Aerodynamic shape optimization (ASO) of hypersonic lifting body has become a significant research topic due to its significant performance advantages. As a universal parameterization, the free form deformation (FFD) technique has benefits including geometric independence, random deformation, and mesh synchronization. In this paper, an effective design method to apply the FFD technique in the ASO of a hypersonic lifting body is presented. Some commonly used basis functions are researched in FFD modeling of the windward side of a typical lifting body, including the Bernstein polynomial, the B-spline function, and the non-uniform rational B-spline (NURBS) function. An efficient aerodynamic simulation method combining Euler equations (non-viscous component) and skin friction drag (viscous component based on the compressible turbulence model) is then developed to minimize computational requirements. The accuracy of the proposed method is validated, and a significant decrease in processing time is observed. In addition, a kriging surrogate model combined with infilling sampling expected improvement (EI) criterion is developed to improve optimization efficiency. To obtain a lifting body with high lift-to-drag ratio that satisfies inner loading constraint, a baseline is optimized by manipulating its shape using the NURBS-based FFD technique. The results show that the optimal shape displays outstanding aerodynamic performance, and the effective design method can provide practical support for ASO of the hypersonic lifting body.

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The aerodynamic shape of the hypersonic glide vehicle (HGV) has become a research topic nowadays due to its excellent aerodynamic performances. Some limitations need to be reduced when the free-form deformation (FFD) method is applied to parametric modeling and design of an HGV. In this paper, a typical lifting body is considered as an example, and we propose a border-based FFD modeling method that transforms the boundary of FFD lattice into the border of the windward side. Then, the superiority of the border-based FFD modeling method is demonstrated by comparison with the traditional FFD modeling method, and the mesh quality parameters are used to validate the well-deformed model and good geometric continuity of the proposed method. Finally, the border-based FFD modeling method is applied to deformable modeling and aerodynamic simulation of three typical HGV shapes. The results show that the higher efficiency, wider design space, and better applicability are performed by using the border-based FFD modeling method that outperforms the traditional FFD modeling method, and this method we proposed can allow a designer to achieve the better aerodynamic shape of HGVs. INDEX TERMS Hypersonic gliding vehicle, aerodynamic shape design, parametric modeling, free form deformation, windward side.

In order to make the space flexible webs system have more effective capability of capture, this paper designs a new space debris removal device, which consists of bionic flexible webs, central hub, magnetic mass and rotating mechanism. According to the principle of bionics and institutional design method, which based on the research of spider web structure and capture performance analysis. Firstly, the image processing system of spider web is established, and the spider web image is digitally processed to extract the structure shape of the spider web. According to the structure of spider web, a simplified cobweblike flexible structure is proposed and a ''cobweb-like'' flexible capture device is designed. Then, the model of flexible web is established based on the finite element method, and the capture effect is compared with the traditional quadrilateral webs. Finally, a ground experiment system of ''cobweb-like'' flexible capture device is designed, and a verification experiment of the capture effect of the flexible webs is carried out. The results show that the bionic design scheme in this paper can fully meet the design requirements for the flexible webs capture system in space and the research provides theoretical and experimental references for the engineering realization of the space flexible webs capture system.INDEX TERMS Space flexible webs, bionic design, collision analysis, ground test.

The lift of an aircraft can be effectively enhanced by circulation control (CC) technology at subsonic speeds, but the efficiency at transonic speeds is greatly decreased. The underlying mechanism of this phenomenon is not fully understood. In this study, Reynolds averaged Navier—Stokes simulation with k−ω shear stress transport model was utilized to investigate the mechanism of lift enhancement by CC in transonic flow. For validation, the numerical CC results were compared with the NASA experimental data obtained for transonic CC airfoil. Thereafter, the RAE2822 airfoil was modified with a Coanda surface. The lift enhancement effects of CC via steady blowing with different momentum coefficients were tested at Ma=0.3 and 0.8 at α=3∘, and various fluid mechanics phenomena were investigated. The results indicate that the flow structure of the CC jet is insensitive to the incoming flow conditions because of the similarity to the local static pressure field around the trailing edge of the airfoil. Owing to the appearance of shockwaves on the airfoil surface in the transonic regime, the performance of the CC jet is restricted to the trailing edge of the airfoil. Transonic CC achieved a slight improvement in aerodynamic performance owing to a favorable shift in the shockwave pattern and accelerated flow in the separation region on the airfoil surfaces. Revealing the mechanism of lift enhancement of CC in the transonic regime can facilitate the rational design of new fluidic actuators with high activity and expand the potential applications of CC technology.