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本論文では，緩衝材として砕石を用いた実規模 RC 製ロックシェッドの重錘落下衝撃実験を対象に，三次元弾塑性衝撃応答解析を実施し，実験結果との比較によって解析手法の妥当性を検討した。その結果，提案の数値解析モデルを用いることにより，1) 入力エネルギーが小さい弾性範囲内の場合には重錘衝撃力を大きく評価しているものの，提案の緩衝モデルおよび解析手法を用いることによって，動的応答性状をほぼ適切に再現可能である。2) 一方，入力エネルギーが大きい弾塑性応答を示す場合には，載荷履歴の影響を考慮していないことから，実験結果における変位を過小評価する傾向にあることが明らかとなった。

In this paper, in order to establish a rational impact response analysis method of the RC rockfall protection galleries, elasto-plastic response analyses of a full-scale gallery with sand cushion under falling weight impact loading were conducted. Here, a new constitutive model for sand cushion was proposed, which was modified by adding the initial stiffness and yield plateau to a previous model. An applicability of the proposed model and analysis method were investigated comparing with the experimental results. From this study, it was seen that applying the proposed cushion model and analysis method, the dynamic response behavior of the gallery can be accurately predicted irrespective of the magnitude of the impact energy.

Transient thermal response behavior of hypersonic reentry flight test vehicle HYFLEX (Hypersonic Flight Experiment) was investigated. The iterative CFD (Computational Fluid Dynamics)/FEM (Finite Element Method) coupling analysis was carried out. In this study, flow field around the body is computed by the finite volume Navier-Stokes equation solver FIVAD. On the other hand, heat conduction behavior is calculated by the finite element solver THAP. The NWT (Numerical Wind Tunnel) system and CMS (Common work Station) system of NAL are used for simulation, with the data file transfer by LAN (Local Area Network)., 極超音速で大気圏に再突入する実験機HYFLEX(極超音速飛行実験)について、空力加熱解析と構造熱伝導解析を連成させて、非定常熱応答の数値シミュレーションを試みた。対象をHYFLEX機体前胴部とし、空力解析は有限体積法コードFIVADを用い、熱伝導解析は有限要素法コードTHAPを用いた。計算には航空宇宙技術研究所の大規模並列ベクトルコンピュータシステムである数値風洞(NWT)と構造計算用ワークステーションシステム(CMS)を用い、データファイル転送による分散処理を行った。

Transient thermal response behavior of hypersonic reentry flight test vehicle HYFLEX (Hypersonic Flight Experiment) was investigated. The iterative CFD (Computational Fluid Dynamics)/FEM (Finite Element Method) coupling analysis was carried out. In this study, flow field around the body was computed using the finite volume Navier-Stokes equation solver FIVAD. On the other hand, heat conduction behavior was calculated using the finite element solver THAP. The NWT (Numerical Wind Tunnel) system and CMS (Common Work Station) system of NAL were used for simulation, with the data file transfer by LAN (Local Area Network)., 極超音速で大気圏に再突入するHYFLEX(極超音速飛行実験)実験機について、過渡熱応答挙動を研究した。ここでは反復CFD/FEM(計算流体力学/有限要素法)結合解析を実施した。本研究では機体周りの流れ場をナビエ・ストークス方程式有限体積法コードFIVADを用いて計算した。熱伝導挙動は有限要素法コードTHAPを用いて計算した。シミュレーション計算には航空宇宙技術研究所の数値風洞(NWT)と共通ワークステーションシステム(CMS)を用い、データファイル転送は局地ネットワーク(LAN)を使用した。

This article introduces the ongoing research on aeroelastic analysis using Navier-Stokes equations loosely coupled with finite-element structures. A computational fluid dynamics code with moving grid capability, a grid system which can conform to the structural movements, a Finite-Element-Method-based structural dynamics code, and a program for exchanging displacements and pressures between the two processes of fluid and structure have been newly developed. The system is planned to be applied to a flow analysis with structural deformations. The both codes are simultaneously executed using multiple program multiple data parallelism, while each code is executed on single program multiple data process. Although current efforts are focused on aircraft applications, the approach may be useful for other engineering problems which concern with interactions among multiple disciplines., 本論文では、有限要素構造と緩く結合するナビエ・ストークス方程式を用いた空力弾性解析に関する現在進行中の研究を紹介した。移動格子上の計算機能、構造的移動に追随できる格子系、有限要素法を基にした構造力学コード、および流体と構造の2過程間での変形と圧力を交換するためのプログラムを持つ数値流体力学コードを新しく開発した。構造的変形を伴う流れの解析に適用できるように本システムを構築した。両コードは多重プログラム多重データ並列処理で同時実行され、さらに、各々のコード自体も単一プログラム多重データ処理で並列化される。有限要素ベースの構造的ダイナミックコード、および流体と構造との2つの行程間の変位および圧力交換のプログラムを含む。構造的変形を伴う流れの解析に適用できるように本システムを計画した。多プログラム多データ並列処理を用いて、両コードを同時実行し、一方、単プログラム多データ処理で、各コードごとに実行した。現在、航空機への適用に焦点を絞っているが、本手法は多原理間の結合に関連する他の工学問題にも有用であることを示唆した。

This article preferentially describes advanced computational aeroelasticity and its multidisciplinary applications based on the coupled CFD (Computational Fluid Dynamics) and CSD (Computational Structural Dynamics) method. A modal-based coupled nonlinear aeroelastic analysis system incorporated with unsteady Euler aerodynamics has been developed based on the high-speed parallel processing technique. It is clearly expected to give accurate and practical engineering data in the design fields of generic flight vehicles. Also, efficient and robust computational system for the flutter optimization has been developed using the coupled computational method with the micro genetic algorithm. Vibration and flutter characteristics of composite curved wing are also investigated in this study. Virtual flutter tests for the spanwise curved composite missile fin are effectively conducted using the present advanced computational method with high speed parallel processing technique. As computational demonstrations, the effects of ply orientation and stacking sequence on the flutter speed have been investigated and compared with the case of isotropic curved shell model with the same structural weight., JAXA Special Publication, 宇宙航空研究開発機構特別資料

There is a concept of a space solar power system (SSPS) using solar power satellites (SPS), which is discussed at the institute for unmanned space experiment free flyer (USEF). Before realizing the actual SSPS, a solar power demonstration satellite will be conducted. This study discusses the structural and dynamical feasibility of the demonstration SPS. For the purpose, this study formulates the structural and dynamical model of the demonstration SPS using a finite element model. The mathematical model enables some analysis and derives the following results. Operational static loads are negligible for the system structural strength. Orbit keeping thrusts causes the worst dynamic loads to the structure. Truss part has critical load and additional strength may be requested to an existing Japanese truss structures. The requirements of the antenna shape accuracy will be satisfied.

Under the cooperation of Japan, United States, Europe and Canada, Japanese Experiment Module (JEM) vibration analysis in microgravity environment was conducted by mathematical models and disturbance of Space Station (SS) and JEM. On microgravity environment requirements, duration time, applied position, provision conditions and vibration conditions defined in SSP3000, part 3 'Space Station system requirements' are explained. On analysis of microgravity environment for stationary disturbance, in order to analyze and evaluate JEM microgravity environment for stationary disturbance, analysis for following six stationary disturbances was conducted. On analysis of microgravity environment for vibration disturbance, analysis of microgravity environment for frequency of 0.01-420 Hz was conducted by use of finite element method structural analysis program. In this analysis, the data of stationary mechanical vibration generated in JEM was considered. Following items were discussed: summary of analysis method (finite element model, disturbance data, establishment of simplified analysis method, study of structural analysis method for plural disturbance, comparison method with required conditions and its evaluation method), analytical results (SS/JEM coupling vibration dynamics analysis, SS/JEM coupling response analysis, JEM rigidity analysis). On investigation of vibration suppression requirement, management of disturbance data and vibration suppression requirement were described. As results of the above analysis, possibility of satisfying the microgravity requirements for JEM microgravity environment was presented., 日･米･欧･加の国際協力による宇宙ステーション(SS)およびJEM(日本宇宙ステーション実験モジュール)の数学モデルと外乱条件を用いて、JEMの微小重力環境における振動解析を行った結果について報告した。(1)SSP3000の第3章｢宇宙ステーションシステム要求｣に規定されている継続期間、適用位置、準備環境、振動環境などの微小重力環境について解説した。(2)定常外乱に対するJEMの微小重力環境の解析･評価を行うため、以下の6つの定常外乱に対する解析を実施した。(3)振動外乱に対する微小重力環境について、有限要素法構造解析プログラムを用いて0.01-420Hzまでの周波数について解析を行った。解析においては、JEM内部で発生する定常的機械振動などの値を考慮した。以下の事項について論じた。解析手法概要(有限要素モデル、外乱データ、簡易解析手法の確立、複数外乱に対する構造解析手法の検討、要求条件との比較･評価法)、解析結果(SS/JEM結合振動特性解析、SS/JEM結合応答解析、JEM剛性評価解析)。(4)外乱データの管理と振動制限要求についての検討を述べた。以上の解析の結果、JEMの微小重力環境は微小重力要求を満足する可能性が高いことが明らかになった。

Spacecraft are placed at the top of launch vehicles, and are excited with mechanical vibrations via interfaces between spacecraft and launch vehicles during launch. In addition to such mechanical vibrations, the spacecraft are also exposed to acoustic pressure with wide frequency range. Lightweight and large area structures, such as solar arrays and antenna dishes, and components with relatively high natural frequencies are sensitive to acoustic loads. We have studied on a series of numerical simulation techniques for searching main acoustic sources at lift-off, and analyzing acoustic wave propagation, transmission through fairing and spacecraft acoustic vibrations. This paper focuses on numerical prediction approaches for steady-state coupled interior vibro-acoustic problems, especially for spacecraft structural vibrations by acoustic loads with the wide frequency range acted during the lift-off. Numerical prediction of vibro-acoustic responses might enable us to cover the ground acoustic tests, and is therefore quite important to design and develop reliable spacecraft. For spacecraft vibro-acoustic simulations, there are deterministic prediction techniques such as Finite Element Method (FEM) and Boundary Element Method (BEM) applicable in the low frequency range, and statistical ones such as Statistical Energy Analysis (SEA) in the high frequency range. However, there generally exists mid-frequency range where no mature numerical methods are applicable. In this paper, some FE (Finite Element) analyses are firstly investigated using some simple models to check FE modeling techniques and responses by structural analysis with random acoustic loads. In addition, the simple primary structure with some stiffeners of a large spacecraft is modeled, and is used to solve the eigen value problem, and transient and steady-state analysis with random acoustic loads. Some results show that FEM is limited to be applied in low frequency range. Then, a novel deterministic predictio, 打上げ時の宇宙機には、ロケットの間のインターフェイスを通じて機械振動が加わる。さらに、広い周波数成分をもつ音圧が宇宙機表面に加わることにより振動する。太陽電池パドルやアンテナなど軽量で大きな面積をもつ構造や、比較的高い固有振動数をもつコンポーネントは、音響荷重に影響されやすい。この音響振動の数値予測手法に着目すると、既存の解析手法としては、低周波側では有限要素法(FEM: Finite Element Method)などの決定論的手法、高周波側では統計的エネルギー法(SEA: Statistical Energy Analysis)などの確率統計的手法が適用されている。しかし、一般に両手法では信頼性の高い解析のできない中間周波数領域が存在することが知れている。そこで、本論文では、まず、低周波領域における解析に留まっているFEMの性質について議論するため、FEMの基本的なモデリング手法や解析手法などについて整理し、単純なモデルのランダム応答解析を実施した。さらに、補強材を含む単純な衛星主構造モデルを用いて、FEMによる衛星の音響振動解析を実施した。これらの解析結果から、数値分散誤差の影響や音響と構造の連成解析の重要性について明らかにした。次に、このような要素ベース手法の欠点を克服するために新たに提案された波動ベース法(WBM: Wave Based Method)について議論した。まず、本研究において開発した2次元WBM解析コードと商用FEMソフトウェアを用いて、いくつかの単純な音響構造連成解析と非連成音響解析を行い、WBMコードの検証を行うとともに基本的なWBMの性質を把握した。そして、この結果を踏まえて、フェアリング内の衛星の音響振動連成解析を実施した。以上の結果から、WBMの音響振動連成解析における高精度な決定論的性質が確かめられた。つまり、支配方程式を厳密に満たす波動関数の性質により数値分散誤差を伴わないことから、既存の解析手法で精度の高い解析ができない中間周波数領域を含む広い周波数領域における解析が可能であることが分かった。さらに、空間離散化(メッシュ)を必要としないため、モデル化が非常に容易で計算負荷の小さい実用的な手法であることが分かった。, JAXA Research and Development Report, 宇宙航空研究開発機構研究開発報告

The large sized solar arrays of satellite are installed in the fairing section of by being folded up. So the thickness of air layer between two panels is very thin comparing with the in-plate size of the panel. Because the panel is extremely light, the vibration of the panel is affected by the air layer. This paper presents that the effects of layer thickness on frequency of a panel including viscous, incompressibility air., JAXA Special Publication, 宇宙航空研究開発機構特別資料

Coupled Fluid/Rubberlike Membrane Systems is widely applied in various fields because of its economical and structural advantages. In this study, the FEM analysis of the systems is performed in order to understand its characteristics. In the analysis, geometrically and materially nonlinearity of the membrane and large deformation of moving boundary are taken into consideration. Moreover, in order to construct more practically model, the dynamic analysis including membrane wrinkling and contact its outside rigid tank is performed. Thus it is found that the dynamic characteristic of coupled Fluid/Rubberlike Membrane Systems is strongly affected by wrinkling and contact., JAXA Special Publication, 宇宙航空研究開発機構特別資料

The purpose of this paper is to apply a stabilized finite element method using a new bubble element to the unsteady fluid flow expressed by the compressible Navier-Stokes equations to save efficient computational memory for computers. The formulation is based on the mixed interpolation for a transient term. The main idea of the present paper is the mixed interpolation of the transient term with bubble function as the weighting function and with linear function as the interpolation function. The stabilizing effect of the bubble function is effectively used. Temporal discretization is based on the theta method. The formulation leads to the stabilizing effect and efficiency to the unsteady fluid flow problems and is verified by the numerical studies, in which, a shock tube problem, Carter's flat plate problem and compression corner problem are carried out. The present method is shown to be useful for the computation of the compressible viscous flow., JAXA Special Publication, 宇宙航空研究開発機構特別資料

We give an overview of the ADER (Arbitrary high order schemes using DERivatives) approach for constructing numerical schemes of arbitrary order of accuracy in space and time, for solving evolutionary partial differential equations., JAXA Special Publication, 宇宙航空研究開発機構特別資料

This research aimed at developing a structural weight estimation computer program, which was useful for parametric studies. The weight estimation method used the process of piling up structural elements' weight, which was determined by static strength analysis. The input parameters were vehicle geometry, structural arrangement, load conditions and material data. The computational flow introduced an iteration process between load calculations and mass summations, so that convergence judgment parameter could be the primary structural mass. The static strength analysis determined the cross section areas of structural beam elements and the thickness of structural shell elements under the condition of zero strength margins. Verification was made on the HOPE-X (H-2 Orbiting Plane Experimental) configuration in comparison with FEM (Finite Element Method) weight analysis. The estimated weight difference was about 15 percent. Body stringer pitch optimization was performed on the same configuration, which showed that the program was able to quickly calculate the corresponding structural weight to the input parameter changes. Structure mass sensitivity to load levels was analyzed on the body mass, the wing mass and the tip fin mass, which showed the necessary amount of load level reduction for the goal of the target weight., 助変数的入力変化が可能な構造重量推算法コンピュータ・プログラムを開発した。これは、静強度解析に基づいた各構造部位重量を加算する手順によった。入力変数は飛翔体形状、構造配置、荷重条件および材質データであった。コンピュータ・プログラムでは、荷重計算と重量積分の間に繰り返し計算過程を導入し、計算収束判定は主構造重量について行った。静強度解析は、縦通材の断面積と、外板の板厚を決定した。これには、強度余裕は存在していない。検証として、HOPE-X(宇宙往還技術試験機)形状について、有限要素法重量解析と比較した。結果は、15%の差異を生じた。また、胴体縦通材ピッチ最適化計算を実施した。結果は、入力変化に対して、構造重量が迅速に出力した。さらに、荷重レベル変化に対する構造各部位重量の感度も検討した。この結果、目標重量を達成する荷重レベルの引き下げ量が明らかになった。

Although several out-of-plane test methods are proposed in MIL-HDBK-17 (MILitary-HanDBooK-17) and in research publications, their reliability remains to be established. The present study focuses on the flatwise tension test. Finite element analyses and experiments were carried out to find the most suitable specimen configuration to evaluate out-of-plane stiffness and strength. Several variations of specimen configuration (cylindrical column and spool column) were examined. Nine types of cylindrical model were investigated, with the diameter fixed at 25 mm and the thickness varied between 2 mm and 100 mm. The numerical calculations indicated stress concentrations near the adhesive layer and a multi-axial stress state in the cylindrical model. The 'stress ratio' is defined as a representative value in which the nominal stress is divided by the maximum stress in order to describe the apparent strength. Based on stress ratios, the best configuration among the cylindrical column models was determined to be the thinnest. In the case of spool specimens, stress concentration near the minimum diameter at the center of a specimen was predicted. Through these calculations, it was concluded that the degree of multi-axial stress was lower in the spool specimens than in the column specimens, and the stress ratio approaches unity as the minimum diameter approaches zero. This suggests that the strength of a spool specimen increases as the center diameter decreases. Several experimental tests were also carried out on cylindrical and spool specimens. Failure (including delamination in the adhesive layer) was confirmed for cylindrical specimens, whereas failure at the center of the specimen was confirmed for spool specimens., 複合材料の面内特性や破壊靱性を評価するための試験は各団体(JIS(Japanese Industrial Standards)、ISO(International Organization for Standardization)、ASTM(American Society for Testing and Materials))により定められているが、面外引張特性(層間引張特性)を評価するための直接負荷試験は未だ規格化されていない。本研究では、炭素繊維強化プラスチック(Carbon Fiber Reinforced Plastic: CFRP)の面外方向の引張特性を取得するための試験方法を検討した。負荷形態はハニカムサンドイッチ板のフラットワイズ試験と同様の直接負荷方式とし、最初に試験片形状の検討のため、有限要素解析を実施した、CFRPの0度1方向積層板を対象とし、供試体形状は円柱と板厚中心部がくびれたスプール状円柱(糸巻き形状)を検討した。有限要素法ソフトABAQUSを使用して供試体内の応力状態や供試体の各位置の歪みによる見かけの弾性率を検討した。解析結果より円柱形状の供試体の場合、治具接着面近傍の特定の位置で応力集中が発生することが予測された。また、スプール状円柱形状供試体の場合、板厚中心部で応力集中が発生し、供試体評定部内での破断が予測された。中心部の直径を減少させることで、この応力集中の度合いが緩和されることが予測された。次に解析で検討した形状の供試体を製作し、検証試験を実施した。スプール状円柱の供試体の各試験結果は応力集中が予測された位置での破断が確認され、最小断面部の直径の違いによる破断強度の違いも解析予測と同様の傾向を得た。なお、円柱形状では試験実施の不安定性が確認され、標準化する試験法としては採用しがたいことも明らかにした。, JAXA Research and Development Report, 宇宙航空研究開発機構研究開発報告

This paper presents a new framework for the coupled optimization of aero-structural systems. The framework permits the use of high-fidelity modeling of both the aerodynamics and the structures and represents our first step in an effort towards the development of a high-fidelity multidisciplinary optimization capability. The approach is based on efficient analysis methodologies for the solution of the aerodynamics and structures subproblems, an adjoint solver to obtain aerodynamic sensitivities, and a multiprocessor parallel implementation. We have placed a geometry database representing the Outer Mold Line (OML) of the configuration of interest at the core of our framework. Using this geometry description, the information exchange between aerodynamics and structures is accomplished through an independent coupling of each discipline with the OML database. The framework permits the later inclusion of other disciplines, such as heat transfer and radar signatures, with relative ease. Specific results from the coupling of a finite volume flow solver for the Euler and Reynolds Averaged Navier-Stokes equations with two different linear finite element structural models are explored. Care is taken in the treatment of the coupling of the disciplines such that a consistent and conservative scheme is achieved. Direct comparisons with wind-tunnel data are presented to demonstrate the importance of aeroelastic solutions. In addition, simplified design examples are presented to illustrate the possible advantages of the new aero-structural design methodology in evaluating trade-offs between aerodynamic performance and structural weight for complete aircraft configurations., JAXA Special Publication, 宇宙航空研究開発機構特別資料

Accuracy of CFD (Computational Fluid Dynamics) is investigated by comparing numerical results with the measured flight temperature data on the TPS (Thermal Protection System) material of OREX (Orbital Reentry Experiments). Flow is calculated by the nonequilibrium Navier-Stokes code and internal thermal response is computed by FEM (Finite Element Method). Coupling CFD and FEM along the OREX flight trajectory, temperature increase of the TPS during reentry is favorably predicted. In FEM analysis, the effects of temperature and directional dependence of heat conduction coefficient and radiation effects of TPS material are evaluated. These works have been done as the joint research of NAL and NASDA., OREX(軌道再突入実験)のTPS(熱防護系)材料の計測飛行温度データと数値データを比較することによりCFD(計算流体力学)の精度を調べた。非平衡ナビエ・ストークスコードにより流れを計算し、有限要素法(FEM)により内部熱応答を計算した。OREX飛行軌道に沿ってCFD とFEMの組合せで、再突入時のTPSの温度上昇がかなり予測される。FEM解析でTPS材料の温度効果および熱伝導効率と輻射効果の方向依存性が評価される。これらの作業は,NALとNASDAとの共同研究として行われた。

A computer code for aeroelastic tailoring of an arrow wing supersonic cruise configuration is developed. A direct search method is employed to find the optimum fiber orientation angles and thickness distributions of the upper and lower skin panels of the wing box for the minimum weight design under the multiple constraints. The static strength, symmetric and antisymmetric flutter velocities are taken into account at the same time as the constraints. The code is applied to a typical arrow wing configuration to demonstrate its capabilities., JAXA Special Publication, 宇宙航空研究開発機構特別資料

NATAS provides control GUIs for running aero elastic solvers in including DPM (Double-Point Method), FP (Full Potential) and ELNS (Euler-Navier Stokes). In addition the system is equipped with NatasView, which helps visualize 3-Dimmensional results from the solvers. To make it cross-platform program, c++ visualization library based on OpenGL and Java programming language designed mostly for GUI building are chosen as the basic building blocks for the system. It consequently obtained easy-to-use GUI and first enough to meet user's requirement. The paper not only schematically descries the paradigm and details of the system, but also provides several graphic. This demonstrates its user-friendliness and cross-platform capabilities., JAXA Special Publication, 宇宙航空研究開発機構特別資料

In the strength analysis of aircraft structures mostly made of metals, the strength of each individual structural member is evaluated by inputting the load of the structural member derived from an FEM (Finite Element Method) model of the entire structure into calculation formulas and design charts backed up by theories and experiences. On the other hand, in evaluating structures made of composites that have come to be used for primary structures recently, it has been clarified through the development of various products that there are limits to the simple extension of the conventional evaluation procedures used for metallic structures. It is not practical to obtain design charts only from elemental tests, because a great many design variables are required compared to metals. Consequently, it is necessary to establish a special method to analyze the strength of composites. Especially, to take advantage of the composite material merits such as lightweight, high-strength and so on, the development of a strength analysis method with high accuracy and high reliability is required. This report presents the strength analysis approaches for composite structures based on the microscopic fracture mechanics and the macroscopic progressive failure. In the microscopic analysis, the fracture process to a delamination is clarified by FEM analysis using microstructure models that can indicate differences between layers. In the macroscopic analysis, the tuning method between theoretical and experimental results based on the building block approach is applied to evaluate a global structure behavior by analysis code GENOA., JAXA Special Publication, 宇宙航空研究開発機構特別資料

Parallel blade-vortex interactions have been calculated using the finite difference lattice Boltzmann method of the compressible Euler model. The perturbed discrete Boltzmann equation based on a prescribed vortex method has been proposed in order to prevent a vortex from diffusing by numerical dissipation. The discretization of the governing equation is based on a second order accurate explicit Runge-Kutta time integration and a fifth order accurate upwind scheme which includes additional terms to capture shock waves clearly. Transonic flow around an airfoil without vortexes has been simulated to validate the perturbed discrete Boltzmann equation system. A surface pressure distribution and pressure contour lines around the airfoil have been compared with other numerical data, and good agreements have been obtained. As a simple model of parallel blade-vortex interaction, two-dimensional blade-vortex interaction has been calculated using the proposed numerical method. An instantaneous pressure coefficient, a time history of a lift coefficient and patterns of acoustic waves have been compared with other numerical results, and agreed with them very well. Mechanism of noise generation has been also captured from numerical results. Three-dimensional calculations of parallel blade-vortex interaction have been performed using the present numerical procedure. Time variations of surface pressure distributions have been compared with Euler calculation and experimental data, and good agreements have been obtained., JAXA Special Publication, 宇宙航空研究開発機構特別資料

The CFD and thermal coupling analyses system had been developed which software configuration was very compact to need less computational resource named CCAS (Compact Coupling Analyses System). A nodal method was applied for the thermal analyzer in the system because it essentially needed less memory resources and computation time, while a finite element method is generally used in other coupling analyses system. Also a set of assistance software was made that semi-automatically produced a thermal mathematical model from a CFD model to make a series of analyses work more efficient. A test analysis was done around H-2A 4S fairing during a flight. Heat flux at the stagnation point was compared with the value derived from theoretical equations, and analysis value was about 20 percent higher than from theoretical equations. Also compared were temperatures in the faring body with values of actual measurement at the first flight, and these from analysis were a little higher than actual. Although these calculation results of heat flux and temperatures from analysis indicated higher values, its differences were not so significant and were thought to be in the range of error by modeling uncertainty so the results from analysis were relatively correct and the system was confirmed to be valid., Special Publication of National Aerospace Laboratory, 航空宇宙技術研究所特別資料

HYFLEX (Hypersonic Flight Experiment) was conducted in February, 1996. In this hypersonic flight, aerodynamic data and temperature data on TPS (Thermal Protection System) materials and internal structure parts were obtained along its flight trajectory. Surface temperature history of HYFLEX TPS parts were simulated by CFD-FEM (Computational Fluid Dynamics-Finite Element Method) coupling analysis and this type of multi-disciplinary simulation demonstrated its usefulness for high quality evaluation of aerothermal environments of reentry flight. On the present paper, CFD-FEM coupling method is applied to the total thermal structural analysis including internal aluminum structures, such as frames and stringers. This analysis is made to the flight time of 300 sec and good agreements with flight data are obtained for temperature increase of HYFLEX vehicle., HYFLEX(極超音速飛行実験)が1996年の2月に行われた。この極超音速飛行では、空力データ、耐熱材や内部構造の温度データが飛行軌跡に沿って得られた。HYFLEXのTPS(耐熱システム)部の表面温度履歴をCFD-FEM(数値流体力学-有限要素法)カップリング解析で模擬し、この種の多様な解法を含む模擬は、再突入飛行時における空力熱特性環境の質の高い評価に有効であることを示した。本論文では、CFD-FEMカップリング法が、フレームや縦通材のような内部アルミニウム構造を含む全熱構造解析に適用された。この解析を300秒の飛行時間でおこない、極超音速飛行実験の温度上昇について得られた飛行データと良好な一致が得られた。

JAXA Special Publication, 宇宙航空研究開発機構特別資料

Navier-Stokes CFD (Computational Fluid Dynamics) code and FEM (Finite Element Method) thermal response analysis are coupled in order to simulate more completely the aerothermal environments of hypersonic flight of space transportation vehicles. Present coupling methods are first applied to the analysis of the infrared aerothermodynamic heating measurements of a sphere model at NAL Mach 10 hypersonic wind tunnel. Through this analysis, basic validation has been made by comparisons of the temperature increase on the sphere surface. The present coupling analysis is also made to simulate aerothermodynamic environments of OREX (Orbital Re-Entry Experiment) and HYFLEX (Hypersonic Flight Experiment) re-entry flights. Numerical computations are performed along each flight trajectory. For HYFLEX flight analysis, simulations are further extended to the total thermal-structural analysis including internal aluminum structures, such as frames and stringers. Numerical results are compared with the flight data of OREX and HYFLEX experiments and it is demonstrated that the aerothermodynamic heating and temperature history can be almost completely reproduced by the present coupling simulations. Finally, TPS (Thermal Protection System) thermal response analyses of HOPE-X (H-2 Orbiting Plane-Experimental) re-entry flight are being made and recent numerical results are introduced., ナビエ-ストークスCFD(計算流体力学)コードとFEM(有限要素法)熱応答解析を連成させて宇宙輸送機の極超音速飛行の熱空力環境のより完全なシミュレーションを行った。今回の連成手法を、最初に航空宇宙技術研究所のマッハ10極超音速風洞における球型モデルの周りの赤外線空力加熱計測の解析に適用した。この手法による解析結果と球表面の温度上昇の測定結果を比較することによって、基本的有効性を確認した。この連成手法を、またOREX(軌道再突入実験機)とHYFLEX(極超音速飛行実験)の再突入飛行時の熱空力環境のシミュレーションに適用することができた。各々の飛行軌道に沿って数値計算を行った。HYFLEX飛行解析に関して、シミュレーションを、さらにフレーム部やストリンジャ部のような内部アルミニウム構造部材を含む全体の熱構造解析に拡張した。数値解析の結果をOREXやHYFLEXの飛行データと比較し、この連成手法のシミュレーションによって熱空力加熱および温度の履歴をほぼ完全に再現できることが分かった。最後に、HOPE-X(H-2宇宙往還技術試験機)の再突入飛行時のTPS(熱防護システム)熱応答解析を行ない、最新の数値解析の結果を紹介する。