TY - JOUR
T1 - Low-Reynolds-Number effect on film cooling in Turbines
T2 - Jet-induced vortex structures on cooling effectiveness and aerodynamic loss
AU - Mu, Chengyu
AU - Zhang, Weihao
AU - Wang, Junheng
AU - Huang, Dongming
AU - Jiang, Chiju
N1 - Publisher Copyright:
© 2025 Elsevier Ltd
PY - 2025/9/1
Y1 - 2025/9/1
N2 - To address the challenges involved in film cooling in turbine cascades at low Reynolds numbers (Re), this study investigated the effects of Re on coolant jets in turbine environments using large eddy simulation. Film holes were placed at 25 % of the axial chord length on the suction surface of a high-pressure turbine guide vane, and low Re (0.2 × 105 to 1 × 105) were set to analyze the effects of coolant jet vortices on film cooling efficiency and aerodynamic losses. The results showed that various vortex structures are present downstream of the coolant jet under low Re conditions, including horseshoe vortices, counter-rotating vortex pairs, shear-layer vortices, and hairpin vortices. Shear layer and horseshoe vortices contributed to increasing the lateral coverage of the coolant, thereby enhancing film cooling efficiency. As Re decreased, the relative influence of viscous forces in the flow field increased, suppressing vortex generation. This reduced the diversity of jet-induced vortices, diminished coolant wall attachment, and narrowed the lateral coverage of the coolant. Therefore, as Re decreases, the cooling efficiency of coolant jet decrease. At Re = 1 × 105, the average cooling efficiency downstream of the film cooling hole was 13.1 % higher than that at Re = 0.6 × 105 and 31.9 % higher than that at Re = 0.2 × 105. Losses caused by the coolant jet were mainly concentrated at the interface between the coolant and the mainstream. As Re decreased, the aerodynamic losses caused by the coolant jet increased, at Re = 1 × 105, the total pressure loss coefficient was 23.9 % lower than that at Re = 0.6 × 105 in this region and 63.7 % lower than that at Re = 0.2 × 105. However, owing to the decrease in vortex intensity induced by the coolant, their proportion relative to the total losses decreased. This study provides valuable insights into the influence of Re (particularly low Re) on the vortex structures, cooling efficiency, and aerodynamic losses of coolant jets in turbine guide vanes.
AB - To address the challenges involved in film cooling in turbine cascades at low Reynolds numbers (Re), this study investigated the effects of Re on coolant jets in turbine environments using large eddy simulation. Film holes were placed at 25 % of the axial chord length on the suction surface of a high-pressure turbine guide vane, and low Re (0.2 × 105 to 1 × 105) were set to analyze the effects of coolant jet vortices on film cooling efficiency and aerodynamic losses. The results showed that various vortex structures are present downstream of the coolant jet under low Re conditions, including horseshoe vortices, counter-rotating vortex pairs, shear-layer vortices, and hairpin vortices. Shear layer and horseshoe vortices contributed to increasing the lateral coverage of the coolant, thereby enhancing film cooling efficiency. As Re decreased, the relative influence of viscous forces in the flow field increased, suppressing vortex generation. This reduced the diversity of jet-induced vortices, diminished coolant wall attachment, and narrowed the lateral coverage of the coolant. Therefore, as Re decreases, the cooling efficiency of coolant jet decrease. At Re = 1 × 105, the average cooling efficiency downstream of the film cooling hole was 13.1 % higher than that at Re = 0.6 × 105 and 31.9 % higher than that at Re = 0.2 × 105. Losses caused by the coolant jet were mainly concentrated at the interface between the coolant and the mainstream. As Re decreased, the aerodynamic losses caused by the coolant jet increased, at Re = 1 × 105, the total pressure loss coefficient was 23.9 % lower than that at Re = 0.6 × 105 in this region and 63.7 % lower than that at Re = 0.2 × 105. However, owing to the decrease in vortex intensity induced by the coolant, their proportion relative to the total losses decreased. This study provides valuable insights into the influence of Re (particularly low Re) on the vortex structures, cooling efficiency, and aerodynamic losses of coolant jets in turbine guide vanes.
KW - Aerodynamic Loss
KW - Coolant Jet
KW - Film cooling
KW - Large Eddy Simulation
KW - Low Reynolds Numbers
KW - Turbine Guide Vane
KW - Vortex Structure
UR - https://www.scopus.com/pages/publications/105003802948
U2 - 10.1016/j.applthermaleng.2025.126325
DO - 10.1016/j.applthermaleng.2025.126325
M3 - 文章
AN - SCOPUS:105003802948
SN - 1359-4311
VL - 274
JO - Applied Thermal Engineering
JF - Applied Thermal Engineering
M1 - 126325
ER -