58995 - High-Fidelity Simulations of a High-Pressure Turbine Stage: Effects of Reynolds Number and Inlet Turbulence 

For the first time, we present wall-resolved high-fidelity simulations of high-pressure turbine (HPT) stages at engine-relevant conditions. The HPT stage consists of a stator vane from the VKI LS-89 experiment (T. Arts et al., 1990) and rotor blades from open literature (Kopriva, 2017). The blade/vane count is set as 2:1 to maintain computational periodic boundary conditions, and a sliding interface method is applied at the stator-rotor interface to accurately resolve the development of the stator wakes into the rotating section. A series of cases, with varying vane exit Reynolds numbers (0.57 million to 1.1 million) and inlet turbulence (intensities from 8% to 20% of the inlet mean velocity and length scales from 8% to 20% of the stator axial chord length), have been investigated. To adequately resolve the development of the free-stream turbulence and the blade boundary layers at engine-relevant Reynolds numbers, the total number of grid points goes up to 8.2 billion in the present simulations.

The high-fidelity data generated by the present cases are analyzed to investigate the effects of varying Reynolds numbers and inlet turbulence on the aerothermal behaviors of the stage. While all of the cases have similar mean pressure distribution, the cases with higher Reynolds number show enhanced wall shear stresses and heat fluxes around the vane and rotor blades. Moreover, stronger turbulence fluctuations at the inlet enhance heat transfer on the pressure-side and induce early transition on the suction-side of the vane, although the rotor blade boundary layers are not significantly affected.

In addition to the time-averaged results, phase-lock averaged statistics are also collected to characterize the evolution of the stator wakes in the rotor passages. It is shown that the stretching and deformation of the stator wakes are dominated by the mean flow shear, and their interactions with the rotor blades can significantly intensify the heat transfer on the suction side. Furthermore, we have provided a quantitative analysis of the different mechanisms responsible for the losses of the stages based on the recently proposed entropy analysis (Zhao and Sandberg, GT2019-90126), showing that the losses related to the evolution of the stator wakes is caused by the turbulence production, i.e. the direct interaction between the wake fluctuations and the mean flow shear through the rotor passages.