A modified STRUCT model for efficient engineering computations of turbulent flows in hydro-energy machinery

• Published in: The International journal of heat and fluid flow Vol. 85; p. 108628
• Main Authors: Wang, Chaoyue, Wang, Fujun, Li, Chenfeng, Ye, Changliang, Yan, Tingting, Zou, Zhichao
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.10.2020
• Subjects: Hydro-energy machinery; Rotation and curvature; STRUCT; Turbulence model; Turbulence model; Rotation and curvature; STRUCT; Hydro-energy machinery
• ISSN: 0142-727X; 1879-2278
• DOI: 10.1016/j.ijheatfluidflow.2020.108628

•A modified STRUCT turbulence model (MST) is proposed.•A new URANS baseline is employed to improve the sensitivity to rotation and curvature.•A new time-scale ratio is defined to improve the adaptability of damping function to flow fields.•The normalized helicity is introduced to detect the energy backscatter phenomenon.•Efficient engineering computations of turbulence in hydro-energy machinery can be achieved. A modified STRUCT (MST) turbulence model for efficient engineering computations of turbulent flows in hydro-energy machinery is proposed in this paper. The MST model switches between URANS and LES-like modes using a new damping function to adjust the turbulent viscosity. Compared with the original STRUCT method, the modifications are as follows: (1) the BSL k-ω model with the Spalart-Shur correction is chosen as the new baseline to improve the sensitivity to rotation and curvature; (2) a new adaptive time-scale ratio is proposed to avoid the arbitrariness of geometric averaging operation in the original method; (3) the normalized helicity is introduced into the new damping function to detect the energy backscatter phenomenon. Five classical high Reynolds number flow cases are tested. The results show that the turbulent viscosity of the MST model is reasonably reduced in the massively separated regions and LES-like mode is activated, which captures more turbulent vortices and fluctuations on the URANS grids. With high efficiency and robustness, the MST model inherits the advantages of the original STRUCT method and improves the prediction accuracy of the turbulence with rotation and curvature, which enables efficient engineering computations of turbulent flows in hydro-energy machinery.