著者

西澤 宇一 亀田 正治 渡辺 安

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.56, no.654, pp.315-323, 2008 (Released:2008-08-27)

参考文献数

12

---

The performance of a two-dimensional Mach 1.64 external compression air intake is investigated by computational fluid dynamics. The intake model consists of a 10-degree wedge and a subsonic diffuser. The flow in and around the intake with different configurations of the slit at the diffuser entrance is calculated to examine the effect of the configurations for pressure recovery and stability of the shock system. The numerical results indicate that the natural bleed fairly improves the intake performance at subcritical operation: It improves the maximum pressure recovery and the tolerance of the mass flow rate through the diffuser to guarantee the stability of the shock. The bleed mass flow rate strongly depends on the slit configuration. Large bleed mass flow rate increases the tolerance of the diffuser mass flow rate for the shock stability. However, the presence of the slit provides no gain in efficiency of the intake at supercritical operation.

著者

林 寛 碓井 美由紀 中山 宜典 清水 幸夫 西山 和孝 國中 均

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.55, no.647, pp.604-611, 2007 (Released:2007-12-27)

参考文献数

21

被引用文献数

1

---

An ion engine with 10,000sec-class high specific impulse is expected as primary propulsion for interplanetary space mission with extremely high delta-V, and needs high voltage for ion acceleration over 10kV. The microwave discharge ion source without solid electrodes can supply sophisticated technologies and simple composition on electrical isolation for such a high voltage. New electro-static grid made of carbon-carbon composite material was fabricated based on the numerical simulation of “igx” code. The “μ10HIsp” ion engine combining the ECR ion source, microwave discharge neutralizer, DC blocks, propellant isolators, carbon-carbon composite grid and so on generated successfully a plasma beam with 10,000sec specific impulse using 15kV acceleration voltage.

著者

小木曽 望 内海 智仁 室津 義定

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.50, no.586, pp.458-465, 2002 (Released:2003-09-02)

参考文献数

12

被引用文献数

1 1

---

This study is concerned with a shape optimum design of a propeller blade operating in a low Reynolds number range, 1.0–2.0×105. The objective is to minimize the power-required under the constraints on the thrust and the angle of attack in terms of chord length and twist angle distributions where the power-required is evaluated by 3-D panel method. The profile drag is also considered in the optimization, because the effect cannot be ignored in a low Reynolds number range. For calculation efficiency, the profile drag coefficient is approximated by higher order polynomials in terms of Reynolds number and angle of attack. The effectiveness of the proposed method is demonstrated by the design of a propeller blade of a human-powered aircraft. Additionally, effect of the profile drag is discussed by comparing the designs with and without considering the profile drag.

著者

丸山 祐一

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.57, no.667, pp.309-316, 2009 (Released:2009-08-17)

参考文献数

18

被引用文献数

2 1

---

Two kinds of methods of explaining the physical mechanism of the Magnus effect are compared with each other and fully discussed. The first method uses Bernoulli's theorem and the fluid velocity difference between both sides of the body. The second one is based on the momentum theorem which relates the lift force with the fluid acceleration perpendicular to the uniform flow direction, which is caused by the asymmetry of separation points. It is shown that the latter method is preferable because it can be strictly applied to the real flow field containing both the rotational and the irrotational flow regions.

著者

勝部 駿 佐原 宏典

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.70, no.1, pp.1-6, 2022 (Released:2022-02-05)

参考文献数

5

---

In spacecraft systems, it is important to quickly detect and deal with anomalies. However, the increasing complexity of spacecraft systems makes it difficult to avoid failures using previous anomaly detection methods. In recent years, anomaly detection methods based on machine learning have been studied. But it is difficult for a spacecraft to detect anomalies autonomously in orbit. In this study, we propose an anomaly detection method that defines and monitors a single variable representing the health status of a spacecraft system, instead of monitoring a huge amount of telemetry data. We have confirmed that the single variable can represent the health status of a spacecraft system and can be applied to the anomaly detection method.

著者

田原 弘一 弓削 政郎 白崎 篤司 マルチネスサンチェス マヌエル

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 = Journal of the Japan Society for Aeronautical and Space Sciences (ISSN:13446460)

巻号頁・発行日

vol.52, no.608, pp.408-415, 2004-09-05

被引用文献数

4 2

---

Low-power Hall thruster flowfields were calculated using a simple one-dimensional model to understand plasma characteristics and ion acceleration processes and to predict thruster performance. The influences of magnetic field strength and acceleration channel length were mainly examined. The thruster model for calculation is the THT-IV low power thruster developed in Osaka University. Generally, ions were produced in an upstream region from the anode to some axial location of the acceleration channel, and then they were intensively accelerated in a region downstream just from the ionization region. With too short channel, ionization began downstream just from the anode, and then ion acceleration also occurred in the same region, resulting in poor ion flux and low thrust performance. In large channel length, the channel was long enough to produce a fully-ionized plasma, and efficient ion production and acceleration occurred. When the magnetic field strength increased in the channel, ionization occurred in a more upstream region, and ion acceleration began in the same region; that is, ionization and acceleration overlapped in the relatively long region. On the other hand, with a weak magnetic field ion production and acceleration, intensively and efficiently, occurred in their thin regions. Furthermore, we tried to include unclear anomalous electron diffusions by changing a Bohm diffusion coefficient at each high magnetic field strength in order to fit a calculated performance to the measured one. The calculated discharge current almost equaled the measured one, and the thrust characteristic also agreed well with the measured one.

著者

東野 和幸 杉岡 正敏 棚次 亘弘 湊亮 二郎 笹山 容資 磯田 浩志

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.60, no.3, pp.115-120, 2012 (Released:2012-10-23)

参考文献数

8

被引用文献数

1 1

---

The pyrolysis of Methylcyclohexane (MCH) is investigated for the purpose of a regenerative cooling system of hypersonic propulsion by using Endothermic Fuel (EF). The experimental apparatus has heating tube made from INCONEL alloy where MCH would pass through and be decomposed. To confirm the effects of endothermic reaction on the heat absorption, heat fluxes are measured at 9 cross sections in this heating tube. For each section, temperatures are measured at the inner and the outer radii of heating tube and heat flux can be evaluated by these temperature differences. The experimental results show that the endothermic reaction of MCH can confine the temperature increment of MCH in the heating tube and increase the heat fluxes when its temperature was greater than 900K. The numerical simulation can also indicate that MCH pyrolysis have begun around the same temperature. The chemical heat capacity by MCH pyrolysis can increase its total heat capacity to 1.4 times. These facts indicate the usefulness of the endothermic fuels and the possibilities of the regenerative cooling by them.

著者

越智 徳昌

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.51, no.598, pp.621-627, 2003 (Released:2003-11-28)

参考文献数

8

被引用文献数

1 2

---

Precise normal acceleration control is essential for missile guidance. Missiles with both front and rear control surfaces have a higher ability to control normal acceleration than missiles with front or rear control surfaces only. From the viewpoint of control, however, the control problem becomes a two-input-one-output problem, where generally control input cannot be determined uniquely. This paper proposes controlling angle of attack as well as normal acceleration, which makes the problem a two-input-two-output one and determines the controls uniquely. Normal acceleration command is given by a guidance system, but angle of attack command must be generated in accordance to the acceleration command without affecting the normal acceleration control. This paper also proposes such a command generator for angle of attack. Computer simulation is conducted using a nonlinear missile model to investigate the effectiveness of the control system along with control systems designed using three other methods.

著者

松永 三郎 神澤 拓也 狼 嘉彰

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.47, no.550, pp.433-441, 1999-11-05 (Released:2009-07-09)

参考文献数

7

被引用文献数

2 1

---

This paper discusses a method for damping the angular momentum of an uncontrolled target satellite in order to make it easy to capture using a chaser-satellite-mounted manipulator. During the capture operation of an uncontrolled floating target, it may be difficult for a manipulator to grapple it directly because of target nutation or tumbling. In this paper, we propose using a cushion type damper in order to absorb the rotational motion. The scenario is as follows: 1) a cushion type damper is attached to the end-effector of the manipulator, 2) the manipulator softly pushes the damper on carefully selected points on the target, and 3) the contact force between the damper and the target causes the angular momentum of the target to decrease. The validity and feasibility of the proposed method are verified through numerical simulations.

著者

小林 弘明 吹場 活佳 本郷 素行 佐藤 哲也 溝端 一秀

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.55, no.644, pp.418-425, 2007 (Released:2007-10-10)

参考文献数

8

---

Experimental studies on telescopic aerospikes for aerodynamic control are reported in this paper. Parametric study on the aerodynamic characteristics of the aerospike has performed including the effect of spike length L, base diameter of tip cone D, spike translating speed and direction. The Axial force coefficient Ca of the aerospike suddenly increases at L/D=3.0 due to flow mode transition from the separation to the reattachment. Reattachment/separation flow mode transition phenomenon can be applicable to a newly invented aerodynamic control device, which is called air-breathing aerospike. In this paper, verification test results of this air-breathing aerospike are also reported. A small solenoid valve in the body cylinder successfully controls reattachment/separation flow mode transition at the angle of attacks from 0 to 12 degree. The spiked bodies’ Ca varies according to the mode transition. As a result, we can control the aerodynamic property of the spiked body by opening/closing the valves periodically.

著者

小松 敬治 佐野 政明 角田 義秋

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.51, no.591, pp.158-163, 2003 (Released:2003-09-16)

参考文献数

10

被引用文献数

3 2

---

Progress in materials technology has produced a much more durable synthetic fabric envelope for the non-rigid airship. Flexible materials are required to form airship envelopes, ballonets, load curtains, gas bags and covering rigid structures. Polybenzoxazole fiber (Zylon) and polyalirate fiber (Vectran) show high specific tensile strength, so that we developed membrane using these high specific tensile strength fibers as a load carrier. The main material developed is a Zylon or Vectran load carrier sealed internally with a polyurethane bonded inner gas retention film (EVOH). The external surface provides weather protecting with, for instance, a titanium oxide integrated polyurethane or Tedlar film. The mechanical test results show that tensile strength 1,000 N/cm is attained with weight less than 230g/m2. In addition to the mechanical properties, temperature dependence of the joint strength and solar absorptivity and emissivity of the surface are measured.

著者

河原 淳人 岩堀 太紀 山川 宏 佐藤 亨 山本 衛 橋口 浩之

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.64, no.3, pp.189-199, 2016 (Released:2016-06-05)

参考文献数

18

---

Shape estimation of space debris is an important task in evaluating its trajectory evolution and collision probability with resident objects in space. This paper shows the magnitude and rotation of space debris can be estimated by investigating the Doppler shift with a Single Range Doppler Interferometry (SRDI) method. The theory of SRDI method is discussed and its usefulness is confirmed by numerical simulations. Furthermore, fluctuation of Doppler shift of known space debris were successfully observed by the MU radar of Kyoto University and the size and spin rate of some space debris were successfully estimated.

著者

杉浦 綾 横関 智弘 平野 義鎭

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.61, no.5, pp.133-140, 2013 (Released:2013-10-25)

参考文献数

24

---

This paper describes the development and the wind tunnel test of a variable geometry morphing airfoil using corrugated structures. Feasibility of a morphing wing with corrugated flexible seamless flap-like structure is verified by the finite element analysis, and a prototype is manufactured using carbon fiber reinforced plastics. For the actuation system, two servomotors are installed inside the prototype wing to control the airfoil shape by the chord-wise tension of the connected wires. Successful actuation of the prototype wing is demonstrated under the air speed up to 30m/s in the wind tunnel test. Basic aerodynamic properties are also evaluated in comparison to traditional airfoil with a hinged control surface. Lift increase of variable corrugated wing is recognized when the flap angle increases.

著者

元田 敏和

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.55, no.638, pp.117-124, 2007 (Released:2007-04-20)

参考文献数

15

---

In aerospace projects preflight evaluation is crucial for mission success, because flight testing in a real environment is often difficult or impossible. Monte Carlo simulation is a powerful tool for the preflight evaluation because a nonlinear system incorporating various uncertain parameters can be evaluated directly. Monte Carlo simulation has been used in various aerospace projects throughout the world as the computer power increases. After the system evaluation, it is important to detect influential uncertain parameters which cause significant performance degradation so that measures for the system improvement can be studied. However, detecting those parameters is often uneasy because various uncertain parameters are incorporated simultaneously and their magnitudes are randomly generated in Monte Carlo simulation. An interaction of more than two uncertain parameters might be affected. This paper presents a simple approach to detect influential uncertain parameters applying a statistical test to the Monte Carlo results.

著者

中谷 辰爾 笠原 希仁 芝 世弐 大坂 淳 津江 光洋 河野 通方

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.52, no.610, pp.487-493, 2004 (Released:2005-01-05)

参考文献数

46

---

Numerical analysis of O3 depletions by exhaust plume from stratospheric flight at the altitude of 25km was conducted. Expanding box method was employed to simulate a diffusion of exhaust plume in the stratosphere. Concentrations of chemical species and normarized sensitivities of O3 concentration for reactions were estimated by fifth-order BDF method. Chemical kinetics include NOx, HOx and Ox chemistry. As results, it takes over two days that O3 concentration within a plume becomes ambient lebel within 1ppb. O3 perturbations were changed by an effect of plume-emission time, and they are bigger in daytime than in nighttime. Distributions of sensitivities of O3 concentrations for reactions are also changed for the plume-emission time. O3 depletion is greater by NOx than by HOx in exhaust plume.

著者

平田 邦夫 上條 謙二郎 升谷 五郎

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.53, no.614, pp.123-129, 2005 (Released:2005-05-20)

参考文献数

3

---

Idle spin phenomena were observed at rapid transient phase in liquid hydrogen pumps for rocket engines. Failure analyses were conducted and evaluation equations to estimate the shift of the operation point of the pump were derived in this paper. It was revealed that rapid fall of hydrogen flow rate resulted in decrease of pump efficiency which caused excessive temperature rise up to the saturation of the pump fluid.

著者

前川 昭二 斉藤 勝也

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 = Journal of the Japan Society for Aeronautical and Space Sciences (ISSN:13446460)

巻号頁・発行日

vol.51, no.595, pp.412-418, 2003-08-05

参考文献数

8

---

An airship has usually two or three ballonets in its envelope in which air is contained. Its buoyancy and attitude control is performed by changing the air content of each ballonet. It is said that ballonet slosh may influence airship's stability or ride quality. However, no quantitative treatment has been performed so far to investigate this phenomenon. In this paper the coupled equations of an airship longitudinal motion are formulated by modeling the ballonets as cylindrical containers. Some numerical calculations are performed for a 25m class airship and it has been shown that the ballonet slosh may become a design issue when the shape of the ballonet is thinner or when the size becomes larger.

著者

水野 貴秀 津野 克彦 奥村 英輔 中山 通雄

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 = Journal of the Japan Society for Aeronautical and Space Sciences (ISSN:13446460)

巻号頁・発行日

vol.54, no.634, pp.514-521, 2006-11-05

被引用文献数

2 1

---

Hayabusa, launched May 2003, is the first Japanese spacecraft to explore the small asteroid Itokawa (1998SF36) and touched down on Itokawa twice to sample of the surface material. LIDAR (LIght Detection And Ranging) is an important navigation sensor for the asteroid explorer to measure distance between the spacecraft and the asteroid. Since it is carried in a planetary exploration spacecraft, the weight of LIDAR is very lightweight of 3.7kg. In the rendezvous and touchdown operation, LIDAR supplied the ranging data to the spacecraft navigation system to approach Itokawa down to 50m and its total shots number of laser pulse was more than 4 million. The composition and basic performance of LIDAR are explained and this paper also reports the ranging data at the time of landing to asteroid Itokawa of the autumn of 2005.

著者

石本 淳 上條 謙二郎

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.51, no.592, pp.228-235, 2003 (Released:2003-09-26)

参考文献数

20

---

The basic characteristics of the two-dimensional cavitating flow of liquid helium through a horizontal converging-diverging channel near the lambda point are numerically investigated to realize the further development and high performance of new multiphase superfluid cooling systems. First, the governing equations of the cavitating flow of liquid helium based on the unsteady thermal nonequilibrium multifluid model with generalized curvilinear coordinates system are presented, and several flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the cavitating flow of liquid helium though horizontal converging-diverging channel is shown in detail, and it is also found that the generation of superfluid counterflow against normal fluid flow based on the thermo mechanical effect is conspicuous in the large gas phase volume fraction region where the liquid- to gas-phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase.

著者

川瀬 成一郎

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.58, no.673, pp.31-37, 2010 (Released:2010-02-19)

参考文献数

10

被引用文献数

2 2

---

In order to mitigate the overcrowding problem of geosynchronous orbits, we propose a monitoring satellite placed in a sub-synchronous, retrograde circular orbit. The monitoring satellite has an on-board optical sensor, and observes look-angles of the target geosynchronous satellites that come into the field of view one after another. This kind of monitoring makes it possible to determine the orbit of every target satellite in a short term. Covariance analyses show that the target position determination can be accurate to 350m. The monitoring satellite's orbit determination will be obtained from ranging at two ground stations, with a sufficient accuracy because range biases can be estimated.