用低精度模拟加速机翼优化,大幅减少高精度计算次数。
Optimization-Embedded Active Multi-Fidelity Surrogate Learning for Multi-Condition Airfoil Shape Optimization
- 结合低精度模拟与自适应高精度验证,动态分配计算资源。
- 巡航效率提升41.05%,起降升力提升20.75%,仅需14.78%的高保真评估。
- 适合追求高效气动设计优化的研究者或工程团队。
为降低高保真计算流体力学(CFD)成本,同时保持RANS一致的气动性能指标,本文提出一种主动多保真代理学习框架,用于多工况机翼形状优化。该框架将低保真度的XFOIL评估作为低成本特征输入,结合高斯过程回归转移模型与不确定性触发采样;当预测不确定性超过阈值时,才进行稀疏的RANS模拟,并强制对精英个体进行高保真验证。同时,种群在每轮进化后重新评估,防止基于过时代理状态的选择偏差。针对雷诺数$Re=6\times10^6$下的两工况问题(巡航:α=2°,最大化$E=L/D$;起降:α=10°,最大化$C_L$),采用12参数CST表示法进行优化。每个工况独立构建多保真代理模型,实现解耦优化。最终优化设计相较第一代最优个体,巡航效率提升41.05%,起降升力提升20.75%。在整个优化过程中,巡航与起降阶段仅分别需14.78%和9.5%的高保真评估量,显著低于固定自动化RANS工作流的基准。
原文摘要 · Abstract (English)
Active multi-fidelity surrogate modeling is developed for multi-condition airfoil shape optimization to reduce high-fidelity CFD cost while retaining RANS-consistent aerodynamic metrics. The framework couples a low-fidelity-informed Gaussian process regression transfer model with uncertainty-triggered sampling and a synchronized elitism rule embedded in a hybrid genetic algorithm. Low-fidelity XFOIL evaluations provide inexpensive features, while sparse RANS simulations are adaptively allocated when predictive uncertainty exceeds a threshold; elite candidates are mandatorily validated at high fidelity, and the population is re-evaluated to prevent evolutionary selection based on outdated fitness values produced by earlier surrogate states. The method is demonstrated for a two-point problem at $Re=6\times10^6$ with cruise at $α=2^\circ$ (maximize $E=L/D$) and take-off at $α=10^\circ$ (maximize $C_L$) using a 12-parameter CST representation. Independent multi-fidelity surrogates per flight condition enable decoupled refinement. The optimized design improves cruise efficiency by 41.05% and take-off lift by 20.75% relative to the best first-generation individual. Over the full campaign, RANS evaluations were required for only 14.78% and 9.5% of the condition-specific candidate evaluations at cruise and take-off, respectively. These percentages quantify the reduction in high-fidelity usage relative to the fixed automated RANS workflow adopted as the high-fidelity reference in this study.
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