用神经微分方程建模激光点火火箭燃烧,速度提升数个量级。
Generative prediction of laser-induced rocket ignition with dynamic latent space representations
- 用卷积自编码器压缩流场,再用神经微分方程学习动态演化。
- 预测一次点火耗时降低多个数量级,支持快速参数探索。
- 适合需要实时仿真与不确定性分析的复杂燃烧系统研究者。
激光点火火箭发动机的高保真模拟因涉及湍流燃料氧化剂混合、激光能量沉积及高速火焰发展而极为耗时,且设计空间大,主要由激光工作条件和靶点位置决定。为实现快速探索与不确定性量化,本文提出一种数据驱动的代理建模方法,结合卷积自编码器(cAEs)与神经微分方程(neural ODEs)。cAE将高维流场压缩至低维隐空间,神经ODE在该空间中学习系统的时序动态。模型训练后,可从初始条件与指定输入快速生成时空预测。通过替代完整时间演化模拟,单次点火预测成本降低数个数量级,实现输入参数空间的高效探索。此外,由于输出为时空场,模型物理合理性更易评估。该方法标志着代理模型向复杂多物理场系统迈进的重要一步,推动激光点火火箭燃烧室向实时数字孪生发展。
原文摘要 · Abstract (English)
Accurate and predictive scale-resolving simulations of laser-ignited rocket engines are highly time-consuming because the problem includes turbulent fuel-oxidizer mixing dynamics, laser-induced energy deposition, and high-speed flame growth. This is conflated with the large design space primarily corresponding to the laser operating conditions and target location. To enable rapid exploration and uncertainty quantification, we propose a data-driven surrogate modeling approach that combines convolutional autoencoders (cAEs) with neural ordinary differential equations (neural ODEs). The present target application of an ML-based surrogate model to leading-edge multi-physics turbulence simulation is part of a paradigm shift in the deployment of surrogate models towards increasing real-world complexity. Sequentially, the cAE spatially compresses high-dimensional flow fields into a low-dimensional latent space, wherein the system's temporal dynamics are learned via neural ODEs. Once trained, the model generates fast spatiotemporal predictions from initial conditions and specified operating inputs. By learning a surrogate to replace the entirety of the time-evolving simulation, the cost of predicting an ignition trial is reduced by several orders of magnitude, allowing efficient exploration of the input parameter space. Further, as the current framework yields a spatiotemporal field prediction, appraisal of the model output's physical grounding is more tractable. This approach marks a significant step toward real-time digital twins for laser-ignited rocket combustors and represents surrogate modeling in a complex system context.
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