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,以典型工况下轴向力系数CA和法向力系数CN作为输入,快速生成大量图像化的火箭气动外形方案;然后,再使用气动性能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。本文数据集共包含165 000组气动外形及对应的气动性能。采用典型轴对称布局火箭对气动性能预测模型进行了测试,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%,这说明采用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思路。最后本文还分析了交叉注意力机制对模型的影响,发现其并不能对模型精度产生优化效果,此探索研究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 tedious iterative optimization, this study proposes a generative rapid inverse design method for rocket aerodynamic shapes. This method employs image-based geometric characterization of rocket aerodynamic shapes and integrates three main components: a conditional diffusion model-based rocket aerodynamic shape generation model, a convolutional neural network (CNN)-based rocket aerodynamic performance rapid prediction model, and a rocket design parameter discrimination model. The aerodynamic shape generation model takes the axial force coefficient CA and the normal force coefficient CN under typical operating conditions as inputs to rapidly generate numerous imaged rocket aerodynamic shape schemes. Subsequently, the performance prediction model screens the designs that meet the specified targets. Finally, the design parameter discrimination model extracts parameters from the selected scheme for validation or converts it into a three-dimensional shape. The dataset used in this study contains 165000 sets of rocket aerodynamic shapes and their corresponding aerodynamic performance. The prediction model was tested on a typical axisymmetric rocket configuration, requiring only about 30 seconds to predict 100 imaged rocket aerodynamic shapes. The optimal design exhibits remarkable accuracy, with deviations of only 0.0827% and 0.7124% for the axial and normal force coefficients, respectively. These results demonstrate the feasibility of the proposed method for rocket aerodynamic shape design and offer new insights for related research. Additionally, this paper analyzes the impact of the cross-attention mechanism and finds that it does not optimize model accuracy; this exploratory finding provides a reference for subsequent model optimization.

     

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