[en] Self-Aligned Focusing Schlieren (SAFS) is a recently developed variant of focusing schlieren that overcomes the demanding alignment requirements of conventional focusing schlieren while preserving a narrow depth of field in a compact and flexible configuration. In this work, a double-lens SAFS setup is applied to a turbomachinery test case, imaging the exit flow of a transonic low-pressure turbine cascade. Time-resolved schlieren measurements were acquired at 180 kHz around the trailing edge of one blade, and image pre-processing was applied to highlight vortical, acoustic, and weak pressure-wave features. The resulting data were analyzed using three complementary approaches. First, space–time maps of the wake region and the corresponding two-dimensional power spectral density (PSD) distributions were used to extract the vortex-shedding frequency, the associated Strouhal number, and the convection velocity, all found to be consistent with previous measurements and literature. Second, pointwise PSDs and Fourier maps were employed to visualize the spatial distribution of spectral energy and to identify frequency coupling between vortex shedding and acoustic-wave generation. Third, a proper orthogonal decomposition analysis was conducted to isolate the dominant coherent structures and to further confirm their coupling.
Disciplines :
Aerospace & aeronautics engineering
Author, co-author :
Zammit, Enrico ; Université de Liège - ULiège > Aérospatiale et Mécanique (A&M) ; von Karman Institute for Fluid Dynamics, Belgium
D’aguanno, Alessandro; von Karman Institute for Fluid Dynamics, Belgium ; University of Liège, Liège, Belgium ; Turbomachinery and Propulsion department, Belgium
Halby, Alexandre ; Université de Liège - ULiège > Aérospatiale et Mécanique (A&M) ; von Karman Institute for Fluid Dynamics, Belgium
Di Lucia, Giovanni; von Karman Institute for Fluid Dynamics, Belgium ; University of Liège, Liège, Belgium ; Turbomachinery and Propulsion department, Belgium
Lavagnoli, Sergio ; Université de Liège - ULiège > Département d'aérospatiale et mécanique > Design of Turbomachines and Propulsors (DoTP) ; von Karman Institute for Fluid Dynamics, Belgium ; Turbomachinery and Propulsion department, Belgium
Language :
English
Title :
Time-Resolved Self-Aligned Focusing Schlieren Applied to a Transonic Turbine Cascade
Publication date :
12 January 2026
Event name :
AIAA SCITECH 2026 Forum
Event place :
Orlando, Usa
Event date :
12-01-2026 => 16-01-2026
Main work title :
AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2026
Publisher :
American Institute of Aeronautics and Astronautics Inc, AIAA
The authors gratefully acknowledge the European Defence Fund (EDF) for the financial support through the NEUMANN project (Grant Agreement Number 01103504). The program is funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them. I would also like to thank the VKI PhD representatives Jorge, Carlo, and Alice, whose support made the presentation of this paper possible.
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