Dynamics and Unsteady Features of the Turbulent Separation over a Forward-Facing Step

AIAA Scitech 2021 Forum

Abstract

View Video Presentation: https://doi.org/10.2514/6.2021-1554.vid The flow across two-dimensional forward-facing step geometries occurs in many aerospace applications, amongst them leading edge panels, doubler patches, as well as control surfaces. Because of the high level of complexity of this type of flow, related to the coincident occurrence of separation and reattachment events, various dynamic and unsteady features are still not entirely understood. With the present study, we intend to gain further insight into the flow dynamics, the coherent turbulent structures, and the turbulence behavior in the flow field over a forward-facing step interacting with a turbulent boundary layer. Experiments are performed in a low-speed wind tunnel in a range of Reynolds numbers between 13,138 and 39,416. A recently developed Stereo-Dual-PIV system provides simultaneous access to all three components of the velocity vector. On the basis of measurements of all three components of the mean and turbulent velocity field throughout the flow domain, the large-scale flow organization is discussed, along with links between upstream and downstream mechanisms. Statistical methods are employed to analyze the turbulence behavior, with particular focus on the spanwise flow components. Furthermore, we attempt to acquire a deeper understanding of the coherent turbulent structures and their inherent unsteady motions. Therefore, Proper Orthogonal Decomposition is applied to the longitudinal (u') and transverse (w') velocity fluctuation components to capture the behavior of the energetically relevant coherent spatial structures across the flow field.

Authors 2

1. Christopher J. Schauerte Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University

2. Anne-Marie Schreyer Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University