On the relevance of turbulent structures resolution for cross-flow in a helical-coil tube bundle

Helical-coil steam generators are being adopted in a number of advanced nuclear reactor designs because of their increased heat transfer efficiency and compactness. Due to the limited operational experience and the expected high cost of dedicated experiments, it is imperative to demonstrate the modeling capability. Computational fluid dynamics is ideally suited for this problem, due to its high resolution and accuracy. However, traditional low-cost URANS turbulence models have shown limited applicability for cross-flow in helical tube bundles. On the other hand, LES methods provide high-accuracy and high-fidelity data with prohibitively high computational cost for design use. In this work, the recently proposed hybrid second-generation model STRUCT is compared to classic URANS turbulence formulations against high-fidelity LES simulations. The STRUCT model produces accurate predictions for all relevant quantities, demonstrating high potential for reproducing helical-coil tube bundle flow phenomena accurately, at an affordable computational cost.