Neural Network-Based Optimization for RANS Simulations of Flow Field in Fuel Bundle Channels with Spacer Grid
摘要
The flow region downstream of the spacer grid in a Pressurized Water Reactor (PWR) fuel rod bundle channel is characterized by intense shear effects and vortex structures, which significantly enhance lateral mixing and intensify heat transfer between the fuel rods and the coolant. However, due to the limitations of the Reynolds-averaged Navier-Stokes (RANS) equations, the computational accuracy of the flow field downstream of the spacer grid is insufficient. To achieve more accurate Computational Fluid Dynamics (CFD) simulation results, this paper proposes a neural network-based turbulence model optimization framework. By utilizing velocity data obtained from Particle Image Velocimetry (PIV) measurements of the fine-scale flow field downstream of the spacer gid, a Particle Swarm Optimization (PSO)-optimized turbulence closure model is developed. This optimized model is then embedded into RANS simulations to enhance the accuracy of the predicted velocity field in the downstream region of the fuel rod bundle channel. The results show that the proposed method significantly improves the RANS model’s performance in complex flow fields, yielding a velocity field that closely matches experimental measurements. The approach demonstrates the potential of coupling RANS and neural network models to improve computational performance in challenging flow scenarios.