Weidan Ni
Flow separation control over a rounded ramp with spanwise alternating wall actuation
Ni, Weidan; Lu, Lipeng; Fang, Jian; Moulinec, Charles; Emerson, David R.; Yao, Yufeng
Authors
Lipeng Lu
Jian Fang
Charles Moulinec
David R. Emerson
Yufeng Yao Yufeng.Yao@uwe.ac.uk
Professor in Aerospace Engineering
Abstract
An implicit large-eddy simulation is carried out to study turbulent boundary-layer separation from a backward-facing rounded ramp with active wall actuation control. This method, called spanwise alternating distributed strips control, is imposed onto the flat plate surface upstream of a rounded ramp by alternatively applying out-of-phase control and in-phase control to the wall-normal velocity component in the spanwise direction. As a result, the local turbulence intensity is alternatively suppressed and enhanced, leading to the creation of vertical shear-layers, which is responsible for the presence of large-scale streamwise vortices. These vortices exert a predominant influence on the suppression of the flow separation. The interaction between the large-scale vortices and the downstream recirculation zone and free shear-layer is studied by examining flow statistics. It is found that in comparison with the non-controlled case the flow separation is delayed, the reattachment point is shifted upstream, and the length of the mean recirculation zone is reduced up to 8.49%. The optimal control case is achieved with narrow in-phase control strips. An in-depth analysis shows that the delay of the flow separation is attributed to the activation of the near-wall turbulence by the in-phase control strips and the improvement of the reattachment location is mainly due to the large-scale streamwise vortices, which enhance the momentum transport between the main flow and separated region.
Citation
Ni, W., Lu, L., Fang, J., Moulinec, C., Emerson, D. R., & Yao, Y. (2019). Flow separation control over a rounded ramp with spanwise alternating wall actuation. Physics of Fluids, 31(1), 015101. https://doi.org/10.1063/1.5055948
Journal Article Type | Article |
---|---|
Acceptance Date | Dec 7, 2018 |
Online Publication Date | Jan 4, 2019 |
Publication Date | Jan 1, 2019 |
Deposit Date | Jan 15, 2019 |
Publicly Available Date | Jan 15, 2019 |
Journal | Physics of Fluids |
Print ISSN | 1070-6631 |
Electronic ISSN | 1089-7666 |
Publisher | AIP Publishing |
Peer Reviewed | Peer Reviewed |
Volume | 31 |
Issue | 1 |
Pages | 015101 |
DOI | https://doi.org/10.1063/1.5055948 |
Public URL | https://uwe-repository.worktribe.com/output/854374 |
Publisher URL | http://doi.org/10.1063/1.5055948 |
Files
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