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

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 C_A and the normal force coefficient C_N 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.