Дисертації з теми "Turbulent swirling"
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Jones, Lee Nicholas. "Modelling of turbulent swirling flows." Thesis, University of Leeds, 2004. http://etheses.whiterose.ac.uk/1192/.
Повний текст джерелаZhang, Huangwei. "Extinction in turbulent swirling non-premixed flames." Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/254974.
Повний текст джерелаRiahi, Ardeshir. "Turbulent swirling flow in short cylindrical chambers." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30810.
Повний текст джерелаApplied Science, Faculty of
Mechanical Engineering, Department of
Graduate
García-Villalba, Navaridas Manuel. "Large eddy simulation of turbulent swirling jets." Karlsruhe : Univ.-Verl. Karlsruhe, 2006. http://deposit.d-nb.de/cgi-bin/dokserv?idn=979664586.
Повний текст джерелаRanga-Dinesh, K. K. J. "Large eddy simulation of turbulent swirling flames." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/21086.
Повний текст джерелаVondál, Jiří. "Computational Modeling of Turbulent Swirling Diffusion Flames." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234149.
Повний текст джерелаMüller, Sebastian. "Numerical investigations of compressible turbulent swirling jet flows." kostenfrei, 2007. http://e-collection.ethbib.ethz.ch/view/eth:30052.
Повний текст джерелаRegunath, Gavita Shamuna. "Measurements and Investigation of Helicity in Turbulent Swirling Flow." Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489741.
Повний текст джерелаChang, T. H. "An investigation of turbulent swirling flow with heat transfer." Thesis, Swansea University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636228.
Повний текст джерелаCroft, Thomas Nicholas. "Unstructured mesh : finite volume algorithms for swirling, turbulent, reacting flows." Thesis, University of Greenwich, 1998. http://gala.gre.ac.uk/6371/.
Повний текст джерелаFu, Song. "Computational modelling of turbulent swirling flows with second-moment closures." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267917.
Повний текст джерелаArmfield, S. (Steve) 1956. "Numerical simulation of incompressible turbulent swirling flow in conical diffusers." Phd thesis, Department of Mechanical Engineering, 1988. http://hdl.handle.net/2123/8074.
Повний текст джерелаCho, Nam-Hyo. "Computation of turbulent swirling flows in conical diffusers with tailpipes." Phd thesis, Department of Mechanical Engineering, 1990. http://hdl.handle.net/2123/7998.
Повний текст джерелаGarcía-Villalba, Navaridas Manuel [Verfasser]. "Large eddy simulation of turbulent swirling jets / Manuel García-Villalba Navaridas." Karlsruhe : Univ.-Verl. Karlsruhe, 2006. http://d-nb.info/979664586/34.
Повний текст джерелаKong, L. "Finite element analysis to confined turbulent swirling flow with heat transfer." Thesis, Swansea University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637821.
Повний текст джерелаIkhlaq, Muhammad. "Flow and heat transfer characteristics of turbulent swirling impinging jets [thesis]." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2021. https://ro.ecu.edu.au/theses/2389.
Повний текст джерелаHaber, Ludwig Christian. "Investigation of Dynamics in Turbulent Swirling Flows Aided by Linear Stability Analysis." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/11076.
Повний текст джерелаPh. D.
Ahmed, Zahir Uddin. "An experimental and numerical study of surface interactions in turbulent swirling jets." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2016. https://ro.ecu.edu.au/theses/1790.
Повний текст джерелаKarasu, Tahir. "Numerical prediction of incompressible turbulent swirling flows in circular sectioned ducts and annuli." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/8804.
Повний текст джерелаLin, Chao-An. "Three-dimensional computations of injection into swirling cross-flow using second-moment closure." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280543.
Повний текст джерелаOberleithner, Kilian [Verfasser], and Christian Oliver [Akademischer Betreuer] Paschereit. "On Turbulent Swirling Jets:Vortex Breakdown, Coherent Structures,and their Control / Kilian Oberleithner. Betreuer: Christian Oliver Paschereit." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2012. http://d-nb.info/1024771504/34.
Повний текст джерелаFrancia, Garcia Victor. "Spray drying of detergents in counter current towers : a study of turbulent swirling flows, fouling and agglomeration." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5646/.
Повний текст джерелаTaamallah, Soufien. "Impact of fuel and oxidizer composition on premixed flame stabilization in turbulent swirling flows : dynamics and scaling." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103437.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 205-214).
The world relies on fossil fuels as its main energy source (86.7% in 1973, 81.7% in 2012). Several factors including the abundance of resources and the existing infrastructure suggest that this is likely to continue in the near future (potentially 75% in 2040). Meanwhile climate change continues to be a pressing concern that calls for the development of low CO2 energy systems. Among the most promising approaches are pre-combustion capture technologies, e.g., coal gasification and natural gas reforming that produce hydrogen-rich fuels. Another approach is oxy-combustion in which air is replaced by a mixture of O2/CO2/H2O as the oxidizer stream. However, modern gas turbines have been optimized to operate on methane-air combustion and several challenges, notably thermo-acoustic instability, arise when using other fuels or oxidizers because of their different thermochemical and transport properties. While these phenomena constitute a major challenge under conventional operations, using hydrogen-rich fuels or CO2-rich oxidizer exacerbates the problem by modifying the combustor stability map in ways that are not well understood. In this thesis, we identify combustion modes most prone to dynamics, predict the onset of thermo-acoustic instability over a wide range of fuel and oxidizer compositions, and define parameters that can scale the data. To this end, a combination of experimental and numerical tools were deployed. We carried out a series of experiments in an optically accessible laboratory-scale swirl-stabilized combustor typical of those found in modern gas turbines, using high-speed chemiluminescence to examine the flame macrostructure; high-speed Particle Image Velocimetry and OH Planar Laser Induced Fluorescence to probe the flow and flame microstructure. Numerical simulations were used to complement experiments and examine the complex three-dimensional two-way interaction between the flame and the turbulent swirling flow. Experimental data were used to construct the stability maps for different CH4-H2 mixtures and analyze the dynamic flame macrostructures and their transitions. A comparison with acoustically uncoupled combustion shows that the onset of thermo-acoustic instability is concomitant with a specific transition associated with the intermittent appearance of the flame in the outer recirculation zone (ORZ) and stabilization along the outer shear layer (forming between the swirling jet and the ORZ, as revealed by the PIV-PLIF data). The sudden onset of large amplitude limit cycle oscillations and the observed hysteresis suggest the existence of a sub-critical Hopf bifurcation typically characterized by a bistable or "triggering" zone; the flame intermittency in the ORZ can potentially provide the disturbance required to trigger these oscillations. Using a dual-camera method to track chemiluminescence in space and time, this flame transition was found to originate from a reacting kernel that detaches from the inner shear layer flame (forming between the jet and the vortex breakdown zone), reaching the ORZ and spinning at a specific frequency; its characteristic Strouhal number is independent of the Reynolds number and the fuel/oxidizer, only a function of the swirl strength. We propose a new Karlovitz number based criterion that defines the transition on a flow time - flame time space, the former being the inverse of the spinning frequency and the latter being the flame extinction strain rate. According to this scaling, the flame survives in the ORZ if and when it can overcome the region's bulk strain rate. This criterion is valid over a wide range of operating, fuel and oxidizer composition, covering a wide range of fast to slow chemistry scenarios. Given the role of this flame transition in triggering the instability, the same criterion is applicable to predicting the onset of thermo-acoustics. The interaction of the turbulent swirling flow with the flame is further examined using large eddy simulations. Numerical simulations show that the experimentally observed large scale flame structures along the inner shear layer are due to a helical vortex core that originates at the swirler's centerbody. This vortical structure stays aligned with the centerline in the combustor upstream section, but bends and reaches the inner shear layer-stabilized flame around the sudden expansion where it causes the flame wrinkling. We propose that the flame kernel igniting the ORZ/ OSL observed in the experiment may be related to the interaction between the helical vortical structure and the outer shear layer.
by Soufien Taamallah.
Ph. D.
Roussillo, Mathieu. "Development of optical diagnostics for soot particles measurements and application to confined swirling premixed sooting flames under rich conditions." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC060/document.
Повний текст джерелаThe control of soot particles production represents today a major industrial issue because of their harmful impact on both the climate and the human health and their strong contribution to the radiative transfers. To better understand and control the production of these polluting emissions, it is essential to improve our knowledge on this subject in a turbulent burner. The objective of this Ph.D. is to set up optical diagnostics for the study of turbulent flames and to experimentally characterize soot production in a new academic turbulent premixed combustion configuration while approaching industrial configurations, generally confined and swirled flows. For this, a laminar experimental configuration is first considered to validate the implementation of the Laser Induced Incandescence (LII) technique to measure the soot volume fraction fv. This burner designed at Yale University allows the stabilization of a laminar ethylene/air diffusion flame. This burner has been widely studied in the literature, so that it is possible to compare the quality of our measurements with the results of different international teams. Through collaborations with the UPMC, we calibrated the LII signal with the MAE (Modulated Absorption Emission) technique, making it possible to quantitatively measure fv and to compare the MAE and LII techniques. Finally, the burner was equipped with a loudspeaker to modulate the flow and to study the effects of a controlled perturbation on the soot production, thus approaching the unsteady phenomena characteristics of turbulent flows. Finally, the effects of the enlargement of the laser sheet on LII results were also investigated in order to be able to apply this diagnostic technique in an innovative large turbulent configuration. This experimental configuration, called EM2Soot, was developed to measure the production of soot in a turbulent swirled rich confined premixed ethylene/air flame. This burner makes it possible to independently quantify the effects of the equivalence ratio, the total flame power and the thermal environment on the total soot production. A representative operating point was then characterized, in parallel with LII measurements, Particle Image Velocimetry (PIV) and Laser Induced Phosphorescence (LIP) techniques have been employed in order to characterize the effect of the turbulence on soot production and to establish a database for the validation of future numerical simulations. Finally, the geometry of the burner has been modified allowing a different stabilization of the flame (V flame shape). A new operating point is then studied in order to highlight the role of the injector geometry on the stabilization of the flame and, consequently, on the total soot production
Nabhani, Nader. "Hot-wire anemometry study of confined turbulent swirling flow : development of a hot-wire technique for measurement in confined turbulent swirling flow and an investigation of the effect of inlet flow rate and geometrical conditions on the velocity field." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.256901.
Повний текст джерелаKalpakli, Vester Athanasia. "Vortices in turbulent curved pipe flow-rocking, rolling and pulsating motions." Doctoral thesis, KTH, Mekanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145311.
Повний текст джерелаQC 20140523
Hilares, Luis Roberto Tay Wo Chong [Verfasser], Wolfgang H. [Akademischer Betreuer] Polifke, and Thierry [Akademischer Betreuer] Schuller. "Numerical Simulation of the Dynamics of Turbulent Swirling Flames / Luis Roberto Tay Wo Chong Hilares. Gutachter: Thierry Schuller. Betreuer: Wolfgang H. Polifke." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1020915129/34.
Повний текст джерелаÖrlü, Ramis. "Experimental studies in jet flows and zero pressure-gradient turbulent boundary layers". Doctoral thesis, KTH, Mekanik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10448.
Повний текст джерелаQC 20100820
VERFAILLIE, SWANN. "CORRELATIVE STUDIES AND COHERENT STRUCTURES EDUCTION BASED ON PROPER ORTHOGONAL DECOMPOSITION AND LINEAR STOCHASTIC ESTIMATION." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1099519886.
Повний текст джерелаBarre, David. "Numerical simulation of ignition in aeronautical combustion chambers." Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0004/document.
Повний текст джерелаFor evident operational and safety reasons, ignition is a key feature of aeronautical gas turbine applications. In fact the design of a gas turbine combustion chamber imposes multiple contradicting objectives one of them being efficient ignition or re-ignition. Among all the parameters available to the engineers, the number of fuel injection systems and their spacing are crucial elements, that must be fixed early on in the design phase. Such choices however not only impact the manufacturing cost and size of the combustor but they also affect the operability of the engine as well as its ignition. To improve knowledge of the ignition process occurring in real engines, current research combines fundamental and increasingly complex experiments complemented by high fidelity numerical simulations. These actions focus on the one hand on the initial instants where the first flame kernel appears as well as the follow-on instants corresponding to the light-around phase or burner to burner flame propagation phase. Both phases are clearly important but are difficult to study simultaneously. The first purpose of this thesis aims at assessing LES models on a single experimental burner located at CORIA (France) to provide a reliable numerical methodology to achieve an ignition sequence in real engines. Indeed, various phenomena are involved in such numerical studies dedicated to real aeronautical combustion chambers and all need to be reproduced by numerics: swirling flows, ignition, quenching, flame propagation, flame/turbulence interactions. All of these processes interact and clearly raise the level of difficulty notably in terms of turbulent combustion modeling of an ignition transient. Having assessed the method on a single burner configuration, the work then investigates the second phase, using a multi-injector experiment simulated by LES to study the flame propagation during ignition. The comparison of numerical fully transient ignition sequences with experimental data shows that LES recovers features found in the experiment. Global events such as the propagation of the flame front to neighboring swirlers are well captured and correct propagation modes (radial or axial) as well as correct overall ignition time delay are obtained. Finally the detailed analysis of LES data allows to identify the driving mechanisms governing each of these propagation modes
Stone, Christopher. "Large-Eddy simulation of combustion dynamics in swirling flows." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/13430.
Повний текст джерелаPascau, Benito Antonio. "The application of second order turbulence closures to isothermal and combusting swirling flows." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46491.
Повний текст джерелаQuaranta, Hugo. "Instabilities in a swirling rotor wake." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0052.
Повний текст джерелаThis work studies the instabilities associated with the wake of a rotor. These devices are used in many applications such as energy harvesting or propulsion,and their optimisation is crucial for both industry and the environment. The wakebehind a rotor is broadly defined as a system of interlaced helical vortices, whose dynamics governs the transition from the near-wake to the far-wake regime. In our first study, we investigate the wake behind different small-scale rotors in their design operating condition. We use the resulting flows in a subsequent linear stability analysis, aiming at predicting long-wavelength instability modes in the helical vortex. We find that the theoretical prediction of the modes growth-rates matches our experimental measurements. We also show that the dynamics of helical vortex filaments can be predicted from simple two-dimensional theory. In more critical flow configurations, instabilities are suspected to promote the transition to hazardous regimes such as the so called Vortex-Ring State, characterised by large-scale recirculating structures.The second part of this work is thus dedicated to the spatio-temporal evolution of localised perturbations in the rotor plane, and their potential tendency to propagate upstream in the flow
Salhi, Abdelaziz. "Etude de l'ecoulement couette poiseuille, liquide et liquide-gaz, dans un espace annulaire reduit." Nantes, 1986. http://www.theses.fr/1986NANT2066.
Повний текст джерелаÖrlü, Ramis. "Experimental study of passive scalar mixing in swirling jet flows." Licentiate thesis, KTH, Mechanics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4142.
Повний текст джерелаDespite its importance in various industrial applications there is still a lack of experimental studies on the dynamic and thermal field of swirling jets in the near-field region. The present study is an attempt to close this lack and provide new insights on the effect of rotation on the turbulent mixing of a passive scalar, on turbulence (joint) statistics as well as the turbulence structure.
Swirl is known to increase the spreading of free turbulent jets and hence to entrain more ambient fluid. Contrary to previous experiments, which leave traces of the swirl generating method especially in the near-field, the swirl was imparted by discharging a slightly heated air flow from an axially rotating and thermally insulated pipe (6 m long, diameter 60 mm). This gives well-defined axisymmetric streamwise and azimuthal velocity distributions as well as a well-defined temperature profile at the jet outlet. The experiments were performed at a Reynolds number of 24000 and a swirl number (ratio between the angular velocity of the pipe wall and the bulk velocity in the pipe) of 0.5.
By means of a specially designed combined X-wire and cold-wire probe it was possible to simultaneously acquire the instantaneous axial and azimuthal velocity components as well as the temperature and compensate the former against temperature variations. The comparison of the swirling and non-swirling cases clearly indicates a modification of the turbulence structure to that effect that the swirling jet spreads and mixes faster than its non-swirling counterpart. It is also shown that the streamwise velocity and temperature fluctuations are highly correlated and that the addition of swirl drastically increases the streamwise passive scalar flux in the near field.
Ko, Jordan. "Numerical modelling of highly swirling flows in a cylindrical through-flow hydrocyclone." Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293.
Повний текст джерелаCazan, Radu. "Dynamics of swirling flows induced by twisted tapes in circular pipes." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33944.
Повний текст джерелаCapiaux, Sylvie. "Application et développement de la vélocimétrie par images de particules pour l'étude de la phase d'admission dans les moteurs à allumage commandé." Rouen, 1997. http://www.theses.fr/1997ROUES068.
Повний текст джерелаBuntine, James D. Saffman P. G. "Part 1. Inviscid, swirling flows and vortex breakdown. : Part 2. A numerical investigation of the Lundgren turbulence model /." Diss., Pasadena, Calif. : California Institute of Technology, 1994. http://resolver.caltech.edu/CaltechETD:etd-10182005-082716.
Повний текст джерелаBai, Haitong. "A Study of the Swirling Flow Pattern when Using TurboSwirl in the Casting Process." Doctoral thesis, KTH, Tillämpad processmetallurgi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-196806.
Повний текст джерелаTidigare studier visar att ett roterande flöde kan ge en mer likformig hastighetsfördelning och en lugnare fyllning i både göt- och stränggjutning av stål. De befintliga metoderna för att generera ett roterande flöde har vissa begränsningar. En ny metod för att generera det roterande flödet, en så kallad TurboSwirl, föreslogs nyligen. I detta arbete undersöktes ett konvergent munstycke med olika vinklar för att se hur detta påverkade det roterande flödet som genererades i anordningen. Resultaten visar att skjuvspänningen i systemet kan reduceras genom att ändra munstyckets vinkel mellan 40º till 60º. En lägre maximal axiell hastighet kan också uppnås med en mindre konvergent vinkel på munstycket. Det är även möjligt att påverka den maximala axiella hastigheten och skjuvspänningen i systemet genom att förflytta den vertikala kanalen i anordningen. Vattenmodellexperiment har utförts för att validera simuleringsresultaten. Det kraftigt roterande flödet kunde endast beskrivas väl av Reynolds Stress Model (RSM). Validering utfördes också genom att mäta den radiella hastigheten i den vertikala kanalen med en Ultrasonic Velocity Profiler (UVP). TurboSwirl-anordningen vändes och kopplades till gjutröret för att generera det roterande flödet. Detta studerades både med numeriska modeller och med vattenmodellering. Ett periodiskt asymmetriskt roterande flöde observerades både i numeriska modellerna och i vattenmodellerna. För att modellera detta periodiska flöde så användes detached eddy simulation (DES) modellen. Resultaten då denna modell användes stämmer väl med de experimentella mätningarna. Denna nya design med TurboSwirl kan uppnå liknande styrka på det roterande flödet som när elektromagnetisk omrörning användes. Det resulterande roterande flödet leder till en lägre axiell hastighet i gjutröret samt en lugnare yta och ett lugnare flöde i kokillen.
QC 20161123
Kucukal, Erdem. "EXPERIMENTAL AND CFD INVESTIGATIONS OF THE FLUID FLOW INSIDE A HYDROCYCLONE SEPARATOR WITHOUT AN AIR CORE." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1424174590.
Повний текст джерелаKelson, Neil. "Study of industrially relevant boundary layer and axisymmetric flows, including swirl and turbulence." Thesis, Queensland University of Technology, 2000. https://eprints.qut.edu.au/37083/1/37083_Digitised%20Thesis.pdf.
Повний текст джерелаHamma, Laurence. "Etude de la diffusion de la chaleur en aval d'un cylindre chauffé à faible nombre de Reynolds (40." Rouen, 1988. http://www.theses.fr/1988ROUES031.
Повний текст джерелаRangwala, Aliasgar H. "Structure of Turbulent, Swirling Round Jets." Thesis, 2022. https://etd.iisc.ac.in/handle/2005/6008.
Повний текст джерела紀丕鴻. "Numerical simulation and analysis of the swirling turbulent combustor." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/12596785457982922469.
Повний текст джерелаZhang, Dehong. "Turbulent swirling combustion of premixed natural gas and air." Thesis, 1995. http://hdl.handle.net/2429/8828.
Повний текст джерелаKhademi, Shamami Keivan. "Performance of RANS models for simulating turbulent swirling and free jet flows." 2008. http://hdl.handle.net/1993/21292.
Повний текст джерелаIyogun, Christopher Omokhowa. "Effect of nozzle geometry on the stability of a turbulent jet flame with and without swirling co-flow." 2009. http://hdl.handle.net/1993/21452.
Повний текст джерелаChen, Jian Chou, and 陳建州. "Modelling confined swirling flow field by nonlinear pressure- strain turbulence model." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/45770267151017905489.
Повний текст джерелаBuntine, James D. "Part I: Inviscid, swirling flows and vortex breakdown. Part II: A numerical investigation of the Lundgren turbulence model." Thesis, 1994. https://thesis.library.caltech.edu/4155/1/Buntine_jd_1994.pdf.
Повний текст джерела