Aerodynamic and stealth integrated design of hypersonic vehicle based on discrete adjoint method

Aerodynamic and stealth characteristic are important indicators that affect the combat capability of hypersonic weapons. In order to coordinate the contradiction between the two disciplines and improve the penetration ability of hypersonic vehicle, the multidisciplinary optimization design based on discrete adjoint method was adopted to optimize the shape of hypersonic vehicle. Firstly, an integrated design platform for aerodynamic and stealth was built by coupling the numerical method of aerodynamics and stealth, the gradient calculation method based on adjoint equation, the free-form deformation (FFD) parameterization method and the RBF-TFI dynamic grid technology. Secondly, taking the HTV-2 aircraft as an example, the aerodynamic shape of the hypersonic vehicle was optimized. After aerodynamic optimization, the lift-to-drag ratio was increased by 11.85%, and the aerodynamic characteristics were greatly improved. While, the stealth characteristics in the main threat area changed little. Finally, the aerodynamic and stealth integrated optimization design of HTV-2 hypersonic vehicle was carried out. The results shown that after the aerodynamic and stealth integrated optimization, the lift-to-drag ratio was increased by 7.82%. At the same time, the average radar cross section (RCS) of head direction ± 60 ° angle domain in the yaw plane was decreased by 40.21%, and the average RCS head direction ± 30 ° angle domain in the pitch plane was decreased by 30.47%. It was verified that the design system based on discrete adjoint method established in this study could realize the aerodynamic and stealth integrated optimization design of hypersonic vehicle under hundred-dimensional design variables and constraints, so that the aerodynamic and stealth characteristics of the aircraft were substantially improved after optimization.