基于贝叶斯优化的CNN-BiLSTM飞机尾涡预测方法

Aircraft wake vortex prediction method based on bayesian optimization with CNN-BiLSTM

  • 摘要: 针对传统尾涡反演模型在复杂大气条件下对尾涡演化过程的预测精度受限,以及单一机器学习方法对尾涡特征识别不充分的问题,提出一种基于贝叶斯优化的卷积神经网络(convolutional neural network, CNN)与双向长短期记忆网络(bidirectional long short-term memory, BiLSTM)融合的飞机尾涡预测方法。将尾涡演化过程建模为多输入多输出的时间序列回归问题,构建CNN-BiLSTM时序回归模型,并采用贝叶斯优化实现模型关键超参数的自适应寻优。此外,通过采用蒙特卡洛丢弃法(Monte Carlo dropout, MC Dropout)实现尾涡概率预测与不确定性量化。实验结果表明,在独立测试集上,所提CNN-BiLSTM模型相较于CNN-长短期记忆网络(long short-term memory, LSTM)、BiLSTM、LSTM、CNN及开尔文-亥姆霍兹(Kelvin-Helmholtz, K-H)模型表现出更高的预测精度,平均误差和均方根误差分别最大降低12%~16%和17%~21%;同时,德国航空航天中心DLR水洞实验数据验证了该模型具出良好的泛化能力。基于MC Dropout方法构建的95%预测区间可有效表征尾涡环量与高度演化的不确定性,在独立测试集中,环量和高度的预测空间对实际值的覆盖率分别为62.10%和59.34%。此方法可有效提升尾涡演化预测的精度,为动态化尾流间隔的制定与实施提供技术支撑。

     

    Abstract: This paper proposes a Bayesian optimization-based CNN-BiLSTM method is proposed for predicting aircraft wake vortex evolution under complex atmospheric conditions. Traditional wake vortex inversion models suffer from limited predictive accuracy in such environments, and single machine learning methods often fail to adequately capture the essential features of wake vortex evolution. In this work, we formulate wake vortex evolution as a multi-input multi-output time-series regression problem and develop a hybrid model that integrates convolutional neural networks (CNN) and bidirectional long short-term memory (BiLSTM) networks. Bayesian optimization is employed to adaptively tune the key hyperparameters of the model, and Monte Carlo dropout (MC Dropout) is introduced to achieve probabilistic wake vortex prediction and quantify predictive uncertainty. Experiments on an independent test set show that the proposed CNN-BiLSTM model consistently outperforms CNN-LSTM, BiLSTM, LSTM, CNN, and the Kelvin-Helmholtz (K-H) model, reducing the mean absolute error and root mean square error reaching 12%~16% and 17%~21%, respectively. Additional validation using DLR water tunnel experimental data demonstrates the good generalization capability of the proposed model. Furthermore, the 95% prediction intervals constructed based on MC Dropout can effectively characterize the uncertainty in the evolution of wake vortex circulation and height, with prediction interval coverage probabilities of 62.10% and 59.34% on the independent test set, respectively. These results indicate that the proposed method can effectively improve the accuracy of wake vortex evolution prediction and provide technical support for the formulation and implementation of dynamic wake separation procedures.

     

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