Shock Oscillation Mechanism of Highly Separated Transitional Shock-Wave/Boundary-Layer Interactions

Journal Article (2025)
Author(s)

Philipp L. Nel (RWTH Aachen University, TU Delft - Aerodynamics)

Anne Marie Schreyer (RWTH Aachen University)

Ferry Schrijer (TU Delft - Aerodynamics)

Bas W. Van Oudheusden (TU Delft - Aerodynamics)

Christian Janke (Rolls-Royce Germany Ltd. & Co. KG)

Ilias Vasilopoulos (Rolls-Royce Germany Ltd. & Co. KG)

Marius Swoboda (Rolls-Royce Germany Ltd. & Co. KG)

Research Group
Aerodynamics
DOI related publication
https://doi.org/10.2514/1.J064567
More Info
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Publication Year
2025
Language
English
Research Group
Aerodynamics
Bibliographical Note
Green Open Access added to TU Delft Institutional Repository as part of the Taverne amendment. More information about this copyright law amendment can be found at https://www.openaccess.nl. Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. @en
Issue number
5
Volume number
63
Pages (from-to)
1703-1715
Reuse Rights

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Abstract

Reynolds numbers at cruise altitude can be such that a laminar boundary layer persists on the suction side of a transonic fan blade up to the shock-wave/boundary-layer interaction (SBLI). In a transitional SBLI which exhibits sufficiently large shock-induced separation, a shock oscillation mechanism characterized by growth and natural suppression of the upstream laminar section of the separation bubble occurs. To validate the shock oscillation mechanism observed in large eddy simulations (LES), the shock oscillation mechanism is studied experimentally using high-speed Schlieren and spark-light shadowgraphy. A characteristic length based on the distance of laminar separation shock travel is proposed. Strouhal numbers from LES and the experiment collapse at around 0.075. A strong dependency of the oscillation mechanism on free-stream turbulence and boundary-layer state is shown. Dominant oscillation frequencies are an order of magnitude lower for the turbulent interaction as opposed to the laminar case. For the laminar case, dynamic mode decomposition showed a strong relationship of the laminar separation shock with the separation bubble and reflected shock movement. The turbulent interaction shows a significantly lower reflected shock travel distance. The findings experimentally confirm that stabilization of the shock is achieved by tripping the boundary layer.

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