The wing aerodynamic shape optimization is a typical high-dimensional problem with numerous independent design variables. Researching methods to reduce the dimensionality of optimization from the perspective of aerodynamic characteristics is necessary. One traditional aerodynamic-based approach decouples the wing’s camber and thickness according to the thin airfoil theory, but it has limitations due to unclear application scope and effectiveness. This paper proposes an improved approach that determines the values of certain thickness variables based on a data-driven aerodynamic characteristics model before optimization, which considers longitudinal stability. By reducing the number of design variables, the dimensionality of optimization is decreased effectively. The derivation of the improved approach is accomplished through the design of experiments, parametric modeling, computational fluid dynamics, and sensitivity analysis. The effectiveness of the improved approach is validated by applying it to the aerodynamic optimization of an ONERA-M6 wing in subsonic flow based on the surrogate-based optimization algorithm. The results demonstrate that the improved approach significantly accelerates the optimization process while maintaining global effectiveness.

The accuracy of the RCS (Radar Cross Section) test is closely related to the conductivity of the model surface. The Chinese military standard has stringent surface resistance criteria for models. If the resistance criteria are appropriately relaxed, model processing can be more effective and expenses can be reduced. However, there are few quantitative evaluations of the relationship between surface resistance and RCS test error, making it impossible to design the model surface resistance in accordance with RCS test accuracy requirements. In this paper, firstly, the influence of model surface resistance on RCS is clarified through theoretical, simulation, and experimental research. The RCS analysis approach of the finite conductivity model is established. Subsequently, taking various typical shapes as research objects, such as the sphere, cube, flying wing aircraft, wing-body combination, and stealth aircraft, the simulation analysis of radar scattering characteristics is carried out under varied sheet resistances and multiple frequencies. A more attainable surface conductivity control standard for the RCS test model has been formulated, which is relaxed by 93% and 727% for models with average RCS of less than and higher than -30dBsm compared with the indicator in the Chinese military standard.

Surface conductivity is one of the key factors in judging whether the RCS (Radar Cross Section) test model is qualified, but the accuracy of traditional detection methods is insufficient. Furthermore, the resistance between two points obtained by traditional methods cannot be directly applied to the electromagnetic simulation analysis of the test model. In this paper, the theoretical model of the relationship between resistivity and resistance between two points on the model surface is proposed. The simulation method for the resistance between two points on the model surface is established. The advantage of the method proposed in this paper compared with the traditional method in detecting the surface resistance of the model is demonstrated intuitively. The experiments are carried out on ITO (Indium Tin Oxide) conductive films with several dimensions and resistivity. Results show that the measured resistance between two points on the model surface is highly consistent with the theoretical and simulated values. Moreover, the comparison of experiments shows that the measurement error of the traditional method is 150% to 200% higher than that of the method proposed in this paper.

Most existing studies on aerodynamic shape optimization have not considered longitudinal trim under control surface deflection, typically achieving self-trim through a constraint of zero pitching moment or adjusting the optimized configuration for longitudinal trim. However, adjustments to the optimized configuration might introduce additional drag, reducing overall optimization benefits. In this paper, a novel approach of incorporating control surface deflection for longitudinal trim in aerodynamic optimization is proposed. Firstly, an aerodynamic computation program based on the high-order panel method was developed, introducing velocity perturbations on specific mesh surfaces to simulate actual control surface deflections. Subsequently, a comprehensive optimization framework was established, encompassing parametric modeling, aerodynamic computation, and variable-fidelity control surface deflection analysis. Finally, aerodynamic optimization analysis was conducted under both subsonic and supersonic conditions. Thirty-one design variables were selected with the trimmed lift-to-drag ratio in cruising condition as the objective function and the control surface deflection angle as the constraint. The results indicated an 8.52% increase in the trimmed lift-to-drag ratio compared to the baseline model under subsonic conditions and an 8.1% increase under supersonic conditions.