BibTex format
@inproceedings{Gouder:2017,
author = {Gouder, KA and Naguib, AM and Lavoie, PL and Morrison, JF},
title = {Control of boundary layer streaks induced by freestream turbulence using plasma actuators},
year = {2017}
}
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TY - CPAPER
AB - Copyright © 2016 Zakon Group LLC. Previously, a systematic series of investigations, such as those of Hanson et al. (2010), Hanson et al. (2014) and Bade et al. (2016) were carried out aimed at assessing the capability of plasma-actuator-based Feedforward-Feedback control system to weaken streaks that were artificially induced into a Blasius boundary layer using dynamic roughness elements. In contrast, the current work builds on these previous works and drives towards the delay of bypass boundary layer transition, where in the presence of a freestream flow with turbulence intensity exceeding approximately 1%, streaks form naturally and stochastically in the underlying boundary layer. For the freestream velocity of the current experiment, turbulent spot formations were first observed at a streamwise location x ≈ 350 mm from the leading edge. Upstream of this location, the naturally-occurring high and low-speed streaks exhibit linear transient growth. Two wall-shear-stress sensors - one feed-forward (FF) and one feedback (FB) - and two plasma actuators capable of producing positive and negative wall-normal forcing to oppose high and low-speed streaks respectively were placed in the linear growth region. The output from the FF sensor was used in conjunction with single-point Linear Stochastic Estimation (LSE) and actuator-flow identified response models in order to generate a counter-disturbance, which, at the (downstream) FB sensor location, was equal in magnitude but opposite in sign to the natural streak estimate. The output of the FB sensor was fed to a PI controller to correct for any remaining, uncancelled disturbance resulting from, for example, inaccuracies in the LSE model of streak growth. Results, such as notable changes in the mean and rms wall normal velocity profiles and energy spectra, for FF only, and FF + FB control, provide an evaluation of the viability of the control approach to weaken boundary layer streaks and delay transition.
AU - Gouder,KA
AU - Naguib,AM
AU - Lavoie,PL
AU - Morrison,JF
PY - 2017///
TI - Control of boundary layer streaks induced by freestream turbulence using plasma actuators
ER -