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- Groot, K.J. (author), Serpieri, J. (author), Kotsonis, M. (author), Pinna, Fabio (author) conference paper 2017
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Serpieri, J. (author), Kotsonis, M. (author)Time-resolved PIV measurements of the secondary instability modes of cross-flow vortices are presented. Measurements are performed on a large scale 45o swept wing at chord Reynolds number of 2.17 million in a low turbulence wind-tunnel facility. Using acquisition frequencies of 20 kHz, the present study is the first experimental demonstration...conference paper 2017
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Michelis, Theodorus (author), Kotsonis, M. (author), Yarusevych, S. (author)The present study considers the development of a Laminar Separation Bubble on the suction side of a NACA0018 airfoil under natural and forced conditions. Deterministic forcing is applied by means of a two-dimensional plasma actuator installed on the airfoil surface. The spatiotemporal characteristics of the bubble are measured using time...conference paper 2017
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Zong, H. (author), Kotsonis, M. (author)This study experimentally investigates the influence of exit orifice shape on the performance characteristics of a three-electrode plasma synthetic jet actuator. High-speed Schlieren imaging system and phase-locked two-component PIV measurements are used for flowfield characterisation in quiescent conditions. Two actuator configurations with...journal article 2017
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Zong, H. (author), Kotsonis, M. (author)This paper experimentally investigates the interaction between a plasma synthetic jet (PSJ) and a subsonic turbulent boundary layer (TBL) using a hotwire anemometer and phase-locked particle imaging velocimetry. The PSJ is interacting with a fully developed turbulent boundary layer developing on the flat wall of a square wind tunnel section...journal article 2017
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Michelis, Theodorus (author), Yarusevych, S. (author), Kotsonis, M. (author)The spatial and temporal response characteristics of a laminar separation bubble to impulsive forcing are investigated by means of time-resolved particle image velocimetry and linear stability theory. A two-dimensional impulsive disturbance is introduced with an alternating current dielectric barrier discharge plasma actuator, exciting...journal article 2017
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Localised estimation and control of linear instabilities in two-dimensional wall-bounded shear flowsTol, H.J. (author), Kotsonis, M. (author), de Visser, C.C. (author), Bamieh, B. (author)A new framework is presented for estimation and control of instabilities in wall-bounded shear flows described by the linearised Navier-Stokes equations. The control design considers the use of localised actuators/sensors to account for convective instabilities in an optimal control framework. External sources of disturbances are assumed to...journal article 2017
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- Zong, H. (author), Kotsonis, M. (author) journal article 2017
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Zong, H. (author), Kotsonis, M. (author)The performance of a two–electrode plasma synthetic jet actuator (PSJA) is investigated for a wide range of dimensionless actuation frequencies (f*) using high-speed phase-locked Particle Imaging Velocimetry (PIV) measurements. The jet-induced velocity fields in the axisymmetric plane are measured during both...journal article 2017
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Rezaeiha, Abdolrahim (author), Balbino dos Santos Pereira, R. (author), Kotsonis, M. (author)Unsteady loads are a major limiting factor for further upscaling of HAWTs considering the high costs associated to strict structural requirements. Alleviation of these unsteady loads on HAWT blades, e.g. using active flow control (AFC), is of high importance. In order to devise effective AFC methods, the unsteady loading sources need to be...journal article 2017
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Serpieri, J. (author), Yadala, Srikar (author), Kotsonis, M. (author)In the current study, selective forcing of cross-flow instability modes evolving on a swept wing at is achieved by means of spanwise-modulated plasma actuators, positioned near the leading edge. In the perspective of laminar flow control, the followed methodology holds on the discrete roughness elements/upstream flow deformation (DRE/UFD)...journal article 2017
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Rius Vidales, A.F. (author), Kotsonis, M. (author), Antunes, Alexandre (author), Cosin, Renato (author)An experimental investigation was carried out to examine the effect of two-dimensional Forward Facing Steps surface irregularities, on the laminar-to-turbulent boundary-layer transition on a 45° swept-wing. For the clean reference case, the numerical boundary-layer flow is calculated from pressure measurements, and a thorough linear stability...conference paper 2018
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Yadala, Srikar (author), Hehner, M.T. (author), Serpieri, J. (author), Benard, Nicolas (author), Kotsonis, M. (author)In the present work, laminar flow control, following the discrete roughness elements (DRE) strategy, also called upstream flow deformation (UFD) was applied on a 45<sup>◦</sup> swept-wing at a chord Reynold’s number of Re<sub>c</sub> = 2.1 · 10<sup>6</sup> undergoing cross-flow instability (CFI) induced transition. Dielectric barrier...conference paper 2018
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Yadala, Srikar (author), Hehner, M.T. (author), Serpieri, J. (author), Benard, Nicolas (author), Dörr, Philipp C. (author), Kloker, Markus J. (author), Kotsonis, M. (author)Control of laminar-to-turbulent transition on a swept-wing is achieved by base-flow modification in an experimental framework, up to a chord Reynolds number of 2.5 million. This technique is based on the control strategy used in the numerical simulation by Dörr & Kloker (J. Phys. D: Appl. Phys., vol. 48, 2015b, 285205). A spanwise uniform...journal article 2018
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Michelis, Theodorus (author), Yarusevych, S. (author), Kotsonis, M. (author)This work investigates the three-dimensional, spatio-Temporal flow development in the aft portion of a laminar separation bubble. The bubble is forming on a flat plate geometry, subjected to an adverse pressure gradient, featuring maximum reverse flow of approximately 2Â % of the local free-stream velocity. Time-resolved velocity measurements...journal article 2018
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Serpieri, J. (author), Kotsonis, M. (author)In this study, experiments are performed towards the identification and measurement of unsteady modes occurring in a transitional swept wing boundary layer. These modes are generated by the interaction between the primary stationary and travelling cross-flow instabilities or by secondary instability mechanisms of the stationary cross-flow...journal article 2018
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Groot, K.J. (author), Serpieri, J. (author), Pinna, Fabio (author), Kotsonis, M. (author)A combined experimental and numerical approach to the analysis of the secondary stability of realistic swept-wing boundary layers is presented. Global linear stability theory is applied to experimentally measured base flows. These base flows are three-dimensional laminar boundary layers subject to spanwise distortion due to the presence of...journal article 2018
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Kurelek, J.W. (author), Kotsonis, M. (author), Yarusevych, S. (author)Transition and flow development in a separation bubble formed on an airfoil are studied experimentally. The effects of tonal and broadband acoustic excitation are considered since such acoustic emissions commonly result from airfoil self-noise and can influence flow development via a feedback loop. This interdependence is decoupled, and the...journal article 2018
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Zong, H. (author), van Pelt, T. (author), Kotsonis, M. (author)Abstract: An array of 26 plasma synthetic jet actuators (PSJA) is flush-mounted on a NACA-0015 airfoil model to control the leading-edge flow separation at moderate Reynolds number (Re<sub>c</sub>= 1.7 × 10 <sup>5</sup>). The stall angle of this airfoil is postponed from 15. 5 <sup>∘</sup> to approximately 22 <sup>∘</sup>, and the peak lift...journal article 2018
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Zong, H. (author), Chiatto, Matteo (author), Kotsonis, M. (author), de Luca, Luigi (author)The plasma synthetic jet actuator (PSJA), also named as sparkjet actuator, is a special type of zero-net mass flux actuator, driven thermodynamically by pulsed arc/spark discharge. Compared to widely investigated mechanical synthetic jet actuators driven by vibrating diaphragms or oscillating pistons, PSJAs exhibit the unique capability of...review 2018