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  2. 大山 聖

大山 聖

オオヤマ アキラ  (Akira Oyama)

基本情報

所属
国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 教授
東京大学大学院 教授
東京理科大学 理工学研究科機械工学専攻 客員教授
学位
博士（工学）(2000年3月 東北大学大学院)
研究者番号
10373440
J-GLOBAL ID
200901044748363926
researchmap会員ID
5000069161
外部リンク
宇宙科学航空研究開発機構宇宙科学研究所の大山です．
自分の研究分野にとらわれず，新しい研究分野にも挑戦していきたいと考えています．

研究キーワード

 17

研究分野

 6

経歴

 13
もっとみる

学歴

 5

委員歴

 7
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受賞

 13
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論文

 91
  • 立川智章, 渡辺毅, 大山聖
    進化計算学会論文誌 6(3) 126-136 2015年  査読有り
    Advantages of evolutionary computation with very large population for many-objective optimization problems are investigated. Effects of the population size are investigated up to 1,000,000 while the number of generations is fixed to 100. To overcome difficulty in computational time, we use a many-objective evolutionary algorithm designed for massive parallelization (CHEETAH) and use the supercomputer K. As for unimodal test problems DTLZ2 and DTLZ4, IGD property are improved up to population size 1,000,000 while GD property is saturated at population size of 10,000. Even when the total number of evaluations is fixed, this conclusion stays same. As for multimodal test problems DTLZ1 and DTLZ3, GD and IGD properties are improved up to population size 10,000 while they are not drastically improved with population size larger than that. It is probably due to the difficulty in obtaining good Pareto-optimal solutions of DTLZ1 and DTLZ3 with the current CHEETAH, which bases on NSGA-II.
  • DongHwi Lee, Taku Nonomura, Akira Oyama, Kozo Fujii
    JOURNAL OF AIRCRAFT 52(1) 296-306 2015年1月  査読有り
    The flowfields around the NACA 0012 airfoil at Reynolds numbers 1 x 10(4), 3 x 10(4), and 5 x 10(4) are studied, and the predictability of aerodynamic characteristics derived from various numerical methods is examined. Two-dimensional laminar simulation, two-dimensional Reynolds-averaged Navier-Stokes simulation using the Baldwin-Lomax turbulence model, and three-dimensional implicit large-eddy simulation are employed in this study. The two-dimensional laminar and three-dimensional implicit large-eddy simulations accurately predict the separation point, and capture the characteristics of a separation bubble for each Reynolds number and each angle of attack. Nonlinearity in the lift curve is also captured in the results of the two-dimensional laminar and three-dimensional implicit large-eddy simulations. The two-dimensional Reynolds-averaged Navier-Stokes simulation using the Baldwin-Lomax turbulence model predicts the separation point nearer the trailing edge than does the two-dimensional laminar and three-dimensional implicit large-eddy simulations, and the separation bubble is not captured for any Reynolds number and angle of attack by this method. Nonlinearity of the lift curve does not appear in the results of the two-dimensional Reynolds-averaged Navier-Stokes simulation using the Baldwin-Lomax turbulence model. The two-dimensional laminar simulation can predict airfoil aerodynamic characteristics qualitatively, and it can be used as an appropriate numerical method at lower Reynolds numbers. The three-dimensional-implicit-large-eddy-simulation technique can be employed when more accurate qualitative characteristics are needed.
  • Masayuki Anyoji, Taku Nonomura, Hikaru Aono, Akira Oyama, Kozo Fujii, Hiroki Nagai, Keisuke Asai
    JOURNAL OF AIRCRAFT 51(6) 1864-1872 2014年11月  査読有り
    A high-performance Ishii airfoil was analyzed using both a wind-tunnel and large-eddy simulations at a low-Reynolds-number condition (Re = 23,000). The design guidelines for an airfoil shape with a high lift-to-drag ratio under the aforementioned condition are described by analyses of flowfields and aerodynamic characteristics of the Ishii airfoil. Compared with conventional airfoils, such as the NACA 0012 and NACA 0002, the shape characteristic effects of the Ishii airfoil on its flowfield and aerodynamic characteristics are discussed. The shape on the suction side of the Ishii airfoil can cause delays in the flow separation at low angle of attacks. The separated flow reattaches, and a separation bubble forms even when trailing-edge separation changes to leading-edge separation. The separation bubble contributes to an increase in lift coefficient. In addition, the Ishii airfoil can gain a high positive pressure on the pressure side as compared with the other two symmetric airfoils due to the camber near the trailing edge. On the other hand, the pressure drag of the Ishii airfoil, which is a dominant factor of total drag, is considerably smaller than those of the other two airfoils. It was found that the shape on the suction side as well as that on the pressure side (such as the leading-edge roundness and the camber) are very significant in the low-Reynolds-number airfoil with a high lift-to-drag ratio.
  • Masayuki Anyoji, Masato Okamoto, Hidenori Hidaka, Taku Nonomura, Akira Oyama, Kozo Fujii
    Transactions of the Japan Society for Aeronautical and Space Sciences 12(ists29) 7-12 2014年5月  査読有り
  • 大山聖, 立川智章, 渡辺毅
    日本機械学会第11回最適化シンポジウム2014講演論文集 2014 1218-1218 2014年  
    Large-scale multiobjective design exploration using K computer is presented. This presentation includes aeroacoustic design optimization problem of a rocket launch site and aerodynamic design optimization problem of a plasma actuator applied to a wing model. Non-dominated solutions visualization tool named iSPM is also introduced.
  • Schlueter Martin, Watanabe Takeshi, Oyama Akira
    日本機械学会第11回最適化シンポジウム2014講演論文集 2014 1112-1112 2014年  
    A novel algorithm for many-objective optimization based on continuous Ant Colony Optimization (AGO) is proposed.
  • 立川智章, 渡辺毅, 大山聖
    日本機械学会第11回最適化シンポジウム2014講演論文集 2014 1113-1113 2014年  
  • Gaku Sasaki, Tomoaki Tatsukawa, Taku Nonomura, Akira Oyama, Takaaki Matsumoto, Kouichi Yonemoto
    Transaction of The Japan Society for Aeronautical Sciences 12(29) 59-64 2014年  査読有り
    The aim of this study is to find the optimal airfoil for Mars exploration aircraft, which requires high-lift-to-drag ratio. However, existing airfoils for flying in the Earth's atmosphere do not have a high enough lift-to-drag ratio in Mars flight condition. The airfoil studied here was designed using a Genetic Algorithm (GA) and evaluated using two-dimensional Computational Fluid Dynamics (CFD) without turbulence model (laminar). The objectives in this optimization include the maximization of lift and minimization of drag coefficients at only angle of attack of 6 °. The Reynolds number is 2.3 × 104 under the aircraft cruising condition. B-spline curves that connect neighboring control points express the upper and lower surfaces of the airfoil. The results show that some typical types of airfoils excel in aerodynamic performance. Most optimal airfoils have a large upper surface curvature or a strong curvature at the center of the lower surface. The former feature generates a separation bubble that leads to a high negative pressure, and the latter character makes a high positive pressure. Both phenomena generate lift force, and yield higher lift coefficient and high lift-to-drag ratio. Furthermore, most airfoils on the Pareto front have a thickness less than 10 % of the chord length, which is suitable for the wing structure design of the Mars aircraft.
  • Naoya Fujioka, Taku Nonomura, Akira Oyama, Makoto Yamamoto, Kozo Fujii
    The Japan Society of Aeronautical and Space Sciences 12(29) 1-5 2014年  査読有り
    Flow field and aerodynamic performance of the Mars airplane with a complete aircraft configuration are analyzed by RANS simulations. At the Reynolds number of 3.3x104, a flow field is solved by an unstructured three-dimensional compressible CFD solver (LS-FLOW). Here, the Mars airplane is assumed to have the Ishii airfoil as the main wing shape. The Ishii airfoil is known as its good performance at the low Reynolds number condition. An objective of the present study is to clarify flow structures around a complete aircraft, for optimization of design of the Mars airplane. The results show that the features of the aerodynamic coefficients correspond to those of experimental results and the contribution of the main wing is significant on the aerodynamic characteristics of the entire airplane.
  • ANYOJI Masayuki, OKAMOTO Masato, HIDAKA Hidenori, KONDO Katsutoshi, OYAMA Akira, NAGAI Hiroki, FUJII Kozo
    Journal of Fluid Science and Technology 9(5) JFST0072-JFST0072 2014年  査読有り
    Low-speed wind tunnel tests are carried out to investigate the control surface effectiveness at low Reynolds numbers (Re = 20,000-80,000). A thick airfoil, NACA0012, has a nonlinearity of the control surface effectiveness, which are associated with flow separation both on the upper and lower surfaces and a formation of a laminar separation bubble. Thin airfoils such as NACA0006 and a 3%c flat plate have a much smaller nonlinearity of the control surface effectiveness. These differences in the control surface effectiveness are due to the nonlinearity of the lift curve for each airfoil, and the flow separation behavior has a profound effect on the control surface effectiveness.
  • Katsutoshi Kondo, Hikaru Aono, Taku Nonomura, Masayuki Anyoji, Akira Oyama, Tianshu Liu, Kozo Fujii, Makoto Yamamoto
    The Japan Society of Aeronautical and Space Sciences, 12(29) 35-40 2014年  査読有り
    Aerodynamic characteristics and flow fields around an owl-like airfoil at a chord Reynolds number of 23,000 are investigated using two-dimensional laminar flow computations. Computed results demonstrate that the deeply concaved lower surface of the owl-like airfoil contributes to lift augmenting, and both a round leading edge and a flat upper surface lead to lift enhancement and drag reduction due to the suction peak and the presence of the thin laminar separation bubble near the leading edge. Subsequently, the owl-like airfoil has higher lift-to-drag ratio than the high lift-to-drag Ishii airfoil at low Reynolds number. However, when the minimum drag is presented, the Ishii airfoil gains lift coefficient of zero while lift coefficient of the owl-like airfoil does not becomes zero. Furthermore, a feature of unsteady flow structures around the owl-like airfoil at the maximum lift-to-drag ratio condition is highlighted.
  • Tianshu Liu, Akira Oyama, Kozo Fujii
    JOURNAL OF AIRCRAFT 50(5) 1593-1604 2013年9月  査読有り
    The scaling relations between the performance parameters of propeller-driven aircraft flying on Mars and Earth are discussed, including the cruising velocity, power required for cruising flight, and propulsive power generated by propellers. The power ratio criterion for feasible cruising flight of propeller-driven aircraft on Mars is proposed, and the relevant design parameters are identified. This criterion is first used to examine the feasibility of typical and nontypical aircraft for cruising flight on Mars, and then applied as a guideline to the preliminary design of the sample Martian aircraft. In addition, the constraints on the rotational speed of a propeller in cruising flight on Mars are given, which should be considered in the design of propellers. The methods developed in this paper are also applicable to other space exploration aircraft for Venus and Titan.
  • Tomoaki Tatsukawa, Taku Nonomura, Akira Oyama, Kozo Fujii
    Transactions of the Japan Society for Aeronautical and Space Sciences 6182(28) 57-63 2013年  査読有り
    In this study, aerodynamic design exploration for reusable launch vehicle (RLV) is conducted using genetic algorithm with Navier-Stokes solver to understand the aerodynamic characteristics for various body configurations and find design information such as tradeoff information among objectives. The multi-objective aerodynamic design optimization for minimizing zero-lift drag at supersonic condition, maximizing maximum lift-to-drag ratio (L/D) at subsonic condition, maximizing maximum L/D at supersonic condition, and maximizing volume of shape is conducted for bi-conical shape RLV based on computational fluid dynamics (CFD). The total number of evaluation in multi-objective optimization is 400, and it is necessary for evaluating one body configuration to conduct 8 CFD runs. In total, 3200 CFD runs are conducted. The analysis of Pareto-optimal solutions shows that there are various trade-off relations among objectives clearly, and the analysis of flow fields shows that the shape for the minimum drag configuration is almost the same as that of the shape for the maximum L/D configuration at supersonic condition. The shape for the maximum L/D at subsonic condition obtains additional lift at the kink compared with the minimum drag configuration. It leads to enhancement of L/D.
  • Weipeng Li, Taku Nonomura, Akira Oyama, Kozo Fujii
    AIAA JOURNAL 51(1) 253-257 2013年1月  査読有り
  • Ryoji Kojima, Taku Nonomura, Akira Oyama, Kozo Fujii
    Journal of Aircraft 50(1) 187-196 2013年  査読有り
    In this study, the flowfields around NACA0012 and NACA0002 airfoils at Reynolds number of 23,000 and the aerodynamic characteristics of these flowfields were analyzed using implicit large-eddy simulation and laminar-flow simulation. Around this Reynolds number, the flow over an airfoil separates, transits, and reattaches, resulting in the generation of a laminar separation bubble at the angle of attack in a certain degree range. Over an NACA0012 airfoil, the separation point moves toward its leading edge with an increasing angle of attack, and the separated flow may transit to create a short bubble. On the other hand, over an NACA0002 airfoil, the separation point is kept at its leading edge, and the separated flow may transit to create a long bubble. Moreover, nonlinearity appears in the lift curve of the NACA0012 airfoil, but not in that of NACA0002, despite the existence of a laminar separation bubble. Copyright © 2012 by Ryoji Kojima, Taku Nonomura, Akira Oyama, and Kozo Fujii.
  • 立川智章, 大山聖, 藤井孝藏
    進化計算学会論文誌 3(3) 133-142 2012年  査読有り
  • Koichi Okada, Akira Oyama, Kozo Fujii, Koji Miyaji
    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 55(1) 1-11 2012年1月  査読有り
    This paper investigates the effects of nondimensional parameters on the characteristics of synthetic jets. Flow inside the synthetic jet cavity and orifice, the flow outside are simulated together using large-eddy simulations (LES). A comparison of the present results and those of the experiment shows that simulating the flow both inside and outside the jet cavity is essential for accurately estimating the velocity and velocity fluctuations of the synthetic jet. LES results under various flow conditions show that strong three-dimensional vortices are generated when the Reynolds number is large, but finer vortex structures form because of stronger vortex interaction as the Strouhal number increases.
  • Ittetsu Kaneda, Satoshi Sekimoto, Taku Nonomura, Kengo Asada, Akira Oyama, Kozo Fujii
    INTERNATIONAL JOURNAL OF AEROSPACE ENGINEERING 2012 2012年  査読有り
    We conducted large eddy simulations of the control of separated flow over an airfoil using body forces and discuss the role of a three-dimensional vortex structure in separation control. Two types of cases are examined: (1) the body force is distributed in a spanwise uniform layout and (2) the body force is distributed in a spanwise intermittent layout, with three-dimensional vortices being expected to be generated in the latter cases. The flow fields in the latter cases have a shorter separation bubble than those in the former cases although the total momentum of the body force in the latter cases is the same as or half of the former cases. In the flow fields of the latter type, the three-dimensional vortices, which are not observed in the former cases, are generated by the body force downstream of the body force distributed. Thus, three-dimensional vortices are considered to be effective in controlling the separated flow.
  • Seiichiro Morizawa, Taku Nonomura, Akira Oyama, Kozo Fujii, Shigeru Obayashi
    40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011 1 257-262 2011年  査読有り
    Flow and acoustic fields of a supersonic jet impinging on an inclined flat plate are investigated by applying data mining techniques. The data of flow and acoustic fields obtained in the previous study are used. The self-organizing map (SOM) and k-means method are applied to this dataset based on the normalized sound pressure level spectra. The results of SOM and k-means method show the clear characterization of the regions based on the frequency characteristics of acoustic waves. Some of clustered regions correspond to the region at which three kinds of aeroacoustics wave are (i) Mach wave from the main jet, (ii) acoustics waves from impinging, and (iii) Mach waves from the supersonic flow downstream of impinging region. The results of SOM and k-means method validate the relationship among these three kind of aeroacoustic waves which is clarified in the previous study, i.e. lower frequency components are stronger for Mach/acoustic waves with the higher index. Copyright © (2011) by the Institute of Noise Control Engineering.
  • Akira Oyama, Taku Nonomura, Kozo Fujii
    JOURNAL OF AIRCRAFT 47(5) 1756-1762 2010年9月  査読有り
    A new approach to extract useful design information from the shape data of Pareto-optimal solutions of an optimization problem is proposed and applied to the optimization of airfoil shapes for good aerodynamic performance at transonic speed. The proposed approach decomposes shape data into principal modes and corresponding base vectors, using proper orthogonal decomposition. The advantage of the proposed approach is that the knowledge one can obtain does not depend on how the shape is parameterized for design optimization. Analysis of the airfoil shapes obtained as the Pareto-optimal solutions for aerodynamic performance at transonic speeds shows that the optimized airfoils can be categorized into three families (low-drag designs, high-lift-to-drag designs, and high-lift designs), where the lift is increased by changing the camber near the trailing edge among the low-drag designs, while the lift is increased by moving the lower surface upward among the high-lift designs.
  • Koichi Okada, Akira Oyama, Kozo Fujii, Koji Miyaji
    International Journal of Aerospace Engineering 2010 2010年  査読有り
  • 滑慶則, 高木亮治, 大山聖, 藤井孝藏, 山本誠
    日本機械学会論文集C編 76(771) 2811-2818 2010年  査読有り
  • Yongsheng Lian, Akira Oyama, Meng-Sing Liou
    Progress in Aerospace Sciences 2009年9月  査読有り
  • Akira Oyama, Yoshiyuki Okabe, Koji Shimoyama, Kozo Fujii
    Journal of Aerospace Computing, Information and Communication 6(3) 256-270 2009年3月  査読有り
    Aerodynamic knowledge for flapping airfoil is obtained by application of the multiobjective design exploration framework to a multiobjective aerodynamic flapping airfoil design optimization problem. The objectives of the design optimization problem are 1) time-averaged lift coefficient maximization, 2) time-averaged drag coefficient minimization, and 3) timeaveraged required power coefficient where the airfoil oscillates in plunging and pitching modes. Pareto-optimal solutions are obtained by a multiobjective evolutionary optimization and analyzed with the self-organizing map. Aerodynamic performance of each flapping airfoil is evaluated by a two-dimensional Navier-Stokes solver. Analysis of the flow over the extreme Pareto-optimal flapping airfoils provides insights into flow mechanism for thrust maximization, lift maximization, and required power minimization. Analysis of the design objectives and design parameters with the self-organizing map leads to useful guidelines for practical flapping-wing micro air vehicles. The present result ensures that the multiobjective design exploration framework is useful approach for real-world design optimization problems.
  • 久保田孝, 尾川順子, 藤田和央, 大山聖, 藤井孝蔵
    日本惑星科学会学会誌「遊・星・人」 18(2) 2009年  査読有り
  • Koji Shimoyama, Akira Oyama, Kozo Fujii
    Journal of Aerospace Computing, Information and Communication 5(8) 215-233 2008年8月  査読有り
    In this study, a new optimization approach for robust design, design for multi-objective six sigma, has been developed and applied to three robust optimization problems. The design for multi-objective six sigma builds on the ideas of design for six sigma, coupled with multiobjective evolutionary algorithm, for an enhanced capability to reveal tradeoff information considering both optimality and robustness of design. While design for six sigma requires careful input parameter setting, design for multi-objective six sigma needs no such prior tuning, plus it can reveal the tradeoff information in a single optimization run. Three robust optimization problems were taken as to demonstrate the capabilities of design for multi-objective six sigma. Results indicate that design for multi-objective six sigma has a more practical and more efficient capability than the design for six sigma to reveal tradeoff design information considering both optimality and robustness of design. Copyright © 2008 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
  • 大山 聖, 藤本 圭一郎, 飯塚 宣行, 角 有司, 川添 通宏, 高木 亮治, 藤井 孝藏, 沖田 耕一
    設計工学 43(4) 203-210 2008年4月5日  査読有り
  • Kazuhisa Chiba, Akira Oyama, Hiroyuki Morino
    JOURNAL OF AIRCRAFT 44(4) 1100-1112 2007年7月  査読有り
    A large-scale, real-world application of evolutionary multi-objective optimization is reported. The multidisciplinary design optimization among aerodynamics, structures, and aeroelasticity of the wing of a transonic regional-jet aircraft was performed using high-fidelity evaluation models. Euler and Navier-Stokes solvers were employed for aerodynamic evaluation. The commercial software NASTRAN was coupled with a computational fluid dynamics solver for the structural and aeroelastic evaluations. An adaptive range multi-objective genetic algorithm was employed as an optimizer. The objective functions were minimizations of block fuel and maximum takeoff weight in addition to drag divergence between transonic and subsonic flight conditions. As a result, nine nondominated solutions were generated and used for tradeoff analysis among three objectives. Moreover, all solutions evaluated during the evolution were analyzed using a self-organizing map as a data mining technique to extract key features of the design space. One of the key features found by data mining was the nongull wing geometry, although the present multidisciplinary design optimization results showed the inverted gull wings as nondominated solutions. When this knowledge was applied to one optimum solution, the resulting design was found to have better performance and to achieve 3.6 % improvement in the block fuel compared to the original geometry designed in the conventional manner.
  • Akira Oyama, Koji Shimoyama, Kozo Fujii
    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 50(167) 56-62 2007年5月  査読有り
    A new constraint-handling method based on Pareto-optimality and niching concepts for multi-objective multiconstraint evolutionary optimization is proposed. The proposed method does not require any constants to be tuned for constraint-handling. In addition, the present method does not use the weighted-sum of constraints and thus does not require tuning of weight coefficients and is efficient even when all individuals in the initial population are infeasible or the amount of violation of each constraint is significantly different. The proposed approach is demonstrated to be remarkably more robust than the dynamic penalty approach and other dominance-based approaches through the optimal design of a welded beam and conceptual design optimization of a two-stage-to-orbit spaceplane.
  • A Oyama, MS Liou, S Obayashi
    JOURNAL OF PROPULSION AND POWER 20(4) 612-619 2004年7月  査読有り
    The development of a high-fidelity aerodynamic design optimization tool based on evolutionary algorithms for turbomachinery is attempted. A three-dimensional Navier-Stokes solver was used for aerodynamic analysis, so that flowfields would be represented accurately and so that realistic and reliable designs would be produced. For efficient and robust design optimization, the real-coded adaptive range genetic algorithm was adopted, and the computation was parallelized and performed on an SGI Origin 2000 cluster to reduce turnaround time. The aerodynamic redesign of the NASA rotor 67 blade demonstrated the superiority of the present method over the conventional design approach, increasing adiabatic efficiency by 2% over the original design. This increase is achieved not only at the design condition, but over the entire operating range. This design optimization method has proven to be suitable for parallel computing. This promising tool is shown to help turbomachinery designers to design higher-performance machines while shortening the design cycle and reducing design costs.
  • S Obayashi, D Sasaki, A Oyama
    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 47(155) 51-58 2004年5月  査読有り
    The objective of the present study is to demonstrate performances of Evolutionary Algorithms (EAs) and conventional gradient-based methods for finding Pareto fronts. The multiobjective optimization algorithms are applied to analytical test problems as well as to the real-world problems of a compressor design. The comparison results clearly indicate the superiority of EAs in finding tradeoffs.
  • A Oyama, MS Liou
    JOURNAL OF PROPULSION AND POWER 18(3) 528-535 2002年5月  査読有り
    A design optimization method for turbopumps of cryogenic rocket engines has been developed. Multiobjective evolutionary algorithm is used for multiobjective pump design optimizations. Performances of design candidates are evaluated by using the meanline pump flow-modeling method based on the Euler turbine equation coupled with empirical correlations for rotor efficiency. To demonstrate feasibility of the present approach, single-stage centrifugal pump and multistage pump design optimizations are performed. The number of pump performance evaluations necessary to obtain a reasonable pareto-optimal set for the conceptual rocket engine pump design will be investigated using the single-stage centrifugal pump design optimization. In both design optimizations the present method obtains hundreds of reasonable and uniformly distributed pareto-optimal solutions that include some designs outperforming the original design in total head while reducing input power by 1 %. Detailed observation of the design results also reveals some important design criteria for turbopumps in cryogenic rocket engines. These results demonstrate the feasibility of the evolutionary algorithm-based multiobjective design optimization method in this field.
  • A Oyama, S Obayashi, K Nakahashi, T Nakamura
    THIRD INTERNATIONAL CONFERENCE ON NONLINEAR PROBLEMS IN AVIATION AND AEROSPACE, VOLS 1 AND 2, PROCEEDINGS 537-546 2002年  査読有り
    Evolutionary Algorithm (EA) is applied to a practical three-dimensional shape optimization for aerodynamic design of an aircraft wing. Aerodynamic performances of the design candidates are evaluated by using the three-dimensional compressive Navier-Stokes equations. A structural constraint is introduced to avoid an apparent solution of zero thickness wing for low drag in high speeds. To overcome enormous computational time necessary for the optimization, the computation is parallelized on Numerical Wind Tunnel at National Aerospace Laboratory in Japan, a parallel computer with 166 vector-processing elements. The results ensure the capability of the EA in handling large-scale design optimizations.
  • 蓮池尚彦, 大山聖, 中橋和博, 大林茂
    日本航空宇宙学会論文集 50(577) 56-63 2002年  査読有り
    Two-dimensional Navier-Stokes simulations have been performed for three types of flows at stall conditions about NACA633-018, NACA631-012 and NACA64A-006 airfoils. The Baldwin-Lomax algebraic eddy-viscosity model was applied in three different manners. First, a fully turbulent flow was assumed. Second, a transition point from laminar to turbulent was set manually. Third, the Degani-Schiff modification was applied. The fully turbulent computations predicted maximum lift coefficients much higher than experiment in all the cases, while the computations agreed well with experiment when specifying transition points properly. The computations with the Degani-Schiff modification predicted the stall angle close to experiment, but showed different behaviors at post-stall conditions. It is important to capture a laminar separation bubble at the leading-edge for predicting stall angles and post-stall behaviors correctly.
  • AKIRA OYAMA, MENG-SING LIOU
    Transactions of the Aeronautical and Astronautical Society of the Republic of China 34(2、528-535) 2002年  査読有り
  • Akira Oyama, Shigeru Obayashi, Takashi Nakamura
    Applied Soft Computing 1(3) 179-187 2001年  査読有り
    Real-coded adaptive range genetic algorithm (ARGA) has been applied to a practical three-dimensional shape optimization for aerodynamic design of an aircraft wing. The real-coded ARGA possesses both advantages of the binary-coded ARGA and the floating-point representation to overcome the problems of having a large search space that requires continuous sampling. The results confirm that the real-coded ARGA consistently finds better solutions than the conventional real-coded genetic algorithms do. © 2001 Elsevier Science B.V. All rights reserved.
  • A Oyama, S Obayashi, K Nakahashi
    JSME INTERNATIONAL JOURNAL SERIES A-SOLID MECHANICS AND MATERIAL ENGINEERING 43(2) 124-129 2000年4月  査読有り
    Real-coded Adaptive Range Genetic Algorithms (ARGAs) have been developed. The real-coded ARGAs possess both advantages of the binary-coded ARGAs and the use of the floating point representation to overcome the problems of having a large search space that requires continuous sampling. First, the efficiency and the robustness of the proposed approach are demonstrated by test functions. Then the proposed approach is applied to an aerodynamic airfoil shape optimization problem. The results confirm that the real-coded ARGAs consistently find better solutions than the conventional real-coded Genetic Algorithms do. The designed airfoil shape is considered to be the global optimal and thus ensures the feasibility of the real-coded ARGAs in aerodynamic designs.
  • Akira Oyama, Shigeru Obayashi, Kazuhiro Nakahashi, Naoki Hirose
    CFD Journal 8(4) 570-577 2000年  査読有り
  • A Oyama, S Obayashi, K Nakahashi, T Nakamura
    AIAA JOURNAL 37(10) 1327-1328 1999年10月  査読有り
  • 大山 聖, 大林 茂, 中橋 和博, 中村 孝
    日本航空宇宙学会誌 46(539) 682-686 1998年  査読有り
  • S Obayashi, A Oyama
    COMPUTATIONAL FLUID DYNAMICS '96 420-424 1996年  査読有り
    A Genetic Algorithm has been applied to optimize a wing shape for generic subsonic transport aircraft by using Navier-Stokes computations. To overcome enormous computational time necessary for this optimization, Numerical Wind Tunnel at National Aerospace Laboratory, a parallel vector machine with 166 processing elements, was used. Design results indicate feasibility of the: present approach for the aerodynamic optimization in advanced computational environments.

MISC

 59
  • 森穂高, 大山聖, 丸祐介, 坂本勇樹, 小林弘明, 江口光
    日本航空宇宙学会年会講演会講演集(CD-ROM) 54th 2023年  
  • 遠藤桜, 大山聖, 山田和彦
    宇宙科学技術連合講演会講演集(CD-ROM) 67th 2023年  
  • 岸, 祐希, 金崎, 雅博, 杉浦, 正彦, 田辺, 安忠, 大山, 聖, 佐藤, 允, KISHI, Yuki, KANAZAKI, Masahiro, SUGIURA, Masahiko, TANABE, Yasutada, Oyama, Akira, SATO, Makoto
    宇宙航空研究開発機構特別資料: 第53回流体力学講演会/第39回航空宇宙数値シミュレーション技術シンポジウム論文集 = JAXA Special Publication: Proceedings of the 53rd Fluid Dynamics Conference / the 39th Aerospace Numerical Simulation Symposium JAXA-SP-21-008 149-155 2022年2月14日  
    第53回流体力学講演会/第39回航空宇宙数値シミュレーション技術シンポジウム (2021年6月30日-7月2日. 日本航空宇宙学会 : 宇宙航空研究開発機構(JAXA)オンライン会議) The 53rd Fluid Dynamics Conference / the 39th Aerospace Numerical Simulation Symposium (June 30 - July 2, 2021. The Japan Society for Aeronautical and Space Sciences : Japan Aerospace Exploration Agency (JAXA), Online meeting) In this paper, aerodynamic characteristics around the blade of the hexacopter ''HAMILTON (HexAcopter for Martian pIt crater exploraTiON)'' for Mars exploration are investigated to obtain design knowledge regarding multicopter drone flying in Martian atmosphere. Reynolds-averaged Navier-Stokes simulation with the moving overlapped grid was employed for aerodynamic evaluation of two cases; one is hexa-rotor case and the other is single rotor case in order to compare single rotor case and hexa-rotor case and reveal unique characteristics of multirotor case. According to computational results, in both cases, hexa-rotor and single rotor, the maximum figure of merit could be observed at higher hovering thrust conditions. It is suggested that the baseline blade geometry could generate thrust efficiently at higher thrust conditions. The flow structure around the hexa-rotor can be classified into three groups; turn-in side where the flow was drawn the inside by blades rotation, turn-out side where the flow was put out to the outside by blades rotation, and the center side which was located between the turn-in and turn-out sides. The rotors of the center side took the low figure of merit compared with the other rotors because of aerodynamic interference from the turn-in side and the turn-out side rotors. Therefore, the total figure of merit of all rotors increased when the distance among rotors is increased. 形態: カラー図版あり Physical characteristics: Original contains color illustrations 資料番号: AA2130027012 レポート番号: JAXA-SP-21-008
  • 大山聖
    計算工学 27(2) 2022年  
  • 大山聖
    自動車技術 75(4) 2021年  招待有り
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書籍等出版物

 1
  • Akira Oyama
    Springer Verlag 2009年  Refereed
    Constraint-handling techniques for evolutionary multiobjective aerodynamic and multidisciplinary designs are focused. Because number of evaluations is strictly limited in aerodynamic or multidisciplinary design optimization due to expensive computational fluid dynamics (CFD) simulations for aerodynamic evaluations, very efficient and robust constraint-handling technique is required for aerodynamic and multidisciplinary design optimizations. First, in Section 2, features of aerodynamic design optimization problems are discussed. Then, in Section 3 constraint-handling techniques used for aerodynamic and multidisciplinary designs are overviewed. Then, an efficient constraint-handling technique suitable to aerodynamic and multidisciplinary designs is introduced with real-world aerodynamic and multidisciplinary applications. Finally, an efficient geometry-constraint-handling technique commonly used for aerodynamic design optimizations is presented. © 2009 Springer-Verlag Berlin Heidelberg.

講演・口頭発表等

 352
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所属学協会

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共同研究・競争的資金等の研究課題

 7
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