用神经网络融合仿真与实测数据,提升气动分析精度。
Fusing CFD and measurement data using transfer learning
- 用迁移学习构建非线性模型,融合高分辨率仿真与稀疏高精度实测数据。
- 在非线性区域生成更符合物理规律的解,相比传统方法显著提升精度。
- 可推广至复杂网络结构,适用于飞行设计、结构评估等场景。
飞机设计中的气动分析常依赖不同精度与空间分辨率的方法,各有优劣。为有效结合优势,需发展数据融合模型。现有方法多基于主成分分析(POD),为线性方法。本文提出一种基于神经网络的非线性融合方法,通过迁移学习结合仿真与实测数据。首先在仿真数据上训练网络以学习分布量的空间特征;其次在实测数据上进行迁移学习,仅微调部分参数以校正仿真与实测间的系统性偏差。该方法应用于多层感知机架构,在非线性区域生成更符合物理规律的解,显著优于基于POD的传统方法。此外,模型可提供任意流动条件下的解,适用于飞行力学设计、结构尺寸确定及认证。所提训练策略通用性强,未来可拓展至更复杂的神经网络结构。
原文摘要 · Abstract (English)
Aerodynamic analysis during aircraft design usually involves methods of varying accuracy and spatial resolution, which all have their advantages and disadvantages. It is therefore desirable to create data-driven models which effectively combine these advantages. Such data fusion methods for distributed quantities mainly rely on proper orthogonal decomposition as of now, which is a linear method. In this paper, we introduce a non-linear method based on neural networks combining simulation and measurement data via transfer learning. The network training accounts for the heterogeneity of the data, as simulation data usually features a high spatial resolution, while measurement data is sparse but more accurate. In a first step, the neural network is trained on simulation data to learn spatial features of the distributed quantities. The second step involves transfer learning on the measurement data to correct for systematic errors between simulation and measurement by only re-training a small subset of the entire neural network model. This approach is applied to a multilayer perceptron architecture and shows significant improvements over the established method based on proper orthogonal decomposition by producing more physical solutions near nonlinearities. In addition, the neural network provides solutions at arbitrary flow conditions, thus making the model useful for flight mechanical design, structural sizing, and certification. As the proposed training strategy is very general, it can also be applied to more complex neural network architectures in the future.
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