基于并行多点采样策略的串列叶栅多目标优化设计及分析

To improve the design quality of large-turning tandem cascades, an automatic multi-objective optimization system of tandem cascades was developed based on an improved particle swarm optimization algorithm, improved parallel multi-points infill criteria of Kriging model and physical programming. The system can achieve multi-objective optimization design of tandem cascade on design and off design incidence angle. In the multi-objective optimization system, to greatly reduce the computational scale of multi-objective optimization problems, the physical programming method is applied to transform the multi-objective optimization design problem into a single objective optimization problem based on the designer's experience, and improved parallel multi-points infill criteria of Kriging model is used to generate multiple samples that are parallelly evaluated by numerical simulations per optimization cycle. The parallel multi-objective optimization system is validated by realizing the multi-objective of a large-turning tandem cascade. For the optimized tandem cascade, the static pressure ratio is higher and the total pressure loss coefficient is smaller at all incidence angle conditions. At inlet Mach number of 0.7, when incidence angle is -6° and 3°, the total pressure loss coefficient is respectively decreased by 21% and 35%, which proved that the parallel multi-objective optimization system has a good application value. Besides, the effects of five geometric parameters, such as camber ratio (TR), chord ratio (CR), axial overlap (AO), percent pitch (PP) and incidence angle of the rear airfoil (KBB) on the design and off design performance of tandem cascades were studied in detail. Results indicate that tandem cascades with a high PP (about 0.9) and a negative KBB (about -6°) can realize good flow performances on design incidence angle. And a smaller load of front airfoil can improve the flow characteristics of tandem cascades off design incidence angle and increase the stable operation range.