Speciality assessment of sequential and concurrent aerostructuraloptimization based on coupled adjoint technique

The RANS(Reynolds-averaged Navier-Stokes) equation, linear finite element analysis method, local mapping point link method and inverse distance weighting interpolation method were used to analyze the coupling between aerodynamic and structural variables. The gradients of merit function to aerodynamic and structure design variables were solved efficiently using aerostructural coupled adjoint technique. These modules were integrated with free form deformation module and gradient-based optimizer to form an aerostructural optimization design framework. A blend wing body aircraft was chosen to conduct sequential and concurrent aerostructural optimization. Results showed that the concurrent approach achieved 8.4% more range and 8.3% less structural weight, compared with the sequential approach on the same drag level. Moreover, the sequential approach had obvious shock wave on a significant portion of the outer wing. Meanwhile, the concurrent approach exhibited parallel pressure contour lines with roughly equal spacing indicating a shock-free result. All the results confirm that concurrent optimization for the design of the aeroelastic system provides significant advantages over the sequential approach. Given these improvements, the presented methods have the potential to be a useful tool in high flexibility aeroelastic design problems.