Дисертації з теми "Coherent Jet"
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Bin, Baqui Yamin. "Sound generation from coherent structures in subsonic jets." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709362.
Повний текст джерелаMalla, Bhupatindra. "Study of High-speed Subsonic Jets using Proper Orthogonal Decomposition." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1352397174.
Повний текст джерелаValsecchi, Pietro. "Temporal Numerical Simulations of Turbulent Coanda Wall Jets." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195025.
Повний текст джерелаSAKAI, Yasuhiko, Nobuhiko TANAKA, and Takehiro KUSHIDA. "On the Development of Coherent Structure in a Planet Jet (Part2, Investigation of Spatio-Temporal Velocity Structure by the KL Expansion)." The Japan Society of Mechanical Engineers, 2006. http://hdl.handle.net/2237/9010.
Повний текст джерела田中, 伸彦, Nobuhiko TANAKA, 康彦 酒井, Yasuhiko SAKAI, 睦. 山本, Mutsumi YAMAMOTO, 貴. 久保 та Takashi KUBO. "二次元噴流のコヒーレント構造発展に関する実験的研究 (第4報、速度二成分多点同時測定とKL展開による大スケール構造モデル)". 日本機械学会, 2005. http://hdl.handle.net/2237/9007.
Повний текст джерелаDecker, Rodrigo Koerich. "Analise de estruturas coerentes de larga escala em jatos de dispersão bifasicos." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266338.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
Made available in DSpace on 2018-08-10T10:03:01Z (GMT). No. of bitstreams: 1 Decker_RodrigoKoerich_D.pdf: 3679156 bytes, checksum: 9c914896fd9d31753adf9c1bed158cac (MD5) Previous issue date: 2008
Resumo: Este trabalho propõe o estudo de estruturas coerentes de larga escala por meio da utilização da metodologia ¿Interparticle Arrival Time¿ (IAT) no escoamento de um jato bifásico. Experimentos foram desenvolvidos em relação a diferentes condições de velocidade inicial com diâmetro médio de partícula igual a 50 µm, e para duas diferentes misturas de partículas, 50 µm e 90 µm, em diferentes proporções, e comparados em relação a perfis de velocidade média, intensidade de turbulência e velocidade RMS. Medidas relacionadas à distribuição IAT foram também adquiridas para todas as condições analisadas. Os experimentos foram desenvolvidos para diferentes posições axiais e radiais a partir da saída do orifício de formação do jato. Perfis radiais de velocidade média, flutuação de velocidade (velocidade RMS), intensidade de turbulência e ¿interparticle arrival time¿ (em termos de distribuição Chi2 e número de desvios) foram obtidos pelo sistema de ¿Phase Doppler Anemometry¿, atravessando o sistema de medição ponto a ponto na direção desejada. Além disto, as variações das condições de velocidade inicial, distribuição de partículas e razão de carga permitem a obtenção de importantes informações em relação às estruturas locais do escoamento e seus efeitos sobre o transporte macroscópico e turbulento de partículas entre o centro do jato e as regiões de contorno do mesmo. Assim é possível identificar que no centro do jato não existe a formação de Estruturas Coerentes de Larga Escala (ECLE), ou seja, o escoamento é dominado por estruturas incoerentes. Existem também fortes indícios de formação de ECLE em uma região radial entre o centro e a região de contorno, sendo estas dependentes da condição inicial de velocidade da fase gás. Além disto, partículas com maior diâmetro suprimem a formação de ECLE. A distribuição IAT prova ser uma ferramenta importante na identificação dos locais onde ECLEs vêm a influenciar a distribuição de partículas, formando ¿clusters¿. A investigação extensiva de dados experimentais em relação ao comportamento da fase dispersa no escoamento gás sólido em um jato pode ser utilizada como uma importante fonte de dados para uma validação detalhada, por meio de simulação numérica, do escoamento disperso bifásico, incluindo as fortes interações entre as fases gás e particulada
Abstract: A study of large scale coherent structures by Interparticle Arrival Time (IAT) of a two phase jet flow is proposed. Measurements were carried out for different initial velocities with 50 µm particle mean diameter, and for two different particle mixtures with mean particle diameter of 50 µm and 90 µm, in different proportions, and analyzed in relation to different variables. Measurements related to IAT were also acquired for all analysis conditions. The experiments were developed for different axial and radial distances from the nozzle outlet. Radial profiles of mean velocity, RMS velocity, turbulence intensity and the IAT (in terms of Chi2 and number of deviation) were measured by a Phase Doppler Anemometry system, traversing the measuring device stepwise in the desired direction. Furthermore, the variation of the initial velocity conditions, particle diameter distributions, and particle loadings yield important information about the local flow structures and its effect on the macroscopic as well as the turbulent particle transport between the jet centre and the outer shear layer. Thus, it is possible to identify that in the centre line of the jet there is no formation of large scale coherent structures (ECLE), i. e., the flow is dominated by incoherent structures. There is also strong evidence of ECLE formation in a radial position between the centre and the outer shear layer of the jet, which are dependent on the gas initial velocity. Furthermore, particles with large diameter suppress ECLE formation. The IAT distribution proofs to be an important tool to identify regions where large scale coherent structures influence the particle distribution and tend to form particle clusters. The derived extensive experimental data set for the particle behaviour at the two-phase jet may serve as a basis for the detailed validation of numerical simulations of dispersed two phase flow behaviour including strong phase interactions between gaseous and particulate phases
Doutorado
Desenvolvimento de Processos Químicos
Doutor em Engenharia Química
SAKAI, Yasuhiko, Nobuhiko TANAKA, and Takehiro KUSHIDA. "On the Development of Coherent Structure in a Plane Jet (Part1, Characteristics of Two-Point Velocity Correlation and Analysis of Eigenmodes by the KL Expansion)." The Japan Society of Mechanical Engineers, 2006. http://hdl.handle.net/2237/9011.
Повний текст джерелаKaffel, Ahmed. "Analyse des structures des écoulements et des instabilités développées par un rideau d'air cisaillé latéralement par un courant externe : application au cas des meubles frigorifiques de vente." Thesis, Valenciennes, 2017. http://www.theses.fr/2017VALE0011/document.
Повний текст джерелаIn this study, the aerodynamic behavior of the plane wall jet (Re = 8000) sheared laterally by an external lateral stream (ELS) of a uniform velocity profile (Ulf) was studied and analyzed. The experiments were carried out by PIV and LDV on a reduced-scale isothermal aeraulic model of a refrigerated display cabinet. The study focuses on the near-field region of the jet (x / e <10) which corresponds to the zone of transition to turbulence and onset and development of instabilities. The results obtained with and without perturbation showed a significant decrease in the entrainment rate, a strong decrease in the maximum velocity decay rate, a lower jet expansion and an overall increase in the values of second order moments of the Reynolds stress components. The time-resolved PIV analysis (10 kHz) shows a distorted and elongated topology of the Kelvin-Helmholtz (K-H) structures for (Ulf = 0,5 ms-1) and a detached topology for (Ulf = 1 ms-1). The results of the mutual interaction between the inner and outer layers indicate that the ELS partially breaks the vortex dipole formation mechanism which becomes irregular and less predictive, leading to the elongation of the transitional region and a lag effect in the beginning of the self-similarity region. POD technique reveals the role of the ELS in redistributing energy between the modes. The ELS also affects the K-H instabilities by disrupting their two-dimensional organization, topology, alignment and shedding frequency, highlighting the inhibitory effect exerted on the development of primary structures. The spatial correlations Rvv reflect the decrease of the length scales in the case of a perturbed jet
Itasse, Maxime. "Effet sur le bruit de jet de l'excitation de modes instables : rôle des interactions non linéaires." Thesis, Toulouse, ISAE, 2015. http://www.theses.fr/2015ESAE0028/document.
Повний текст джерелаThis study is part of the effort to reduce aircraft noise during take-off. Jet noise is oneof the main contributors, of which lower frequency component can be attributed to thedirective acoustic field generated by the large-scale coherent structures arising from jetmixing-layer instabilities. The development of these instability waves can be describedusing Parabolized Stability Equations (PSE). A first objective was to determine if inthe case of a natural turbulent jet, nonlinear interactions between instability waveshave a significant impact on its dynamic and acoustic behaviour. For this purpose,a nonlinear PSE model has been developed and applied to a realistic configuration.Then, the possibility to manipulate these instability waves by means of nonlinearity wasinvestigated with a view to reduce noise. To this end, a PSE analysis has been carried outto assess the impact on jet noise of exciting one or more unstable modes. The findingsof this doctoral work demonstrate a minor impact of nonlinearities on the dynamics ofinstability waves for natural turbulent jets on the one hand, and the possibility to makethe initially dominant instability acoustically ineffective using nonlinear interactions onthe other hand
SAKAI, Yasuhiko, Nobuhiko TANAKA, Mutsumi YAMAMOTO, and Takehiro KUSHIDA. "On the Development of Coherent Structure in a Planet Jet (Part 3, Multi-Point Simultaneous Measurement of Main Streamwise Velocity and the Reconstruction of Velocity Field by the KL Expansion)." The Japan Society of Mechanical Engineers, 2006. http://hdl.handle.net/2237/9008.
Повний текст джерелаHileman, James Isaac. "Large-scale structures and noise generation in high-speed jets." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1078776079.
Повний текст джерелаTitle from first page of PDF file. Document formatted into pages; contains xxviii, 365 p.; also includes graphics. Includes bibliographical references (p. 269-279).
Suigh, Rafael Oliveira. "Estruturas coerentes no transporte caótico induzido por ondas de deriva." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-08112016-102037/.
Повний текст джерелаIn this thesis we studied the particle transport in the edge of magnetically confined plasma in tokamaks using a model of drift waves due to electrostatic fluctuations generated by the non-uniformity of the plasma. To investigate this issue, we consider the model with two drift waves, which has a complex nonlinear dynamics where we can find both anomalous and diffusive transport. To find the Lagrangian Coherent Structures (LCSs) and the jets, we used Poincaré maps, Finite time Lyapunov exponent diagrams, quadratic displacement diagrams, autocorrelation velocity diagrams and return displacement diagram. To evaluate the impact of LCSs in the transport of particles, we analyzed the time series of both average standard deviation and relative dispertion and also histograms of the distribution of these jumps. It was found that, with two drift waves and for a given combination of parameters, a jet streams appear in the phase space and persist for long periods of time immersed in the chaotic region. We found that, as well as on the islands, the inner region of the jet streams are inaccessible to LCSs. It was also found that when there is a jet stream, the transport observed in the chaotic region is not symmetrical and have a small drift in the opposite direction to the jet. This phenomenon is observed in contrast to the typical case of systems with mixing in wich the LCSs have access to all the phase space and the trasnport is diffusive.
Léon, Olivier. "Étude du rayonnement acoustique d'instabilités hydrodynamiques de jets double-flux par les équations de stabilité parabolisées (PSE)." Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/9138/1/leon_partie_1_sur_2.pdf.
Повний текст джерелаPineau, Pierre. "Etude numérique de la production et de la propagation d'ondes non linéaires dans les jets supersoniques." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC034/document.
Повний текст джерелаNumerical simulations are carried out with the aim of investigating the formation of nonlinear steepened waves at the origin of crackle in the near acoustic field of supersonic jets. In these simulations, the compressible Navier-Stokes equations are solved in cylindrical coordinates using high-order low-dissipative and low-dispersive finite difference schemes.Four temporally-developing isothermal round jets are first simulated at Mach numbers of~2 and~3 and at Reynolds numbers ranging from 3,125 to 50,000. Strong acoustic waves containing sharp pressure variations are observed in the vicinity of the jets. Their formation process is described by the computation of conditional averages which are triggered by the detection of strong pressure peaks in the near field. Such steepened waves are then shown to be produced by the supersonic motion of coherent structures inside the jet shear layers.Temperature effects are then investigated by considering five temporal round jets at temperature ratios of 1, 2 and~4 and at acoustic Mach numbers of 2, 2.8 and 4. For a given jet speed, the sound levels produced by the hot jets are lower than those of the isothermal one. However, the properties of the steepened waves they generate are not significantly affected by a rise of temperature. On the contrary, when the Mach number is held constant, pressure levels are higher at high temperature. The skewness and kurtosis factors of pressure fluctuations are also increased, which indicates a strengthening of the asymmetry and the intermittency of the pressure fluctuations. It is likely that the influence of temperature on these waves results from the variations of the convection speed, which is found to significantly increase with temperature at constant Mach number, but to slightly decrease at constant jet speed.Finally, three simulations of spatially-developing axisymmetric, isothermal and hot jets at a Mach number of~2 and at Reynolds numbers of 12500 and 50000 are performed. Strong Mach waves possessing the distinctive features of crackle are visible in the near vicinity of the jets. As observed for temporal simulations, their formations are associated with the supersonic motion of large-scale coherent structures inside the jet shear layers. The far acoustic field is determined using linear as well as nonlinear extrapolation methods. When nonlinear propagation effects are taken into account, a further steepening of the wavefronts is observed with increasing propagation distance
Lau, Kwok-keung. "Interactions of coherent structures in annular jets /." [Hong Kong] : University of Hong Kong, 1991. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13150364.
Повний текст джерелаChow, Kin-keung. "Acceleration of coherent structures in free shear layer /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21710211.
Повний текст джерела劉國強 and Kwok-keung Lau. "Interactions of coherent structures in annular jets." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31232632.
Повний текст джерела周健強 and Kin-keung Chow. "Acceleration of coherent structures in free shear layer." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31240069.
Повний текст джерелаLaffay, Paul. "Etude aéroacoustique de la détente d'un écoulement haute pression à travers des plaques perforées." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEC020/document.
Повний текст джерелаThe noise generated by the expansion of a pressurized flow through multi-perforated plates or diaphragms is experimentally investigated. The analysis is conducted on two distinct geometrical configurations in which the perforated plate is placed at the outlet of (free jet configuration) or inside (ducted jet configuration) a cylindrical duct.Firstly, an acoustic parametric study is carried out on these two configurations for various perforated plate geometries and for a number of operating points ranging from subsonic to supersonic. The different acoustic sources that can arise from such systems are thus identified. Furthermore, the effect of each geometrical parameter onto the radiated sound field is highlighted, thus providing guidelines for the silent design of such pressure release devices.In a second step, the focus is on the dominant broadband component, that is, the mixing noise. This part of the study is dedicated to the free jet configuration and is based on Schlieren imaging, as well as on Particle Image Velocimetry measurements, both coupled far-field sound measurements.In the diaphragm cases, the aerodynamic results show that the source mechanisms are similar to those reported in the literature about isolated jets from conventional nozzles. The downstream radiation is generated by the interaction of large coherent structures at the end of the jet potential core, while in the other directions it is generated by the small-scale turbulence from the shear layer.For multi-perforated plates, comparable mechanisms are also observed. However, depending on the plate geometry, two distinct source regions contributing to the downstream radiation are identified. They explain the presence of two broadband humps in the far-field spectra. In the case of widely spaced perforations, the higher frequency hump in the downstream spectrum increases and the interaction of the large turbulent structures occurs mainly at the end of the potential core of the small jets issuing the perforations. Conversely, when these perforations are close to each other, the small jets rapidly merge into a single larger one that has a longer potential core. As a result, larger coherent structures interact downstream of the small jet mixing region and therefore, a low-frequency hump dominates the downstream spectrum. In the other directions, the perforation spacing has also a significant impact on the acoustic radiation, due to a more or less rapid interaction of the jets. Consequently, the turbulence, as well as the shear zones of the various mixing layers, are modified. The geometric parameters thus have similar effects on the cross-stream as on the downstream radiation
Wang, Tao. "Flow and cleaning behaviour of stationary coherent liquid jets impinging on vertical walls." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648883.
Повний текст джерелаSpinosa, Emanuele. "Control of near-wall coherent structures in a turbulent boundary layer using synthetic jets." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/control-of-nearwall-coherent-structures-in-a-turbulent-boundary-layer-using-synthetic-jets(3a712f25-67b1-445d-8272-dc54a9f7aadc).html.
Повний текст джерелаDanaila, Ionut. "Etude des instabilites et des structures coherentes dans la zone de proche sortie d'un jet axisymetrique." Aix-Marseille 2, 1997. http://www.theses.fr/1997AIX22113.
Повний текст джерелаSpeth, Rachelle Lea. "Controlling The Development of Coherent Structures in High Speed Jets and The Resultant Near Field." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1447419083.
Повний текст джерелаNance, Donald Kirby. "Separating contributions of small-scale turbulence, large-scale turbulence, and core noise from far-field exhaust noise measurements." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19768.
Повний текст джерелаCommittee Chair: Ahuja, Krishan K.; Committee Member: Cunefare, Kenneth; Committee Member: Lieuwen, Tim C.; Committee Member: Mendoza, Jeff; Committee Member: Sankar, Lakshmi.
Favre-Marinet, Michel. "Structures cohérentes dans un jet rond excité." Grenoble 1, 1986. http://www.theses.fr/1986GRE10061.
Повний текст джерелаSilva, Carlos Frederico Neves Bettencourt da. "Le Rôle des structures cohérentes dans le contrôle et interactions entre échelles dans les jets ronds, plans et coaxiaux." Grenoble INPG, 2001. http://www.theses.fr/2001INPG0060.
Повний текст джерелаGardner, Michael D. "Scan-Based Near-Field Acoustical Holography on Partially Correlated Sources." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3167.pdf.
Повний текст джерелаLeong-Hoï, Audrey. "Etude des techniques de super-résolution latérale en nanoscopie et développement d'un système interférométrique nano-3D." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAD048/document.
Повний текст джерелаThis manuscript presents the study of the lateral super-resolution techniques in optical nanoscopy, which is a new high-resolution imaging method now widely used in biophysics and medical imaging, to observe and measure nanostructures, with the advantages of far field optical imaging, such as a large field of view, visualization and analysis in real time…One of the future challenges of 3D super resolution microscopy is to avoid the use of fluorescent markers. Interferometric microscopy is a 3D label-free imaging technique enabling the detection of nanostructures. To improve the detection capability of this optical system, a first version of a protocol composed of image processing methods was developed and implemented, revealing structures initially unmeasurable. Then, to improve the lateral resolution of the system, a new technique combining interferometry and the principle of the photonic nano-jet has been developed, thus allowing the observation of objects of a size smaller than the diffraction limit of the optical instrument
Soulisse, Pierre. "Développement d'un dispositif expérimental pour la diffraction d'atomes rapides et étude de surfaces d'isolants ioniques." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00625450.
Повний текст джерелаIqbal, Muhammad Owais. "Coherent structure in a turbulent axisymmetric jet via a vector implementation of the proper orthogonal decomposition." 2006. http://etd.nd.edu/ETD-db/theses/available/etd-04172006-140501/.
Повний текст джерелаThesis directed by Flint O. Thomas for the Department of Aerospace and Mechanical Engineering. "April 2006." Includes bibliographical references (leaves 117-121).
Riese, Michael. "Study of large-scale coherent structures in the near field and transition regions of a mechanically oscillated planar jet." 2009. http://hdl.handle.net/2440/54150.
Повний текст джерелаhttp://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1349701
Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 2009
Barannyk, Oleksandr. "Shear layer instabilities and flow-acoustic coupling in valves: application to power plant components and cardiovascular devices." Thesis, 2014. http://hdl.handle.net/1828/5372.
Повний текст джерелаGraduate
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Amini, Noushin. "Turbulent Flow Analysis and Coherent Structure Identification in Experimental Models with Complex Geometries." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10659.
Повний текст джерелаMüller, Christian. "Zeitaufgelöste Fluoreszenzspektroskopie unimolekularer Reaktionen im Überschalldüsenstrahl: trans-cis-Photoisomerisierung, Phenylringtorsion, intramolekularer Wasserstoffatomtransfer." Doctoral thesis, 2005. http://hdl.handle.net/11858/00-1735-0000-0006-B0C2-1.
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