Session: 40-06: Turbine Secondary Flows and Interactions I

Paper Number: 152194

Large-Eddy Simulations of a 3 Stages High-Speed Low-Pressure Turbine Cascade 

Compact high-speed low-pressure turbines allow to increase the performance of engines with respect to conventional low Mach and Reynolds numbers turbines. The flow in low-pressure turbine passages is extremely sensitive to unsteadiness, including background turbulence and deterministic unsteadiness induced by potential effects and wakes. Losses are primarily due to wall phenomena (profile losses) where transition is critical. Wakes as well as secondary flows have also non-negligeable contributions to losses and can be promoters for transition. Efforts need to be done to characterize turbulence in high-speed low-pressure turbines to adapt industrial design tools based on empirical data as well as RANS modeling.

 

This study numerically characterizes the production, transport and dissipation of turbulence in a configuration representative of future industrial high-speed low-pressure turbines with the in-house CFD solver AVBP. Thanks to Wall-Resolved Large-Eddy Simulations (WRLES), high-fidelity databases are generated.  The configuration investigated is a CFD friendly 3 stages high-speed low-pressure turbine: to limit the CPU cost while keeping the physics of interest, the periodicity of each row of blade is set to one passage. The focus is on the effect of the inlet turbulence on the flow and turbulence development all along the machine. Only the mid-vein part is simulated in order to remove secondary flow effects. 

 

The first part of the paper details the numerical methodology in terms of physical domain simulated and meshing strategy to ensure the production of reliable results. The second part of the paper characterizes the turbulence production, transport and dissipation in the passage and the interaction of turbulence and wakes with the boundary layers around the blades with a special focus on laminar to turbulent transition. The numerical data allows to quantify the effect of the operating conditions for two inlet turbulence levels on the flow feature development as well as to quantify associated losses. WRLES results are compared to RANS simulations.

Presenting Author: Florent Duchaine CERFACS

Presenting Author Biography: Dr Florent Duchaine received his phd From Institut National Polytechnique de Toulouse in 2007. He joined CERFACS as a researcher in 2010, working in the field of Large-Eddy Simulation and heat transfer in combustion systems and turbomachinery.

Authors:

Florent Duchaine CERFACS
Jérôme Dombard Safran Aircraft Engines