Thematische Bibliographien / Impinging flame

Auswahl der wissenschaftlichen Literatur zum Thema „Impinging flame“

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Veröffentlicht am 25. Mai 2024

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Zeitschriftenartikel zum Thema "Impinging flame"

Leu, Jai Houng, und Ay Su. „Structure of Combustion Enhancement on Impinging Diffusion Flame“. Applied Mechanics and Materials 152-154 (Januar 2012): 872–76. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.872.

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For the purpose to clear obverse the impingement and entrainment of the impinging diffusion flame, numbers of the tests are executed under various sets of momentum ratios in this paper. The oxidizer-fuel impinging flames shorten the fully development length. The peak temperature distributions are also greater than that of pure methane impinging flame. Furthermore, its flame width in YZ plane is thicker than that of the pure impinging flame. This effect is more obvious under lean combustion condition. Also, nitrogen gas in the mixture can increase the mixing rate.

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Ko, H. S., S. S. Ahn, S. H. Baek und T. Kim. „Development of Combined Optical System for Thermal Analysis of Impinging Flames“. Key Engineering Materials 326-328 (Dezember 2006): 71–74. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.71.

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Three-dimensional density distributions of an impinging and eccentric flame have been analyzed numerically and experimentally by a combined optical system with a digital speckle tomography. The flame has been ignited by premixed butane/air from air holes and impinged vertically against a plate located at the upper side of the burner nozzle. In order to compare with experimental data, computer synthesized phantoms of impinging and eccentric flames have been derived and reconstructed by a developed three-dimensional multiplicative algebraic reconstruction technique (MART). A new scanning technique has been developed for the analysis of speckle displacements to investigate wall jet regions of the impinging flame including sharp variation of the flow direction and pressure gradient. The reconstructed temperatures by the digital speckle tomography have been compared with a temperature photography by an infrared camera and results of a numerical analysis using a finite element method.

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Park, Kweonha. „The flame behaviour of liquefied petroleum gas spray impinging on a flat plate in a constant volume combustion chamber“. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, Nr. 5 (01.05.2005): 655–63. http://dx.doi.org/10.1243/095440705x11031.

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Liquefied petroleum gas (LPG) sprays and diffusion flames are investigated in a constant volume combustion chamber having an impingement plate. The spray and flame images are visualized and compared with diesel and gasoline images over a wide range of ambient pressure. The high-speed digital camera is used to take the flame images. The injection pressure is generated by a Haskel air-driven pump, and the initial chamber pressure is adjusted by the amount of pumping air. The LPG spray and flame photographs are compared with those of gasoline and diesel fuel at the same conditions, and then the spray and flame development behaviour is analysed. The spray photographs show that the dispersion characteristics of LPG spray are sensitive to the ambient pressure. In a low initial chamber pressure LPG fuel in the liquid phase evaporates quickly and does not reach down easily to the impinging plate having a hot coil for ignition. That makes the temperature and equivalence ratio low near the ignition coil, thus making ignition diffcult. On the other hand, in a high initial chamber pressure the spray leaving the nozzle gathers around the ignition site after impinging on the plate, which makes an intense flame near the plate. If applied to small-sized direct injection engines that are not able to avoid spray impinging on a cylinder wall, LPG will have faster and cleaner combustion than diesel or gasoline fuels. However, the chamber geometry should be carefully designed to enable a sufficient amount of vaporized fuel to get to the ignition site

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BERGTHORSON, JEFFREY M., SEAN D. SALUSBURY und PAUL E. DIMOTAKIS. „Experiments and modelling of premixed laminar stagnation flame hydrodynamics“. Journal of Fluid Mechanics 681 (23.06.2011): 340–69. http://dx.doi.org/10.1017/jfm.2011.203.

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The hydrodynamics of a reacting impinging laminar jet, or stagnation flame, is studied experimentally and modelled using large activation energy asymptotic models and numerical simulations. The jet-wall geometry yields a stable, steady flame and allows for precise measurement and specification of all boundary conditions on the flow. Laser diagnostic techniques are used to measure velocity and CH radical profiles. The axial velocity profile through a premixed stagnation flame is found to be independent of the nozzle-to-wall separation distance at a fixed nozzle pressure drop, in accord with results for non-reacting impinging laminar jet flows, and thus the strain rate in these flames is only a function of the pressure drop across the nozzle. The relative agreement between the numerical simulations and experiment using a particular combustion chemistry model is found to be insensitive to both the strain rate imposed on the flame and the relative amounts of oxygen and nitrogen in the premixed gas, when the velocity boundary conditions on the simulations are applied in a manner consistent with the formulation of the streamfunction hydrodynamic model. The analytical model predicts unburned, or reference, flame speeds that are slightly lower than the detailed numerical simulations in all cases and the observed dependence of this reference flame speed on strain rate is stronger than that predicted by the model. Experiment and simulation are in excellent agreement for near-stoichiometric methane–air flames, but deviations are observed for ethylene flames with several of the combustion models used. The discrepancies between simulation and experimental profiles are quantified in terms of differences between measured and predicted reference flame speeds, or position of the CH-profile maxima, which are shown to be directly correlated. The direct comparison of the measured and simulated reference flame speeds, ΔSu, can be used to infer the difference between the predicted flame speed of the combustion model employed and the true laminar flame speed of the mixture, ΔSOf, i.e. ΔSu=ΔSOf, consistent with recently proposed nonlinear extrapolation techniques.

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Ay, Su, und Liu Ying-Chieh. „Enhancements of impinging flame by pulsation“. Journal of Thermal Science 9, Nr. 3 (September 2000): 271–75. http://dx.doi.org/10.1007/s11630-000-0062-6.

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Jiang, Xi, Hua Zhao und Kai H. Luo. „Direct Numerical Simulation of a Non-Premixed Impinging Jet Flame“. Journal of Heat Transfer 129, Nr. 8 (20.09.2006): 951–57. http://dx.doi.org/10.1115/1.2737480.

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A non-premixed impinging jet flame at a Reynolds number 2000 and a nozzle-to-plate distance of two jet diameters was investigated using direct numerical simulation (DNS). Fully three-dimensional simulations were performed employing high-order numerical methods and high-fidelity boundary conditions to solve governing equations for variable-density flow and finite-rate Arrhenius chemistry. Both the instantaneous and time-averaged flow and heat transfer characteristics of the impinging flame were examined. Detailed analysis of the near-wall layer was conducted. Because of the relaminarization effect of the wall, the wall boundary layer of the impinging jet is very thin, that is, in the regime of viscous sublayer. It was found that the law-of-the-wall relations for nonisothermal flows in the literature need to be revisited. A reduced wall distance incorporating the fluid dynamic viscosity was proposed to be used in the law-of-the-wall relations for nonisothermal flows, which showed improved prediction over the law of the wall with the reduced wall distance defined in terms of fluid kinematic viscosity in the literature. Effects of external perturbation on the dynamic behavior of the impinging flame were found to be insignificant.

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Uppatam, Nuttamas, Wongsathon Boonyopas, Chattawat Aroonrujiphan, Natthaporn Kaewchoothong, Somchai Sae-ung und Chayut Nuntadusit. „Heat Transfer Characteristic for Premixed Flame Jet from Swirl Chamber“. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 77, Nr. 2 (14.11.2020): 33–46. http://dx.doi.org/10.37934/arfmts.77.2.3346.

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The objective of this research is to study flame structure and heat transfer characteristics for the premixed flame jet from the swirling chamber. In this study, LPG and air was utilized as gas fuel and oxidizer for a premixed flame. The equivalence ratios () of LPG and air were considered at 0.8, 1.0, and 1.2 under a Reynolds number Re = 4,000. The swirl flame was generated by double tangential inlets in cylindrical chamber. The diameter of chamber was fixed at D = 20 mm and the hydraulic diameter of the inlet was Dh = 5 mm. In this study, the effect of chamber geometry on flame structure was investigated by varying the chamber from H = 2.2Dh to 7.0Dh. The structures and temperature of the free flame jet was recorded with camera and measured with a thermocouple. The heat transfer rate of impinging flame jet was also measured at distance from chamber outlet to flame impingement surface varying from L = 4Dh to 10Dh. The results show that the maximum of flame temperature occurs at =1.2. Impinging flame jet for case of chamber height at H = 4.6Dh and impingement distance at L = 4Dh give the highest heat transfer for all equivalence ratios due to the reaction zone of combustion reached to approach near the heat transfer surface.

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Chen, Yiran, Tong Yao, Qian Wang und Kai Hong Luo. „Large eddy simulation of impinging flames: Unsteady ignition and flame propagation“. Fuel 255 (November 2019): 115734. http://dx.doi.org/10.1016/j.fuel.2019.115734.

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., Shankar Badiger. „FLAME SHAPES AND HEAT TRANSFER CHARACTERISTICS OF AN IMPINGING FLAME JET“. International Journal of Research in Engineering and Technology 05, Nr. 25 (25.09.2016): 115–18. http://dx.doi.org/10.15623/ijret.2016.0525020.

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Sun, Meng, Jieyu Jiang, Yongzhe Yu, Canxing He, Kun Liu und Bin Zhang. „The impinging wall effect on flame dynamics and heat transfer in non-premixed jet flames“. Thermal Science, Nr. 00 (2022): 76. http://dx.doi.org/10.2298/tsci220126076s.

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The impinging jet flame is studied experimentally and numerically accounting for the complex flame-wall interactions in practical combustion devices. Flame dynamics and heat transfer with the effect of impinging wall are analyzed. 3D large eddy simulation coupled with detailed chemical reaction mechanism and particle image velocimetry experiment based on cross-correlation measurement principle are performed for verification and further analysis. Results show that vortices are generated due to the Kelvin-Helmholtz instability originated from velocity gradient. 3D vortex interactions involving vortex rings and spirals are also indicated by vorticity and the convection of stream wise vorticity is responsible for the effect of vortex spirals associated with turbulent flow transition. In addition, results calculated from four wall thermal conditions are compared and analyzed. Dirichlet condition is inferred to be more suitable for the case of wall materials with higher thermal conductivity. It is indicated that wall thermal condition mainly affects the heat transfer in the near-wall region, but has little effect on the momentum transfer. This study provides references for the adoption of wall conditions in numerical simulation and near-wall treatment in combustion systems.

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Dissertationen zum Thema "Impinging flame"

Wang, Aijuan. „Experimental and numerical investigation of the confinement effect on the impinging flame in a compartment“. Electronic Thesis or Diss., Bourges, INSA Centre Val de Loire, 2021. http://www.theses.fr/2021ISAB0002.

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Le phénomène de flamme de diffusion impactant une paroi est fréquent dans les scénarios d’incendie en milieu clos. Celui-ci peut entraîner à avoir des conséquences désastreuses en termes de vie humaine et de biens matériels. En effet, lorsqu'une flamme incidente se produit dans un compartiment, elle peut augmenter le risque de propagation du feu de celui-ci vers une autre pièce à travers une explosion de fumée représentant une menace pour les personnes pié-gées. Afin d’apporter des éléments de compréhension sur le comportement de ce type de flamme, de nombreuses études ont réalisé. Celles-ci se sont intéressées sur des flammes impac-tant un plafond en milieu ouvert ou semi-confiné. Cependant il y a peu, voire aucuns travaux qui se sont penchés sur l’étude du comportement d’une flamme incidente dans un compartiment confiné sous ventilé. Dans l’objectif d’apporter des éléments de compréhension en lien avec l’effet du confinement sur la dynamique d’une flamme impactant un plafond, une étude expé-rimentale et numérique est réalisée dans le cadre de cette thèse.L’ensemble des données a été obtenu à l’aide d’un dispositif expérimental représentant un appartement d’étudiant à échelle réduite.Le banc d'essai est un compartiment représentant une maquette d’appartement à petite échelle (1 :10). La conception et dimensionnement a été réalisée sur la base des lois de simili-tudes. Les niveaux de confinement ont été définis en fonction des ouvertures de l’enceinte et du débit calorifique potentielle. A partir de ces deux paramètres, le niveau de confinement peut être associé à la richesse de l’enceinte. Pour cela, huit débits caloriques différents ainsi que cinq possibilités d’ouvertures ont été proposés. À partir des expériences réalisées avec les huit débits calorifiques et les cinq configurations d’ouvertures, l'effet de confinement sur la dynamique d’une flamme impactant un plafond a été effectué en se basant sur les paramètres physico-chimiques, tels que l'extension de la flamme, l'oscillation de la flamme, la distribution de la température et l'analyse des gaz.De plus, grâce à la modélisation numérique de la flamme impactant le plafond à l’aide du code CFD : Fire Dynamics Simulator (FDS), il a été possible d’apporter des éléments supplé-mentaires dans l’analyse des écoulements réactifs associée à l’interaction flamme paroi en fonc-tion du niveau de confinement. Le choix des modèles numériques a été effectué à partir d’une étude préliminaire visant à justifier la fiabilité et la précision du modèle numérique à reproduire les données expérimentales ainsi que des évolutions obtenues à partir de corrélations empiriques obtenues dans les littératures.A partir des analyses réalisées dans cette étude, il est possible de fournir des éléments de décisions lors de la conception et la mise en place de détecteurs d'incendie au plafond dans un compartiment et également d’aider à une meilleure estimation de la probabilité de propagation du feu lors d'un incendie de compartiment par le biais d’une explosion de fumée riche en gaz imbrûlés
The phenomenon of diffusion impinging flame is common in industrials, leading to disas-trous consequences in terms of life and property. When impinging flame occurs in a compart-ment, it may enhance the risk of fire propagation and pose a greater threat to trapped people. Lots of studies dealt with flame impinging an unconfined or confined ceiling while little work focused on the impinging flame in a confined compartment. With the objective of providing understanding related to the confinement effect on the impinging flame in a compartment, both experimental and numerical studies carried out to build up the framework of this thesis. A compartment model representing a reduced scale (1:10) student compartment was uti-lized based on the scaling law such that a test bench with suitable instrumentations for carrying out measurements was developed. Configurations of five confinement levels were constructed by the condition of windows and door in the compartment and heat release rate (HRR) was var-ied between 0.5 kW and 18.6 kW. Through series of experiments, the confinement effect on the dynamics of flame impinging a ceiling was addressed with physicochemical parameters, such as flame extension, flame oscillation, temperature distribution and gas analysis. In addition, on account of the numerical modeling of flame impinging a ceiling using the CFD code: Fire Dynamics Simulator (FDS), it was possible to provide additional elements in the analysis of reactive flows associated with the flame-wall interaction as a function of the confinement level. The choice of numerical models was made on the basis of a preliminary study aimed at justifying the reliability and precision of the numerical modelling in reproducing the experimental data as well as the empirical correlations obtained in the literatures. From the analyzes in this study, it is possible to provide guidance for fire safety engineering in the field of fire risk assessment and fire protection design of buildings

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Asgyer, Abulkasem A. „Turbulent premixed impinging flames“. Thesis, University of Manchester, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488202.

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Abdullatif, Tawfik A. „Turbulent diffusion impinging flames“. Thesis, University of Manchester, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488402.

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Chien, Yu-Chien. „Electrical Aspects of Impinging Flames“. Thesis, University of California, Irvine, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3682710.

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This dissertation examines the use of electric fields as one mechanism for controlling combustion as flames are partially extinguished when impinging on nearby surfaces. Electrical aspects of flames, specifically, the production of chemi-ions in hydrocarbon flames and the use of convective flows driven by these ions, have been investigated in a wide range of applications in prior work but despite this fairly comprehensive effort to study electrical aspects of combustion, relatively little research has focused on electrical phenomena near flame extinguishment, nor for flames near impingement surfaces. Electrical impinging flames have complex properties under global influences of ion-driven winds and flow field disturbances from the impingement surface. Challenges of measurements when an electric field is applied in the system have limited an understanding of changes to the flame behavior and species concentrations caused by the field. This research initially characterizes the ability of high voltage power supplies to respond on sufficiently short time scales to permit real time electrical flame actuation. The study then characterizes the influence of an electric field on the impinging flame shape, ion current and flow field of the thermal plume associated with the flame. The more significant further examinations can be separated into two parts: 1) the potential for using electric fields to control the release of carbon monoxide (CO) from surface-impinging flames, and 2) an investigation of controlling electrically the heat transfer to a plate on which the flame impinges. Carbon monoxide (CO) results from the incomplete oxidation of hydrocarbon fuels and, while CO can be desirable in some syngas processes, it is usually a dangerous emission from forest fires, gas heaters, gas stoves, or furnaces where insufficient oxygen in the core reaction does not fully oxidize the fuel to carbon dioxide and water. Determining how carbon monoxide is released and how heat transfer from the flame to the plate can be controlled using the electric field are the two main goals of this research. Multiple diagnostic techniques are employed such as OH chemiluminescence to identify the reaction zone, OH PLIF to characterize the location of this radical species, CO released from the flame, IR imaging and OH PLIF thermometry to understand the surface and gas temperature distribution, respectively. The principal finding is that carbon monoxide release from an impinging diffusion flame results from the escape of carbon monoxide created on the fuel side of the flame along the boundary layer near the surface where it avoids oxidation by OH, which sits to the air side of the reaction sheet interface. In addition, the plate proximity to the flame has a stronger influence on the emission of toxic carbon monoxide than does the electric field strength. There is, however, a narrow region of burner to surface distance where the electric field is most effective. The results also show that heat transfer can be spatially concentrated effectively using an electric field driven ion wind, particularly at some burner to surface distances.

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Virk, Akashdeep Singh. „Heat Transfer Characterization in Jet Flames Impinging on Flat Plates“. Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/52985.

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The experimental work involves calculation of radial distribution of heat transfer coefficient at the surface of a flat Aluminium plate being impinged by a turbulent flame jet. Heat transfer coefficient distribution at the surface is computed from the measured heat flux and temperature data using a reference method and a slope method. The heat transfer coefficient (h) has a nearly bell shaped radial distribution at the plate surface for H/d =3.3. The value of h drops by 37 % from r/d =0 to r/d= 2. Upon increasing the axial distance to H/d = 5, the stagnation point h decreased by 15%. Adiabatic surface temperature (AST) distribution at the plate surface was computed from the measured heat flux and temperature. AST values were found to be lower than the measured gas temperature values at the stagnation point. Radial distribution of gas temperature at the surface was estimated by least squares linear curve fitting through the convection dominated region of net heat flux data and was validated by experimental measurements with an aspirated thermocouple. For low axial distances (H/d =3.3), the gas temperature dropped by only 15 % from r/d = 0 to r/d = 2. Total heat flux distribution is separated into radiative and convective components with the use of calculated heat transfer coefficient and estimated gas temperatures. At H/d = 3.3, the radiation was found to be less than 25 % of the net heat flux for r/d ≤ 2.
Master of Science

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Bergthorson, Jeffrey Myles Dimotakis Paul E. „Experiments and modeling of impinging jets and premixed hydrocarbon stagnation flames /“. Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-05242005-165713.

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Wasson, Rachel Ann. „Separation of the Heat Transfer Components for Diffusion Flames Impinging onto Ceilings“. Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50588.

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Two series of experiments were performed to determine the flow characteristics and to quantify the heat transfer components from a propane diffusion flame impinging onto a ceiling. A 0.3 m square sand burner with propane as the fuel type provided a steady-state fire. In the first series of experiments, measurements of gas temperature and velocity were made at 76 mm vertical intervals above the burner up to the ceiling. Fire heat release rates (HRRs) of 50 kW and 90 kW with free flame length to ceiling height ratios, Lf/H, of 2, 1.5, 1, 0.8, 0.85 were used to determine their effects on the measured parameters. Gas temperatures within the continuous flaming region were relatively constant, and measured to be independent of ceiling height and HRR, while velocities increased with elevation and were independent of ceiling height yet weakly dependent on HRR. Within the intermittent region, gas temperature was weakly affected by the presence of the ceiling at various heights, while the effect on velocity was more pronounced. HRR had an effect on both temperature and velocity within the intermittent region of the fire plume. Comparisons with existing fire plume correlations showed that the unbounded correlations can be used to provide a good approximation of the gas temperature for the ceiling bounded case; while the correlations for the velocity can only be used for elevations up to approximately 60% of the ceiling height. Elevations above this cutoff were significantly affected by the presence of the ceiling. The second series of experiments investigated HRRs of 50 kW and 90 kW with free flame length to ceiling height ratios, Lf/H, of 2, 1.5, and 1. Heat flux and gas temperature at the stagnation point of the ceiling were measured using hybrid heat flux gauges and an aspirated Type K thermocouple. Four methods of calculating the convective heat transfer coefficient, h, were developed and adapted; two reference methods and two slope methods. The components of heat transfer at the impingement point were separated using these calculated h values. The reference method 2, and both slope methods only required the use of the non-cooled hybrid gauge measurements and were in overall good agreement with one another. The reference method 1 differed significantly, being up to 15.8 times lower than the others. The trends in the two groups were contradictory, with the h calculated using the reference method 1 increasing with ceiling height while the others showed no strong trend with ceiling height. The disagreements between the methods greatly affected the components of heat transfer, particularly at the lowest ceiling heights. Convection calculated using the h from reference method 1 contributed only 2-5% of the total exposure heat flux at the lowest ceiling heights, whereas with the other methods convection contributed 20-50% of the total exposure heat flux. The limitations of each method are discussed. Further investigation is required for all methods to determine their applicability within the flaming region of a fire.
Master of Science

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McDaid, Chloe. „Developing and implementing advanced optical diagnostics for the investigation of fuel and flow effects on impinging jet flames“. Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/5166/.

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Experimental diagnostic techniques have been utilised and developed to investigate the flame wall interaction for impinging flames of propane, methane, hydrogen and syngas. Thermal imaging has been used to evaluate the plate temperatures and radiation losses at steady state. A methodology has been developed for temperature dependent emissivity materials. Schlieren and direct imaging have been used to visualise flame shapes and flow structure. A methodology has been developed to quantify the relative effects of visual turbulent structures on the flame wall interaction. High speed schlieren has been used to assess the time dependent flame front propagation following ignition at various ignition locations. The combination of these techniques has allowed the flame wall interaction to be analysed for fuel composition, thermal loading, equivalence ratio, nozzle-to-plate distance, Reynolds number, geometry and fuel exit velocity. It has been found that fuel composition significantly affects the wall temperature profiles even at similar nozzle conditions. Mixing in different regions of the impingement configuration caused significant differences in the wall temperature profiles for the different fuels due to differences in diffusivity and laminar flame speed. Syngas premixed flames produce similar wall temperature profiles near the lift-off limit but at different equivalence ratios and Reynolds numbers, due to the similar turbulence shown in the schlieren images. Plate material and nozzle-to-plate distance significantly affected the wall temperature profiles. Radiation losses from the plate helped to explain the differences in heat transfer for the different conditions. Delays in the initial downwards propagation were observed for the hydrogen flames. The competing factors of the upstream propagation and heat production, causing decelerations and accelerations of the flame front respectively, differed significantly for different fuels and conditions. The propagation of the flame front immediately after ignition was observed to be very complex, changing significantly for relatively small changes in nozzle conditions.

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Wen, Ming-Houng, und 溫明晃. „A study on Jet Impinging Flame“. Thesis, 1999. http://ndltd.ncl.edu.tw/handle/06516648712659137193.

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碩士
元智大學
機械工程研究所
87
The structures of the jet impinging flame are observed under different impinging angles, Renolds number and fuel dilution. The impinging flame of methane fuel is therefore constructed at the stagnation plane. This simple mechanism may reduce the combustion length and the combustion efficiency. But there is a high temperature flashback in the root of flame. When the Renolds number increase, the temperature of impinging flame reduce at the stagnation point and the combustion efficiency increase. Along with the ration of volume nitrogen and volume methane, the combustion length is reduced and the blue proportion of flame is increased. The temperature distribution of flame is uniform, too. Along with the impinging angle is increased, the area of flashback in the root of flame obvious more and more.

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Shu, Ke-Neng, und 徐可能. „A Study on Impinging Angle Effect on Jet-to-Jet Impinging Pulsation Flame“. Thesis, 2001. http://ndltd.ncl.edu.tw/handle/04022024674672860663.

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碩士
元智大學
機械工程研究所
89
Experimental investigations on the pulsating jet-impinging diffusion flame were executed. A solenoid valve was aligned upstream of the jet orifice and the methane fuel and the outlet-field condition were controlled in open-closed cycles from 2 Hz to 17 Hz. By changing some parameters such as impinging angle, outlet fuel Renault Number and fuel supplying pulsation frequencies, to confer the changing of the temperature contours of a impinging jet diffusion flame. Results show that a solenoid which is the impinging jet flame source supplying a regular disturbing fountainhead to increase the turbulence flow strength can get better flame stability; the flame length between 13 Hz to 15 Hz was lower than that without pulsating, and the impinging angle at 54 degree with more obviously shorting phenomenon can improve the designed length of the burning room; observing temperature contour plane, a solenoid as a fuel supplying source can burn the fuel more completely because the reacting fuel molecules in the flame increase as a result of sucking more air by interrupted frequency. We can get a better burning efficiency when the operating frequency at about 13 Hz in flame temperature contours. Results show that the best operating frequency is at about 13 Hz, and if the frequency were below 10 Hz, it would result an uncontinuous burning and decrease the stability of the flame.

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Buchteile zum Thema "Impinging flame"

Lim, S., Y. Yoon, C. Lee und I. S. Jeung. „Effect of strain rate on NOx emission in opposed impinging jet flame combustor“. In Laser Techniques for Fluid Mechanics, 527–39. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-08263-8_32.

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Ko, H. S., S. S. Ahn, S. H. Baek und T. Kim. „Development of Combined Optical System for Thermal Analysis of Impinging Flames“. In Experimental Mechanics in Nano and Biotechnology, 71–74. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-415-4.71.

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„Modeling Impinging Flame Jets“. In Computational Fluid Dynamics in Industrial Combustion, 471–512. CRC Press, 2000. http://dx.doi.org/10.1201/9781482274363-21.

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Mahmud, Rizal, und Iis Rohmawati. „Effect of Injection Pressure on Local Temperature and Soot Emission Distribution of Flat-Wall Impinging Diesel Flame under Diesel Engine like-Condition“. In Diesel Engines [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102867.

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Increasing heat transfer and heat transfer coefficient as the combined effect of impingement distance and injection pressure has been explored in the previous report. However, local temperature distribution was limited to the discussion. Clearly, investigation of near-wall temperature in the heat transfer analysis is absolutely necessary. This has a crucial effect on the local heat flux to understand the heat transfer phenomenon on the combustion chamber walls. The local temperature and KL factor were investigated by using a high-speed video camera and a two-color method by using a volume vessel with a fix-impingement wall. We found that the local temperature and KL factor distribution increase in low injection pressure. This result had a dominant effect on local heat transfer.

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Konferenzberichte zum Thema "Impinging flame"

Dong, Mingchun, und David G. Lilley. „Impinging Flame Prediction for CVD Diamond Synthesis“. In ASME 1993 International Computers in Engineering Conference and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/cie1993-0056.

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Abstract High-temperature flames impinging normally onto adiabatic surfaces are considered. These are important in the CVD (chemical vapor deposition) diamond synthesis method for diamond growth on surfaces. Problems of complex chemistry and the mechanism of diamond growth are discussed. The present paper has illustrated the effects of several key parameters on the substrate surface temperature and flowfield for CVD diamond synthesis by impinging oxy-acetylene jet flames. The studies were concerned with combustion flowfield predictions, oxy-acetylene flames, axisymmetric-vertical impingement on an adiabatic surface, and the effects of varying the nozzle-substrate separation distance, nozzle size, overall equivalence ratio and flow rate on the substrate surface temperature and flowfield. This investigation provides a key to linking the flame with diamond growth rate on the substrate surface, complements the other facets of the project, and shows that the parametric influences can be predicted with relative ease, thereby extending the range of previously found experimental data.

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Chander, Subhash, und Anjan Ray. „Investigation of Flame Structure for Laminar Methane/Air Flame Impinging on a Flat Surface“. In ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88195.

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A combined experimental and numerical study has been conducted to investigate the impinging flame structure. Inflame temperature profiles were obtained and compared with corresponding simulated profiles. For detailed understanding of flame structure numerical simulations were carried out using commercial CFD code FLUENT. Simulated temperature, heat flux and species profiles were analyzed. Further investigations were done by plotting streamlines, velocity magnitude profiles and species profiles. It has been seen that bulk of the combustion products were burnt rapidly in the narrow reaction zone at the tip of the flame. This was because of exponential relationship between the chemical reaction rate and temperature. Simulation results show high temperature in the region between the inner premixed and the outer non-premixed (diffusion) reaction zones. The burnt gas along the inner zone expands and molecules change their directions from initially parallel to diverging lines. Flow accelerated from stagnation point and attained maximum velocity at the start of wall-jet region.

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Kaushal, Arun, Gurpreet Singh, Subhash Chander und Anjan Ray. „Heat Transfer Characteristics of Low Reynolds Number Turbulent Swirling LPG/Air Flame Impinging on a Flat Surface“. In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22366.

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An experimental study has been conducted to determine the heat transfer characteristics for low Reynolds number turbulent swirling LPG/Air flames impinging on a flat surface. Effect of variation of Reynolds number (3000–7000), dimensionless separation distance (H/d = 1 to 6) and equivalence ratio (φ = 0.8 to 2) on heat transfer characteristics has been determined at constant swirl number of 4. Further, experiments were also conducted to investigate the effect of swirl number on heat transfer characteristics at Re = 7000, φ = 1.0 and H/d = 5. It has been concluded that the major drawback of flame impingement i.e., non-uniformity in the heating can be resolved by using swirling flames in place of non-swirling flames. With increase in Reynolds number the flame becomes longer and broader. Also, at higher Re the flame becomes noisy and violent because of the enhanced turbulences in the flame. A dip in the temperature was observed at the stagnation point at all Re and this dip was more significant at higher Re. At small separation distances (H/d = 1 and 2) and at large Reynolds numbers (Re = 7000) heating is comparatively more non-uniform because of close proximity of the visible reaction zone to the plate resulting in intense heating in the stagnation region. High average heat fluxes were obtained at low separation distances and at larger Reynolds numbers.

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Ahmed, Ikram, und Ildar Sabirov. „Inverse Calculation of Flame Impingement Heat Transfer“. In 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/fedsm2006-98450.

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Inverse calculations are presented here for the estimation of heat transfer from an impinging flame on a flat surface. This work is a preliminary exercise for estimating heat transfer from an impinging plasma jet, where direct measurements can be very difficult and costly, and the correlations based on air or water jet impingement measurements may not be applicable because of the very high temperature (and property) gradients. As the gas flame impinges on an initially cold flat plate, the temperature evolution on the backside is recorded using an infrared camera. The time–temperature data thus obtained are then compared with those predicted by a finite volume method based code. The code uses a polynomial series for estimating the convection coefficient, which varies with radial distance. The coefficients of this polynomial are treated as a set of parameters to be estimated through the Levenberg-Marquardt approach. The results obtained so far indicate that it may be possible to use such an approach for estimating heat transfer from a plasma jet.

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Fan, Luming, Bruno Savard, Benoît Fond, Antoine Durocher, Jeffrey Bergthorson, Spencer Carlyle und Patrizio Vena. „Mechanisms Leading to Stabilization and Incomplete Combustion in Lean CH4/H2 Swirling Wall-Impinging Flames“. In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-104140.

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Abstract In gas turbines, confined highly turbulent flames unavoidably propagate in the vicinity of a relatively cool combustor liner, affecting both the local flame structure and global operation of the combustion system. In our recent work, we demonstrated, using simultaneous [OH] × [CH2O] PLIF and stereo-PIV, that lean CH4/H2 flames at a high Karlovitz number can present a highly broken structure near wall, highlighted by a diffuse CH2O cloud which suggests local quenching and incomplete oxidation. Such high Karlovitz numbers were achieved using an inclined plate, which substantially extended the lean flammability of the low swirl flames. Yet, how a cooled wall acting as a heat sink played a conducive role in stabilizing high Ka flames remains unanswered. In addition, the origin of the CH2O cloud is also unclear. Hence, in this work, we look to better understand the stabilization mechanisms for lean and ultra-lean flames on the same configuration, and how they may change with a parametric variation of plate incident angle, plate-nozzle distance, and bulk velocity up to the critical values that lead to flame blow off. The results show that the impinging swirling flow creates a low speed region that helps hold the flame, while the wall prevents mixing with ambient cold air. The production of diffuse CH2O, which indicates the occurrence of local quenching, is associated with a mean strain rate K beyond the extinction strain rate Ke. For CH4 flames, most of the reaction zones reside within |K|/Ke < 1; for 70% H2 flames at ϕ = 0.4, the reaction zones are highly broken and scattered in a large area where |K|/Ke < 8, the interspace of which is fully filled by CH2O. In other words, high H2 fraction flames appear to be more robust to persistent strain rate, thus extending their stability envelope. However, these flames can subsist as highly broken flames featuring strong incomplete combustion.

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Huang, X. Q., C. W. Leung und C. K. Chan. „Effect of Swirl Intensity on the Heat Performance of a Premixed Circular Impinging Flame Jet With Swirl Induced“. In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72750.

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Swirl has been successfully introduced to a small scale premixed circular impinging flame jet under low Reynolds number. The study on the flow and heat transfer characteristics of such a swirling impinging flame found that it could provide a more uniform heat flux and flame temperature distribution around the stagnation point. The swirl ratio, which is indicated by swirl angle and axial velocity at the exit of the nozzle is changed to investigate the effect of swirling intensity on the heat performance of the flame jet.

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Gomez-Ramirez, David, Srinath V. Ekkad, Brian Y. Lattimer, Hee-Koo Moon, Yong Kim und Ram Srinivasan. „Separation of Radiative and Convective Wall Heat Fluxes Using Thermal Infrared Measurements Applied to Flame Impingement“. In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52322.

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Flame impingement is critical for the processing and energy industries. The high heat transfer rates obtained with impinging flames are relevant in metal flame cutting, welding, and brazing; in fire research to understand the effects of flames on the structures of buildings; and in the design of high temperature combustion systems. Most of the studies on flame impingement are limited to surfaces perpendicular to the flame, and measurements are often performed using heat flux sensors (such as Schmidt-Boelter heat flux transducers) at discrete locations along the target surface. The use of in-situ probes provides high accuracy but heavily limits the spatial resolution of the measurement. Moreover, flame radiation effects are often neglected, due to the small contribution in non-luminous flames, and the entire heat flux to the target is assumed to be due to convection. Depending on the character of the flame and the impingement surface, local radiative heat transfer can be significant, and the contribution of radiation effects has not been fully quantified. This study presents a novel non-intrusive method with high spatial resolution to simultaneously determine the convective and radiative heat fluxes at a wall interacting with a flame or other high temperature environment. Two initial proof of concept experiments were conducted to evaluate the viability of the technique: one consisting of a flame impinging normal to a target and another with a flame parallel to the target surface. Application of the methodology to the former case yielded a stagnation convective heat flux in the order of 106kWm−2 that decreased radially away from the stagnation point. The radiation field for the direct impingement case accounted on average for 4.4% of the overall mean heat flux. The latter experiment exemplified a case with low convective heat fluxes, which was correctly predicted by the measurement. The radiative heat fluxes were consistent between the parallel and perpendicular cases.

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Singh, Gurpreet, und Subhash Chander. „Effect of Swirl Intensity on Heat Transfer Characteristics of Swirling Flame Impinging on a Flat Surface“. In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64178.

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An experimental investigation has been carried out to determine the effect of swirl intensity on heat transfer characteristics of swirling flame impinging on a flat surface. The swirl intensity was varied by using helical vane swirlers having angles of 15°, 30° and 60° (low, medium and high swirl). Qualitative flame structures were studied by taking direct photographs of impinging flames. Experiments were conducted for different helical vane swirlers at different dimensionless separation distances (H/d = 1–6) for fixed value of Reynolds number (Re = 5000) and equivalence ratio (ϕ = 1.0). A dip in heat flux was observed at stagnation point for all levels of swirl. Peak heat flux was observed slightly away from the stagnation point due to centrifugal effect. A comparison of stagnation point heat flux has been done for different swirl intensities and for fixed operating conditions. Most uniform heat flux distribution was obtained corresponds to 30° helical vane swirler (medium swirl) at all separation distances.

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Palies, Paul, Daniel Durox, Thierry Schuller und Se´bastien Candel. „Swirling Flame Instability Analysis Based on the Flame Describing Function Methodology“. In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22294.

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Thermoacoustic instabilities are analyzed by making use of a nonlinear representation of flame dynamics based on the describing function. In this framework, the flame response is determined as a function of frequency and amplitude of perturbations impinging on the combustion region. This methodology is applied to confined swirling flames in a laboratory scale setup (2.5 to 4 kW) comprising an upstream manifold, an injection unit equipped with a swirler (swirl number = 0.55) and a cylindrical flame tube. The flame describing function is experimentally determined and is combined with an acoustic transfer matrix representation of the system to provide growth rates and oscillation frequencies as a function of perturbation amplitude. These data can be used to determine regions of instability, frequency shifts with respect to the acoustic eigenfrequencies and they also yield amplitude levels when self-sustained oscillations of the system have reached a limit cycle. This equilibrium is obtained when the amplitude dependent growth rate equals the damping rate in the system. This requires an independent determination of this last quantity which is here based on measurements of the resonance response curve. Results obtained are compared with observations from systematic experiments carried out by varying the test combustor geometry. The demonstration of the FDF framework in a generic configuration indicates that this can be used in more general situations of technological interest.

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Kreuder, John, Xinfeng Gao und Allan Kirkpatrick. „Computation of Heat Transfer from an Impinging Flame Jet to a Plane Surface“. In 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2013. http://dx.doi.org/10.2514/6.2013-605.

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Berichte der Organisationen zum Thema "Impinging flame"

Kokkala, M. A., und W. J. Rinkinen. Some observations on the shape impinging diffusion flames. Gaithersburg, MD: National Bureau of Standards, 1987. http://dx.doi.org/10.6028/nbs.ir.87-3505.

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