本研究運用流固耦合（Fluid-Structure Interaction, FSI）技術，透過開源軟體建置具計算平行化能力之流固耦合模擬求解器，並以太空探測器之展開式氣動外殼為研究對象，進行流固耦合數值模擬，分析不同流場條件及結構材料參數下氣動外殼之氣動特性與結構響應。

本研究將流體求解器SU2與結構求解器CalculiX進行資料串接，並透過preCICE耦合程式建置分離式流固耦合求解器。在數值方法方面，流體求解器採用JST scheme與雙時間步進法進行流場求解；結構求解器則採用a-method與非線性求解方法進行暫態結構分析。兩求解器透過雙向平行隱式耦合方法交換流體與結構介面資料，並搭配收斂加速方法提升耦合計算之收斂效率，以完成流固耦合模擬。

幾何模型採用氣動外殼縮比模型，並分別建立流體與結構計算網格。模擬條件設計次音速、遷音速及超音速三種不同馬赫數之流場，同時設定三組不同楊氏模數之結構材料參數，藉由不同流場與材料條件之組合，評估求解器於不同模擬條件下之適用性。

首先，本研究針對求解器進行強縮放測試與結構自然模態分析，確立後續計算核心配置與取得結構自然頻率。在氣動分析方面，分析不同馬赫數條件下之流場物理量分布及氣動係數，並利用Q-criterion方法辨識流場中之三維渦流結構。在結構響應分析方面，當氣流由次音速提升至超音速，結構振動行為由結構自然振動主導，逐漸轉變為氣流受激振動與結構自然振動共同作用之結果。在相同馬赫數條件下，提高楊氏模數可增加結構剛性，使最終振動頻率逐漸接近第四自然頻率。顯示當結構剛性提高時，結構自然振動對整體響應之影響亦逐漸增加。

整體而言，本研究完成氣動外殼之前導數值模型與流固耦合模擬求解器之建置，並建立涵蓋氣動分析與結構響應分析之通用化數值分析流程。未來可進一步探討不同飛行姿態及流場條件下之流固耦合特性，作為後續氣動外殼結構設計與性能評估之參考依據。

This study employs Fluid-Structure Interaction (FSI) techniques to develop a computationally parallelized FSI simulation solver using open-source software. A deployable aeroshell for space exploration is adopted as the research subject to perform numerical FSI simulations and investigate the aerodynamic characteristics and structural responses of the aeroshell under different flow conditions and structural material parameters.

The developed solver couples the SU2 fluid solver with the CalculiX structural solver through data exchange and employs the preCICE coupling library to construct a partitioned FSI framework. For the numerical methods, the fluid solver adopts the JST scheme and dual-time stepping method for flow-field calculations, whereas the structural solver employs the a-method and nonlinear solution procedures for transient structural analysis. The two solvers exchange fluid-structure interface data through a bidirectional parallel implicit coupling scheme, while a convergence acceleration method is incorporated to improve coupling efficiency and complete the FSI simulations.

A subscale aeroshell model is adopted, and separate computational meshes are constructed for the fluid and structural domains. Three flow conditions, including subsonic, transonic, and supersonic regimes, are considered at different Mach numbers. In addition, three sets of structural material parameters with different Young's moduli are defined. The applicability of the developed solver under various simulation conditions is evaluated through combinations of different flow and material conditions.

First, strong-scaling tests and structural modal analyses are performed to determine the computational core configuration for subsequent simulations and to obtain the natural frequencies of the structure. For the aerodynamic analysis, flow-field distributions and aerodynamic coefficients under different Mach number conditions are investigated, while the Q-criterion is employed to identify three-dimensional vortex structures in the flow field.

For the structural response analysis, as the flow condition increases from subsonic to supersonic, the structural vibration behavior gradually changes from being dominated by structural natural vibrations to a response jointly influenced by flow-induced excitation and structural natural vibrations.

Under the same Mach number condition, increasing Young's modulus enhances structural stiffness, causing the dominant vibration frequency to gradually approach the fourth natural frequency. These results indicate that the influence of structural natural vibrations on the overall response becomes increasingly significant as the structural stiffness increases.

Overall, this study establishes a numerical model of the aeroshell and develops an FSI simulation solver, thereby providing a generalized numerical analysis procedure encompassing both aerodynamic and structural response analyses. The proposed framework can be further extended to investigate FSI characteristics under different flight attitudes and flow conditions, providing a reference for future aeroshell structural design and performance evaluation.

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