Literatura académica sobre el tema "Aerodynamic lens"
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Artículos de revistas sobre el tema "Aerodynamic lens"
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Du, Xubing, Zeming Zhuo, Xue Li, Xuan Li, Mei Li, Junlin Yang, Zhen Zhou, Wei Gao, Zhengxu Huang y Lei Li. "Design and Simulation of Aerosol Inlet System for Particulate Matter with a Wide Size Range". Atmosphere 14, n.º 4 (31 de marzo de 2023): 664. http://dx.doi.org/10.3390/atmos14040664.
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A novel aerodynamic lens-based inlet system was developed for a wide particle size range, and it could extend the size range of transmitted particulate matter (PM) to 50 nm–10 μm. The lens system adopted a seven-stage aerodynamic focusing orifice to extend the range of transmitted PM, and a relaxation system with a virtual impact function was introduced at the front of the aerodynamic lens. Through the innovative design, the system could concentrate the input samples as well as effectively enhance the focusing effect on large PM. Furthermore, an additional aerodynamic pre-focusing inlet system was innovatively added to the front of the sampling orifice of the traditional aerodynamic lens, and it could pre-focus large PM into the axis region before it entered the small orifice and then solve the previous problem with loss of large PM. Fluid simulations indicated that the inlet system could achieve 100% effective transmission and focusing for PM in the range of 0.18–10 μm. The characterization and verification results obtained from the improved single-particle aerosol mass spectrometer (SPAMS) were remarkably consistent with the theoretical values. The practical tests indicated that bioaerosol particles up to 10 μm could be detected. Compared with the observation for the same type of lens, the focusing performance of this novel lens system has better advantages in particle size range and transmission efficiency and therefore, it has broad application prospects in bioaerosol research, single-cell analysis, etc.
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Wang, Xiaoliang y Peter H. McMurry. "A Design Tool for Aerodynamic Lens Systems". Aerosol Science and Technology 40, n.º 5 (junio de 2006): 320–34. http://dx.doi.org/10.1080/02786820600615063.
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Wang, Xiaoliang y Peter H. McMurry. "Instruction Manual for the Aerodynamic Lens Calculator". Aerosol Science and Technology 40, n.º 5 (junio de 2006): 1–10. http://dx.doi.org/10.1080/02786820600616764.
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OKA, Nobuhito, Masato FURUKAWA, Kenta KAWAMITSU y Kazutoyo YAMADA. "Optimum aerodynamic design for wind-lens turbine". Journal of Fluid Science and Technology 11, n.º 2 (2016): JFST0011. http://dx.doi.org/10.1299/jfst.2016jfst0011.
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Williams, L. R., L. A. Gonzalez, J. Peck, D. Trimborn, J. McInnis, M. R. Farrar, K. D. Moore et al. "Characterization of an aerodynamic lens for transmitting particles greater than 1 micrometer in diameter into the Aerodyne aerosol mass spectrometer". Atmospheric Measurement Techniques 6, n.º 11 (28 de noviembre de 2013): 3271–80. http://dx.doi.org/10.5194/amt-6-3271-2013.
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Abstract. We have designed and characterized a new inlet and aerodynamic lens for the Aerodyne aerosol mass spectrometer (AMS) that transmits particles between 80 nm and more than 3 μm in vacuum aerodynamic diameter. The design of the inlet and lens was optimized with computational fluid dynamics (CFD) modeling of particle trajectories. Major changes include a redesigned critical orifice holder and valve assembly, addition of a relaxation chamber behind the critical orifice, and a higher lens operating pressure. The transmission efficiency of the new inlet and lens was characterized experimentally with size-selected particles. Experimental measurements are in good agreement with the calculated transmission efficiency.
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Gunasekaran, Sidaard, Madison Peyton y Neal Novotny. "Aerodynamic Interactions of Wind Lenses at Close Proximities". Energies 15, n.º 13 (24 de junio de 2022): 4622. http://dx.doi.org/10.3390/en15134622.
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The fundamental aerodynamic interactions between a pair of wind lenses is experimentally investigated. In prior work, wind tunnel testing of lensed turbines in a side-by-side configuration revealed that one lensed turbine outperformed its counterpart in terms of power production. In the current study, particle image velocimetry (PIV) was performed in the wake of three different pairs of wind lens profiles and revealed an inherent bias in the wake properties at close proximities which led to one turbine outperforming the other. The merged wake location is skewed to a single lens in the lens pair depending on the extent of cancellation of inboard vorticity magnitude. At 0.1 to 0.2 x/D,the individual wakes merge as one, at which point the vortex shedding frequency and the modal strength behind the lens pairs is reduced. Coincidentally, it is at this spacing that the net power output of lensed turbines placed in a side-by-side configuration reaches the maximum.
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Novosselov, Igor V. y Peter C. Ariessohn. "Rectangular Slit Atmospheric Pressure Aerodynamic Lens Aerosol Concentrator". Aerosol Science and Technology 48, n.º 2 (13 de diciembre de 2013): 163–72. http://dx.doi.org/10.1080/02786826.2013.865832.
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Grund, J., Ch E. Düllmann, K. Eberhardt, Sz Nagy, J. J. W. van de Laar, D. Renisch y F. Schneider. "Implementation of an aerodynamic lens for TRIGA-SPEC". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 376 (junio de 2016): 225–28. http://dx.doi.org/10.1016/j.nimb.2015.12.017.
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Worbs, Lena, Nils Roth, Jannik Lübke, Armando D. Estillore, P. Lourdu Xavier, Amit K. Samanta y Jochen Küpper. "Optimizing the geometry of aerodynamic lens injectors for single-particle coherent diffractive imaging of gold nanoparticles". Journal of Applied Crystallography 54, n.º 6 (16 de noviembre de 2021): 1730–37. http://dx.doi.org/10.1107/s1600576721009973.
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Single-particle X-ray diffractive imaging (SPI) of small (bio-)nanoparticles (NPs) requires optimized injectors to collect sufficient diffraction patterns to allow for the reconstruction of the NP structure with high resolution. Typically, aerodynamic lens-stack injectors are used for NP injection. However, current injectors were developed for larger NPs (>100 nm), and their ability to generate high-density NP beams suffers with decreasing NP size. Here, an aerodynamic lens-stack injector with variable geometry and a geometry-optimization procedure are presented. The optimization for 50 nm gold-NP (AuNP) injection using a numerical-simulation infrastructure capable of calculating the carrier-gas flow and the particle trajectories through the injector is also introduced. The simulations were experimentally validated using spherical AuNPs and sucrose NPs. In addition, the optimized injector was compared with the standard-installation `Uppsala injector' for AuNPs. Results for these heavy particles showed a shift in the particle-beam focus position rather than a change in beam size, which results in a lower gas background for the optimized injector. Optimized aerodynamic lens-stack injectors will allow one to increase NP beam density, reduce the gas background, discover the limits of current injectors and contribute to structure determination of small NPs using SPI.
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Williams, L. R., L. A. Gonzalez, J. Peck, D. Trimborn, J. McInnis, M. R. Farrar, K. D. Moore et al. "Characterization of an aerodynamic lens for transmitting particles > 1 micrometer in diameter into the Aerodyne aerosol mass spectrometer". Atmospheric Measurement Techniques Discussions 6, n.º 3 (7 de junio de 2013): 5033–63. http://dx.doi.org/10.5194/amtd-6-5033-2013.
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Abstract. We have designed and characterized a new inlet and aerodynamic lens for the Aerodyne aerosol mass spectrometer (AMS) that transmits particles between 80 nm and more than 3 μm in diameter. The design of the inlet and lens was optimized with computational fluid dynamics (CFD) modeling of particle trajectories. Major changes include a redesigned critical orifice holder and valve assembly, addition of a relaxation chamber behind the critical orifice, and a higher lens operating pressure. The transmission efficiency of the new inlet and lens was characterized experimentally with size-selected particles. Experimental measurements are in good agreement with the calculated transmission efficiency.
Tesis sobre el tema "Aerodynamic lens"
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Koolik, Libby (Libby P. ). "Characterization of a 3D printed pumped counterflow virtual impactor and an aerodynamic lens concentrator". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/114346.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 11-12).
Atmospheric aerosols have an important role in cloud formation and, by extension, in the overall climate system. Field studies are required to refine the uncertainty associated with the net radiative effect of atmospheric aerosols. Two pre-existing cloud sampling devices, the pumped counterflow virtual impactor (PCVI) and aerodynamic lens concentrator (ADL), were modelled using computer aided design software and printed using stereolithography printing. These devices were compared against their industrial counterparts. The printed PCVI was proven to be as effective as the industrial PCVI in a smaller working range. The printed concentrator effectively concentrated particles, but at a lower concentration factor than the industrial concentrator. This study revealed potential for further refinement in design features for both devices and it served as an essential pre-study for future field campaigns that will use these 3D printed devices.
by Libby Koolik.
S.B.
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Lai, Shutong. "Synthèse de revêtements nanocomposites photocatalytiques par pulvérisation cathodique assisté par jet d’aérosol". Electronic Thesis or Diss., Bourgogne Franche-Comté, 2023. http://www.theses.fr/2023UBFCD063.
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Un procédé combinant la pulvérisation cathodique magnétron avec un jet divergent de nanoparticules transporté par une lentille aérodynamique est proposé pour la synthèse de films nanocomposites. Ce procédé permet l'incorporation de nanoparticules pendant la croissance du revêtement, avec un contrôle séparé du dépôt de nanoparticules et de la matrice. De plus, l’incorporation de nanoparticules génère la formation de défauts de croissance aidant au développement de la surface du revêtement. Pour ces facultés, il est proposé d’appliquer ce procédé à la synthèse des films nanocomposites photocatalytiques. Le TiO2, reconnu pour ses propriétés photocatalytiques, a été retenu comme matrice. L'objectif de cette thèse est d’étudier les potentialités de ce procédé à partir de trois perspectives principales. La première porte sur le contrôle de la concentration en nanoparticules et leur conséquence sur les propriétés de la matrice. La deuxième perspective concerne la manière d’incorporer les nanoparticules dans la matrice en jouant sur le moment et le temps d’incorporation. La troisième perspective traite de la nature des particules, cinq types différents de nanoparticules (SiO2, Au, Bi2O3, Cu2O, P25) ont été incorporés avec succès, et une comparaison de ces différents types de nanoparticules a été effectuée. Il est démontré qu’une architecturation judicieuse des revêtements peut être facilement implémentée et conduire à des résultats prometteursA process combining magnetron sputtering with a divergent jet of nanoparticles transported by an aerodynamic lens is proposed for the synthesis of nanocomposite films. This process enables the incorporation of nanoparticles during coating growth, with separate control of nanoparticle and matrix deposition. In addition, the incorporation of nanoparticles generates the formation of growth defects that aids coating surface development. This is why it is proposed to apply this process to the synthesis of photocatalytic nanocomposite films. TiO2, recognized for its photocatalytic properties, was chosen as the matrix. The aim of this thesis is to investigate the potential of this process from three main perspectives. The first concerns the control of nanoparticle concentration and its impact on the matrix properties. The second concerns how to incorporate the nanoparticles into the matrix, by adjusting the time sequence and time of incorporation. The third perspective deals with the nature of the particles: five different types of nanoparticles (SiO2, Au, Bi2O3, Cu2O, P25) have been successfully incorporated, and a comparison of these different types of nanoparticles has been carried out. It is demonstrated that judicious coating architecture can be easily implemented and lead to promising results
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Matouk, Rabea. "Calculation of Aerodynamic Noise of Wing Airfoils by Hybrid Methods". Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/240641.
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This research is situated in the field of Computational AeroAcoustics (CAA). The thesis focuses on the computation of the aerodynamic noise generated by turbulent flows around wing, fan, or propeller airfoils. The computation of the noise radiated from a device is the first step for designers to understand the acoustical characteristics and to determine the noise sources in order to modify the design toward having acoustically efficient products. As a case study, the broadband or trailing-edge noise emanating from a CD (Controlled-Diffusion) airfoil, belonging to a fan is studied. The hybrid methods of aeroacoustic are applied to simulate and predict the radiated noise. The necessary tools were researched and developed. The hybrid methods consist in two steps simulations, where the determination of the aerodynamic field is decoupled from the computation of the acoustic waves propagation to the far field, so the first part of this thesis is devoted to an aerodynamic study of the considered airfoil. In this part of the thesis, a complete aerodynamic study has been performed. Some aspects have been developed in the used in-house solver SFELES, including the implementation of a new SGS model, a new outlet boundary condition and a new transient format which is used to extract the noise sources to be exported to the acoustic solver, ACTRAN. The second part of this thesis is concerned with the aeroacoustic study where four methods have been applied, among them two are integral formulations and the two others are partial-differential equations. The first method applied is Amiet’s theory, implemented in Matlab, based on the wall-pressure spectrum extracted in a point near the trailing edge. The second method is Curle’s formulation. It is applied proposing two approaches; the first approach is the implementation of the volume and surface integrals in SFELES to be calculated simultaneously with the flow in order to avoid the storage of noise sources which requires a huge space. In the second approach, the fluctuating aerodynamic forces, already obtained during the aerodynamics simulation, are used to compute the noise considering just the surface sources. Finally, Lighthil and Möhring analogies have been applied via the acoustic solver ACTRAN using sources extracted via SFELES. Maps of the radiated noise are demonstrated for several frequencies. The refraction effects of the mean flow have been studied.Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
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Baugher, Skyler Keil. "Development of a Hybrid Methodology for RANS and LES Modeling of Aerodynamic Flows". University of Toledo / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1588873661973254.
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Afailal, Al Hassan. "Numerical simulation of non-reactive aerodynamics in Internal Combustion Engines using a hybrid RANS/LES approach". Thesis, Pau, 2020. http://www.theses.fr/2020PAUU3028.
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L'aérodynamique interne est un élément fondamental pour améliorer la combustion dans les moteurs à allumage commandé. Une meilleure maitrise des écoulements internes est permise grâce aux outils de simulation CFD qui sont de plus en plus utilisés dans le processus de développement des moteurs à allumage commandé. Cette thèse avait pour objectif d’étendre l'approche hybride RANS/LES-temporelle dite HTLES, initialement dédiée pour des écoulements statistiquement stationnaires, aux écoulements moteurs avec des parois mobiles et des modes opératoires cycliques, puis de la valider dans des configurations représentatives des écoulements moteurs. Cette approche vise à modéliser les régions proches parois par approche statistique RANS et tend continûment vers la LES temporelle loin des parois si la discrétisation spatiale et temporelle est suffisamment résolue. Le formalisme temporel permet une hybridation RANS/LES consistante dans un écoulement statistiquement stationnaire, les deux méthodes se basant sur des opérateurs temporels (respectivement la moyenne temporelle et le filtrage temporel). Une première amélioration de l’approche HTLES a été proposée en ajoutant une fonction de protection qui impose le mode RANS dans la région proche paroi, indépendamment de la discrétisation locale (spatiale et temporelle). Dans les écoulements cycliques, l’approche HTLES modélise les échelles turbulentes non-résolues en se basant sur des moyennes de phase des grandeurs résolues qui sont inconnues lors de la simulation. La moyenne glissante exponentielle (EWA) a été utilisée afin d’approximer ces moyennes de phase. Une formule pour définir la largeur de la moyenne glissante a été proposée de sorte que les fluctuations turbulentes (hautes fréquences) soient filtrées des quantités résolues, tout en conservant les composantes cycliques (basses fréquences). Cette approche a été implémentée dans le code de calcul industriel CONVERGE CFD. Elle a d'abord été validée dans deux configurations stationnaires : un canal plan infini et un banc volute. A cet effet, les résultats ont été comparés aux données de référence et aux résultats RANS et LES. Dans les régions proches parois où le maillage est sous résolu pour la LES, EWA-HTLES a mieux prédit l’écoulement grâce à l'utilisation du mode RANS, permettant une meilleure prédiction des pertes de charge. La résolution des grandes échelles dans la région centrale a permis d'obtenir des prédictions aussi précises qu’une simulation LES en termes de vitesses moyennes et des fluctuations. La validation de l'EWA-HTLES a également été effectuée dans deux configurations moteurs : le tumble compressé et le moteur Darmstadt, tous deux présentant des caractéristiques aérodynamiques typiques aux moteurs à allumage commandé telles que la génération et la compression du mouvement de tumble et la variabilité cyclique. Pour chaque configuration, un nombre total de 40 cycles consécutifs simulés à l'aide de EWA-HTLES a été utilisé pour calculer les deux premiers moments statistiques. Les résultats ont été comparés aux données de la PIV, et aux résultats donnés par les simulations RANS et LES. Les résultats ont montré que le modèle développé arrive à contrôler correctement la transition RANS-LES dans des configurations complexes avec des conditions d'écoulement non stationnaires et des déformations géométriques importantes, assurant le mode RANS aux parois et la LES au centre du cylindre. La résolution des grandes échelles a permis une bonne prédiction des phénomènes instationnaires, particulièrement l'évolution des caractéristiques du mouvement de tumble et des phénomènes associés aux variabilités cycliques, tels que l'augmentation locale de vitesses fluctuantes. Les résultats de l'EWA-HTLES sont similaires à ceux prédits par la LES et meilleurs que ceux donnés par les simulations RANS. Ces résultats montrent des perspectives encourageantes pour l'application de cette méthode dans de nombreuses configurations industriellesInternal aerodynamics is a key element for improving the combustion efficiency in Spark-Ignition (SI) engines. Within this context, CFD tools are increasingly used to investigate in-cylinder flows and to support the design of fuel-efficient engines. The present research aimed at extending and validating a non-zonal hybrid Reynolds-Averaged Navier-Stokes / Temporal Large-Eddy Simulation (HTLES) approach, initially formulated for stationary flows, to cyclic SI engine flows with moving walls. The aim was to model the near-wall regions and coarse mesh regions in RANS, while solving the turbulent scales in core regions with sufficient mesh resolution using temporal LES, in a seamless approach with no a priori user input. HTLES was retained as it proposed a consistent hybridization combining time-averaging in RANS regions with temporal filtering in TLES.A first development consisted in implementing a smooth shielding function that enforces the RANS mode in near-wall regions, regardless of the local temporal and spatial resolution. The extension of HTLES to cyclic flows was then achieved via the formulation of a method allowing approximating the phase averages of resolved flow quantities based on an Exponentially Weighted Average (EWA). A dynamic expression for the width of the weighted average was proposed, in order to ensure that the high frequency turbulent fluctuations be filtered out from the resolved quantities, while keeping the low frequency cyclic components of the flow variables. The resulting EWA-HTLES model was implemented in the commercial CONVERGE CFD code. The developed EWA-HTLES model was first applied to the simulation of two steady flow configurations: a minimal turbulent channel and a steady flow rig. Predictions were confronted with reference data, as well as with those from RANS and LES. All simulations relied on the use of standard wall laws and coarse grids at walls. Imposing the RANS mode at walls yielded EWA-HTLES predictions of pressure losses much closer to DNS and experimental findings than with LES. At the same time, it allowed yielding results in terms of mean and RMS velocities s in the core regions of the same quality than LES, and superior to RANS.Finally, EWA-HTLES was applied to the simulation of two cyclic flows representative of SI engines: the compressed tumble and the Darmstadt single-cylinder pentroof 4valve engine. For each configuration, a total number of 40 consecutive cycles were simulated. The results were confronted to PIV data, and to RANS and LES predictions obtained using the same numerical set-up. It was shown that EWA-HTLES successfully drives the RANS-to-LES transition in such complex configurations exhibiting unsteady flow features and important cyclic geometrical deformations. It switched from the RANS mode at the walls to LES in the core region of the cylinder, allowing a better prediction of unsteady phenomena including the evolution of the overall tumble characteristics and phenomena associated to cyclic variability. The EWA-HTLES results were shown to be comparable to those predicted by LES, and superior to RANS.The performed developments and obtained results open encouraging perspectives for the application of this hybrid RANS/LES method in industrial configurations involving non-stationary conditions and in particular moving boundaries
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Zhang, Di. "Turbulence Modeling and Simulation of Unsteady Transitional Boundary Layers and Wakes with Application to Wind Turbine Aerodynamics". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/81137.
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Wind energy industry thrived in the last three decades, environmental concerns and government regulations stimulate studies on wind farm location selection and wind turbine design. Full-scale experiments and high-fidelity simulations are restrictive due to the prohibitively high cost, while the model-scale experiments and low-fidelity calculations miss key flow physics of unsteady high Reynolds number flows.
A hybrid RANS/LES turbulence model integrated with transition formulation is developed and tested by a surrogate model problem through joint experimental and computational fluid dynamics approaches. The model problem consists of a circular cylinder for generating coherent unsteadiness and a downstream airfoil in the cylinder wake. The cylinder flow is subcritical, with a Reynolds number of 64,000 based upon the cylinder diameter.
The quantitative dynamics of vortex shedding and Reynolds stresses in the cylinder near wake were well captured, owing to the turbulence-resolving large eddy simulation method that was invoked in the wake. The power spectrum density of velocity components showed that the flow fluctuations were well-maintained in cylinder wake towards airfoil and the hybrid model switched between RANS/LES mode outside boundary layer as expected. According to the experimental and simulation results, the airfoil encountered local flow angle variations up to ±50 degrees, and the turbulent airfoil boundary layer remained attached. Inspecting the boundary layer profiles over one shedding cycle, the oscillation about mean profile resembled the Stokes layer with zero mean. Further processing the data through phase-averaging technique found phase lags along the chordwise locations and both the phase-averaged and mean profiles collapsed into the Law of Wall in the range of 0 < y+ < 50. The features of high blade loading fluctuations due to unsteadiness and transitional boundary layers are of interest in the aerodynamic studies of full-scale wind turbine blades, making the model problem a comprehensive benchmark case for future model development and validation.Ph. D.
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Mossi, Michele. "Simulation of benchmark and industrial unsteady compressible turbulent fluid flows /". [S.l.] : [s.n.], 1999. http://library.epfl.ch/theses/?nr=1958.
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Szubert, Damien. "Physics and modelling of unsteady turbulent flows around aerodynamic and hydrodynamic structures at high Reynold number by numerical simulation". Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/15129/2/szubert_1.pdf.
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This thesis aims at analysing the predictive capabilities of statistical URANS and hybrid RANS-LES methods to model complex flows at high Reynolds numbers and carrying out a physical analysis of the near-region turbulence and coherent structures. This study handles configurations included in the European research programmes ATAAC (Advanced Turbulent Simulation for Aerodynamics Application Challenges) and TFAST (Transition Location Effect on Shock Wave Boundary Layer Interaction). First, the detached flow in a configuration of a tandem of cylinders, positionned behind one another, is investigated at Reynolds number 166000. A static case, corresponding to the layout of the support of a landing gear, is initially considered. The fluid-structure interaction is then studied in a dynamic case where the downstream cylinder, situated in the wake of the upstream one, is given one degree of freedom in translation in the crosswise direction. A parametric study of the structural parameters is carried out to identify the various regimes of interaction. Secondly, the physics of the transonic buffet is studied by means of time-frequency analysis and proper orthogonal decomposition (POD), in the Mach number range 0.70–0.75. The interactions between the main shock wave, the alternately detached boundary layer and the vortices developing in the wake are analysed. A stochastic forcing, based on reinjection of synthetic turbulence in the transport equations of kinetic energy and dissipation rate by using POD reconstruction, has been introduced in the so-called organised-eddy simulation (OES) approach. This method introduces an upscale turbulence modelling, acting as an eddy-blocking mechanism able to capture thin shear-layer and turbulent/non-turbulent interfaces around the body. This method highly improves the aerodynamic forces prediction and opens new ensemble-averaged approaches able to model the coherent and random processes at high Reynolds number. Finally, the shock-wave/boundary-layer interaction (SWBLI) is investigated in the case of an oblique shock wave at Mach number 1.7 in order to contribute to the so-called "laminar wing design" studies at European level. The performance of statistical URANS and hybrid RANS-LES models is analysed with comparison, with experimental results, of integral boundary-layer values (displacement and momentum thicknesses) and wall quantities (friction coefficient). The influence of a transitional boundary layer on the SWBLI is featured.
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Liggett, Nicholas Dwayne. "Numerical investigation of static and dynamic stall of single and flapped airfoils". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45834.
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Separated flows about single and multi-element airfoils are featured in many scenarios of practical interest, including: stall of fixed wing aircraft, dynamic stall of rotorcraft blades, and stall of compressor and turbine elements within jet engines. In each case, static and/or dynamic stall can lead to losses in performance. More importantly, modeling and analysis tools for stalled flows are relatively poorly evolved and designs must completely avoid stall due to a lack of understanding. The underlying argument is that advancements are necessary to facilitate understanding of and applications involving static and dynamic stall.
The state-of-the-art in modeling stall involves numerical solutions to the governing equations of fluids. These tools often either lack fidelity or are prohibitively expensive. Ever-increasing computational power will likely lead to increased application of numerical solutions. The focus of this thesis is improvements in numerical modeling of stall, the need of which arises from poorly evolved analysis tools and the spread of numerical approaches. Technical barriers have included ensuring unsteady flow field and vorticity reproduction, transition modeling, non-linear effects such as viscosity, and convergence of predictions.
Contributions to static and dynamic stall analysis have been been made. A hybrid Reynolds-Averaged Navier-Stokes/Large-Eddy-Simulation turbulence technique was demonstrated to predict the unsteadiness and acoustics within a cavity with accuracy approaching Large-Eddy-Simulation. Practices to model separated flows were developed and applied to stalled airfoils. Convergence was characterized to allow computational resources to be focused only as needed. Techniques were established for estimation of integrated coefficients, onset of stall, and reattachment from unconverged data. Separation and stall onset were governed by turbulent transport, while the location of reattachment depended on the mean flow. Application of these methodologies to oscillating flapped airfoils revealed flow through the gap was dominated by the flap angle for low angles of attack. Lag between the aerodynamic response and input flap scheduling was associated with increased oscillation frequency and airfoil/flap gap size. Massively separated flow structures were also examined.
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Hodara, Joachim. "Hybrid RANS-LES closure for separated flows in the transitional regime". Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/54995.
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The aerodynamics of modern rotorcraft is highly complex and has proven to be an arduous challenge for computational fluid dynamics (CFD). Flow features such as massively separated boundary layers or transition to turbulence are common in engineering applications and need to be accurately captured in order to predict the vehicle performance. The recent advances in numerical methods and turbulence modeling have resolved each of these issues independent of the other. First, state-of-the-art hybrid RANS-LES turbulence closures have shown great promise in capturing the unsteady flow details and integrated performance quantities for stalled flows. Similarly, the correlation-based transition model of Langtry and Menter has been successfully applied to a wide range of applications involving attached or mildly separated flows. However, there still lacks a unified approach that can tackle massively separated flows in the transitional flow region. In this effort, the two approaches have been combined and expended to yield a methodology capable of accurately predicting the features in these highly complex unsteady turbulent flows at a reasonable computational cost. Comparisons are evaluated on several cases, including a transitional flat plate, circular cylinder in crossflow and NACA 63-415 wing. Cost and accuracy correlations with URANS and prior hybrid URANS-LES approaches with and without transition modeling indicate that this new method can capture both separation and transition more accurately and cost effectively.
This new turbulence approach has been applied to the study of wings in the reverse flow regime. The flight envelope of modern helicopters has increased significantly over the last few decades, with design concepts now reaching advance ratios up to μ = 1. In these extreme conditions, the freestream velocity exceeds the rotational speed of the blades, and a large region of the retreating side of the rotor disk experiences reverse flow. For a conventional airfoil with a sharp trailing edge, the reverse flow regime is generally characterized by massive boundary layer separation and bluff body vortex shedding. This complex aerodynamic environment has been utilized to evaluate the new hybrid transitional approach. The assessment has proven the efficiency of the new hybrid model, and it has provided a transformative advancement to the modeling of dynamic stall.
Libros sobre el tema "Aerodynamic lens"
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Ambrose, James E. Simplified building design for wind and earthquake forces. 2a ed. New York: Wiley, 1990.
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1933-, Vergun Dimitry, ed. Simplified building design for wind and earthquake forces. 3a ed. New York: Wiley, 1995.
Buscar texto completoCapítulos de libros sobre el tema "Aerodynamic lens"
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Xia, Zhenhua, Zuoli Xiao, Yipeng Shi y Shiyi Chen. "Constrained Large-Eddy Simulation for Aerodynamics". En Progress in Hybrid RANS-LES Modelling, 105–15. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15141-0_8.
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Angerbauer, Rupert y Thomas Rung. "Hybrid RANS/LES Simulations of Aerodynamic Flows Around Superstructures of Ships". En Progress in Hybrid RANS-LES Modelling, 367–77. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-27607-2_30.
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Krajnović, Siniša y Guglielmo Minelli. "Status of PANS for Bluff Body Aerodynamics of Engineering Relevance". En Progress in Hybrid RANS-LES Modelling, 399–410. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15141-0_32.
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Favre, T., B. Diedrichs y G. Efraimsson. "Detached-Eddy Simulations Applied to Unsteady Crosswind Aerodynamics of Ground Vehicles". En Progress in Hybrid RANS-LES Modelling, 167–77. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14168-3_14.
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Jakirlic, S., L. Kutej, B. Basara y C. Tropea. "On PANS-ζ-f Model Assessment by Reference to Car Aerodynamics". En Progress in Hybrid RANS-LES Modelling, 143–56. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-27607-2_11.
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Li, Hongshuai, Lei Tan y Huanxin Zhao. "Influence of Blade Geometry on Performance of Hydrogen Vortex Blower in Fuel Cell System". En Proceedings of the 10th Hydrogen Technology Convention, Volume 1, 163–73. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8631-6_18.
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AbstractHydrogen fuel cell has great potential in replacement of traditional fossil energy systems to decrease carbon dioxide emission. Vortex blower is a key device in the hydrogen recirculation system, which need to be studied deeply to improve the performance of the whole fuel cell. In this paper, the steady internal flow of a hydrogen vortex bower was numerical simulated, and the effect of blade number and blade flapping angle on the performance was studied. The simulation results were compared with experimental data, and the deviation of simulation in choking condition was observed. With the validated simulation method, the influence of blade number and flapping angle was studied. Higher blade number causes more friction, and less blade number leads to flow separation. The negative flapping angle also has the effect on depressing low-pressure region. This research illuminates the simulation method can be further applied to the aerodynamic study and structure optimization of vortex blower.
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Weiss, Pierre-Élie y Sébastien Deck. "Advanced Numerical Strategy for the Prediction of Unsteady Flow Aerodynamics Around Complex Geometries". En Progress in Hybrid RANS-LES Modelling, 181–91. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-27607-2_14.
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Ngouani, M. M. Siewe, Yong Kang Chen, R. Day y O. David-West. "Low-Speed Aerodynamic Analysis Using Four Different Turbulent Models of Solver of a Wind Turbine Shroud". En Springer Proceedings in Energy, 149–54. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63916-7_19.
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AbstractThis study presents the effect of four different turbulent models of solver on the aerodynamic analysis of a shroud at wind speed below 6 m/s. The converting shroud uses a combination of a cylindrical case and an inverted circular wing base which captures the wind from a 360° direction. The CFD models used are: the SST (Menter) k-ω model, the Reynolds Stress Transport (RST) model, the Improved Delay Detached Eddies Simulation model (IDDES) SST k-ω model and the Large Eddies Simulation Wall Adaptive model. It was found that all models have predicted a convergent surface pressure. The RST, the IDDES and the WALE LES are the only models which have well described regions of pressure gradient. They have all predicted a pressure difference between the planes (1–5) which shows a movement of the air from the lower plane 1 (inlet) to the higher plane 5 (outlet). The RST and IDDES have predicted better vorticities on the plane 1 (inlet). It was also found that the model RST, IDDES, and WALE LES have captured properly the area of turbulences across the internal region of the case. All models have predicted the point of flow separation. They have also revealed that the IDDES and the WALE LES can capture and model the wake eddies at different planes. Thus, they are the most appropriate for such simulation although demanding in computational power. The movement of air predicted by almost all models could be used to drive a turbine.
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Brahimi, Tayeb y Ion Paraschivoiu. "Aerodynamic Analysis and Performance Prediction of VAWT and HAWT Using CARDAAV and Qblade Computer Codes". En Entropy and Exergy in Renewable Energy [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96343.
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Wind energy researchers have recently invited the scientific community to tackle three significant wind energy challenges to transform wind power into one of the more substantial, low-cost energy sources. The first challenge is to understand the physics behind wind energy resources better. The second challenge is to study and investigate the aerodynamics, structural, and dynamics of large-scale wind turbine machines. The third challenge is to enhance grid integration, network stability, and optimization. This chapter book attempts to tackle the second challenge by detailing the physics and mathematical modeling of wind turbine aerodynamic loads and the performance of horizontal and vertical axis wind turbines (HAWT & VAWT). This work underlines success in the development of the aerodynamic codes CARDAAV and Qbalde, with a focus on Blade Element Method (BEM) for studying the aerodynamic of wind turbines rotor blades, calculating the induced velocity fields, the aerodynamic normal and tangential forces, and the generated power as a function of a tip speed ration including dynamic stall and atmospheric turbulence. The codes have been successfully applied in HAWT and VAWT machines, and results show good agreement compared to experimental data. The strength of the BEM modeling lies in its simplicity and ability to include secondary effects and dynamic stall phenomena and require less computer time than vortex or CFD models. More work is now needed for the simulation of wind farms, the influence of the wake, the atmospheric wind flow, the structure and dynamics of large-scale machines, and the enhancement of energy capture, control, stability, optimization, and reliability.
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Frolov, Vladimir. "Critical Mach Numbers of Flow around Two-Dimensional and Axisymmetric Bodies". En Aerodynamics. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.94981.
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The paper presents the calculated results obtained by the author for critical Mach numbers of the flow around two-dimensional and axisymmetric bodies. Although the previously proposed method was applied by the author for two media, air and water, this chapter is devoted only to air. The main goal of the work is to show the high accuracy of the method. For this purpose, the work presents numerous comparisons with the data of other authors. This method showed acceptable accuracy in comparison with the Dorodnitsyn method of integral relations and other methods. In the method under consideration, the parameters of the compressible flow are calculated from the parameters of the flow of an incompressible fluid up to the Mach number of the incoming flow equal to the critical Mach number. This method does not depend on the means determination parameters of the incompressible flow. The calculation in software Flow Simulation was shown that the viscosity factor does not affect the value critical Mach number. It was found that with an increase in the relative thickness of the body, the value of the critical Mach number decreases. It was also found that the value of the critical Mach number for the two-dimensional case is always less than for the axisymmetric case for bodies with the same cross-section.
Actas de conferencias sobre el tema "Aerodynamic lens"
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Oka, Nobuhito, Masato Furukawa, Kazutoyo Yamada y Kota Kido. "Aerodynamic Design for Wind-Lens Turbine Using Optimization Technique". En ASME 2013 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fedsm2013-16569.
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An optimum aerodynamic design method has been developed for the new type of wind turbine called “wind-lens turbine”. The wind-lens turbine has a diffuser with brim called “wind-lens”, by which the wind concentration on the turbine rotor and the significant enhancement of the turbine output can be achieved. The present design method is based on a genetic algorithm (GA) and a quasi-three-dimensional design of turbine rotor. The quasi-three-dimensional design consists of two parts: meridional viscous flow calculation and two-dimensional blade element design. In the meridional viscous flow calculation, an axisymmetric viscous flow is numerically analyzed on a meridional plane to determine the wind flow rate through the wind-lens and the spanwise distribution of the rotor inlet flow. In the two-dimensional rotor blade element design, the turbine rotor blade profile is determined by a one-dimensional through flow modeling for the wind-lens turbine and a two-dimensional blade element theory based on the momentum theorem of the ducted turbine. In the present optimization method, the Non-dominated Sorting Genetic Algorithm II (NSGA-II) is used as evaluation and selection model. The Real-coded Ensemble Crossover (REX) is used as crossover model. The present aerodynamic design method has been applied to the coupled design of turbine rotor and wind-lens. Total performances and flow fields of the wind-lens turbines designed have been investigated by Reynolds averaged Navier-Stokes simulations, in order to verify the present design method.
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Oka, Nobuhito, Masato Furukawa, Kazutoyo Yamada, Kenta Kawamitsu, Kota Kido y Akihiro Oka. "Simultaneous Optimization of Rotor Blade and Wind-Lens for Aerodynamic Design of Wind-Lens Turbine". En ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25770.
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An optimum aerodynamic design method for the new type of wind turbine called “wind-lens turbine” has been developed. The wind-lens turbine has a diffuser with brim called “wind-lens”, by which the wind concentration on the turbine rotor and the significant enhancement of the turbine output can be achieved. In order to design efficient wind-lens turbines, an aerodynamic design method for the simultaneous optimization of rotor blade and wind-lens has been developed. The present optimum design method is based on a genetic algorithm (GA) and a quasi-three-dimensional design of turbine rotor. In the GA procedure, the Non-dominated Sorting Genetic Algorithm II (NSGA-II) is used as evaluation and selection model. The Real-coded Ensemble Crossover (REX) is used as crossover model. The quasi-three-dimensional design consists of two parts: meridional viscous flow calculation and two-dimensional blade element design. In the meridional viscous flow calculation, an axisymmetric viscous flow is numerically analyzed on a meridional plane to determine the wind flow rate through the wind-lens and the spanwise distribution of the rotor inlet flow. In the two-dimensional rotor blade element design, the turbine rotor blade profile is determined by a one-dimensional through flow modeling for the wind-lens turbine and a two-dimensional blade element theory based on the momentum theorem of the ducted turbine. Total performances and three-dimensional flow fields of the optimized wind-lens turbines have been investigated by Reynolds averaged Navier-Stokes (RANS) simulations, in order to verify the present design method. The RANS simulations and the flow visualization have been applied to conventional and optimum design cases of the wind-lens turbine, in order to elucidate the relation between their aerodynamic performances and the flow fields around them. The numerical results show that separation vortices behind the wind-lens brim play a major role in the wind concentration and the diffuser performance of the wind-lens. As a result, it is found that the aerodynamic performance of wind-lens turbine is significantly affected by the interrelationship between the internal and external flow fields around the wind-lens.
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Oka, Nobuhito, Masato Furukawa, Kazutoyo Yamada, Akihiro Oka y Yasushi Kurokawa. "Aerodynamic Performances and Flow Fields of Pareto Optimal Solutions in an Aerodynamic Design of a Wind-Lens Turbine". En ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43619.
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The new type of shrouded wind turbine called “wind-lens turbine” has been developed. The wind-lens turbine has a brimmed diffuser called “wind-lens”, by which the wind concentration on the turbine blade and the significant enhancement of the turbine output can be achieved. A simultaneous optimization method for the aerodynamic design of rotor blade and wind-lens has been developed. The present optimal design method is based on a genetic algorithm (GA) which enables multi objective aerodynamic optimization. In the present study, aerodynamic performances and flow fields of the Pareto optimal solutions of wind-lens turbines designed by the present optimal design method have been investigated by wind-tunnel tests and three-dimensional Reynolds averaged Navier-Stokes (RANS) analyses. Output power coefficients obtained from the wind-tunnel tests in the optimal wind-lens turbine exceeded the Betz limit, which is the performance limitation for bare wind turbines. The numerical results and the experimental results show that the suppression of flow separations in the diffuser is important to achieve significant improvement in aerodynamic performances. As a result, it is found that the aerodynamic performance of wind-lens turbine is significantly affected by the interrelationship between the internal and external flow fields around the wind-lens.
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Spencer, Harvey M. "Optical Design and Fabrication of an Infrared Conformal Window". En International Lens Design. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/ild.1990.ltue3.
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The growing need to incorporate Forward Looking Infrared (FLIR) optical systems in high speed aircraft has brought with it the aerodynamic requirement for zero power windows which are conformal with the sensor mounting pod. Such asymmetric, dome-like optical elements must have the same diffraction limited performance capabilities as their predecessor symmetric dome counterparts if the performance of the FLIR used with them is not to be compromised. When of large diameter and used considerably off-axis, the optical design and opto-mechanical considerations become significant and challenging for both the optical designer and the component fabricator.
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He, Yun, Hongyu He y Zhixing Gao. "Improvement on the plasma excitation probability of aerosol particles based on aerodynamic lens". En Advanced Fiber Laser Conference (AFL2022), editado por Pu Zhou. SPIE, 2023. http://dx.doi.org/10.1117/12.2669005.
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Nikbakht, Abbas, Omid Abouali y Goodarz Ahmadi. "3-D Modelling of Brownian Motion of Nano-Particles in Aerodynamic Lenses". En ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98488.
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A computer code for analyzing nano-particle motions in an aerodynamic particle beam focusing system was developed. The effectiveness of the focusing system consisting of several lenses, nozzle and downstream tube of the nozzle was analyzed. The code included an accurate 3-dimensional model for the Brownian diffusion of nano-particles in sharply varying pressure field in the aerodynamic lens system. Lagrangian particle Trajectory analysis was performed assuming a one-way coupling model. The particle equation of motion used included drag and Brownian forces. Trajectories of different size nano-particles in an aerodynamic lens were analyzed, and the particle beam focusing process was studied. The numerical results of 3-D model for particle beam diameter, penetration efficiency and beam divergence angle were compared with axisymmetric model and discussed. The importance of the accuracy of the computational model for the simulation of the Brownian diffusion for predicting the focusing performance of the aerodynamic lenses was discussed. The simulation results showed that for particle diameters less than 50 nm in helium, the Brownian force could significantly affect the beam focusing and particle collection efficiency. Furthermore, the nano-particle trajectories in this range are three-dimensional and an axisymmetric model may not correctly capture the features of particle motions in aerodynamic lenses.
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Abouali, Omid y Goodarz Ahmadi. "Numerical Simulation of Supersonic Flow and Particle Motion in Aerodynamic Lenses". En ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45074.
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Airflow and particle motions in aerodynamic lenses are studied. The computational grid is generated with the use of GAMBIT code and FLUENT 5 is used in the analysis. The axisymmetric compressible form of the Navier-Stokes equation is solved and the airflow conditions are evaluated. One-way coupling is assumed in that the air transports the particles, but the effect of dilute particle concentrations on flow field is ignored. The particle equation of motion including drag, lift and Brownian forces is used and the particle trajectories in the aerodynamic a lens are analyzed. In addition, the airflow field and particles motions downstream of the nozzle are also studied. A series of sensitivity analyses on the effect of inlet flow stagnation pressure and backpressure of the nozzle on the aerodynamic performance of the lens is performed. Sample streamlines and particles trajectories in an axisymmetric plane of a combination of three aerodynamic lenses and a nozzle are shown in the figures.
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Davino, Michael, Tobias Saule, Jeffrey A. Powell, Nora G. Helming y Carlos Trallero-Herrero. "Strong field ionization for the characterization of aerosolized nanoparticles in vacuum". En International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/up.2022.tu4a.67.
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Strong field ionization is used to attain the three-dimensional nanoparticle density distribution for aerosol nanoparticle beams produced by an aerodynamic lens. This technique bypasses nanoparticle size limitations of light-scattering characterization techniques.
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Goeltenbott, Uli, Yuji Ohya, Takashi Karasudani y Peter Jamieson. "Aerodynamics of Clustered Wind Lens Turbines". En ASME/JSME/KSME 2015 Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ajkfluids2015-28601.
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Wind lens turbines, developed by Kyushu University have increased performance due to the duct surrounding the rotor [1]. A Multi rotor system is a promising concept to upscale wind turbine systems beyond 20MW [2]. Results of experimental research on a seven turbine array have shown no loss in performance with closely spaced rotors [3]. In the presented research we analyze the feasibility of using wind lens turbines in multi rotor systems. In a wind tunnel experiment we placed three wind lens turbines in a triangle array normal to smooth flow. At various spacing maximum output power was measured and compared to the values of a stand-alone setup. Optimum tip speed ratio didn’t change when the turbines are set closely next to each other. In a side-by-side setup of two turbines it was found that the rotation direction of the rotors had no influence on the turbines performance. In the three turbines in triangle arrangement the performance of the turbines is influenced by the width of the gap between the brims. At the closest possible spacing (brims of neighboring turbines are in direct contact) the cumulative power of all three turbines decreases compared to the cumulative power of three stand-alone turbines. The brims of the wind lens turbines shed vortices that establish a low pressure region behind the turbine. When the brims are in direct contact vortex shedding is inhibited and hence power drops. When increasing the gap between the turbines the power output restores to the same value, in some cases the power even exceeds the value of the three stand-alone turbines. Further, it was observed that the individual power output doesn’t follow the trend of the cumulative power output. These phenomena can be explained with flow patterns observed in gap flow analysis of bluff bodies where biased wake flow changes drag coefficients of flat plates [5]. However, smoke wire technique used to visualize the flow field couldn’t give us any indication of these known patterns. Further research is necessary to fully understand which mechanisms in three dimensional gap flow cause the effect on the performance of the turbines.
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Muylaert, J., L. Walpot, M. Spel, G. Tumino y R. Steijl. "Nonequilibrium computational analysis of blunt cone experiments performed in LENS and HEG". En 14th Applied Aerodynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1996. http://dx.doi.org/10.2514/6.1996-2436.
Texto completoInformes sobre el tema "Aerodynamic lens"
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Goodarz Ahmadi. Developing Supersonic Impactor and Aerodynamic Lens for Separation and Handling of Nano-Sized Particles. Office of Scientific and Technical Information (OSTI), junio de 2008. http://dx.doi.org/10.2172/941125.
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Fuchs, Marcel, Jerry Hatfield, Amos Hadas y Rami Keren. Reducing Evaporation from Cultivated Soils by Mulching with Crop Residues and Stabilized Soil Aggregates. United States Department of Agriculture, 1993. http://dx.doi.org/10.32747/1993.7568086.bard.
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Field and laboratory studies of insulating properties of mulches show that the changes they produce on the heat balance and the evaporation depend not only on the intrinsic characteristics of the material but also on the structure of air flow in boundary layer. Field measurements of the radiation balance of corn residue showed a decrease of reflectivity from 0.2 to 0.17 from fall to spring. The aerodynamic properties of the atmospheric surface layer were turbulent, with typical roughness length of 12 to 24 mm. Evaporation from corn residue covered soils in climate chambers simulating the diurnal course of temperature in the field were up to 60% less than bare soil. Wind tunnel studies showed that turbulence in the atmospheric boundary layer added a convective component to the transport of water vapor and heat through the mulches. The decreasing the porosity of the mulch diminished this effect. Factors increasing the resistance to vapor flow lowering the effect of wind. The behavior of wheat straw and stabilized soil aggregates mulches were similar, but the resistance to water of soil aggregate layer with diameter less than 2 mm were very large, close to the values expected from molecular diffusion.
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Wissink, Andrew, Jude Dylan, Buvana Jayaraman, Beatrice Roget, Vinod Lakshminarayan, Jayanarayanan Sitaraman, Andrew Bauer, James Forsythe, Robert Trigg y Nicholas Peters. New capabilities in CREATE™-AV Helios Version 11. Engineer Research and Development Center (U.S.), junio de 2021. http://dx.doi.org/10.21079/11681/40883.
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CREATE™-AV Helios is a high-fidelity coupled CFD/CSD infrastructure developed by the U.S. Dept. of Defense for aeromechanics predictions of rotorcraft. This paper discusses new capabilities added to Helios version 11.0. A new fast-running reduced order aerodynamics option called ROAM has been added to enable faster-turnaround analysis. ROAM is Cartesian-based, employing an actuator line model for the rotor and an immersed boundary model for the fuselage. No near-body grid generation is required and simulations are significantly faster through a combination of larger timesteps and reduced cost per step. ROAM calculations of the JVX tiltrotor configuration give a comparably accurate download prediction to traditional body-fitted calculations with Helios, at 50X less computational cost. The unsteady wake in ROAM is not as well resolved, but wake interactions may be a less critical issue for many design considerations. The second capability discussed is the addition of six-degree-of-freedom capability to model store separation. Helios calculations of a generic wing/store/pylon case with the new 6-DOF capability are found to match identically to calculations with CREATE™-AV Kestrel, a code which has been extensively validated for store separation calculations over the past decade.
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Lawson. L51597 Feasibility Study of New Technology for Intake Air Filtration. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), junio de 1989. http://dx.doi.org/10.55274/r0010105.
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Inlet air filters are widely used to remove solids and liquid droplets from the ambient air before it enters the compressor of a gas turbine. Clean inlet air provides many advantages: Less corrosion of the compressor and of gas-path hot parts, such as the turbine, decreased compressor fouling, less erosion of the compressor bladeThese in turn prevent deterioration of output and heat rate, and reduce maintenance costs. Compressor fouling is caused by the ingestion of substances that deposit and adhere to blade surfaces, resulting in reduced aerodynamic efficiency and decreased available output. Air contamination could be significantly reduced by the use of more efficient air filtration systems, especially through the reduction of the quantity of smaller particles ingested. The consequent lower loss of output power and decreased cleaning efforts provide lower costs of operation and increased shaft power. This work was composed of three major efforts: 1) A literature search was performed to establish the state of the art for particle removal from gases, particularly by electrostatic precipitation, and to identify the leading vendors of the equipment-considering both experience and technical expertise. 2) Two chosen companies were visited to determine their technical capabilities as they apply to gas turbine inlet air filtration. 3) A representative gas turbine was specified by PRCI as being the equivalent of a GE Model 3002J turbine, with airflow of 91,200 acfm. A specification based upon that airflow was prepared and submitted to the two vendors. Each vendor prepared a proposal for a filter system compliant with the specification. The proposed air filtration equipment is sufficiently different from existing products that it was judged not beneficial to visit manufacturing facilities. Both vendors are reputable suppliers of air filtration equipment. This study is intended to provide definitive information relative to the use of new technology for air inlet filtration on gas turbines in gas pipeline pumping applications.