Extremum seeking to control the amplitude and frequency of a pulsed jet for bluff body drag reduction

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Title: Extremum seeking to control the amplitude and frequency of a pulsed jet for bluff body drag reduction
Authors: Brackston, RD
Wynn, A
Morrison, JF
Item Type: Journal Article
Abstract: Feedback control of fluid flows presents a challenging problem due to nonlinear dynamics and unknown optimal operating conditions. Extremum seeking control presents a suitable method for many flow control situations but involves its own challenges. In this paper we provide a brief analysis of the extremum seeking method, with attention to modifications that we find to be advantageous. In particular, we present an adaptation for optimisation of the frequency of a harmonic input signal, a common scenario for open-loop flow control systems. We then present results from the experimental implementation of our modified method to the open-loop control system of Oxlade et al (2015, J. Fluid Mech., vol. 770), an axisymmetric bluff body wake, forced by a pulsed jet. We find that the system is able to achieve optimal operating conditions in both the amplitude and frequency of the harmonic input signal, and is able to largely reject the disturbances arising from measurements of a highly turbulent flow. We finally show the ability of the extremum seeking system to adapt to changing conditions.
Issue Date: 23-Sep-2016
Date of Acceptance: 5-Sep-2016
URI: http://hdl.handle.net/10044/1/39924
DOI: https://dx.doi.org/10.1007/s00348-016-2243-4
ISSN: 1432-1114
Publisher: Springer Verlag (Germany)
Journal / Book Title: Experiments in Fluids
Volume: 57
Copyright Statement: © The Author(s) 2016. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Sponsor/Funder: Engineering & Physical Science Research Council (E
Funder's Grant Number: EP/K503733/1
Keywords: Fluids & Plasmas
0913 Mechanical Engineering
0915 Interdisciplinary Engineering
0901 Aerospace Engineering
Publication Status: Published
Article Number: 159
Appears in Collections:Faculty of Engineering

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