Highly Resolved LES of a Linear HPT Vane Cascade Using Structured and Unstructured Codes

Abstract

Conventionally meridian, RANS or URANS simulations are used in design. However, their accuracy is not always satisfactory. Higher order methods like direct and large eddy simulation have shown improved results for various case. While traditionally many direct numerical simulation (DNS) and large eddy simulation (LES) studies have been conducted using highly tailored research codes. These codes often use high order methods with both low numerical dissipation and dispersion often in conjunction with structured grids. While these features allow for high efficiency and accuracy they require a considerable effort to obtain appropriate grids. The ongoing rapid increases in available computer power have allowed commercial software packages to also include LES using lower order methods and unstructured grids. These are more flexible and robust to apply but it is not clear how they compare to the higher accuracy research solvers. In this work an initial comparison between a structured research code and an unstructured commercial code is presented. To that end, the paper compares compressible LES conducted with a high-resolution research code and with a commercial code of a statistically 2D linear transonic high pressure turbine vane cascade. The geometry investigated is that of Arts and Rouvroit [1] at isentropic exit Reynolds number approximately 590,000 and isentropic exit Mach number 0.93 with a target inlet turbulence intensity of 4%. The results are also compared to Direct Numerical Simulation results, published by Wheeler et al. [2], for boundary layer and wake development for low levels of freestream inlet turbulence. In the research code inlet turbulence is generated synthetically while the turbulence grid comprised of bars is simulated in the commercial code. While the flow around the blade is in good agreement differences are present in the wake data.

LES of the LS89 cascade: influence of inflow turbulence on the flow predictions

“…Some have used a range of values as Gourdain et al (2010), others have estimated it from available data and presumed features as in Jee et al (2016). Pichler et al (2016) have even simulated the grid located ahead of the cascade in the experiments to obtain the length scale value and characterize the turbulence to use. While the latter was ruled out due to cost, the values used in this paper have been taken from the literature.…”

Future Directions of High Fidelity CFD for Aerothermal Turbomachinery Analysis and Design

“…As noted by LopezMorales (2014), significant advances in High-Order methods over the last 20 years has resulted in robust, efficient and accurate high-order schemes that will support development of new and emerging aircraft roles. The ideas are also valid for internal flows and are the focus of numerous recent studies relevant to the gas turbine industry (Michelassi et al, 2014;Lu and Dawes, 2015;Mangani et al, 2015;Wiart et al, 2015;Rodebaugh et al, 2015;Garal et al, 2015;Marty et al, 2015;Pichler et al, 2016). Various solution algorithm techniques have emerged in support of higher fidelity turbulence modeling (e.g.…”

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.…”