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Littérature scientifique sur le sujet « Transition control by suction »

Auteur : Grafiati

Publié le 8 mars 2025

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Articles de revues sur le sujet "Transition control by suction"

Wang, A., et H. Lai. « Control of separated flow at low Reynolds number around NACA0012 airfoil by boundary layer suction ». Journal of Physics : Conference Series 2707, n^o 1 (1 février 2024) : 012122. http://dx.doi.org/10.1088/1742-6596/2707/1/012122.

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Abstract The separated flow at low Reynolds number around the NACA0012 airfoil is numerically studied by large-eddy simulation. Strategies of boundary layer suction to control flow separation are investigated. A method of using two-zone suctions, near the leading edge and near the trailing edge, are calculated. Based on verification with direct numerical simulation (DNS) and experimental data, the results of the lift and the drag, the vortices, and the strength of near-field pressure fluctuations, are checked. The results show that the two-zone suctions can supress flow transition and separation, thereby increase the lift and reduce the drag. The shedding of vortices is weakened, and the near-field pressure fluctuations are attenuated. For comparison with the two-zone suctions, the strategies of suction near the leading edge only and suction near the trailing edge only are also studied. It is found that suction near the leading edge only may suppress transition and delay separation when the suction zone is large enough, but the flow property deteriorates due to shedding vortices in the wake. The suction near the trailing edge only may improve the flow performance by reducing the size of the vortices in the rear section of the airfoil and in the wake region, but it has little effect on the separation bubble and transition.

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Balakumar, P., et P. Hall. « Optimum Suction Distribution for Transition Control ». Theoretical and Computational Fluid Dynamics 13, n^o 1 (1 avril 1999) : 1–19. http://dx.doi.org/10.1007/s001620050109.

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Liu, Yuanqiang, Yan Liu, Zubi Ji, Yutian Wang et Jiakuan Xu. « Receptivity and Stability Theory Analysis of a Transonic Swept Wing Experiment ». Aerospace 10, n^o 10 (23 octobre 2023) : 903. http://dx.doi.org/10.3390/aerospace10100903.

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Surface suction provides an efficient way to delay boundary layer transitions. In order to verify the suction effects and determine the mechanism of suction control in transonic swept wing boundary layers, wind tunnel transition measurements in a hybrid laminar flow control (HLFC) wind tunnel model uses an infrared thermography technique in the Aircraft Research Association (ARA) 2.74 m × 2.44 m low turbulence level transonic wind tunnel. Based on the experimental data of stationary crossflow dominant transitions without and with surface suction in transonic swept wing boundary layers, in this paper, the effects on the receptivity and linear and nonlinear evolution of stationary crossflow vortices have been analyzed with the consideration of curvature. Theoretical analysis agreed with the experimental observations in regard to the transition delay caused by boundary layer suction near the leading-edge region.

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Ma, Dongli, Guanxiong Li, Muqing Yang et Shaoqi Wang. « Research of the suction flow control on wings at low Reynolds numbers ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 232, n^o 8 (21 février 2017) : 1515–28. http://dx.doi.org/10.1177/0954410017694057.

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Laminar separation and transition have significant effects on aerodynamic characteristics of the wing under the condition of low Reynolds numbers. Using the flow control methods to delay and eliminate laminar separation has great significance. This study uses the method combined with water tunnel test and numerical calculation to research the effects of suction flow control on the flow state and aerodynamic force of the wing at low Reynolds numbers. The effects of suction flow rate and suction location on laminar separation, transition and aerodynamic performance of the wing are further researched. The results of the research show that, the suction can control laminar separation and transition effectively, when the suction holes are in the interior of the separation bubble, and close to the separation point, the suction has the best control effect. When the Reynolds number is Re = 3.0 × 105, the suction flow control can make the lift-to-drag ratio of the wing increase by 8.62%, and the aerodynamic characteristics of the wing are improved effectively.

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Wong, P. W. C., M. Maina et A. M. Cobbin. « Transition and separation control in the leading edge region ». Aeronautical Journal 105, n^o 1049 (juillet 2001) : 371–78. http://dx.doi.org/10.1017/s0001924000012288.

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Abstract This paper describes an investigation of methods of controlling transition and separation in the leading edge region of military aircraft wings. For wings with the high leading edge sweep relevant to some military aircraft, if attachment line contamination can be prevented then transition is predominantly caused by crossflow instability close to the leading edge. The use of surface suction or cooling for suppressing these instabilities in order to delay transition, has been investigated in a parametric study. The placing of a short suction panel close to the leading edge has been found to be an effective means of controlling instability. Conversely, the level of cooling required to suppress crossflow instability may be too high for practical aircraft applications. The use of suction for preventing laminar separation for pressure distributions with a leading edge suction peak has also been included in the parametric study. The suction quantity required is strongly dependent on the peak height. The suction quantity that can be achieved in practice will limit the maximum peak height that can be attained without laminar separation. An investigation of leading edge stall and control has also been carried out. The analysis suggests that it is important to be able to identify whether the stall is due to laminar bubble bursting or turbulent re-separation, since different methods of controlling the stall may be required.

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Lei, Juanmian, Qingyang Liu et Tao Li. « Suction control of laminar separation bubble over an airfoil at low Reynolds number ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 233, n^o 1 (24 août 2017) : 81–90. http://dx.doi.org/10.1177/0954410017727025.

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A laminar separation bubble appears generally on the NACA2415 airfoil at low Reynolds number. In this paper, suction control of the laminar separation bubble over the NACA2415 airfoil at low Reynolds number are simulated. The effects of suction control on the flow field and the aerodynamic characteristics of the airfoil are focused on at different angles of attack. Numerical simulations show that employing the γ-Reθt transition model coupling the k–ω shear stress transport turbulence model can predict the laminar separation bubbles accurately. The results indicate that suction control can delay the transition, decrease the velocity gradient of the boundary layer and inhibit the production of the separation bubble. The effect of the suction control becomes better with the suction location getting closer to the separation bubble and the suction speed (the suction gas speed of suction hole) getting faster. The figure of merit is introduced to evaluate energy consumption of the suction control. In consideration of the economic effects, the suction control is suitable for the larger angle of attack situation at low Reynolds number.

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Ebrahimisadr, Hesam, et Bertrand Francois. « Water retention curves and tensile strength for studying desiccation cracking of compacted clay soils ». E3S Web of Conferences 382 (2023) : 09003. http://dx.doi.org/10.1051/e3sconf/202338209003.

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Desiccation cracking is a natural phenomenon caused by drying in near-surface earth soils subjected to constrained shrinkage. In this research, the water retention curve of two clayey soils, prepared by compaction under standard proctor conditions, are determined to study the desiccation cracking. Two techniques of suction control are applied to control the drying process and to reach the water retention curve of the soils. For the suction values higher than 4 MPa, the saline-solution method was used to impose variousrelative humidity and so, various suctions. In addition, the osmotic method was applied for the suction values between 0.5 MPa and 2 MPa. Additionally, the dynamic vapor sorption (DVS) technique is used to corroborate the water retention curves obtained with the two other techniques. The volume changes is also tracked showing significant shrinkage upon drying. To reach the tensile strength of the soil, the Braziliantest is performed on samples prepared by compaction and submitted to various suctions. According to the results, for the two tested soils, the soil with the higher plasticity index shows consistently the higher retention capacity and the larger shrinkage upon drying. Also, the obtained water retention curves exhibit a smooth transition when the suction control technique change (at suctions between 2 and 4 MPa).

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Yang, Peng, Chiye Zhang, Hongyeyu Yan, Yifan Ren, Changliang Ye, Yaguang Heng et Yuan Zheng. « Numerical Investigation on Suction Flow Control Technology for a Blunt Trailing Edge Hydrofoil ». Mathematics 11, n^o 16 (21 août 2023) : 3618. http://dx.doi.org/10.3390/math11163618.

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The generation of hydro-mechanical resonance is related to the transition of the boundary layer and the development of vortex shedding. The application effect of suction control in hydrodynamics is equally deserving of consideration as an active control technique in aerodynamics. This study examines how suction control affects the flow field of the NACA0009 blunt trailing edge hydrofoil using the γ transition model. Firstly, the accuracy of the numerical method is checked by performing a three-dimensional hydrofoil numerical simulation. Based on this, three-dimensional hydrofoil suction control research is conducted. According to the results, the suction control increases the velocity gradient in the boundary layer and delays the position of transition. The frequency of vortex shedding in the wake region lowers, and the peak value of velocity fluctuation declines. The hydrofoil hydrodynamic performance may be successfully improved with a proper selection of the suction coefficient via research of the suction coefficient and suction position on the flow field around the hydrofoil. The lift/drag ratio goes up as the suction coefficient goes up. The boundary layer displacement thickness and momentum thickness are at their lowest points, and the velocity fluctuation amplitude in the wake region is at its lowest point as the suction coefficient Cμ = 0.003. When the suction slots are at the leading edge, the momentum loss in the boundary layer is minimal and the velocity fluctuation in the wake zone is negligible.

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Biringen, S., W. E. Nutt et M. J. Caruso. « Numerical study of transition control by periodic suction blowing ». AIAA Journal 25, n^o 2 (février 1987) : 239–44. http://dx.doi.org/10.2514/3.9613.

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Ahmadi-Baloutaki, M., A. Sedaghat, M. Saghafian et M. Badri. « Control of Transition over Aerofoil Surfaces using Active Suction ». International Journal of Flow Control 5, n^o 3-4 (septembre 2013) : 187–200. http://dx.doi.org/10.1260/1756-8250.5.3-4.187.

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Thèses sur le sujet "Transition control by suction"

Fransson, Jens H. M. « Flow control of boundary lagers and wakes ». Doctoral thesis, KTH, Mekanik, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3664.

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Both experimental and theoretical studies have beenconsidered on flat plate boundary layers as well as on wakesbehind porous cylinders. The main thread in this work iscontrol, which is applied passively and actively on boundarylayers in order to inhibit or postpone transition toturbulence; and actively through the cylinder surface in orderto effect the wakecharacteristics. An experimental set-up for the generation of the asymptoticsuction boundary layer (ASBL) has been constructed. This studyis the first, ever, that report a boundary layer flow ofconstant boundary layer thickness over a distance of 2 metres.Experimental measurements in the evolution region, from theBlasius boundary layer (BBL) to the ASBL, as well as in theASBL are in excellent agreement with boundary layer analysis.The stability of the ASBL has experimentally been tested, bothto Tollmien-Schlichting waves as well as to free streamturbulence (FST), for relatively low Reynolds numbers (Re). For the former disturbances good agreement is foundfor the streamwise amplitude profiles and the phase velocitywhen compared with linear spatial stability theory. However,the energy decay factor predicted by theory is slightlyoverestimated compared to the experimental findings. The latterdisturbances are known to engender streamwise elongated regionsof high and low speeds of fluid, denoted streaks, in a BBL.This type of spanwise structures have been shown to appear inthe ASBL as well, with the same spanwise wavelength as in theBBL, despite the fact that the boundary layer thickness issubstantially reduced in the ASBL case. The spanwise wavenumberof the optimal perturbation in the ASBL has been calculated andis β = 0.53, when normalized with the displacementthickness. The spanwise scale of the streaks decreases withincreasing turbulence intensity (Tu) and approaches the scale given by optimalperturbation theory. This has been shown for the BBL case aswell. The initial energy growth of FST induced disturbances hasexperimentally been found to grow linearly as Tu2Rexin the BBL, the transitional Reynolds numberto vary as Tu-2, and the intermittency function to have a relativelywell-defined distribution, valid for all Tu. The wake behind a porous cylinder subject to continuoussuction or blowing has been studied, where amongst other thingsthe Strouhal number (St) has been shown to increase strongly with suction,namely, up to 50% for a suction rate of 2.5% of the free streamvelocity. In contrast, blowing shows a decrease ofStof around 25% for a blowing rate of 5% of the freestream velocity in the considered Reynolds number range. Keywords:Laminar-turbulent transition, asymptoticsuction boundary layer, free stream turbulence,Tollmien-Schlichting wave, stability, flow control, cylinderwake.
QC 20100607

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Sattarzadeh, Shirvan Sohrab. « Boundary layer streaks as a novel laminar flow control method ». Doctoral thesis, KTH, Stabilitet, Transition, Kontroll, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-181899.

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A novel laminar flow control based on generation of spanwise mean velocity gradients (SVG) in a flat plate boundary layer is investigated where disturbances of different types are introduced in the wall-bounded shear layer. The experimental investigations are aimed at; (i) generating stable and steady streamwise streaks in the boundary layer which set up spanwise gradients in the mean flow, and (ii) attenuating disturbance energy growth in the streaky boundary layers and hence delaying the onset of turbulence transition. The streamwise streaks generated by four different methods are investigated, which are spanwise arrays of triangular/rectangular miniature vortex generators (MVGs) and roughness elements, non-linear pair of oblique waves, and spanwise-periodic finite discrete suction. For all the investigated methods the boundary layer is modulated into regions of high- and low speed streaks through formation of pairs of counter-rotating streamwise vortices. For the streaky boundary layers generated by the MVGs a parameter study on a wide range of MVG configurations is performed in order to investigate the transient growth of the streaks. A general scaling of the streak amplitudes is found based on empiricism where an integral amplitude definition is proposed for the streaks. The disturbances are introduced as single- and broad band frequency twodimensional Tollmien–Schlichting (TS) waves, and three-dimensional single and a pair of oblique waves. In an attempt to obtain a more realistic configuration compared to previous investigations the disturbances are introduced upstream of the location were streaks are generated. It is shown that the SVG method is efficient in attenuating the growth of disturbance amplitudes in the linear regime for a wide range of frequencies although the disturbances have an initial amplitude response to the generation of the streaks. The attenuation rate of the disturbance amplitude is found to be optimized for an integral streak amplitude of 30% of the free-stream velocity which takes into account the periodic wavelength of the streaky base flow. The stabilizing effect of the streamwise streaks can be extended to the nonlinear regime of disturbances which in turn results in transition to turbulence delay. This results in significant drag reduction when comparing the skin friction coefficient of a laminar- to a turbulent boundary layer. It is also shown that consecutive turbulence transition delay can be obtained by reinforcing the streaky boundary layer in the streamwise direction. For the streaky boundary layer generated by pair of oblique waves their forcing frequency sets the upper limit for the frequency of disturbances beyond which the control fails.

QC 20160208

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Egreteau, Baptiste. « Contrôle de transition laminaire turbulent par aspiration pariétale à travers des matériaux poreux innovants ». Electronic Thesis or Diss., Toulouse, ISAE, 2024. http://www.theses.fr/2024ESAE0069.

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Cette thèse porte sur le développement et la mise en œuvre de matériaux perméables faits à partir de poudres métalliques pour le contrôle de transition laminaire-turbulent de la couche limite par aspiration pariétale. Cette aspiration, habituellement appliquée à travers des tôles de titane microperforées par laser, a pour but de retarder la transition de la couche limite vers le régime turbulent, et donc de réduire la traînée et ainsi de réduire la consommation de carburant des avions.Deux procédés de fabrication différents ont été utilisés pour fabriquer de nouveaux matériaux poreux : le Spark Plasma Sintering (SPS) et la fusion laser sur lit de poudre (LPBF en anglais). Le SPS est un système de frittage assisté sous champ électrique. Il a été employé en densification partielle avec de la poudre grossière de TA6V afin de contrôler la perméabilité des matériaux via les paramètres de fabrication. Le LPBF est un procédé de fabrication additive. Il a été employé avec de la poudre d’Inconel 718 de deux manières différentes : en concevant des matériaux à structure lattice et en créant du manque de fusion par diminution de l’énergie apportée à la poudre. Ces trois familles de matériaux ont été caractérisées en mesurant leur perméabilité, la rugosité, résistance acoustique et la morphologie de leurs réseaux poreux.La caractérisation des matériaux microporeux faits par SPS et LPBF a montré qu’il était possible de contrôler la perméabilité avec une large gamme de porosités. ’analyse de la morphologie de leurs réseaux poreux a notamment mis en lumière l’anisotrpoie des réseaux poreux. Pour le SPS, cette anisotropie apparait avec une pression de frittage de 20 MPa et est favorable à l’écoulement à travers le matériau. Tandis que pour le LPBF, cette anisotropie est favorable à l’écoulement dans le plan des lits de poudre.Cette caractérisation a permis de comparer leurs performances et choisir le procédé avec les paramètres de fabrication adéquats afin de réaliser un panneau perméable de grandes dimensions. Cette étude d’upscaling a été menée pour le LPBF en manque de fusion ainsi que le SPS, et la fabrication d’un panneau d’aspiration complet a abouti pour ce dernier procédé. Le panneau SPS est plus rugueux qu’une tôle microperforée laser, d’une perméabilité similaire et légèrement moins résistif acoustiquement.Pour étudier la transition de la couche limite dans un écoulement 2D sans gradient de pression, une maquette type plaque plane a été conçue en y intégrant des chambres d’aspiration. Cette maquette a été installée dans la soufflerie de recherche TRIN2, dédiée aux expériences sur la transition. Dans un premier temps, la position de transition sur la plaque plane pour un cas lisse a été déterminée afin d’avoir un cas de référence. Ensuite, une tôle microperforée et le panneau SPS ont été montés successivement. La position de transition a été mesurée pour chacun de ces panneaux avec et sans aspiration. Pour les deux panneaux poreux, la position de transition sans aspiration est avancée par rapport au cas lisse. Pour la tôle microperforée, c’est principalement dû à une condition d’impédance acoustique sur-amplifiant les ondes de Tollmien-Schlichting responsables de la transition. Pour le panneau SPS, la transition est encore plus avancée, principalement à cause de la rugosité de surface. En appliquant l’aspiration pariétale, la position de transition est repoussée de la même distance par rapport à la position sans aspiration pour les deux panneaux
This thesis focuses on the development and implementation of permeable materials made from metal powders for controlling the laminar-turbulent transition of the boundary layer by wall suction. This suction, usually applied through laser-microperforated titanium sheets, aims to delay the transition of the boundary layer to the turbulent regime, reduce drag and thus reduce aircraft fuel consumption.Two different manufacturing processes have been used to produce new porous materials: Spark Plasma Sintering (SPS) and Laser Powder Bed Fusion (LPBF). SPS is an electric field assisted sintering process. It has been used in partial densification with coarse TA6V powder to control material permeability via manufacturing parameters. LPBF is an additive manufacturing process. It was used with Inconel 718 powder in two different ways: by designing materials with a lattice structure and by creating a lack of fusion by reducing the energy supplied to the powder. These three families of materials were characterised by measuring their permeability, roughness, acoustic resistance and the morphology of their porous networks.The characterisation of microporous materials made by SPS and LPBF showed that it was possible to control permeability with a wide range of porosities. Analysis of the morphology of their porous networks has highlighted the anisotropy of the porous networks. For SPS, this anisotropy appears with a sintering pressure of 20 MPa and is favourable to flow through the material. For LPBF, the anisotropy is favourable to flow in the plane of the powder beds.This characterisation made it possible to compare their performances and choose the process with the appropriate manufacturing parameters in order to produce a large permeable panel. This upscaling study was carried out for the LPBF in the absence of fusion as well as the SPS, and the manufacture of a complete suction panel was completed for the latter process. The SPS panel is rougher than a laser microperforated sheet, with similar permeability and slightly less acoustic resistivity.This characterisation made it possible to compare their performance and choose the process with the appropriate manufacturing parameters to produce a large-scale permeable panel. This upscaling study was carried out for LPBF with a lack of fusion as well as for SPS, and the manufacture of a complete suction panel was completed for the latter process. The SPS panel is rougher than a laser microperforated sheet, of similar permeability and slightly less acoustically resistive.A flat plate-type model incorporating suction chambers was designed to study the transition of the boundary layer in a 2D flow without a pressure gradient. This model was installed in the TRIN2 research wind tunnel, dedicated to experiments on the transition. First, the transition position on the flat plate for a smooth case was determined to have a reference case. Then, a microperforated sheet and the SPS panel were mounted successively. The transition position was measured for each panel with and without suction. For the two porous panels, the transition position without suction was earlier than for the smooth case. For the microperforated sheet, this is mainly due to an acoustic impedance condition that over-amplifies the Tollmien-Schlichting waves responsible for the transition. The transition is even more advanced for the SPS panel, mainly due to the surface roughness. By applying wall suction, the transition position is delayed by the same distance compared with the position without suction for both panels

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Khapko, Taras. « Transition to turbulence in the asymptotic suction boundary layer ». Licentiate thesis, KTH, Stabilitet, Transition, Kontroll, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-141344.

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The focus of this thesis is on the numerical study of subcritical transition to turbulence in the asymptotic suction boundary layer (ASBL). Applying constant homogeneous suction prevents the spatial growth of the boundary layer, granting access to the asymptotic dynamics. This enables research approaches which are not feasible in the spatially growing case. In a first part, the laminar–turbulent separatrix of the ASBL is investigated numerically by means of an edge-tracking algorithm. The consideration of spanwise-extended domains allows for the robust localisation of the attracting flow structures on this separatrix. The active part of the identified edge states consists of a pair of low- and high-speed streaks, which experience calm phases followed by high energy bursts. During these bursts the structure is destroyed and re-created with a shift in the spanwise direction. Depending on the streamwise extent of the domain, these shifts are either regular in direction and distance, and periodic in time, or irregular in space and erratic in time. In all cases, the same clear regeneration mechanism of streaks and vor- tices is identified, bearing strong similarities with the classical self-sustaining cycle in near-wall turbulence. Bifurcations from periodic to chaotic regimes are studied by varying the streamwise length of the (periodic) domain. The resulting bifurcation diagram contains a number of phenomena, e.g. multistability, intermittency and period doubling, usually investigated in the context of low-dimensional systems. The second part is concerned with spatio–temporal aspects of turbulent ASBL in large domains near the onset of sustained turbulence. Adiabatically decreasing the Reynolds number, starting from a fully turbulent state, we study low-Re turbulence and events leading to laminarisation. Furthermore, a robust quantitative estimate for the lowest Reynolds number at which turbulence is sustained is obtained at Re $\approx$ 270.

QC 20140213

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Davidsson, Niklas. « Stability and transition in the suction boundary layer and other shear flows / ». Luleå : Luleå University of Technology, 2007. http://epubl.ltu.se/1402-1544/2007/04/.

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Hackenberg, Petra. « Numerical optimization of the suction distribution for laminar flow control aerofoils ». Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241170.

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Huang, Liang. « OPTIMIZATION OF BLOWING AND SUCTION CONTROL ON NACA0012 AIRFOIL USING GENETIC ALGORITHM WITH DIVERSITY CONTROL ». UKnowledge, 2004. http://uknowledge.uky.edu/gradschool_diss/385.

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Active control of the flow over an airfoil is an area of heightened interest in the aerospace community. Previous research on flow control design processes heavily depended on trial and error and the designers knowledge and intuition. Such an approach cannot always meet the growing demands of higher design quality in less time. Successful application of computational fluid dynamics (CFD) to this kind of control problem critically depends on an efficient searching algorithm for design optimization. CFD in conjunction with Genetic Algorithms (GA) potentially offers an efficient and robust optimization method and is a promising solution for current flow control designs. But the traditional binary GA and its operators need to be transformed or re-defined to meet the requirements of real world engineering problems. Current research has combined different existing GA techniques and proposed a realcoded Explicit Adaptive Range Normal Distribution (EARND) genetic algorithm with diversity control to solve the convergence problems. First, a traditional binary-coded GA is replaced by a real-coded algorithm in which the corresponding design variables are encoded into a vector of real numbers that is conceptually closest to the real design space. Second, to address the convergence speed problem, an additional normal distribution scheme is added into the basic GA in order to monitor the global optimization process; meanwhile, design parameters boundaries are explicitly updated to eliminate unnecessary evaluations (computation) in un-promising areas to balance the workload between the global and local searching process. Third, during the initial 20% evolution (search process), the diversity of the individuals within each generation are controlled by a formula in order to conquer the problem of preliminary convergence to the local optimum. In order to better understand the two-jet control optimization results and process, at first, a single jet with a width of 2.5% the chord length is placed on a NACA 0012 airfoils upper surface simulating the blowing and suction control under Re=500,000 and angle of attack 18 degree. Nearly 300 numerical simulations are conducted over a range of parameters (jet location, amplitude and angle). The physical mechanisms that govern suction and blowing flow control are determined and analyzed, and the critical values of suction and blowing locations, amplitudes, and angles are discussed. Moreover, based on the results of single suction/blowing jet control on a NACA 0012 airfoil, the design parameters of a two-jet system are proposed. Our proposed algorithm is built on top of the CFD code, guiding the movement of two jets along the airfoils upper surface. The reasonable optimum control values are determined within the control parameter range. The current study of Genetic Algorithms on airfoil flow control has been demonstrated to be a successful optimization application.

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Huang, Liang. « Optimization of blowing and suction control on NACA0012 airfoil using genetic algoirthm with diversity control ». Lexington, Ky. : [University of Kentucky Libraries], 2004. http://lib.uky.edu/ETD/ukymeen2004d00153/LiangDis.pdf.

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Thesis (M.S.)--University of Kentucky, 2004.
Title from document title page (viewed Oct. 12, 2004). Document formatted into pages; contains xii, 113 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 102-112).

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Wang, Yu. « Suction Detection and Feedback Control for the Rotary Left Ventricular Assist Device ». Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6032.

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The Left Ventricular Assist Device (LVAD) is a rotary mechanical pump that is implanted in patients with congestive heart failure to help the left ventricle in pumping blood in the circulatory system. The rotary type pumps are controlled by varying the pump motor current to adjust the amount of blood flowing through the LVAD. One important challenge in using such a device is the desire to provide the patient with as close to a normal lifestyle as possible until a donor heart becomes available. The development of an appropriate feedback controller that is capable of automatically adjusting the pump current is therefore a crucial step in meeting this challenge. In addition to being able to adapt to changes in the patient's daily activities, the controller must be able to prevent the occurrence of excessive pumping of blood from the left ventricle (a phenomenon known as ventricular suction) that may cause collapse of the left ventricle and damage to the heart muscle and tissues. In this dissertation, we present a new suction detection system that can precisely classify pump flow patterns, based on a Lagrangian Support Vector Machine (LSVM) model that combines six suction indices extracted from the pump flow signal to make a decision about whether the pump is not in suction, approaching suction, or in suction. The proposed method has been tested using in vivo experimental data based on two different LVAD pumps. The results show that the system can produce superior performance in terms of classification accuracy, stability, learning speed, and good robustness compared to three other existing suction detection methods and the original SVM-based algorithm. The ability of the proposed algorithm to detect suction provides a reliable platform for the development of a feedback control system to control the current of the pump (input variable) while at the same time ensuring that suction is avoided. Based on the proposed suction detector, a new control system for the rotary LVAD was developed to automatically regulate the pump current of the device to avoid ventricular suction. The control system consists of an LSVM suction detector and a feedback controller. The LSVM suction detector is activated first so as to correctly classify the pump status as No Suction (NS) or Suction (S). When the detection is “No Suction”, the feedback controller is activated so as to automatically adjust the pump current in order that the blood flow requirements of the patient's body at different physiological states are met according to the patient's activity level. When the detection is “Suction”, the pump current is immediately decreased in order to drive the pump back to a normal No Suction operating condition. The performance of the control system was tested in simulations over a wide range of physiological conditions.
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering

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Eustace, Richard. « Stabilisation of roughness particle induced turbulence using laminar flow control suction surfaces ». Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299503.

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Center, Langley Research, dir. Optimum suction distribution for transition control. Hampton, Va : National Aeronautics and Space Administration, Langley Research Center, 1996.

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Center, Langley Research, dir. Optimum suction distribution for transition control. Hampton, Va : National Aeronautics and Space Administration, Langley Research Center, 1996.

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United States. National Aeronautics and Space Administration. Scientific and Technical Information Office., dir. A numerical study of transition control by periodic suction-blowing. [Washington, DC] : National Aeronautics and Space Administration, Scientific and Technical Information Office, 1987.

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Smith, A. Instability and transition of flow at, and near, an attachment-line : Including control by surface suction. Hampton, Va : National Aeronautics and Space Administration, Langley Research Center, 1998.

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A, Poll D. I., et United States. National Aeronautics and Space Administration., dir. Instability and transition of flow at, and near, an attachment-line : Including control by surface suction : contract number NCC1-218. [Washington, DC : National Aeronautics and Space Administration, 1996.

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1945-, Gad-el-Hak Mohamed, et Tsai Her Mann, dir. Transition and turbulence control. New Jersey : World Scientific, 2006.

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United States. National Aeronautics and Space Administration., dir. Instabilities originating from suction holes used for laminar flow control (LFC). [Washington, DC : National Aeronautics and Space Administration, 1994.

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Kozarzewski, Piotr. State Corporate Control in Transition. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78562-8.

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International Erosion Control Association. Conference. Erosion control : Technology in transition. Steamboat Springs, CO : International Erosion Control Association, 1990.

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author, Dong Gang 1970, dir. Principles of turbulence control. Singapore : John Wiley & Sons, 2015.

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Chapitres de livres sur le sujet "Transition control by suction"

Bakchinov, Andrey A., Michael M. Katasonov, P. Henrik Alfredsson et Viktor V. Kozlov. « Control of streaky structures by localized blowing and suction ». Dans Laminar-Turbulent Transition, 161–66. Berlin, Heidelberg : Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-662-03997-7_22.

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Hein, S., E. Schülein, A. Hanifi, J. Sousa et D. Arnal. « Laminar Flow Control by Suction at Mach 2 ». Dans Seventh IUTAM Symposium on Laminar-Turbulent Transition, 189–94. Dordrecht : Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-3723-7_29.

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Lundell, Fredrik, et P. Henrik Alfredsson. « Feed-forward Control of Streak Instabilities in Plane Poiseuille Flow by Localized Suction ». Dans Laminar-Turbulent Transition, 229–34. Berlin, Heidelberg : Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-662-03997-7_33.

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Cathalifaud, Patricia, et Paolo Luchini. « Optimal Control by Blowing and Suction at the Wall of Algebraically Growing Boundary Layer Disturbances ». Dans Laminar-Turbulent Transition, 307–12. Berlin, Heidelberg : Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-662-03997-7_45.

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Friederich, Tillmann A., et Markus J. Kloker. « Direct Numerical Simulation of Crossflow-Transition Control Using Pinpoint Suction ». Dans Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 235–43. Berlin, Heidelberg : Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-35680-3_29.

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Bakchinov, A. A., M. M. Katasonov, P. H. Alfredsson et V. V. Kozlov. « Control of Boundary Layer Transition at High Fst by Localized Suction ». Dans IUTAM Symposium on Mechanics of Passive and Active Flow Control, 159–64. Dordrecht : Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4199-4_26.

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Donelli, R. S., F. De Gregorio, M. Buffoni et O. Tutty. « Control of a trapped vortex in a thick airfoil by steady/unsteady mass flow suction ». Dans Seventh IUTAM Symposium on Laminar-Turbulent Transition, 481–84. Dordrecht : Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-3723-7_80.

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Seraudie, A., M. Correge, G. Casalis et P. Mouyon. « Control of the Laminar-Turbulent Transition by Suction of the Boundary Layer in 2D Flow. » Dans IUTAM Symposium on Mechanics of Passive and Active Flow Control, 177–82. Dordrecht : Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4199-4_29.

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Gad-el-Hak, Mohamed. « Flow Control by Suction ». Dans Structure of Turbulence and Drag Reduction, 357–60. Berlin, Heidelberg : Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-50971-1_30.

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Crowley, B., et C. Atkin. « Effect of Discrete Widely Spaced Suction on a Transitioning Flow at High Suction Rates ». Dans IUTAM Laminar-Turbulent Transition, 359–68. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-67902-6_31.

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Actes de conférences sur le sujet "Transition control by suction"

Rath, Aishwarya, Chang Liu et Dennice F. Gayme. « A structured input-output approach to evaluating the effects of uniform wall-suction on optimal perturbations in transitional boundary layers ». Dans 2024 IEEE 63rd Conference on Decision and Control (CDC), 7714–19. IEEE, 2024. https://doi.org/10.1109/cdc56724.2024.10886180.

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Balakumar, P., et P. Hall. « Optimum suction distribution for transition control ». Dans Fluid Dynamics Conference. Reston, Virigina : American Institute of Aeronautics and Astronautics, 1996. http://dx.doi.org/10.2514/6.1996-1950.

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BIRINGEN, S., W. NUTT et M. CARUSO. « Transition control by periodic suction-blowing ». Dans 18th Fluid Dynamics and Plasmadynamics and Lasers Conference. Reston, Virigina : American Institute of Aeronautics and Astronautics, 1985. http://dx.doi.org/10.2514/6.1985-1700.

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Wright, M., et P. Nelson. « Optimization of distributed suction for automatic transition control ». Dans 4th AIAA/CEAS Aeroacoustics Conference. Reston, Virigina : American Institute of Aeronautics and Astronautics, 1998. http://dx.doi.org/10.2514/6.1998-2372.

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Friederich, Tillmann, et Markus Kloker. « Control of Crossflow-Vortex Induced Transition : DNS of Pinpoint Suction ». Dans 41st AIAA Fluid Dynamics Conference and Exhibit. Reston, Virigina : American Institute of Aeronautics and Astronautics, 2011. http://dx.doi.org/10.2514/6.2011-3884.

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RIOUAL, J.-L., PA NELSON et MJ FISHER. « AUTOMATIC CONTROL OF BOUNDARY LAYER TRANSITION USING A DOUBLE SUCTION PANEL ». Dans Acoustics '93. Institute of Acoustics, 2024. http://dx.doi.org/10.25144/20508.

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Hackenberg, P., O. Tutty et P. Nelson. « Numerical studies of the automatic control of boundary-layer transition via multiple suction panels ». Dans Fluid Dynamics Conference. Reston, Virigina : American Institute of Aeronautics and Astronautics, 1994. http://dx.doi.org/10.2514/6.1994-2214.

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Pralits, Jan O., et Ardeshir Hanifi. « Optimization of Steady Suction for Disturbance Control on Infinite Swept Wings ». Dans ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31055.

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Theory and results are presented on transition control using steady suction to suppress convectively unstable disturbances in a growing boundary layer on infinite swept wings. The suction profiles are computed using optimal control theory and the optimization process is gradient based. Here, the gradient is evaluated using the adjoint of the parabolized stability equations and the adjoint of the boundary layer equations. Results are presented for an application of the theory on a wing-profile designed for medium range commercial aircrafts.

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Huang, ZhangFeng, et Xuesong Wu. « The effect of local steady suction on the stability and transition of boundary layer on a flat plate ». Dans 8th AIAA Flow Control Conference. Reston, Virginia : American Institute of Aeronautics and Astronautics, 2016. http://dx.doi.org/10.2514/6.2016-3471.

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Saric, William S., et Helen L. Reed. « Control of Transition in Supersonic Boundary Layers : Experiments and Computations (Keynote) ». Dans ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31258.

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The present work addresses a technique that can lead to drag reduction on supersonic wings by means of passive laminar flow control. Recent developments in the stability and transition in swept-wing flows in low-disturbance environments have offered the promise of controlling transition without suction. It has been demonstrated in low-speed experiments that distributed roughness near the attachment line can control the crossflow instability provided the roughness spacing is below a critical value. This is extended to supersonic flow over highly swept wings where the combined computational and experimental work gives design criteria for airfoils swept beyond the characteristic Mach angle.

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Rapports d'organisations sur le sujet "Transition control by suction"

Gursul, Ismet. Control of Leading-Edge Vortices With Suction. Fort Belvoir, VA : Defense Technical Information Center, octobre 1996. http://dx.doi.org/10.21236/ada320167.

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Saric, William S., Rodney D. Bowersox, Helen Reed, Sharath Girimaji, Edward White, Simon North, Hermann Fasel, Joseph Shepherd, Anatoli Tumin et Xiaolin Zhong. Integrated Theoretical, Computational, and Experimental Studies for Transition Estimation and Control. Fort Belvoir, VA : Defense Technical Information Center, juin 2014. http://dx.doi.org/10.21236/ada606147.

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Moin, Parviz, et Thomas Bewley. Optimal and Robust Control Transition and Turbulence in Plane Channel Flow. Fort Belvoir, VA : Defense Technical Information Center, décembre 1996. http://dx.doi.org/10.21236/ada329660.

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Hopkins, Matt, et William Lazonick. Tesla as a Global Competitor : Strategic Control in the EV Transition. Institute for New Economic Thinking Working Paper Series, septembre 2024. http://dx.doi.org/10.36687/inetwp225.

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In this paper, we assess the implications of Elon Musk’s strategic control over Tesla, the pioneering company that has become central to the electric-vehicle transition. We document how, as Tesla’s CEO for 16 years, Musk has exercised strategic control to direct the transformation of the company from an uncertain startup to a global leader. Now that Tesla is profitable corporate predators (aka hedge-fund activists) may challenge Musk’s strategic control—a possibility of which the CEO is well aware. To retain his control over Tesla as a publicly listed company, Musk depends on holding a sufficient proportion of Tesla’s shares outstanding to possess the voting power to fend off predatory value extractors. In addition to accumulating Tesla shares by investing $291.2 million at early stages of the company’s evolution, Musk has relied upon massive stock-option grants from the Tesla board, under the guise of “compensation”, in 2009, 2012, and 2018, to boost his shareholding and, with it, his voting power. Hence the Delaware Court of Chancery’s decision in January 2024 to rescind Musk’s 2018 stock-option package—by far the largest ever granted to a corporate executive—poses a threat to Musk’s strategic control at Tesla. As the “Technoking” of Tesla strategizes to maintain his control over the company’s decision-making, anyone concerned with the role that Tesla will play in the evolving EV transition should be asking how CEO Musk might use, or abuse, his powerful position.

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Carlson, A. B. Interface control document between PUREX Plant Transition and Solid Waste Disposal Division. Office of Scientific and Technical Information (OSTI), septembre 1995. http://dx.doi.org/10.2172/447985.

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Venetz, T. J. Interface control document between FFTF Transition Project and Solid Waste Disposal Division. Office of Scientific and Technical Information (OSTI), novembre 1994. http://dx.doi.org/10.2172/10194693.

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Venetz, T. J. Interface control document between PFP Transition Project and Solid Waste Disposal Division. Office of Scientific and Technical Information (OSTI), janvier 1995. http://dx.doi.org/10.2172/10110704.

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Davis, Myron B., Helen Reed, Harold Youngren, Brian Smith et Erich Bender. Control of Aerodynamic Flows. Delivery Order 0051 : Transition Prediction Method Review Summary for the Rapid Assessment Tool for Transition Prediction (RATTraP). Fort Belvoir, VA : Defense Technical Information Center, juin 2005. http://dx.doi.org/10.21236/ada442886.

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Yang, Xi, Charles M. Ankenbrandt, James MacLachlan et Valeri A. Lebedev. A proposed transition scheme for the longitudinal emittance control in the Fermilab Booster. Office of Scientific and Technical Information (OSTI), août 2005. http://dx.doi.org/10.2172/15020250.

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Oji, L. Analysis of Tank 38H (HTF-38-15-119, 127) Surface, Subsurface and Tank 43H (HTF-43-15-116, 117 and 118) Surface, Feed Pump Suction and Jet Suction Subsurface Supernatant Samples in Support of Enrichment, Corrosion Control and Salt Batch Planning Programs. Office of Scientific and Technical Information (OSTI), décembre 2015. http://dx.doi.org/10.2172/1233731.

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