The intricate structure of turbulent flow fields strongly influences turbulent flame behavior. To improve the accuracy of turbulent combustion simulations in complex scenarios, this study evaluates the performance of an improved Gao–Yong (G–Y) turbulence model in non-premixed flames. The G–Y model enhances its capability to capture complex flow features by incorporating the first-order statistical characteristics of the turbulent fluctuation, which is the drift velocity. By integrating the flamelet-generated manifold (FGM) method with a low-dimensional combustion flow pattern modeling strategy, a high-accuracy and engineering-oriented simulation framework is established. The improved G–Y model is implemented in Ansys Fluent via user-defined functions (UDFs) and validated against the Sandia CO/H2/N2 (chnA) syngas flame and the Sydney swirling methane (SM1) flame. For the chnA flame, the G–Y/FGM framework achieves predictive accuracy comparable to that of conventional models, confirming the correctness of the UDF-based implementation. In the SM1 bluff-body swirl flame, however, the improved G–Y model more accurately reconstructs the bluff-body recirculation zone and the necking flame. Detailed analysis shows that conventional models overpredict the turbulent viscosity μt by inferring excessively large turbulent length scales in the bluff-body recirculation zone, whereas the improved G–Y model predicts a more realistic length scale and lower μt, enabling a more faithful capture of the low-Re recirculating flow behind the bluff body. This accurate reproduction of the bluff-body recirculation region indicates that the G–Y/FGM framework offers clear advantages for modeling swirl-stabilized non-premixed flames and provides useful guidance for improving Reynolds-averaged Navier–Stokes-based approaches in similar engineering applications.
Sun et al. (Sun,) studied this question.