Session: 40-07 Turbine Secondary Flows and Interactions

Paper Number: 128710

128710 - Optimization of Low-Pressure Turbine Blade by Means of Fine Inspection of Loss Production Mechanisms 

In the present work, Proper Orthogonal Decomposition (POD) has been applied to Large Eddy Simulations (LES) of a high-loaded low-pressure turbine cascade operating under unsteady inflow for the detailed investigation of the entropy production in the different part of the blade passage: the bulk flow, the boundary layer, and the wake regions. To this end, the Turbulent Kinetic Energy (TKE) production, diffusion and dissipation terms appearing into the stagnation pressure transport equation have been integrated all over the computational domain to firstly verify the equivalence between the exploited local loss analysis with the common global loss metric based on stagnation pressure flux. The POD-based procedure allows splitting the contribution due to different coherent flow structures to the turbulent kinetic energy production and dissipation, due to the migration, bowing, tilting and reorientation of the incoming wake filaments, as well as to the boundary layer streaks rupture into the blade boundary layer and/or to the formation of Von Karman vortices into the wake of the blade, propagating downstream of the trailing edge. This enables a designer to identify the dominant POD modes (i.e., turbulent flow structures) responsible for loss generation mechanisms, their dynamics and the spatial locations where they mainly act, thus providing a so far unmatched deep view on the physical phenomena to be controlled. Following this optimization strategy, a new low pressure turbine profile has been designed. After running a LES calculation on the new optimized geometry, POD results showed that it is possible to design a higher-loaded profile which operate with a lower global loss coefficient.  Thanks to the more gradual diffusion of the flow in the main passage, the new loading distribution is shown to be responsible for lower upstream wake migration losses, as well as for a smaller amount of TKE production in the trailing edge wake zone, as a result of the early suction side boundary layer transition.

Presenting Author: Matteo Russo Università degli Studi di Genova

Presenting Author Biography: I am a Ph.D. Student at University of Genoa, where I graduated as a M.S. in Mechanical Engineering - Energy and Aeronautics. My research interests include design optimization of axial flow turbomachines, advanced analysis of turbomachinery flow unsteadiness and post-processing of big data from high-fidelity CFD simulations.

Authors:

Matteo Russo Università degli Studi di Genova
Andrea Carlucci Università degli Studi di Genova
Matteo Dellacasagrande Università degli Studi di Genova
Daniele Petronio Università degli Studi di Genova
Davide Lengani Università degli Studi di Genova
Daniele Simoni Università degli Studi di Genova
Juri Bellucci Morfo Design
Matteo Giovannini Morfo Design
Angelo Alberto Granata Morfo Design
Monica Gily Avio Aero
Carlotta Manca Avio Aero