Approache And Application Research On Aerodynamic Shape Optimization Design

The fast development of aeronautic and aerospace industry in China and high requirements on flight vehicle design techniques by the intense competition of global markets, precise and efficient design techniques are favorable. The design of aerodynamic shape of flight vehicle is an important part of flight vehicle design, which can influence flight capability and quality significantly. Mathematic optimization theoriesare utilized by optimization design of aerodynamic shape which can be applied in engineering design problems. By the assistant of flow field simulation, optimization design methods, including parameterization methods, surrogate model techniques and optimization searching methods et al, provide a wide design space. Design cycle can be reduced efficiently and shape design can be processed more precisely to improve flight performance. Optimization design of aerodynamic shape has drawn substantive attentions recently. The adaptability of parameterization methods, precise of surrogate model and global convergence of optimization searching methods are main topics. Aiming at above key problems encountered in optimization design, aerodynamic optimization design methods and practical applications are combined in this paper. Main contents are as follows: 1. FFD parameterization method is investigated. Firstly, Patch of multi-block FFD is constructed to adapt to complex geometry. Then, computational method of local coordinates of non-regular FFD control volume is put forward. Simultaneously, the application of FFD parameterization method in automatic mesh deformation of flow field is investigated.Patch of multi-block FFD method divides complex geometry into different parts and parameterizes separately, tosimplifythe parameterization of each block. Moreover, the harmony and continuumin separating surface between different blocks are maintained during entire deformation process. It is proved that the computational method of FFD local coordinates can providerigor solutions of local coordinates of arbitrary FFD control volume. In practical applications, ranges of convergence residual are given to calculate local coordinates. 2. Convergence of standard differential evolution algorithm is analyzed, FA-DE optimization algorithm is further put forward. It is proved that standard DE algorithm cannot be ensured to converge to global optimal point by Markov chainmethod, while the FA-DE method converges to global optimal point in 100% probability.Compared with standard DE algorithm, FA-DE methodare introduced in new mutation operator and selection strategy, which enhances global convergence capability and convergence rate. It is manifested that FA-DE can converge to global optimal point more quickly and reliably that standard DE method. 3. Adaptive RBF neutral network model is put forward, and the prediction of profile Cp distribution by adaptive RBF neutral network model is advanced.Comparing with original RBF neutral network model, optimal mapping relationship can be identified according specific application environment in the adaptive model. In addition, prediction space is reconstructed by optimization, which augments the generalization, adaptability and forecast precision. The prediction of profile Cp distribution by adaptive RBF neutral network model presented here can predict Cp distribution efficiently and precisely. 4. Aerodynamic optimization design method based on prediction of Cp distribution is put forward. Aiming at typical characteristics of Cp distribution of airfoil and wing profiles, inverse design and optimization methods are combined to acquire aerodynamic shape tallied with certaincharacteristics of Cp distribution by adaptive RBF neutral network and FA-DE algorithm. It is illustrated that this method can obtain high optimization efficiency and reliability in optimization designs of single-point and multi-points. 5. By the combination of FFD parameterization method, FA-DE optimization algorithm and adaptive neutral network model, aerodynamic design system is constructed,which adopts aerodynamic design method based on prediction of Cp distribution. It is shown that the drag reductions are significant in optimization designs of single-point and multi-points of a certain wide-body aircraft. 6. Adaptive variable cambers of airfoil and wing are investigated. Camber of airfoil trailing-edge based on FFD parameterization method and wing camber along the span are explored. It is shown that better aerodynamic performance can be achieved by variable camber in different flight conditions.