Air Inlet/Airframe Integration Optimization Based on the Discrete Adjoint Method

Advanced combat aircraft pursue extreme stealth, and the aerodynamic design presents a distinctive integrated design feature. The traditional inlet/airframe separate design means can no longer meet the development needs of highly integrated inlet/airframe of the aircraft. A discrete adjoint optimization framework based on the Vanleer scheme and full turbulence variation is constructed to carry out the integrated airframe/intake design for a flying wing configuration. The optimization results show that under the paper condition, the inlet overflow drag is the main source of the whole aircraft drag, and after the optimization, the whole aircraft drag decreases by 2 drag units, the radius of the leading edge of the airfoil decreases, and the position of the maximum thickness is shifted back, so that the pressure recovery is more moderate. After optimization, the total pressure recovery of the inlet is increased to 0.978, the total pressure distortion is reduced by 94%, and the centerline distribution shows the characteristics of “sharp in the front and slow in the back”. The adjoint optimization platform constructed in this paper can meet the requirements of inlet/airframe integrated design and significantly improve the aerodynamic performance of the whole aircraft. This paper only focuses on the optimization of the aerodynamic performance of the whole aircraft, and the aerodynamic/stealth optimization research based on the discrete adjoint method will be carried out for the integrated design of the air inlet/airframe in the future.