关键词: 跨域变体飞行器, 气动力热, 非层次多模型融合, 模型降阶, 机翼变后掠, 机翼变展长

Abstract: In order to improve the large airspace and wide speed range flight capability, cross-domain morphing aircrafts are able to change their configuration to adapt to different flight conditions, which has become a current topic of interest. This paper constructs the high-fidelity aerodynamic and aerothermodynamic model of a quasi-waverider cross-domain morphing aircraft based on RANS equations, and the low-fidelity models are constructed based on engineering estimation methods. The nonhierarchical multi-model fusion method using multi-level Kriging and quadratic programming (NMF-MKQP) is proposed considering the existence of non-hierarchical multi-fidelity models for hypersonic aerodynamic and aerothermodynamic analysis. The uncoupled expression of mean squared error is derived to convert the scaling factors maximum likelihood estimation global optimization problem into a quadratic programming problem, and the scaling factors are analytically determined accordingly. In this way, the efficiency of the proposed model reduction method is significantly improved via reducing the computation cost. Compared with state-of-the-art multi-fidelity surrogate modeling methods, NMF-MKQP outperforms regarding approximation accuracy. The cross-domain morphing aircraft aerodynamic and aerothermodynamic characteristics with varying sweep angle and span is assessed based on the constructed reduced-order model, which leads to a morphing strategy during cross-domain gliding. The flight performance increases with the lift-to-drag ratio, while ensuring a decreasing maximum heat flux.

Key words: cross-domain morphing aircraft, aerodynamics and aerothermodynamics, non-hierarchical multi-model fusion, model order reduction, wing sweep angle morphing, wing span morphing