宇宙技術
Online ISSN : 1347-3832
ISSN-L : 1347-3832
7 巻
選択された号の論文の7件中1~7を表示しています
  • 大南 香織, 小川 博之, 林 光一
    原稿種別: 論文
    専門分野: 原動機・推進
    2008 年 7 巻 p. 1-10
    発行日: 2008年
    公開日: 2008/03/11
    ジャーナル フリー
    Hydrazine (N2H4) and NTO (dinitrogen tetroxide: N2O4) mixtures are used in spacecraft bipropellant systems, having the advantage, for sampling missions, of having no carbon composition. However, no reasonable hydrazine and NTO combustion model has been developed. To construct a hydrazine and NTO combustion model that is useful for bipropellant thruster CFD simulation, we extracted efficient elementary reactions from detailed kinetic reaction model proposed by Ohminami and Ogawa in 2007. The reduced hydrazine and NTO combustion model was composed of 61 extracted reactions with 23 chemical species and was coincident with the original detailed kinetic reaction model in terms of combustion gas temperatures and ignition delay times over O/F(oxidizer and fuel mass ration) =0.82-1.84. Also the simulated combustion gas temperatures were good agreed with the adiabatic flame temperatures, and the simulated ignition delay time at O/F=1.2 was consistent with the literature value. Chemical reaction paths before and after ignition were showed, and could explain hydrazine and NTO combustion network mechanism change.
  • 鳴海 智博, 花田 俊也, 河本 聡美
    原稿種別: 論文
    専門分野: 宇宙システム・技術
    2008 年 7 巻 p. 11-17
    発行日: 2008年
    公開日: 2008/03/11
    ジャーナル フリー
    Study and long-term prediction of orbital debris environment in low Earth orbits are urgent needs for secure human space development and exploration. This paper introduces some results of Low Earth Orbital Debris Environmental Evolutionary Model (LEODEEM) being researched at Kyushu University with collaboration from JAXA for the purpose of discussing problems of space environment conservation. The model calculates LEO debris evolution (less than 2,000 km altitude of perigee) taking into account collisions, and future launch traffic. It becomes possible to predict a long term LEO environment and investigate future mission hazard evaluation by using this model.
  • 田中 宏明
    原稿種別: 論文
    専門分野: 宇宙システム・技術
    2008 年 7 巻 p. 19-25
    発行日: 2008年
    公開日: 2008/04/01
    ジャーナル フリー
    For a reconfigurable antenna system, antenna surface deformations should be measured to achieve a high precision antenna system. In this study, a novel measurement method of antenna surface deformations is proposed. Relations between surface errors and changes of the antenna gains caused by intentional deformations are derived from the Ruze equation. In this method, an antenna surface is deformed additionally using surface adjustment mechanisms and changes of the gains caused by the intentional deformations are measured. An original deformation of the antenna surface is estimated using the relations. Some numerical simulations are carried out to investigate the feasibility of this method. From the results of the simulations, it is shown that the antenna deformations are estimated adequately by using this method.
  • 武田 和也, 河島 信樹, 矢部 恭一
    原稿種別: 技術ノート
    専門分野: 原動機・推進
    2008 年 7 巻 p. 27-32
    発行日: 2008年
    公開日: 2008/03/28
    ジャーナル フリー
    我々は半導体レーザーを用いた飛翔体へのエネルギー伝送システムを構築した.これはレーザーでエネルギーを受けている間飛行し続けることができるシステムである.これを用いた飛行実験を大阪ドームにおいて行った.その結果,高度50mを旋回飛行する無人飛翔体へ,自動追尾によってエネルギー伝送を行い,長時間飛行に成功した.
  • 小田 靖久, 中須賀 真一, FERNANDO Priya
    原稿種別: 技術ノート
    専門分野: 宇宙システム・技術
    2008 年 7 巻 p. 33-36
    発行日: 2008年
    公開日: 2008/06/14
    ジャーナル フリー
    A correction method of orbit elements for nano-satellites using simple and low cost facilities is required. In this study, the Doppler shift of the beacon signal from a cubesat was observed using an amateur radio. The history of frequency variation was recorded for different TLEs with different epoch time. The frequency difference translated into seconds (FDTS) was deduced as a ratio of the maximum frequency variation in the pass to the 1s-periodic variation. The FDTS has dependency on TLE. For the old TLE, the FDTS was larger than the new one. Because the FDTS is related to satellite's phase variation in the orbit, the TLE's epoch time was corrected using the measurement result. The FDTS with the observation using the corrected TLE was small.
  • 池田 哲平, 中邨 康弘, 山極 芳樹, 大津 広敬, 河本 聡美, 大川 恭志, 中島 厚
    原稿種別: 論文
    専門分野: 宇宙システム・技術
    2008 年 7 巻 p. 37-43
    発行日: 2008年
    公開日: 2008/08/21
    ジャーナル フリー
    The Japan Aerospace Exploration Agency (JAXA) is investigating an active space debris removal system that employs highly-efficient electrodynamic tether (EDT) technology. As an electron collector of the EDT for debris de-orbiting, a multiple bare tethers are to be used. In order to simulate the EDT operation, current-voltage (I-V) characteristics of the multiple bare tethers need to be investigated on conditions that a theoretical formula cannot be applied. Therefore, numerical simulations and ground experiments have been conducted to obtain the I-V characteristics. A result of the numerical simulations and the ground experiments showed a double-line bare tethers can collect larger current density than a single-line bare tether.
  • 渡邉 力夫, 林 浩平, 岩尾 正樹, 井河 恵大, 冨田 信之
    原稿種別: 論文
    専門分野: 原動機・推進
    2008 年 7 巻 p. 45-52
    発行日: 2008年
    公開日: 2008/10/11
    ジャーナル フリー
    When liquid nitrogen and heated water are mixed in a chamber, pressure increase due to evaporation expansion inside the chamber becomes high enough to generate thrust force for rocket propulsion. This thrust system is safer and environment-friendly compared to conventional rocket engines utilizing combustion process. This new type of rocket engine system is called "Water-Liquid Nitrogen rocket engine system" and it can be used for small payload mission with expected altitude of several kilometers. In this paper, experimentally obtained thrust characteristics are shown and analyzed. As a result, relations between the thrust force and the mixing chamber pressure are clarified. Also, it is found that the present injector can attain only half of the theoretically expected specific impulse due to insufficient mixing efficiency.
feedback
Top