Improved Prediction of Losses With Large Eddy Simulation in a Low-Pressure Turbine

Abstract

There is a need to improve predictions of losses resulting from large eddy simulations (LES) of low-pressure turbines (LPT) in gas turbines. This may be done by assessing the accuracy of predictions against validation data and understanding the source of any inaccuracies. LES is a promising approach for capturing the laminar/turbulent transition process in a LPT. In previous studies, the authors utilized LES to model the flow field over a Variable Speed Power Turbine (VSPT) blade and successfully captured characteristic features of separation/reattachment and transition on the suction side at both the cruise (positive incidence) and take-off conditions (negative incidence) and as well, simulated the effect of freestream turbulence (FST) on those phenomena. The predicted pressure loading profiles agreed well with the experimental data for both a high and a low FST case at a Reynolds number of Reex = 220,000. In this paper, we present wake profiles resulting from computations for a range of FST values. Although the predicted wake profiles for the lowest FST case (Tu = 0.5%) matched the experimental data, at higher FST (Tu = 10-15%,) the wake was wider than the experimentally measured wake and for both cases were displaced laterally when compared to the experimental measurements. In our investigation of the causes of the said discrepancies we have identified important effects which could strongly influence the predicted wake profile. Predicted losses were improved by assuring the validity of the flow solution.

A New Type of WENO Scheme for Large Eddy Simulation of Turbomachinery Flows

“…Due to the limitations of turbulence models and transition models [9], traditional Reynolds-Averaged Navier-Stokes (RANS) methods are gradually becoming insufficient to meet the needs of designers. With the continuous improvement in computer performance, applying LES methods in engineering computations has become feasible [10][11][12]. Therefore, developing LES numerical simulation programs with higher computational accuracy and better universality is of great Disclaimer/Publisher's Note: The statements, opinions, and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s).…”