements in previous research shows the backpressure effects can cause unexpectedly-high thrust and discharge current increment in comparison with the theory. In this study, backpressure effects were investigated by sensitivity analysis using Particle-In-Cell plasma simulation. Not only static pressure but also dynamic pressure, or the velocity of background gas flow, were parameterized. The results show that if dynamic pressure exists, > 10% increment of thrust and current can be observed even if the recommended pressure criteria for Hall thruster measurement is satisfied. It is thus suggested that the dynamic pressure of background gas could be one of the main reason of the backpressure-effect issue. The primary cause of the thrust/current increment is identified to be the flux of ingested background gas. It is also observed in the simulation that the channel wall volume erosion rate also increases linearly with the ingested flux.

  • 田村 真規, 手塚 亜聖
    2018 年 66 巻 3 号 p. 69-74
    発行日: 2018年
    公開日: 2018/06/05
    ジャーナル 認証あり

    CARATS has been formulated as a long-term vision for the future air traffic system, and conversion from prediction of weather phenomena affecting aircraft operation to quantitative restrictive conditions for flight is aimed. In this paper, as weather affected aircraft operation, we focused on the jet stream and investigate the relationship between the jet stream and the cruising altitude of each flight using CARATS Open Data and Meso Scale Model (MSM). The result shows that when the altitude of the lower surface of vertical wind shear below 29,000ft observed on the flight path, almost all flights selected lower altitude than the vertical wind shear. When the lower surface altitude is higher than 30,000ft, the ratio of flights that selected lower altitude than the vertical wind shear tends to increase. However, this ratio varies depending on the thickness of the vertical wind shear in the altitude direction. The thicker wind shear, the ratio of flights that selected lower altitudes tends to increase. Based on the results of the survey, we created a flow chart of the model to estimate the selectivity of each cruise altitude considering jet stream.

  • 原田 正志
    2018 年 66 巻 3 号 p. 75-83
    発行日: 2018年
    公開日: 2018/06/05
    ジャーナル 認証あり

    In this paper, a design method to obtain the maximum static thrust ducted fan is proposed. In this method, the shape of the optimum blade is obtained by minimizing the objective function. The objective function includes the effect of the leading edge suction that acts on the duct's rip. The shape of the optimum blade is tapered, however, a small expansion is confirmed at blade tip. The amount of this expansion depends on the radius of duct's rip. From the optimized ducted fan, it is concluded that the duct generates nearly half of the total thrust, which is also predicted by the simple momentum theory.

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