Session: 40-03 Compressor Secondary Flows and Interactions

Paper Number: 128197

128197 - The Unsteady Shock-Boundary Layer Interaction in a Compressor Cascade – Part 3: Mechanisms of Shock Oscillation 

The shock-boundary layer interaction in transonic flows is known to cause strong unsteady flow effects that negatively affect the performance and operability of airfoil and cascade designs. Despite decades of research on the subject, very little is still known about the physical mechanisms that drive this unsteadiness in different applications. In the conclusion of this three-part series, the experimental and numerical data obtained with the Transonic Cascade TEAMAero are analyzed further and compared in detail in order to test the different theories of continuous shock oscillation. This detailed comparison helps elucidate the mechanisms causing the different oscillation frequencies and unsteady flow on this compressor cascade. The comparison suggests that the main oscillation frequency is driven by disturbances generated downstream of the shock that propagate upstream and affect the flow conditions before the shock; a process that repeats continuously. The comparison of the data hints to a mechanism of self-excitement due to the varying inflow angle, as suggested in the literature. However, the second oscillation frequency seems to have a different source and to be linked with the geometry of the cascade itself. The results gathered in previous experimental campaigns at the institute are also used as support in order to test and propose different parameter relations that collapse the unsteadiness measured with all the designs. Although the population of cascades is still rather small, this comparison provides a good basis on which to further study and analyze the unsteady flows in transonic blades.

Presenting Author: Edwin Joseph Munoz Lopez German Aerospace Center (DLR)

Presenting Author Biography: Edwin holds a Bachelor of Engineering degree from Canada's Carleton University, and a Master of Science degree from France's ISAE-SUPAERO. He is currently a PhD candidate at the German Aerospace Center in Cologne, where he studies the unsteady shock-boundary layer interaction on compressor cascades and optimization strategies to mitigate its effects. His areas of research involve the aerodynamics, optimization, and design of compressor blades.

Authors:

Edwin Joseph Munoz Lopez German Aerospace Center (DLR)
Alexander Hergt German Aerospace Center (DLR)
Joachim Klinner German Aerospace Center (DLR)
Bjoern F. Klose German Aerospace Center (DLR)
Chris Willert German Aerospace Center (DLR)
Volker Guemmer Technical University of Munich