Effect of inflow swirl on the vane endwall aerothermal performance with endwall misalignment at transonic condition

Effect of turbine inlet swirl condition (swirl intensity and orientation) on endwall heat transfer performance with combustor-turbine misalignment at transonic condition was numerically investigated, and coolant injection from combustor-turbine interface was also considered. Simulations with two mainstream swirl numbers (SN) of 0.6 and 1.0, two swirl orientations, two endwall misalignment modes and slot coolant injection were conducted by solving the three-dimensional RANS equations coupled with the Reynolds Stress Turbulence Model (RSM). Computational results indicate that for anticlockwise swirled condition, the averaged Nu number of the high heat transfer attachment region upstream of the leading edge decreases from 4400 to 3100 with the increasing SN from 0.6 to 1.0. Negative incidence is caused at hub followed by a low heat transfer region at pressure side junction. Enhanced horseshoe vortex and mainstream direct attachment enlarge the hot ring (uncooled area around the vane leading edge) when SN = 0.6. As for clockwise swirled condition, positive incidence is caused at hub and can have some effect on reducing the passage crossflow. The pressure side low heat transfer region enlarges under aligned mode but shrinks under misaligned mode compared with anticlockwise condition. Averaged Nu distributes more uniformly along axial direction. The hot ring can only be observed when SN = 0.6 under misaligned condition. For aligned mode, endwall heat transfer at x/C-ax < 1.0 is 30-50% higher for SN = 0.6 than SN = 1.0. When coolant is introduced at the combustor-turbine interface, the heat transfer strength at attachment region is largely reduced. Under aligned condition, coolant tends to eject out between two swirl cores. The majority of the coolant is constrained in the recirculation region by cavity vortices under misaligned mode. Averaged Nu number at the attachment region is 4450 and 3600 under aligned and misaligned mode, respectively. But the averaged Nu number downstream of the passage throat is less than 2000 and distributes uniformly. (C) 2019 Elsevier Ltd. All rights reserved.