Direct Numerical Simulations of a High-Pressure Turbine Vane

Abstract

In this paper, we establish a benchmark data set of a generic high-pressure (HP) turbine vane generated by direct numerical simulation (DNS) to resolve fully the flow. The test conditions for this case are a Reynolds number of 0.57 × 106 and an exit Mach number of 0.9, which is representative of a modern transonic HP turbine vane. In this study, we first compare the simulation results with previously published experimental data. We then investigate how turbulence affects the surface flow physics and heat transfer. An analysis of the development of loss through the vane passage is also performed. The results indicate that freestream turbulence tends to induce streaks within the near-wall flow, which augment the surface heat transfer. Turbulent breakdown is observed over the late suction surface, and this occurs via the growth of two-dimensional Kelvin–Helmholtz spanwise roll-ups, which then develop into lambda vortices creating large local peaks in the surface heat transfer. Turbulent dissipation is found to significantly increase losses within the trailing-edge region of the vane.

Linear Stability Prediction of Vortex Structures on High Pressure Turbine Blades

“…These angular frequencies were extracted using a time-correlation method and are highlighted in Figure 3a (red symbols ), showing good agreement with the most unstable modes from temporal linear stability analysis. The phase speed of those modes is found to be about 40% of the BL edge velocity, which corresponds as well to the phase speed of instability waves discovered in the DNS-flowfield by [2].…”

“…The discretisation in the spanwise direction was done by applying a Fourier method using the FFTW3 library. More details regarding the DNS methodology are provided by [2,3].…”

“…Using this approach, Wheeler et al [2] performed a fully resolved DNS for an HPT vane with a Reynolds number of 570,000 and a Mach number of 0.9 (both at reference conditions at the vane exit). The inlet turbulence intensity was set to 3.5%.…”

“…A notable feature is the upstream-travelling waves originating from the trailing edge (TE), which appears to interact with Kelvin Helmholtz (KH) instabilities. An instantaneous snapshot in Figure 1b shows vortex structures and a breakdown into turbulence in the area of interest near the TE, where the main linear instabilities are expected [2]. Wall-normal velocity profiles are extracted and interpolated onto a Chebychev grid.…”

Transition Models for Turbomachinery Boundary Layer Flows: A Review

“…As with natural transition, mean-flow turbulence accelerates and controls the growth of the Kelvin-Helmholtz vortices and makes the process less sensitive to other disturbances. The mechanisms of separation-induced transition were studied by experiments, by LES and by DNS by many researchers [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Generally, the free shear layer, once sufficiently turbulent, reattaches forming a separation bubble.…”