THE EFFECT OF REYNOLDS NUMBER ON THE FLOW AROUND THE T106C VERY HIGH LIFT LOW PRESSURE TURBINE LINEAR CASCADE

Abstract

Low pressure turbines flows are highly dependent on the boundary layer transition and laminar separation because of the low Reynolds number environment and the high blade loading. In the case of a laminar separation, the transition of the shear layer is triggered by instabilities and a recirculation zone appears near the wall. This phenomenon is known as a laminar separation bubble. Depending on its characteristics, the laminar separation bubble can be categorized as open, long or short. Some experiments performed at the von Karman Institute investigated the effect of Reynolds number on the topology of the separation bubble over the suction side of the very high lift T106C blade. In a previous work, the authors have performed a high fidelity simulation on this configuration at the Reynolds number of 100 000 and shown some discrepancies with the experiments. In order to deepen this study, three others simulations at three higher Reynolds numbers have been performed. Thus a wider comparison between QDNS (Quasi Direct Numerical Simulation) and the experiments is proposed in this paper. Moreover, the simulations give a more detailed descriptions of the effect of Reynolds number on the laminar separation bubble. Finally, we discuss the flow predicted by RANS simulations by making a comparison with the flow computed with the QDNS with the intention of validating the γ-Re fθt transition model on low pressure turbine cases.