15th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
Authors
Abstract
Turbomachinery flows are highly turbulent and prone to different types of instabilities. These flow unsteadiness affect the aerodynamic performance of the machines mainly when approaching off-design conditions. The understanding of these complex phenomena is thus crucial in the design phase of a new aeronautical architecture, especially the study of the interaction between consecutive static and rotating parts. These interactions involve potential blade effects, wake interactions and many other sources. This paper focuses on rotor/stator interactions in low-pressure turbine which has the particularity to have a locally transonic flow regime in its vein. The geometry considered consists of a linear blade cascade in front of which bars rotate, acting as wake generators that impact periodically the leading edges of the blades, influencing all the aerodynamics of the cascade. Large-Eddy simulations (LES) of this configuration are carried out and compared to experimental results acquired at the Von Karman Institute during the Cleansky project SPLEEN. The main objective is the thorough investigation of the effect of the bars in such conditions. To do so, an incremental investigation is done, comparing a case with bars only, an isolated vane and finally the complete experimental setup. In particular the influence of the configuration on the flow turbulence is studied followed by the impact on the blade loading and the nature of the fluctuations in the flow downstream of the cascade. Finally, the variation of the blade wakes and the influence on the general topology of the flow are presented. In particular, the recirculation bubble present on the pressure side and the position of the shock waves in the inter-blade channel are detailed.
ETC2023-257
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