著者

Hyun-Ung OH Hye-In KIM Jeong-Ki KIM Jae-Seop CHOI Su-Hyeon KIM

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.62, no.5, pp.256-264, 2019 (Released:2019-09-04)

参考文献数

29

被引用文献数

3

---

This paper reports the Smart Call from the Sky (SCSky) Can Satellite (CanSat) platform developed by Chosun University, South Korea, with a focus on a smart material of shape memory alloy actuator applications. The primary objective of this study is to verify the effectiveness of a remote screen touch system using shape memory alloy wires. The system is currently being utilized to operate the on-board smartphone of a CanSat by telecommands from a ground station. It provides real-time streaming video showing the internal and external states of CanSat through video calls during actual flight. The secondary objective of the mission is to acquire a wide-scan image from the on-board USB cameras, whose elevation angles are actuated using shape memory alloy springs. The effectiveness of the design proposed was validated experimentally through actual flight tests using model rockets.

著者

Takeshi KANDA Masaki SATO Toshiya KIMURA Hiroya ASAKAWA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.61, no.3, pp.106-118, 2018 (Released:2018-05-04)

参考文献数

37

被引用文献数

5 5

---

This paper describes the characteristics of methane-fueled rocket engines and compares these characteristics with those of hydrogen-fueled engines in terms of both expander and coolant-bleed cycles. Methane vaporizes in a cooling jacket under low-pressure operating conditions, whereas it liquefies in the turbine in the coolant-bleed cycle. The thermodynamic property of methane limits the operating range of methane-fueled engines. When the coolant-bleed cycle is used, the specific impulse degradation of methane-fueled engines becomes larger compared to that of hydrogen-fueled engines. This is due to methane having a lower specific heat and temperature after regenerative cooling. Even though the heat absorbing ability of methane is much lower than that of hydrogen, methane-fueled engines can operate with higher chamber pressures using the expander cycle. This is due to the larger density and the higher temperature after the regenerative cooling of liquid methane. Throttling of the methane-fueled engines does not have a great impact on the pump exit pressure in the expander cycle, whereas it increases the bleed ratio and degrades the specific impulse in the coolant bleed cycle of methane-fueled engines.

著者

Yuichi TSUDA Takanao SAIKI Fuyuto TERUI Satoru NAKAZAWA Makoto YOSHIKAWA Seiichiro WATANABE Hayabusa2 Project Team

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.63, no.4, pp.115-123, 2020 (Released:2020-07-04)

参考文献数

8

被引用文献数

2

---

Hayabusa2 arrived at the asteroid Ryugu in June 2018, and as of April 2019, the mission succeeded in conducting two rovers landing, one lander landing, one spacecraft touchdown/sample collection and one kinetic impact operation. This paper describes the initial nine months of the asteroid proximity operation activity of the Hayabusa2 mission, and gives an overview of the achievements thus far. Some important engineering and scientific activities conducted synchronously with spacecraft operations in order to complete all planned operations in time against unexpectedly harsh environment of Ryugu are also described.

著者

Ryodo HEMMI Hideaki MIYAMOTO

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.63, no.4, pp.124-131, 2020 (Released:2020-07-04)

参考文献数

30

被引用文献数

5

---

Estimating the regolith properties of Phobos’ surface is of critical importance for the landing and performance of the Martian Moons eXploration (MMX) sample return mission. Regolith physical properties such as strength, regolith thickness, and the presence of regolith layers are related to morphologies of superposing impact craters. However, the accurate depths of Phobos’ sub-kilometer-diameter craters including irregularly shaped craters have not yet been fully characterized. Here, by using our high-resolution (20 m/pixel) digital elevation model of the nearside (or the sub-Mars side) of Phobos, we investigate the topographic profiles of the sub-kilometer craters. We confirm the presence of crater rims, and bowl-shaped, central-mound, and flat-floored crater geometries. The topography of one flat-floored crater is consistent with a boundary of regolith layers at a depth of ~160–180 meters. Morphometric measurements of 35 sub-kilometer craters show that their depth-to-diameter (d/D) ratios are in the range of 0.037 and 0.174 (mean value = 0.089, median value = 0.093). This suggests either a surface layer composed of rocky debris that effectively dissipates impact energy and causes a reduction in crater depth, or subsequent resurfacing events changed the original crater topography.

著者

Kazuki ISHIHARA Kentaro YONEYAMA Tomoki SATO Hiroaki WATANABE Noboru ITOUYAMA Akira KAWASAKI Ken MATSUOKA Jiro KASAHARA Akiko MATSUO Ikkoh FUNAKI

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.66, no.2, pp.46-58, 2023 (Released:2023-03-04)

参考文献数

57

被引用文献数

4

---

Rotating detonation combustors (RDCs) are among the combustors that use supersonic combustion waves known as detonation waves, and are expected to simplify engine systems and improve thermal efficiency due to their supersonic combustion and compression performance using shock waves. Research is also being actively conducted worldwide on a cylindrical RDC; a RDC without an inner cylinder, which is expected to simplify and downsize the combustor. However, most of the research was performed using gas propellants, and liquid propellants were rarely used. Since liquid propellants are used in many combustors, it is important to evaluate the performance of RDCs with liquid propellants. In this study, a cylindrical RDC with a liquid ethanol–gas oxygen mixture was constructed and tested at a flow rate of 31.5 ± 5.0 g/s, an equivalence ratio of 0.46–1.39, and a back pressure of 14.5 ± 2.5 kPa. The thrust was shown to depend strongly on the combustor bottom pressure history. In addition, the start-up process of the cylindrical RDC with liquid fuel was clarified by self-luminous and CH* radical visualizations. It was found that the detonation wavefront propagated at a distance of 2–3 mm from the combustor bottom, and the main combustion region was 10–15 mm in height.

著者

Ryo SUZUMOTO Satoshi IKARI Norihide MIYAMURA Shinichi NAKASUKA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.64, no.2, pp.101-111, 2021 (Released:2021-03-04)

参考文献数

17

---

Earth remote sensing from geostationary orbit (GEO) can realize high temporal resolution; however, the spatial resolution is commonly worse than observation from low Earth orbit. In order to achieve high-frequency and high-resolution GEO remote sensing, a “Formation Flying Synthetic Aperture Telescope (FFSAT)” with multiple micro-satellites has been proposed. The FFSAT greatly improves the spatial resolution using a synthetic aperture technique. Therefore the relative positions and attitudes between the optical units of each satellite must be controlled with an accuracy better than 1/10 of the observation wavelength. However, even mm-class accuracy control has not been demonstrated on orbit. As a first practical application of the FFSAT, a forest fire monitoring mission using infrared rays is being considered, in which control accuracy requirement is relaxed as its wavelength is longer than visible light. We proposed a point spread function optimization method for controlling formation flying with an accuracy of approximately 1–1,000 times the wavelength (1 µm–1 mm) in the absence of sensors, which can measure absolute distance with µm-accuracy. The effectiveness of the method was demonstrated through simulations in which the satellites’ system and the optical system are coupled. The simulation results show that the method can control the formation within the wavelength order.

著者

Akira IWAKAWA Tatsuro SHODA Ryosuke MAJIMA Son Hoang PHAM Akihiro SASOH

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.60, no.5, pp.303-311, 2017 (Released:2017-09-04)

参考文献数

32

被引用文献数

13

---

Supersonic drag reduction performance using repetitive pulse energy depositions over blunt bodies was experimentally studied under two Mach numbers. The normalized drag reduction and energy deposition efficiency of Mach-1.92 over a 10-mm-dia. blunt-cylinder model were 8% and 1.2 at most, respectively. On the other hand, these values at Mach-3.20 over the same model were 22% and 6.2, respectively. The shock-wave deformation period using single-pulse energy deposition at Mach-3.20 was 64 μs. This duration was shorter than that of 80 μs at Mach-1.92, but the deformation magnitude on the model center axis of 40% at Mach-3.20 was larger than that of 15% at Mach-1.92. These experimental characteristics were consistent as solutions of the Riemann problem. Moreover, a drag reduction performance was much improved with a larger model diameter of 20 mm. Therefore, it has been experimentally demonstrated that the drag reduction performance due to energy deposition improves much at a high Mach number and with large model dimensions.

著者

KITAGAWA Yosuke KITAGAWA Koki NAKAMIYA Masaki KANAZAKI Masahiro SHIMADA Toru

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

Transactions of the Japan Society for Aeronautical and Space Sciences (ISSN:05493811)

巻号頁・発行日

vol.55, no.4, pp.229-236, 2012-07-04

被引用文献数

1 14

---

The multi-objective genetic algorithm (MOGA) is applied to the multi-disciplinary conceptual design problem for a three-stage launch vehicle (LV) with a hybrid rocket engine (HRE). MOGA is an optimization tool used for multi-objective problems. The parallel coordinate plot (PCP), which is a data mining method, is employed in the post-process in MOGA for design knowledge discovery. A rocket that can deliver observing micro-satellites to the sun-synchronous orbit (SSO) is designed. It consists of an oxidizer tank containing liquid oxidizer, a combustion chamber containing solid fuel, a pressurizing tank and a nozzle. The objective functions considered in this study are to minimize the total mass of the rocket and to maximize the ratio of the payload mass to the total mass. To calculate the thrust and the engine size, the regression rate is estimated based on an empirical model for a paraffin (FT-0070) propellant. Several non-dominated solutions are obtained using MOGA, and design knowledge is discovered for the present hybrid rocket design problem using a PCP analysis. As a result, substantial knowledge on the design of an LV with an HRE is obtained for use in space transportation.

著者

Marco GOMEZ-JENKINS Julio CALVO-ALVARADO Adolfo CHAVES-JIMÉNEZ Johan CARVAJAL-GODÍNEZ Esteban MARTINEZ Yeiner ARIAS Ana Julieta CALVO-OBANDO Vladimir JIMENEZ Juan José ROJAS Alfredo VALVERDE-SALAZAR Julio RAMIREZ-MOLINA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.66, no.6, pp.217-225, 2023 (Released:2023-11-04)

参考文献数

19

---

Project Irazú was an innovative space mission that aimed to propel the advancement of the aerospace sector in Costa Rica, by developing a ground to space communication solution for daily monitoring of carbon fixation in forests and tree plantations. Irazú is Central America’s first satellite mission and is a joint endeavor between the Central American Association of Aeronautics and Space and the Costa Rica Institute of Technology, along with national and international partners. The 1U CubeSat developed in this project was deployed from the International Space Station on May 2018, commencing straightaway operations. The scientific mission demonstrated a practical novel solution to monitor daily tree growth by using wireless electronic sensors and a store and forward satellite link. This article presents an overview of the project, along with the mission architecture, summary of the Assembly, Integration and Testing (AI&T) and operations phases, and results from the scientific mission, including the sensor’s performance and measurements of the daily estimated tree diameter during six months. The impacts that the project had on an emerging space nation such as Costa Rica is included as well.

著者

MURUGANANDAN Vishnu Anand PARK Ji Hyun LEE Sangyoon JEUNG In-Seuck KIM Sangkyun JU Gwanghyeok

出版者

一般社団法人 日本航空宇宙学会

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.60, no.6, pp.355-365, 2017

被引用文献数

5

---

The second-generation star tracker estimates pointing knowledge of a satellite without a-priori knowledge. But star trackers are larger in size, heavier, power hungry and expensive for nanosatellite missions. The Arcsecond Pico Star Tracker (APST) is designed based on the limitations of nanosatellites and estimated to provide pointing knowledge in an arcsecond. The APST will be used on the SNUSAT-2, Earth-observing nanosatellite. This paper describes the requirements of APST, trade-off for the selection of image sensor, optics, and baffle design. In addition, a survey of algorithms for star trackers and a comparison of the specifications of APST with other Pico star trackers are detailed. The field of view (FOV) estimation shows that 17° and 22° are suitable for APST and this reduces stray light problems. To achieve the 100% sky coverage, the FOV of 17° and 22° should able to detect the 5.85 and 5.35 visual magnitude of stars, respectively. It is validated by estimating the signal to noise ratio of APST and night sky test results. The maximum earth stray light angle is estimated to be 68° and a miniaturized baffle is designed with the exclusion angle of 27°.

著者

XU Ming XU Shijie

出版者

一般社団法人 日本航空宇宙学会

雑誌

Transactions of the Japan Society for Aeronautical and Space Sciences (ISSN:05493811)

巻号頁・発行日

vol.55, no.5, pp.274-285, 2012-09-04

参考文献数

21

被引用文献数

10

---

This paper deals with the stationkeeping control for halo orbits at <i>EL</i>₁ in the Sun-Earth/Moon system, and proposes an effective adaptive robust controller for the unknown spacecraft mass and perturbation boundaries. The controller has to deal with two divergence sources: one is the instability of the halo orbit, and the other is the perturbation imposed by the natural model onto the nominal model. The former source is displayed by the Floquet multiplier from the Poincaré mapping. However, the latter is revealed by the difference of Hamiltonian functions between the nominal reference model, the circular restricted three-body problem (CR3BP) and the natural simulation model, the spatial bicircular model (SBCM). Firstly, the algorithm of backstepping control theory is employed to generate the initial controller in the nominal reference model of CR3BP. Some improvements are then implemented for the estimations of the unknown parameters as the perturbation boundaries and the spacecraft mass, which may cause the failure of the initial unimproved controller in stationkeeping. The controller proves to be effective in terms of adaptive robust estimation and asymptotic stability from Lyapunov's stability theory. Furthermore, further improvements of the triggers for the on/off schedule are proposed to remedy the weakness in the capability of estimating for excessively long (infinite) time required to converge. Finally, the controller developed in this paper is implemented in the natural simulation model of SBCM to evaluate its performance. In the numerical simulation, the mass and perturbation boundaries will converge only after approximately three iterations. The deviation of the estimating mass is 1 kg from its true mass, but 55 kg for the unimproved controller. The total velocity increment over five years is only 126 m/s, which is equivalent to the fuel consumption of 3.8 kg for the Hall thrust engine carried by SMART-1.

著者

Takahiro SASAKI Yu NAKAJIMA Toru YAMAMOTO

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.64, no.3, pp.136-146, 2021 (Released:2021-05-04)

参考文献数

25

被引用文献数

1

---

As the amount of debris in orbit increases, so does the risk of collisions and their seriousness. All nations involved with space operations acknowledge this growing threat. One solution receiving increased attention is active debris removal. The first step in a debris removal mission would be to approach the debris. In this phase, it is important to ensure passive abort safety and to guarantee the robustness against collisions in the case of off-nominal thruster burns, that may be caused by spacecraft anomalies such as navigation sensor or actuator failures. This paper compares two types of passive abort safe trajectories –the V-bar hopping and spiral approaches– considering the ΔV budget, the duration of operations, and variation in the line-of-sight vector to the target. This paper also proposes design strategies for determining the parameters in the two candidate trajectories, considering passive abort safety. The robustness of the trajectories against collisions due to off-nominal thruster burns is also demonstrated through Monte Carlo simulations. The paper investigates which trajectories are suitable for an active debris removal mission to a non-cooperative target.

著者

Kai DONG Naiming QI Xianlu WANG Jiabao CHEN

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.52, no.177, pp.144-151, 2009 (Released:2009-11-02)

参考文献数

25

被引用文献数

3 5

---

Liquid propellant sloshing, which induces perturbations to dynamic behavior of spacecraft, is a serious problem. This paper proposes an approach based on equivalent mechanics theory and Computational Fluid Dynamics (CFD) technology to estimate the dynamic influence of propellant sloshing on spacecraft. A mechanical model was built by CFD technique and packed as a “sloshing” block utilized in the spacecraft Guidance Navigation and Control (GNC) simulation loop. The block takes the motion characteristics of the spacecraft as inputs and outputs perturbative force and torques induced by propellant sloshing. It is more convenient to utilize in analysis of the coupling effect between propellant sloshing dynamics and spacecraft GNC than CFD packages directly. A validation case is taken to validate the accuracy and the superiority of the approach. The deducing process is applied to practical cases, and the simulation results are presented to demonstrate the proposed approach is efficient in identifying the problems induced by sloshing and evaluating effectiveness of several typical schemes for suppressing sloshing.

著者

Yuhei KIKUYA Yohei IWASAKI Yoichi YATSU Saburo MATUNAGA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.64, no.2, pp.82-90, 2021 (Released:2021-03-04)

参考文献数

23

被引用文献数

2

---

This paper describes a new algorithm to determine the attitude of micro-/nano-satellites using an Earth sensor. For recent micro-/nano-satellites, the requirements for attitude determination accuracy are becoming more stringent, despite its limited volume. Since Earth sensors have the advantage of smaller size, some studies have presented using them as attitude sensors; however, they could not achieve fully automatic processing in real-time. Therefore, we have developed an algorithm that effectively combines geometrical consideration and image recognition technology, thus realizing high autonomy, robustness, and real-time processing. The validity of this algorithm is confirmed through ground experiments. The algorithm operates at a rate of 0.2 Hz and achieves an accuracy of 0.1–1 deg, which is similar to the accuracy of a coarse sun sensor. Furthermore, it is capable of determining the three-axis attitude using only an Earth sensor and a GNSS receiver for position information. This study proves that the bus equipment required for attitude determination systems in micro-/nano-satellites can be reduced, thereby contributing to increased design freedom.

著者

Kenjiro Kamijo Hitoshi Yamada Norio Sakazume Shogo WARASHINA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.44, no.145, pp.155-163, 2001 (Released:2005-07-09)

参考文献数

9

被引用文献数

9 14

---

The first stage of the H-2 rocket used a 110-ton thrust liquid oxygen, liquid hydrogen, pump-fed engine, the LE-7. This engine required high-pressure and high-power liquid oxygen and liquid hydrogen turbopumps to achieve the two-stage combustion cycle in which the combustion pressure is around 13 MPa. Furthermore, it was very important to operate both turbopumps at higher rotational speeds to obtain a smaller, lighter-weight engine because the LE-7 had not low-speed, low-pressure pumps ahead of both the main pumps. The present paper shows the design, test results, and modifications that had been performed until a flight-type liquid oxygen turbopump for the LE-7 engine was completed. The liquid oxygen turbopump had been developed by the use of three models, that is, research, prototype, and flight models.

著者

Nobuyuki YATSUYANAGI

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.52, no.177, pp.180-187, 2009 (Released:2009-11-02)

参考文献数

11

被引用文献数

4 6

---

A comprehensive design method for a LOX/Liquid-Methane (L-CH4) rocket engine combustor with a coaxial injector and the preliminary design of the regenerative cooling combustor with 100-kN thrust in vacuum at a combustion pressure of a 3.43 MPa are presented. Reasonable dimensions for the combustor that satisfy the targeted C* efficiency of more than 98% and combustion stability are obtained.

著者

Qin XU Peter HOLLINGSWORTH Katharine SMITH

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.62, no.4, pp.175-183, 2019 (Released:2019-07-04)

参考文献数

24

被引用文献数

3

---

The rapid developments in micro-technologies and the introduction of modularity and standardization into system designs, present significant opportunities for cost reduction in the design and development of satellite systems. However, the high cost of space launch has become a major hindrance to capitalizing on these opportunities. Therefore, seeking appropriate launch opportunities and reducing launch costs might contribute to further growth of the space market. This paper focuses on the analysis of dedicated launch costs factoring in the effect of launch reliability, which in return, can enable the optimization of system designs. Applying a value-centric architecture, system characteristic space is introduced as the design space to define the characteristics of different systems. Based on our launch vehicle database, the launch cost and reliability of different families of launch vehicles are investigated, where the reliability is calculated using a modified two-level Bayesian analysis. The factors of launch cost and reliability are subsequently integrated into the expected launch cost, acting as the objective function for the analysis and optimization process associated with the manufacturing cost of satellites. Through reviewing and redesigning a few classical launch cases, the effectiveness and applicability of the design architecture proposed are validated.

著者

Hikaru AONO Katsutoshi KONDO Taku NONOMURA Masayuki ANYOJI Akira OYAMA Kozo FUJII Makoto YAMAMOTO

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.63, no.1, pp.8-17, 2020 (Released:2020-01-04)

参考文献数

63

被引用文献数

7

---

Aerodynamics of an owl-like wing model at low Reynolds numbers (Re = O(104–5)) are investigated using large-eddy simulations with high-resolution computational schemes. The airfoil shape of the owl-like wing model is constructed based on a cross-sectional geometry of the owl wing at 40% wingspan from the root. The chord-based Re ranges from 1.0 × 104 to 5.0 × 104 and the angle of attack (α) varies from 0 to 14 deg. The time-averaged lift (Cl) and drag coefficients computed are in reasonable agreement with the results of force measurement. The results computed clarify a nonlinear change in the Cl curve slope, which is due to an increase in the suction peaks in conjunction with the change in type of separation, the formation of a laminar separation bubble (LSB), and pressure recovery on the pressure side. The generation of the LSB on the suction and/or pressure sides at the Re of 2.3 × 104 and 4.6 × 104 are seen, while reattachments are observed only on the pressure side at the Re of 1.0 × 104 due to the camber of the wing. Furthermore, the owl-like wing model demonstrates favorable aerodynamic performance in terms of a maximum lift-to-drag ratio in comparison with several airfoils at the Re range considered. This is due to the strong suction peaks and distribution of surface pressure on the pressure side. It is emphasized that the concave lower surface enhances the time-averaged aerodynamic performance at all of the α even though the LSB is generated and fluctuation in lift history is induced at low α.

著者

Kenji SHIBUSAWA Masato FUNATSU

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.62, no.2, pp.86-92, 2019 (Released:2019-03-04)

参考文献数

20

被引用文献数

4

---

The spectroscopic measurement of low-pressure microwave-discharged nitrogen plasma was conducted in the wavelength region of 550 to 1070 nm. Radiation from the N2 first positive band of the Δv=0 to Δv=+4 band series and nitrogen atomic lines were observed. The experimental spectrum was compared with the theoretical spectrum, showing the effect of the predissociation of N2 B 3Πg state through N2 A′5Σg+ state and triplet splitting for the transition of 3Π to the 3Σ state. They agreed very well with each other for the Δv=0 to Δv=+2 band series, which consisted of the lower vibrational levels of Δv′=0 to 7, but did not agree well for the higher vibrational levels of Δv′=8 to 12 in the Δv=+3 and +4 band series. By comparing the band head intensity of the experimental and theoretical spectra, the experimental vibrational population on each vibrational level for the B 3Πg state was estimated to be a non-Boltzmann distribution at the higher vibrational levels. In addition, the theoretical vibrational population distribution in the B 3Πg state was calculated using a master equation, and then agreement between the experimental spectrum and the theoretical spectrum with the non-Boltzmann distribution obtained from the master equation was improved.

著者

Seiichiro MORIZAWA Taku NONOMURA Akira OYAMA Kozo FUJII Shigeru OBAYASHI

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.61, no.6, pp.258-267, 2018 (Released:2018-11-04)

参考文献数

27

被引用文献数

8

---

The effects of Mach number at Re = 3,000 for different airfoils (NACA0012, NACA0002, NACA4412, NACA4402) with thickness and camber geometries are investigated for the propeller blade design of a Mars airplane. The present study shows that thin and cambered airfoils have larger variations in Cl than symmetric airfoils. As for thin airfoils, Cl at higher α has rapid increases when the M∞ is low. This is because the flow separation occurs at the leading edge, and the flow is reattached on the airfoil surface. However, the rapid increase in Cl disappear as M∞ increases because the flow reattachment does not occurs. As for cambered airfoils, the decrease in Cl becomes larger than that on the symmetric airfoils when M∞ is higher. This is because Cp near the leading edge on the lower surface is smaller than that on the upper surface and the high-speed region on the lower side of the leading edge is enlarged as M∞ increases. Then, the Mcr at Re = 3,000 tends to be larger than that predicted by linear theory.