Optimization of thermal-fluid-structure coupling for variable-span inflatable wings considering case correlation

•According to the experience and mechanical characteristics of the inflatable wing, the KTS is modified by introducing the prior knowledge, which is proved to further improve the efficiency of optimization by an example with 4 cases.•A MDO framework including parametric modeling, the aerodynamic model based on CFD, and a thermal model based on UDF program and the FEM structure model considering the wrinkled zone, is developed in this paper, which is utilized to comprehensively evaluate the performance of inflatable wings.•Based on the analysis of the optimization results, the principle for selecting structural configurations of swept baffled inflatable wings for variable-span aircraft is proposed, and the distribution of the optimal solution is discussed as well. Due to its foldable ability, the inflatable wing can easily achieve a free change in span, enabling cross-domain flight with wider altitude ranges. Meanwhile, the lightweight and flexible characteristics of the inflatable wing make it extremely sensitive to aerodynamic loads and thermal environments, which results in structural instability such as wrinkling and rupture during flight. Therefore, it is important to improve the performance and stability of the inflatable wing under extreme flight conditions. By designing sweeping arranged baffles, the sensitivity of the inflatable wing to both aerodynamic loads and thermal environment can be substantially mitigated. However, the application of this unconventional configuration will intensify the coupling between the aerodynamic and structural characteristics of inflatable wings. Meanwhile, in order to achieve cross-domain flight, various working conditions at different altitudes should be fully considered during the optimization process, which will lead to a multiple cost further. In this paper, a framework is proposed to efficiently obtain the optimal scheme for variable-span inflatable wings. A high-precision model is constructed to investigate the thermal-fluid-structure coupling analysis during the cross-domain flight of inflatable wings. Moreover, the SADE-KTS algorithm is modified to achieve more targeted sampling between weakly correlated working conditions, thereby accelerating convergence. The optimization results indicate that thermal-fluid-structure coupling analysis provides a precise depiction of the performance for inflatable wings, which is beneficial for obtaining feasible solutions. The distribution correlation of variables for the o