Significant advances in the field of computational fluid dynamics (CFD) have ensured its promise as a powerful tool in designing a variety of engineering applications. There is, however, a need to improve and advance large Eddy simulation (LES) capabilities in the area of modeling of gas turbines and assess the accuracy of predictions resulting from LES against validation data.&nbsp;&nbsp;LES is a promising approach for capturing the laminar/turbulent transition process in a low-pressure turbine (LPT). In a previous study, we utilized LES to model the flow field over the VSPT (Variable Speed Power Turbine)&nbsp;&nbsp;blade and successfully captured characteristic features of&nbsp;&nbsp;separation/transition on the suction side at both the cruise (positive incidence) and take-off conditions (negative incidence) [1] and as well, simulated the effect of free-stream turbulence (FST) on the separation [2]. The predicted pressure loading profiles agreed well with the experimental data for both a high- and a low FST case.&nbsp;In this paper, we will present the wake profiles resulting from our previous computations for a range of FSTs.&nbsp;It was noted that although the predicted wake profile for the low FST case matched the experimental data [1] at the higher-FST case the wake wider and both were displaced laterally when compared to the experimental measurements.&nbsp;&nbsp;In our investigation of the causes of the said discrepancies we have identified&nbsp;important physics which could strongly influence the predicted wake profile. We will address key questions such as how the numerics, mesh density in addition to the FST level affect the wake prediction. We&nbsp;will utilize the spectral analysis and investigate the dynamic behavior of the wake as influenced by the flow variations in locations upstream.

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

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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