Session: 35-02 High-Fidelity CFD

Paper Number: 82109

82109 - High-Fidelity Simulations of the Flow Around T106C Cascade at Low Reynolds Number: The Effects of Freestream Turbulence and Stagger Angle 

Flows in low-pressure turbines are characterized by low Reynolds number and high blade loading. Therefore, these flows are highly dependent on the effect of laminar-turbulent transition of boundary layer and laminar boundary layer separation.  Despite improvements in transition models, RANS simulations still have difficulty predicting low-pressure turbines performance. Experiments and high-fidelity simulations are thus essential to study flows in low-pressure turbines. This study aims to use high-fidelity simulations to investigate the effect of freestream turbulence intensity and stagger angle on the flow around a low pressure turbine blade.
This study focuses on the flow around the T106C low-pressure turbine cascade for a low Reynolds number - 100 000 - and a moderately low turbulence intensity - 0.8% -.  This cascade has been experimentally tested at the von Karman Institute in the framework of the European TATMo program. For this study, three direct numerical simulations have been performed. These simulations have been performed in an iterative way in order to understand the differences observed in the literature between simulations and experiments. A first simulation is performed without freestream turbulence. This first simulation reveals the expected physics of separation and transition of the boundary layer for these flow conditions. However, the time-averaged quantities extracted from this simulation do not match exactly with the experiment. In order to understand and reduce this difference, a second one is performed with a modified stagger angle, and then a third one is performed with a synthetic turbulence injection (SEM) at the inlet plane. First, the differences between the simulations and the experiments are discussed by comparing the time-averaged quantities. Then, an in-depth study is conducted on the simulations data to understand the effect of freestream turbulence and stagger angle on the boundary layer development, transition and separation. To achieve this, several quantities are compared between the three simulations: integral losses, boundary layer integral quantities, integral length scales and power spectral densities.

Presenting Author: Antoine Dufau Safran Aircraft Engines

Presenting Author Biography: Antoine Dufau is a PhD student working on simulations of the boundary layer transition in low-pressure turbines.

Authors:

Antoine Dufau Safran Aircraft Engines
Julien Marty ONERA
Estelle Piot ONERA
Daniel Man Safran Aircraft Engines