High-Fidelity Simulations of a Linear HPT Vane Cascade Subject to Varying Inlet Turbulence

Abstract

The effect of inflow turbulence intensity and turbulence length scales have been studied for a linear high-pressure turbine vane cascade at Reis = 590,000 and Mis = 0.93, using highly resolved compressible large-eddy simulations employing the WALE turbulence model. The turbulence intensity was varied between 6% and 20% while values of the turbulence length scales were prescribed between 5% and 20% of axial chord. The analysis focused on characterizing the inlet turbulence and quantifying the effect of the inlet turbulence variations on the vane boundary layers, in particular on the heat flux to the blade. The transition location on the suction side of the vane was found to be highly sensitive to both turbulence intensity and length scale, with the case with turbulence intensity 20% and 20% length scale showing by far the earliest onset of transition and much higher levels of heat flux over the entire vane. It was also found that the transition process was highly intermittent and local, with spanwise parts of the suction side surface of the vane remaining laminar all the way to the trailing edge even for high turbulence intensity cases.

LES and RANS Analysis of the End-Wall Flow in a Linear LPT Cascade: Part I — Flow and Secondary Vorticity Fields Under Varying Inlet Condition

“…At all walls (blade and end-walls) adiabatic no slip boundary conditions have been used whereas the inlet was specified through a Riemann invariant boundary condition, and at the outlet a zonal characteristic boundary condition was employed [18]. For cases where inlet turbulence was prescribed a digital filtering technique has been used that is based on [19,20] as discussed in more detail in Pichler et al [21]. Statistical averaging is performed in time and about the symmetry plane (center plane).…”

Large-Eddy Simulation and RANS Analysis of the End-Wall Flow in a Linear Low-Pressure Turbine Cascade, Part I: Flow and Secondary Vorticity Fields Under Varying Inlet Condition

“…For cases where inlet turbulence was prescribed a digital filtering technique has been used that is based on [19,20] as discussed in more detail in Pichler et al [21]. Statistical averaging is performed in time and about the symmetry plane (center plane).…”

“…This behaviour might indicate an intermittent separation (e.g. [21]). The RANS clearly does not separate, however, the skin friction does not grow to values comparably to the LES.…”

On the Influence of High Turbulence on the Convective Heat Flux on the High-Pressure Turbine Vane LS89

“…Given the significant literature dedicated to predicting the heat transfer distribution of MUR235 (e.g. [15][16][17][18][19][20][21][22]), this test has been selected to be compared with the new result: TUR062. The heat transfer distributions are shown together with a Mach number prediction for M is,out = 0.93 in Figure 4.…”

“…A thorough aero-thermal database was developed at the von Karman Institute (VKI) on a high-pressure inlet guide vane [13] which is still today extensively used for numerical studies [14][15][16][17][18][19][20][21][22]. The major difficulty in these simulations lies in the inlet freestream turbulence generation: the integral length scale size is limited by the available computational resources; lower values lead higher turbulent dissipation and result in a mismatch with the experiments, especially for the stagnation and transition region.…”