High Fidelity Spectral/hp Element Methods for Turbomachinery

Abstract

The high order spectral/hp element methods implemented in the software framework Nektar++ are investigated for scale-resolving simulations of LPT profiles. There is a growing demand for high fidelity methods for turbomachinery to move towards numerical “experiments”. The study contributes at building best practices for the use of emerging high fidelity spectral element methods in turbomachinery predictions, with focus on the numerical details that are specific of these classes of methods. For this reason, the T106A cascade is used as a base reference application because of availability of data from previous investigations. The effects of polynomial order (p-refinement), spanwise domain extent and spanwise Fourier planes are considered, looking at flow statistics, convergence and sensitivity of the results. The performance of the high order spectral/hp element method is also assessed through validation against experimental data at moderately high Reynolds number. Thanks to the reduced computational cost, the proposed methods will have a strong impact in turbomachinery, paving the way to its use for design purposes and also allowing for a deeper understanding of the flow physics.

DNS of secondary flows over oscillating low-pressure turbine using spectral/hp element method

“…See Ref. [40] for more details about the dimensionless geometrical parameters of T106 LPT blade. The numerical investigations of the T106A turbine were performed at moderate Reynolds number (𝑅𝑒 = ) of 51,800.…”

“…Besides, as discussed by Cassinelli et al [40] using 96 Fourier planes in span direction provides an appropriate degree of freedom (DOF) and it highly accurate to capture the details of flow unsteadiness over LPT blades. Therefore, Nz=96 is selected in the span direction for further simulations.…”

The Current State of High-Fidelity Simulations for Main Gas Path Turbomachinery Components and Their Industrial Impact

“…Garai et al [30] performed DNS of a linear T106D cascade and reported that the method was able to capture the main features of the flow, and attributed subtle differences between DNS and the reference data to the fact that freestream turbulence was not included in the simulation. In the DNS of the T106A cascade by Cassinelli et al [9], again no inflow turbulence or wakes were included. The effect of the polynomial order used, the spanwise domain size and the spanwise resolution were investigated and results were compared with experimental data up to exit Reynolds number 160,000, showing excellent agreement.…”

Eddy Resolving Strategies in Turbomachinery and Peripheral Components

“…3. Note, the purple line shows the exciting potential of high-order methods and hence the re-emergence of interest in such approaches in many applications including turbomachinery [8][9][10][11][12]. Flow Classification.…”