Abstract
When a turbulent flow reaches a sudden expansion as in the case of a backward-facing step (BFS), a turbulent separated shear layer originates from the trailing edge. The reattachment location of this shear layer varies in time and space, causing high dynamic loads on the reattachment surface. This is an inherent problem on some of today’s cryogenic space launchers, where the main engine’s nozzle suffers from high buffeting loads during the transonic phase of the ascent, due to a turbulent reattaching shear layer, especially originating from a geometric discontinuity, similar to a BFS. For this reason the aim of the current research focuses on stabilizing and reducing the reattachment length of the separated shear layer on a BFS in transonic flow by the means of passive flow control devices. Several streamwise vortex generators were examined in the Trisonic Wind Tunnel Munich (TWM) with particle image velocimetry (PIV). The investigations were conducted on a 2D model at Mach 0.8 and a Reynolds number of \(1.8 \times 10^5\) with respect to the step height (h). The results show that streamwise vortex generators have a tremendous effect on reducing the size of the recirculation region, reducing the reattachment location by 75 % or more, when compared to the reattachment location of a BFS wake.
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Acknowledgments
Financial support from the German Research Foundation (DFG) in the framework of the TRR 40—Technological foundations for the design of thermally and mechanically highly loaded components of future space transportation systems—is gratefully acknowledged by the authors.
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Bolgar, I., Scharnowski, S., Kähler, C.J. (2016). Control of the Reattachment Length of a Transonic 2D Backward-Facing Step Flow. In: Segalini, A. (eds) Proceedings of the 5th International Conference on Jets, Wakes and Separated Flows (ICJWSF2015). Springer Proceedings in Physics, vol 185. Springer, Cham. https://doi.org/10.1007/978-3-319-30602-5_30
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DOI: https://doi.org/10.1007/978-3-319-30602-5_30
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