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According to radial basis functions, the greedy method and the subspace method are used to develop a deformation solver for hybrid unstructured mesh. The solver is constructed with massive parallel processors to improve the deformation efficiency of complex boundary. ONERA M6 wing of million mesh magnitudes and X48B flying wing of ten million mesh magnitudes are selected as test cases. The parallel acceleration, robustness and efficiency of the solver are validated and compared with different CPU cores and basis functions. The results indicate that the mesh quality can be guaranteed after deformation, and the deformation efficiency can be increased more than 80 times with massive parallel system.

Mitigation of sonic boom to an acceptable stage is a key point for the next generation of supersonic transports. Meanwhile, designing a supersonic aircraft with an ideal ground signature is always the focus of research on sonic boom reduction. This paper presents an inverse design approach to optimize the near-field signature of an aircraft making it close to the shaped ideal ground signature after the propagation in the atmosphere. Using the proper orthogonal decomposition (POD) method, a guessed input of augmented Burgers equation is inversely achieved. By multiple POD iterations, the guessed ground signatures successively approach the target ground signature until the convergence criteria is reached. Finally, the corresponding equivalent area distribution is calculated from the optimal near-field signature through the classical Whitham F-function theory. To validate this method, an optimization example of Lockheed Martin 1021 is demonstrated. The modified configuration has a fully shaped ground signature and achieves a drop of perceived loudness by 7.94 PLdB. Finally, a non-physical ground signature is set as the target to test the robustness of this inverse design method.

A radar cross section gradient calculation method based on adjoint equation of method of moment (MoM) is proposed. The adjoint equation of method of moment as well as the variation of radar cross section is derived. Backscattering RCS of cylinder and missile model are firstly calculated and compared with measured data or FEKO MoM result to verify the reliability of the program adopted. Then, the cylinder and missile are parameterized and disturbed with domain element method. The gradient of design variables are computed with both adjoint method and finite-difference method. Numerical results of both methods are in good agreement proving that adjoint method has high reliability and precision. RCS gradient calculation based on adjoint equation has high efficiency, accuracy and can be applied in the calculation of complex geometry. It forms the basis of the gradient-based aerodynamic-stealth optimization platform.

The coupled aero-structural adjoint-based approach for large civil aircraft multi-disciplinary optimization is studied in this paper. Firstly, computational techniques are introduced. Then the coupled aero-structural adjoint system (CASA) is developed and constructed, solving the structural adjoint equations derived from the structural static equations, with the help of the parallel flow adjoint code PADJ3D and lagged coupled adjoint method. Afterwards, the multi-disciplinary optimization model for the large civil aircraft is established, while the sequential quadratic programming algorithm is used for optimization, freeform deformation method is employed for geometric parameterization and parallel RBF-TFI grid reconstruction technology is used for mesh perturbation. On accounting of the coupled aerodynamic and structural disciplines, the multi-disciplinary optimization for large civil aircraft wing is carried out based on the developed CASA system. The simulation results demonstrate the effectiveness of the CASA system. Under the stress constraints, the aerodynamic drag and the structural weight can be effectively optimized.

Based on the structural overlapped grid technology, the aerodynamic characteristics of DLR-F11 model, which is issued by the Second High Lift Prediction Workshop (HiLiftPW), are predicted by self-developed PMB3D solver. PMB3D is a RANS-equation solver, employing finite-volume discrete and implicit method. The computational accuracy of PMB3D solver with structural overlapped grid is verified by comparing the simulation results with some other CFD solvers, such as FUN3D, CFL3D and OverFlow et al. The simulation results demonstrate that (1) PMB3D could rival the other CFD solvers, since it can precisely predict the aerodynamic characteristics, the pressure distribution and the flow characteristics of the model; (2) the use of the structural overlapped grid technology could largely reduce the difficulty of grid generation for complex geometry, without affecting the accuracy of the flow simulation; (3) PMB3D with structural overlapped grid could quickly and accurately predict the aerodynamic characteristics, and it is a reliable analysis tool for aerodynamic design.