Flow control using optical sensors

title = "Flow control using optical sensors",

titletranslation = "Contr{\^o}le d'ecoulement par capteurs optiques",

school = "Pierre and Marie Curie University - Paris VI",

year = "2014",

month = oct # "~08",

address = "France",

keywords = "genetic algorithms, genetic programming, flow control, graphic processor unit, contr{\^o}le d'ecoulement, GPU, boucle fermee, marche descendante, experimental, [PHYS, MECA, mefl] physics [physics]/mechanics [physics]/mechanics of the fluids [physics, class-ph]",

publisher = "HAL CCSD",

bibsource = "OAI-PMH server at api.archives-ouvertes.fr",

contributor = "Physique et mecanique des milieux heterogenes and Jean-Luc Aider",

identifier = "NNT : 2014PA066640; tel-01150428",

language = "en",

oai = "oai:HAL:tel-01150428v1",

URL = "

https://tel.archives-ouvertes.fr/tel-01150428",

URL = "

https://tel.archives-ouvertes.fr/tel-01150428/document",

URL = "

https://tel.archives-ouvertes.fr/tel-01150428/file/2014PA066640.pdf",

size = "211 pages",

abstract = "Flow control using optical sensors is experimentally investigated. Real-time computation of flow velocity fields is implemented. This novel approach featuring a camera for acquisition and a graphic processor unit (GPU) for processing is presented and detailed. Its validity with regards to speed and precision is investigated. A comprehensive guide to software and hardware optimisation is given. We demonstrate that online computation of velocity fields is not only achievable but offers advantages over traditional particle image velocimetry (PIV) setups. It shows great promise not only for flow control but for parametric studies and prototyping also.

A hydrodynamic channel is used in all experiments, featuring a backward facing step for separated flow control. Jets are used to provide actuation. A comprehensive parametric study is effected to determine the effects of upstream jet injection. It is shown upstream injection can be very effective at reducing recirculation, corroborating results from the literature.",

abstract = "Both open and closed loop control methods are investigated using this setup. Basic control is introduced to ascertain the effectiveness of this optical setup. The recirculation region created in the backward-facing step flow is computed in the vertical symmetry plane and the horizontal plane. We show that the size of this region can be successfully manipulated through set-point adaptive control and gradient based methods.A physically driven control approach is introduced. Previous works have shown successful reduction recirculation reduction can be achieved by periodic actuation at the natural Kelvin-Helmholtz frequency of the shear layer.A method based on vortex detection is introduced to determine this frequency, which is used in a closed loop to ensure the flow is always adequately actuated. Thus showing how recirculation reduction can be achieved through simple and elegant means using optical sensors.

Next a feed-forward approach based on ARMAX models is implemented. It was successfully used in simulations to prevent amplification of upstream disturbances by the backward-facing step shear layer. We show how such an approach can be successful in an experimental setting.

Higher Reynolds number flows exhibit non-linear behaviour which can be difficult to model in a satisfactory manner thus a new approach was attempted dubbed machine learning control and based on genetic programming. A number of random control laws are implemented and rated according to a given cost function. The laws that perform best are bred, mutated or copied to yield a second generation. The process carries on iteratively until cost is minimised. This approach can give surprising insights into effective control laws.",

abstract = "Le contr{\^o}le d'ecoulement en utilisant des capteurs optiques est etudie dans un contexte experimental. Le calcul de champs de vitesses en temps reel en utilisant une camera pour l'acquisition et une carte graphique pour le calcul est detaille. La validite de l'approche en terme de rapidite et de precision est etudiee. Un guide complet pour l'optimisation logicielle et materielle est donne. Nous demontrons que le calcul dynamique de champs de vitesse est non seulement possible mais plus facile {\`a} gerer que l'utilisation d'un appareillage (PIV) classique. Un canal hydrodynamique est utilise pour toutes les experiences. Celui-ci comporte une marche descendante pour le contr{\^o}le d' ecoulements decolles. Les actionneurs sont des jets. Dans le cas de la marche descendante une etude parametrique approfondie est faite pour qualifier les effets d'une injection en amont des jets, celle-ci etant traditionnellement .......",

annote = "oai:HAL:tel-01150428v1 Physique et mecanique des milieux heterogenes (PMMH) ; CNRS - Universite Paris Diderot - Paris 7 (UP7) - ESPCI ParisTech - Universite Pierre et Marie Curie - Paris 6 (UPMC); Universite Pierre et Marie Curie - Paris VI, English. ",