基于条件扩散模型的火箭气动外形快速设计方法

Rapid design method of rocket aerodynamic shape based on conditional diffusion model

  • 摘要: 气动设计在火箭设计中扮演着至关重要的角色,为了缩短火箭气动外形设计周期,减少繁琐的迭代优化过程,提出了一种火箭气动外形生成式快速反设计方法。采用图像对火箭气动外形进行几何表征,构建基于条件扩散模型的火箭气动外形生成模型、基于卷积神经网络的火箭气动性能快速预测模型和火箭设计参数判别模型。首先使用气动外形生成模型,以气动性能指标作为输入,快速生成大量图像化的火箭气动外形方案;然后,再使用预测模型筛选出满足输入指标的设计方案;最后,通过设计参数判别模型提取优选方案的参数,并对其进行验证,或将其转化为三维外形。数据集共包含165 000组气动外形及对应的气动性能,以典型工况下轴向力系数CA和法向力系数CN作为模型输入。采用典型轴对称布局火箭对模型进行了测试,模型在100个图像化的火箭气动外形预测中耗时约30 s。经验证,优选外形方案轴向力系数CA偏差为0.0827%,法向力系数CN偏差为0.7124%,说明本文方法对火箭气动外形进行设计具有可行性,可为相关研究提供新的思路。最后,本文分析了交叉注意力机制对模型的影响,可为模型后续优化提供参考。

     

    Abstract: Aerodynamic design plays a vital role in rocket design. To expedite the design process of rocket aerodynamic shapes and minimize the tedious iterative optimization, we propose a generative rapid inverse design method for rocket aerodynamic shape design. This method uses image-based geometric characterization of rocket aerodynamic shapes and integrates three main components: a rocket aerodynamic shape generation model based on a conditional diffusion model, a rocket aerodynamic performance rapid prediction model based on a convolutional neural network, and a rocket design parameter discrimination model. This method operates in three consecutive steps. First, it uses the aerodynamic shape generation model and aerodynamic performance indicators as input to efficiently generate a large number of imaged rocket aerodynamic shape schemes. Second, the prediction model is used to select the design scheme that meets the input indicators. Third, the selected scheme is verified after extracting parameters through the design parameter discrimination model or converted into a three-dimensional shape. The model is validated using a data set containing 165,000 sets of aerodynamic shapes and corresponding aerodynamic performance for a typical axisymmetric rocket. Taking the axial force coefficient CA and the normal force coefficient CN under typical working conditions as input, the model only takes about 30 seconds to generate 100 rocket aerodynamic shape images. The optimal design exhibits remarkable accuracy, with deviations of only 0.0827% and 0.7124% for the axial and normal force coefficients, respectively. The results demonstrate the potential of the proposed method for rocket aerodynamic shape design. In addition, the influence of the cross-attention mechanism on the model is analyzed, providing valuable insights for the future model optimization.

     

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