Relevant bibliographies by topics / Premixer

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Premixer'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Premixer"

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Dutta, P., J. P. Gore, and P. E. Sojka. "Emissions Characteristics of Liquid-Fueled Pilot Stabilized Lean Premixed Flames in a Tubular Premixer-Combustor." Journal of Engineering for Gas Turbines and Power 119, no. 3 (July 1, 1997): 585–90. http://dx.doi.org/10.1115/1.2817024.

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Global emissions of NOx in a liquid-fueled lean-premixed tubular combustor with a tubular premixer operating under atmospheric pressure are studied experimentally. The effects of equivalence ratio, premixer length, residence time, fuel type, and fuel atomization and dispersion characteristics on NOx emissions are studied. Measurements of exhaust species concentrations are used as the primary indicator of the effectiveness of premixing-prevaporization upstream of the combustor. Qualitative levels of prevaporization-premixing are determined from Mie-scattering signals measured at the exit of the premixer. Emission measurements show that the equivalence ratio is the dominant operating parameter, with premixing length and residence time being less significant within the present operating range. Ultra low NOx operation (<10 ppmv @ 15 percent 02) is feasible for equivalence ratios less than 0.5. More significantly, small drops persist beyond the premixer even for very long premixers, and Mie-scattering measurements show considerable spatial inhomogeneity, while allowing ultralow NOx operation. One-dimensional evaporation calculations for single drop trajectories confirm that complete evaporation for typical drop size distributions is not possible with reasonable premixer lengths under atmospheric pressure. Fuel dispersion is found to be the most critical parameter for high combustion efficiency, and adverse effects of poor fuel dispersion cannot be overcome by using longer premixers.
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Mansour, Adel, and Michael A. Benjamin. "Emissions Performance of the Parker Macrolaminate Premixer Tested Under Simulated Engine Conditions." Journal of Engineering for Gas Turbines and Power 126, no. 3 (July 1, 2004): 465–71. http://dx.doi.org/10.1115/1.1762907.

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Single-injector high-pressure rig evaluation of the prototype Parker macrolaminate dual fuel premixer (previously tested at NETL, Mansour et al., 2001) with pressure swirl macrolaminate atomizers was conducted under simulated engine operating conditions running on No. 2 diesel fuel (DF2). Emissions, oscillations and lean blowout (LBO) performance on liquid fuel at high, part and no load operating points (pressures of 160, 100, 120 psig, and inlet temperatures of 690, 570, 590°F, respectively) and various pressure drops (ΔP/P) and air fuel ratio conditions were investigated. The results indicate that the Parker premixer design has the potential to reduce the DF2 NOX emission to below 15 ppmv, 15% O2. At simulated high load conditions with a nominal flame temperature TPZ of 2700°F, the NOX and CO emissions are approximately 10 and 2.5 ppmv at 15% O2, respectively. These NOX results have not been corrected for fuel bound nitrogen (FBN). From the studies of Lee (2000), small amounts of FBN in the liquid fuel generally are completely converted over to fuel NOX under lean premixed conditions. The fuel tested has a nominal 60 ppmw of FBN which converts to an estimated fuel NOX of 4 ppmv at 15% O2. These results compare extremely favorable to existing commercially available premixer technologies tested under similar rig operating conditions. More importantly, the NOX yield for the Parker Macrolaminate premixer appears to be independent of operating conditions (from high to no load and various pressure drop conditions). Variations in combustor pressure, inlet temperature T2 and residence time (τ) or pressure drop (ΔP/P) does not seem to have an effect on the formation of NOX. According to Leonard and Stegmaier (1993), insensitivity of NOX formation to operating conditions is a good indication of high degree of premixing. Additionally, the premixer NOX data is only 1 to 2 ppmv higher than the jet stirred reactor (JSR) results (ran at T2=661°F,PCD=1 atm and TPZ=2762°F with similar DF2) of Lee et al. (2001) further confirming the quality of premixing achieved. Combustion driven oscillations was not investigated by tuning the rig so that oscillations would not be a factor.
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Steele, Robert C., Luke H. Cowell, Steven M. Cannon, and Clifford E. Smith. "Passive Control of Combustion Instability in Lean Premixed Combustors." Journal of Engineering for Gas Turbines and Power 122, no. 3 (May 15, 2000): 412–19. http://dx.doi.org/10.1115/1.1287166.

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A Solar fuel injector that provides lean premixed combustion conditions has been studied in a combined experimental and numerical investigation. Lean premixed conditions can be accompanied by excessive combustion driven pressure oscillations which must be eliminated before the release of a final combustor design. In order to eliminate the pressure oscillations the location of fuel injection was parametrically evaluated to determine a stable configuration. It was observed that small axial changes in the position of the fuel spokes within the premix duct of the fuel injector had a significant positive effect on decoupling the excitation of the natural acoustic modes of the combustion system. In order to further understand the phenomenon, a time-accurate 2D CFD analysis was performed. 2D analysis was first calibrated using 3D steady-state CFD computations of the premixer in order to model the radial distribution of velocities in the premixer caused by non-uniform inlet conditions and swirling flow. 2D time-accurate calculations were then performed on the baseline configuration. The calculations captured the coupling of heat release with the combustor acoustics, which resulted in excessive pressure oscillations. When the axial location of the fuel injection was moved, the CFD analysis accurately captured the fuel time lag to the flame-front, and qualitatively matched the experimental findings. [S0742-4795(00)01103-0]
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Frey, S. F., A. R. Eaton, D. M. Cusano, M. W. Plesniak, and P. E. Sojka. "Effect of Inlet Turbulence and Premixer Length on Fuel Distribution in Swirling Gas-Turbine Premixer." Journal of Propulsion and Power 16, no. 5 (September 2000): 837–44. http://dx.doi.org/10.2514/2.5649.

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Mansour, A., M. Benjamin, D. L. Straub, and G. A. Richards. "Application of Macrolamination Technology to Lean, Premixed Combustion." Journal of Engineering for Gas Turbines and Power 123, no. 4 (October 1, 2000): 796–802. http://dx.doi.org/10.1115/1.1378296.

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Macrolamination, a novel manufacturing technique, is used to develop a dual-fuel premixer. A spatially distributed injection strategy is used to enhance fuel placement, distribution, and mixing inside the premixer. Parametric studies are conducted with different configurations of the premixer to determine the effects of residence time and nozzle configuration on pollutant emissions and flame stability. Diesel fuel (DF-2) and natural gas are used as fuels. Tests are conducted at a pressure of 400 kPa (5 atmospheres), and an inlet air temperature of 533 K. The pollutant emissions and RMS pressure levels are presented for a relatively wide range of nozzle velocities (50–80 m/s) and equivalence ratios (0.54–0.75). These results indicate very good pollutant emissions for a prototype design. These results also indicate that the time-lag model, previously associated with combustion oscillations for gaseous-fuel applications, also applies to liquid-fuel operation.
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Jackson, M. D., and A. K. Agrawal. "Active Control of Combustion for Optimal Performance." Journal of Engineering for Gas Turbines and Power 121, no. 3 (July 1, 1999): 437–43. http://dx.doi.org/10.1115/1.2818492.

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Combustion-zone stoichiometry and fuel-air premixing were actively controlled to optimize the combustor performance over a range of operating conditions. The objective was to maximize the combustion temperature, while maintaining NOx within a specified limit. The combustion system consisted of a premixer located coaxially near the inlet of a water-cooled shroud. The equivalence ratio was controlled by a variable-speed suction fan located downstream. The split between the premixing air and diffusion air was governed by the distance between the premixer and shroud. The combustor performance was characterized by a cost function evaluated from time-averaged measurements of NOx and oxygen concentrations in products. The cost function was minimized by the downhill simplex algorithm employing closed-loop feedback. Experiments were conducted at different fuel flow rates to demonstrate that the controller optimized the performance without prior knowledge of the combustor behavior.
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Correa, S. M., A. J. Dean, and I. Z. Hu. "Combustion Technology for Low-Emissions Gas-Turbines:Selected Phenomena Beyond NOx." Journal of Energy Resources Technology 118, no. 3 (September 1, 1996): 193–200. http://dx.doi.org/10.1115/1.2793862.

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Since recent reviews cover the issues in NOx formation under gas-turbine canditions, and since regulations essentially dictate use of the premixed mode of combustion for minimum NOx, this review concentrates on phenomena that can arise in premixed combustion. Specifically, 1) the initial unmixedness in a fuel-air premixer has been shown to make overall lean mixtures autoignite sooner than might be expected based on the overall fuel-air ratio, because the richer portions of the mixture lead the process;2) combustion pressure oscillations caused by the interplay between acoustic waves and unsteady heat release in a one-dimensional system can be calculated in good accordance with measured data, and set the stage for multi-dimensional CFD;3) carbon deposition arising from the flow of liquid fuel over metal surfaces such as found in fuel injectors and swirl cups has been described as a function of temperature and of surface composition; and 4) quenching and subsequent emissions of carbon monoxide can be minimized by preservation of a boundary-layer rather than an impingement type of flow over combustor liners.
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Cohen, J. M., J. H. Stufflebeam, and W. Proscia. "The Effect of Fuel/Air Mixing on Actuation Authority in an Active Combustion Instability Control System." Journal of Engineering for Gas Turbines and Power 123, no. 3 (October 1, 2000): 537–42. http://dx.doi.org/10.1115/1.1373399.

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The authority of an active combustion instability control system was improved by increasing the degree of mixing between a modulated gaseous fuel source and the remainder of the premixed reactants in a low-emissions combustor. Nonreacting acetone PLIF measurements were used to assess the mixedness of various fuel injection configurations, in both time-averaged and phase-locked modes. These configurations were also evaluated in combustion tests in which the authority of the actuator and the ability of the control system to attenuate the instability were measured. The results indicated that both control authority and emissions performance are tied directly to the ability to achieve temporal control over the spatially averaged fuel/air ratio leaving the premixer at any point in time while simultaneously maintaining the high spatial uniformity of this mixture. The cold-flow diagnostic techniques were proven to be an effective and low-cost method for screening fuel injection concepts.
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KURANAGA, Atsushi, Riku SATO, Yasuyuki YANO, and Akira KAKAMI. "N2O/DME Bipropellant Thruster with Premixer." TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 19, no. 3 (2021): 442–45. http://dx.doi.org/10.2322/tastj.19.442.

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Koutmos, P., G. Paterakis, E. Dogkas, and Ch Karagiannaki. "The Impact of Variable Inlet Mixture Stratification on Flame Topology and Emissions Performance of a Premixer/Swirl Burner Configuration." Journal of Combustion 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/374089.

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The work presents the assessment of a low emissions premixer/swirl burner configuration utilizing lean stratified fuel preparation. An axisymmetric, single- or double-cavity premixer, formed along one, two, or three concentric disks promotes propane-air premixing and supplies the combustion zone at the afterbody disk recirculation with a radial equivalence ratio gradient. The burner assemblies are operated with a swirl co-flow to study the interaction of the recirculating stratified flame with the surrounding swirl. A number of lean and ultra-lean flames operated either with a plane disk stabilizer or with one or two premixing cavity arrangements were evaluated over a range of inlet mixture conditions. The influence of the variation of the imposed swirl was studied for constant fuel injections. Measurements of turbulent velocities, temperatures, OH* chemiluminescence and gas analysis provided information on the performance of each burner set up. Comparisons with Large Eddy Simulations, performed with an 11-step global chemistry, illustrated the flame front interaction with the vortex formation region under the influence of the variable inlet mixture stratifications. The combined effort contributed to the identification of optimum configurations in terms of fuel consumption and pollutants emissions and to the delineation of important controlling parameters and limiting fuel-air mixing conditions.
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Dissertations / Theses on the topic "Premixer"

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Jansson, Åsa. "En livscykelanalys av en del i livsmedelskedjan." Thesis, Linköping University, Department of Thematic Studies, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2488.

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Framtidens konsumtion och produktion av animalieprodukter måste vara ekologiskt hållbart ur ett globalt och regionalt perspektiv, vilket avser minimal miljöpåverkan och effektivt utnyttjande av naturresurser. Syftet med denna studie är dels att ta fram inventeringsdata för en premix, vilket är en fodertillsatsprodukt, med en omfattning ”från vaggan till färdig produkt”, dels att bedöma om premix utgör en betydande miljöaspekt i förhållande till en persons indirekta årliga konsumtion jämfört med medelsvenskens totala miljöpåverkan. Mot denna bakgrund har en livscykelanalys utförts på en specifik premix för nötkreatur. Bedömningen av miljöpåverkan görs med en metod som baseras på de svenska miljökvalitetsmålen.

Resultatet av den genomförda livscykelanalysen resulterar i inventeringsdata för 1 ton premix. Denna typ av uppgifter kan användas som indata i andra livscykelanalyser. Vidare visar den genomförda LCA att den nuvarande konsumtionen av premixen inte är en betydande miljöaspekt i förhållande till den miljöpåverkan som en individ ger upphov till. Den tillämpade normaliseringsmetoden som baseras på de nationella miljökvalitetsmålen i kombination med en individs årliga orsakade miljöpåverkan gör att denna typ av analyser kan användas för att bedöma om vi har en ekologisk hållbar livsstil. Den största delen av premixens miljöpåverkan utgörs av råvaruframställning och transporter som bidrar till klimatförändring, försurning och eutrofiering men även bildandet av marknära ozon. Det är framförallt användningen av fossila resurser som utgör denna miljöpåverkan. Slutsatsen av studien är att foderindustrin som är en del i livsmedelsektorn, kan minska sin miljöpåverkan genom att främst minska användningen av fossila resurser genom livscykelkedjan. Användningen av fossila bränslen kommer främst ifrån transporter och råvaruframställning.

Livscykelanalyser är ett verktyg som kan hjälpa företag och branscher att identifiera betydande miljöaspekter i livscykelkedjan. Genom att i livscykelanalysen använda en bedömningsmetod som baseras på de nationella miljökvalitetsmålen kan miljömålsarbetet utvärderas och nya mål upprättas. Livscykelanalyser är därmed ett verktyg som kan komma att utgöra ett viktigt verktyg i arbetet att uppnå en ekologiskt hållbar utveckling.

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Gu, Xin. "Numerical Simulation of Conventional Fuels and Biofuels Dispersion and Vaporization Process in Co-flow and Cross-flow Premixers." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5232.

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In order to follow increasingly strict regulation of pollutant emissions, a new concept of Lean Premixed pre-vaporized (LPP) combustion has been proposed for turbines. In LPP combustion, controlled atomization, dispersion and vaporization of different types of liquid fuel in the pre-mixer are the key factors required to stabilize the combustion process and improve the efficiency. A numerical study is conducted for the fundamental understanding of the liquid fuel dispersion and vaporization process in pre-mixers using both cross-flow and co-flow injection methods. First, the vaporization model is validated by comparing the numerical data to existing experiments of single droplet vaporization under both low and high convective air temperatures. Next, the dispersion and vaporization process for biofuels and conventional fuels injected transversely into a typical simplified version of rectangular pre-mixer are simulated and results are analyzed with respect to vaporization performance, degree of mixedness and homogeneity. Finally, collision model has been incorporated to predict more realistic vaporization performance. Four fuels, Ethanol, Rapeseed Methyl Esters (RME), gasoline and jet-A have been investigated. For mono-disperse spray with no collision model, the droplet diameter reduction and surface temperature rise were found to be strongly dependent on the fuel properties. The diameter histogram near the pre-mixer exit showed a wide droplet diameter distribution for all the fuels. In general, pre-heating of the fuels before injection improved the vaporization performance. An improvement in the drag model with Stefan flow correction showed that a low speed injection and high cone angle improved performance. All fuels achieved complete vaporization under a spray cone angle of 140°. In general, it was found that cross-flow injection achieved better vaporization performance than co-flow injection. A correlation is derived for jet-A's total vaporization performance as a function of non-dimensional inlet air temperature and fuel/air momentum flux ratio. This is achieved by curve-fitting the simulated results for a broad range of inlet air temperatures and fuel/air momentum flux ratios. The collision model, based on no-time-counter method (NTC) proposed by Schmidt and Rutland, was implemented to replace O'Rourke's collision algorithm to improve the results such that the unphysical numerical artifact in a Cartesian grid was removed and the results were found to be grid-independent. The dispersion and vaporization processes for liquid fuel sprays were simulated in a cylindrical pre-mixer using co-flow injection method. Results for jet-A and Rapeseed Methyl Esters (RME) showed acceptable grid independence. At relatively low spray cone angle and injection velocity, it was found that the collision effect on the average droplet size and the vaporization performance were very high due to relatively high coalescence rate induced by droplet collisions. It was also found that the vaporization performance and the level of homogeneity of fuel-air mixture could be significantly improved when the dispersion level is high, which can be achieved by increasing the spray cone angle and injection velocity. In order to compare the performance between co-flow and cross-flow injection methods, the fuels were injected at an angle of 40° with respect to the stream wise direction to avoid impacting on the wall. The cross-flow injection achieved similar vaporization performance as co-flow because a higher coalescence rate induced by droplet collisions cancelled off its higher heat transfer efficiency between two phases for cross-flow injections.
ID: 031001450; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Ranganathan Kumar.; Title from PDF title page (viewed July 2, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 148-157).
Ph.D.
Doctorate
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering
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Svatý, Lukáš. "HDR video "plugin" pro Adobe Premier." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2015. http://www.nusl.cz/ntk/nusl-264960.

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Cílem práce je vytvoření podpory pro editovaní videa v HDR formátu. Pro editaci videa je zvolen program Adobe Premiere Pro a na dosažení požadovaného výsledku je vytvořen plugin do zmiňovaného softwaru, který poskytuje požadovanou funkcionalitu. V práci jsou vysvětleny principy vytváření, zobrazení a ukládáni obsahu z rozšíreným dynamickým rozsahem. Zároveň jsou vysvětleny principy vytváření pluginů pro Adobe Premiere Pro za pomoci SDK verze CS6. V praktické části této práce jsou vysvětleny detaily implementace, problémy, které byly řešené, a popis samotného pluginu. Návrh pluginů je vytvořen tak, aby byla možná další práce na tomto softwaru, přidaní další funkcionality a pro umožnění využití tohoto díla na rozvoji obsahu s rozšíreným dynamickým rozsahem.
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Igrényi, Réka. "Controlling." Master's thesis, Vysoká škola ekonomická v Praze, 2012. http://www.nusl.cz/ntk/nusl-165549.

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The aim of this Master's thesis was to characterize the current cost ratio, pricing system and profitability of an agricultural firm, called P.G.TRADE, spol s r.o.. This company is engaged in the production and sale of compound feeds and premixes, resp. in storing different kinds of agricultural commodities. My specific aim was to determine whether the current pricing system and prices cover all the costs which incurred because of the processes of production and sale of finished products and that in doing so provides a satisfactory level of profitability, too. In the first, methodological part, I summarized all the necessary theoretical knowledge that we need to know about controlling. I paid particularly big attention to calculations and budgeting. In the application part I focused on the characteristics of the company itself and on the analysis of the costs and of the pricing system. In the next part I described in details the manufacturing processes of compound feeds and premixes in the company's main factory in Dvory nad Žitavou. The last part is devoted to the calculation of production costs and identifying weaknesses. In addition to the description of the conclusions I tried to propose some measures that could help in improving the company's profitability.
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BREVET, BARBAUD ANNE LAURE. "Le sujet et ses reflets dans l'oeuvre romanesque de doris lessing." Paris 3, 1998. http://www.theses.fr/1998PA030074.

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Dans les romans de dons lessing, il existe une quete de l'unite subjective visant a la formation de l'individu, a travers une ecriture dont l'objet est de rassembler les fragment multiples et contradictoires de l'experience vecue et de l'histoire. Dans les roman autobiographiques, la narration dite + a la troisieme personne ; est toujours sous-tendue par un + je ;, ce qui a pour effet de transmuer la representation traditionnellement realiste en un discours bivocal, renvoyant de maniere indirecte a une image plausible du sujet de l'ecriture aussi le systeme de reflets dans le texte lessinien s'organise-t-il autour du sujet fictif intratextuel, refletant et reflecteur, dont l'identite individuelle s'avere a la fois transcendee e constituee par l'experience d'un espace speculaire inconscient. Tandis que le recit tend a figurer l'avenement d'une identite, qui, en derniere instance, ressortit a l'ipseite du texte, les dispositifs scripturaux, rythmes ou motifs, refletent les origines subjectives du processus de creation litteraire. L'ecriture speculaire offre une narration complexe, fragmentee en recits reflexifs, enchassants ou enchasses. Le roman lessinien, par sa visee memorialiste, aboutit a une combinatoire evenementielle fondee sur la reprise, la redondance, voire le ressassement, tout en convoquant une multiplicite dialogique de recits. L'evenement vecu ainsi repris, rememore. Interprete et ecrit passe necessairement par le filtre analytique de la litterature, ou il se voit reflechi au miroir de la conscience ecrivante
Throughout her novels, doris lessing is seeking to build the subjective oneness of individual self, using her art to reassemble the multiple, often contradictory facets of personal life in its relations with collective history. The narrative handling of this issue, particularly in lessing's autobiographical novels, presents itself as a 'third-person', omniscient 'voice', which nonetheless indirectly conveys the utterance of a tirst-person' self. As a result, traditional representation is reshaped into bivocal discourse, diffusely reflecting a plausible mirror-image of the writer at work. Hence the narrative patterns of reflection appear to be connected to the main character at the core of lessing's fiction, whose role as a fictitious, intradiegetic self is to diffract and focalize a personal image of reality. Besides, selfhood reveals itself as being transcended as well as built up when confronted to the inner mirror of the unconscious. Apart from attempting to state the birth of an individuality - which is eventually relevant to the singular qualities of lessing's novels themselves -, textual devices such as the arrangement of stylistic rhythms and patterns allude to the subjective origins of the writing process. In this respect, metafictional writing provides the reader with the complexities of discontinuous narration, for its 'reflexive' / 'self-conscious' pieces can be regarded, according to their textual location, either a'embedding' or 'embedded'. Since doris lessing's novels also aim at recording the spirit of the times, her fiction leads up to combine re-used material and to ground the action in repetition, indeed redundancy, while creating a variety of dialogic, self-contained stories. Thus reconsidered, remembered and necessarily interpreted, written events are filtered through the prism literature, where they come to be mirrored by the
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Vincent-Munnia, Nathalie. "Les premiers poèmes en prose : généalogie d'un genre dans la première moitié du dix-neuvième siècle français." Lyon 2, 1994. http://www.theses.fr/1994LYO20006.

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L'expression "poème en prose" ne naît pas au 19e siècle : tout au long du 18e siècle, elle sert à caractériser une prose qui peut acquérir un statut poètique, parallèlement au vers, lequel ne détermine plus dès lors systématiquement ni exclusivement l'existence de la poésie. Mais, dans les premières décennies du 19e, la reconnaissance de cette poésie en prose étant plus définitive, la prose peut s'élaborer plus spécifiquement en poème (au sens moderne du terme, non plus au sens classique et analogique d'"ouvrage de style poétique" ou d'"épopée en prose"). Elle suscite alors un nouveau type de poeticité, abandonnant les normes prédéfinies, qui rendent impossible toute définition systématique et modélisante du genre. Ce type de poétique inédit ne trouve son actualisation que dans l'activité de reconnaissance du lecteur. Le poème en prose est par conséquent dépendant de sa réception -problématique au début du 19e. Les auteurs de ces premiers poèmes en prose (L. De Cailleux, A. Rabbe, A. Bertrand, X. Forneret, M. De Guérin, J. Lefebre-Deumier) font en outre de ce nouvel instrument poétique le moyen en même temps que l'objet d'une quête poétique d'un nouvel ordre. Le poème en prose acquiert ainsi une valeur exploratoire et expérimentale. Initiateur de nouveaux types de poéticité, il élabore aussi des processus de réflexivité poétique (de réflexion du poétique par lui-même et sur lui-même), qui détermineront les évolutions ultérieures de la poésie
The expression "prose poem" does not appear in the nineteenth century : throughout the eighteenth century, it is used to distinguish a prose which can pretend to a poetical status, in the same way as verse (that from then on neither systemat ically nor exclusively determines the existence of poetry). But, during the first decades of the nineteenth century, after the more definitive recognition of this prose poetry, the prose can be elaborated more specifically as a poem (in the modern use of the term, and no longer in the classical and analogical sense of "work in poetic style" or "prose epic"). It creates then a new type of poeticity, abandoning the predefined norms and thus benefiting from non predetermined poetic effects which make any systematic and modelising definition of the genre impossible. This kind of original poetic owes its actualization uniquely to the recognition activity of its reader. The prose poem is consequently dependent on its receipt - problematical at the beginning of the nineteenth century. Furthermore, the authors of these first prose poems (ludovic de cailleux, alphonse rabbe, aloysius bertrand, xavier forneret, maurice de guerin and jules lefevre-deumier) not only make this new poetics instrument the object but also the means of a new order poetical quest. The prose poem thus acquires an exploratory and experimental value. Initiator of new types of poeticity, it also elaborates some processes of poetical reflection (by itself and upon itsel), which will determine the subsequent evolutions of poetry. Open and uncertain, the genre therefore also appears as eminently virtual and paradoxical : its generic identity being built upon its capacity to inaugurate new modes of poeticity and genericity, it is doomed to see this generic specificity dissolve at the very moment that it accedes to an entire recognition
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Arpin, Jonatan. "Utilisation d'une approche historico-culturelle dans le matériel didactique de la première année du premier cycle du secondaire en mathématiques." Thèse, Université du Québec à Trois-Rivières, 2009. http://depot-e.uqtr.ca/2009/1/030105450.pdf.

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Porumbel, Ionut. "Large Eddy Simulation of premixed and partially premixed combustion." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14050.

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Large Eddy Simulation (LES) of bluff body stabilized premixed and partially premixed combustion close to the flammability limit is carried out in this thesis. The LES algorithm has no ad-hoc adjustable model parameters and is able to respond automatically to variations in the inflow conditions. Algorithm validation is achieved by comparison with reactive and non-reactive experimental data. In the reactive flow, two scalar closure models, Eddy Break-Up (EBULES) and Linear Eddy Mixing (LEMLES), are used and compared. Over important regions, the flame lies in the Broken Reaction Zone regime. Here, the EBU model assumptions fail. The flame thickness predicted by LEMLES is smaller and the flame is faster to respond to turbulent fluctuations, resulting in a more significant wrinkling of the flame surface. As a result, LEMLES captures better the subtle effects of the flame-turbulence interaction. Three premixed (equivalence ratio = 0.6, 0.65, and 0.75) cases are simulated. For the leaner case, the flame temperature is lower, the heat release is reduced and vorticity is stronger. As a result, the flame in this case is found to be unstable. In the rich case, the flame temperature is higher, and the spreading rate of the wake is increased due to the higher amount of heat release Partially premixed combustion is simulated for cases where the transverse profile of the inflow equivalence ratio is variable. The simulations show that for mixtures leaner in the core the vortical pattern tends towards anti-symmetry and the heat release decreases, resulting also in instability of the flame. For mixtures richer in the core, the flame displays sinusoidal flapping resulting in larger wake spreading. More accurate predictions of flame stability will require the use of detailed chemistry, raising the computational cost of the simulation. To address this issue, a novel algorithm for training Artificial Neural Networks (ANN) for prediction of the chemical source terms has been implemented and tested. Compared to earlier methods, the main advantages of the ANN method are in CPU time and disk space and memory reduction.
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Porumbel, Ionuţ. "Large Eddy Simulation of premixed and partially premixed combustion." Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-11042006-042840/.

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Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2007.
Yeung, Pui-Kuen, Committee Member ; Lieuwen, Tim, Committee Member ; Menon, Suresh, Committee Chair ; Seitzman, Jerry, Committee Member ; Syed, Saadat, Committee Member.
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Staufer, Max. "Large eddy simulation of premixed and partially premixed flames." Düsseldorf VDI-Verl, 2009. http://d-nb.info/995738297/04.

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Books on the topic "Premixer"

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Mendès France, Michel (1936-....). Auteur, ed. Les nombres premiers: Entre l'ordre et le chaos. Paris: Dunod, 2011.

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Bril, Blandine. Materner: Du premier cri aux premiers pas. Paris: Odile Jacob, 2008.

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Lamarche, Jacques. Chauveau, le premier des 26 premiers ministres du Québec. Montréal: Lidec, 1997.

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Azimi, Vida. Les premiers sénateurs français: Consulat et Premier Empire, 1800-1814. Paris: Picard, 2000.

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Poisson, Yves. La naissance des Etats-Unis d'Amérique: Des premiers colons au premier président. Montréal, Québec, Canada: Editions du Fleuve, 1990.

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Vinter, Shirley. L 'emergence du langage de l'enfant: Des premires sons aux premiers mots. Paris: Masson, 1994.

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Kaurin, Lazar. Premijer: Roman. Novi Sad: Prometej, 1994.

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Waldherr, Gregor Arthur. Measurement of correlations involving pressure in a turbulent premixed flame. Atlanta, Ga: Georgia Institute of Technology, 1990.

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Célébrités: Les 20 premiers ministre du Canada. Montréal: LIDEC inc., 1998.

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Premier mal. [Quebec?]: Éditions de Mortagne, 2008.

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Book chapters on the topic "Premixer"

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Kim, W. W., and S. Menon. "Numerical Modeling of Fuel/Air Mixing in a Dry Low-Emission Premixer." In Recent Advances in DNS and LES, 257–68. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4513-8_22.

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McAllister, Sara, Jyh-Yuan Chen, and A. Carlos Fernandez-Pello. "Premixed Flames." In Fundamentals of Combustion Processes, 111–37. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-7943-8_6.

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Date, Anil Waman. "Premixed Flames." In Analytic Combustion, 195–233. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-1853-9_8.

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Bährle-Rapp, Marina. "premier (-ière)." In Springer Lexikon Kosmetik und Körperpflege, 452. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_8485.

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Weil, André. "Premiers voyages, premiers écrits." In Vita Mathematica, 45–61. Cham: Springer International Publishing, 1991. http://dx.doi.org/10.1007/978-3-319-55522-5_3.

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Boeke, Willem, and Paul Le Brun. "Premises." In Practical Pharmaceutics, 585–608. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15814-3_27.

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Gil, Ziv. "Premises." In The Healthcare Efficiency Revolution, 1–31. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-61232-0_1.

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Scher-Zembitska, Lydia. "Chapitre premier. Les premiers contacts." In L’aigle et le phénix, 31–46. CNRS Éditions, 2001. http://dx.doi.org/10.4000/books.editionscnrs.34607.

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Chauvier, Éric. "Première séquence : premiers signes troublants." In Fiction familiale, 50. Presses Universitaires de Bordeaux, 2003. http://dx.doi.org/10.4000/books.pub.31033.

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Bourel, Dominique. "Chapitre premier. Les premiers pas de Kant en France." In La réception de la philosophie allemande en France aux XIXe et XXe siècles, 11–26. Presses universitaires du Septentrion, 1994. http://dx.doi.org/10.4000/books.septentrion.73343.

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Conference papers on the topic "Premixer"

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Sullivan-Lewis, Elliot, and Vincent McDonell. "Predicting Flameholding for Hydrogen and Natural Gas Flames at Gas Turbine Premixer Conditions." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43627.

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Lean premixed gas turbines are one of the most common methods for stationary power generation. By creating a homogeneous mixture of fuel and air upstream of the combustion chamber, temperature variations are reduced within the combustor, which reduces emissions of nitrogen oxides. However, by premixing fuel and air, a potentially flammable mixture is established in a part of the engine not designed to contain a flame. If the flame propagates upstream from the combustor (flashback), significant engine damage can result. While significant effort has been put into developing flashback resistant combustors, these combustors are only capable of preventing flashback during steady operation of the engine. Transient events (e.g. auto ignition within the premixer, pressure spikes during ignition) can trigger flashback that cannot be prevented with even the best combustor design. In these cases, preventing engine damage requires designing premixers that will not allow a flame to be sustained. Experimental studies were conducted to determine under what conditions premixed flames of hydrogen and natural gas can be anchored in a simulated gas turbine premixer. Tests have been conducted at pressures up to 9 atm, temperatures up to 750 K, and free stream velocities between 20 and 100 m/s. Flames were anchored in the wakes of features typical of premixer passageways, including cylinders, steps and airfoils. The results of this study have been used to develop tools that predict when a flame remains anchored to a particular feature.
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Barnes, J. C., and A. M. Mellor. "Quantifying Unmixedness in Lean Premixed Combustors Operating at High Pressure, Fired Conditions." In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-073.

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Lean premixed combustor manufacturers require premixer concepts that provide homogeneity (mixedness) of the fuel which burns in the main flame. Ideally premixer evaluation would be conducted under realistic combustor operating conditions. However, current techniques typically are limited to cold—flow, low pressure (<14 atm) conditions or comparison of measured NOx emissions with others obtained in premixed systems. Thus, a simple, consistent method for quantifying unmixedness in lean premixed combustors operating at high pressure, fired operating conditions is proposed here, using the characteristic time model developed in the companion paper.
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Koyama, Masamichi, Hiroshi Fujiwara, Laurent Zimmer, and Shigeru Tachibana. "Effects of Swirl Combination and Mixing Tube Geometry on Combustion Instabilities in a Premixed Combustor." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90891.

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In this paper, flow fields inside a premixed combustor have been investigated by CFD analysis and PIV measurement in a preheating, non-reacting condition. Four types of premixer are examined. The design of the premixer is determined by the combination of swirlers and mixing tubes. There are two variations of triple-concentric swirlers and three variations of mixing tubes. Comparisons are made among mean velocity distributions derived from CFD and PIV. PDF analysis is performed on the data from PIV to discuss the possibility of the occurrence of flashback. Combustion rig tests have been carried out also on similar condition to see combustion instabilities depending on the choice of premixers and operating conditions. Flame is directly observed from crystal windows placed on the side and downstream of the combustion chamber. A glass rod is installed on the wall of the mixing tube so as to see light emissions inside the tube, i.e. evidence of flashback. Pressure fluctuations at the combustor liner are measured in one position. The spectra of pressure fluctuations are computed to look at the possibility of combustion oscillations. Discussions are made on the relation between the global flame structure and pressure modes. Finally, proper premixer configurations to prevent combustion instabilities are proposed.
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Yu, Zongming, Xinnan Wu, Feifan Wu, Yue Wang, Wenjun Kong, Yongzhi Feng, and Hui Wang. "Numerical Analysis of the Conceptual Design of Arrayed-Vanes Premixer for Gas Turbine Combustors Burning High-Hydrogen Fuels." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94952.

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Using high-hydrogen fuels in industrial gas turbines is an effective way to achieve near-zero carbon emission power generation. Lean premixed combustion can effectively reduce NOx emission. However, due to the strong flashback and auto-ignition tendencies during fuel-air mixing, it is a challenge to use lean premix combustion mode of high hydrogen fuels under gas turbine operation conditions. An innovative conceptual design of arrayed-vanes premixer was proposed to achieve safe and uniform mixing of fuel and air. Inside the arrayed-vanes premixer, a cascade of mixing vanes is arranged in the axial annular air flow passage. Fuel-air mixing and flow field stretch are improved and well controlled by the arrayed vanes. The conditions of auto-ignition and flame stabilization inside the vanes are unsatisfied. Meanwhile the upstream flow disturbance will be inhibited by the arrayed vanes, which benefits combustion stability. The arrayed-vanes premixer was designed and its flow field was numerically simulated under the operation condition of F class gas turbine combustors. The flow and fuel-air mixing behavior was analyzed and compared with a typical swirl-based premixer now widely used in DLN combustors of F class gas turbines. The results show that the non-uniformity index of fuel concentration distribution at the exit plane of the arrayed-vanes premixer is 50% lower than that of the swirl-based premixer. The responses of flow field at the exit plane to the inlet flow disturbance was calculated and compared for the two types of permixer. The inlet flow disturbance includes the velocity distortion and the oscillation of the pressure. The results show that the arrayed-vanes premixer absorbs and damps the inlet flow disturbance better than the swirl-based premixer. And it exhibits highly monochromatic characteristic through the acoustic signature analysis. Furthermore, the tendencies of auto-ignition and flashback were investigated by examining the flow field and the flammability of hydrogen. The results show that there is a low risk of auto-ignition or flashback due to the short residence time and the high discharge velocity. The present study indicates that the arrayed-vanes premixer achieves ultra uniform fuel-air mixing, good adaptability to inlet flow disturbance and anti auto-ignition and flash back, which is benefit to DLN combustor designed for high-hydrogen fuels. This design will be possibly used in DLN combustors after future developments.
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Lin, Yuzhen, Yunhui Peng, and Gaoen Liu. "Investigation on NOx of a Low Emission Combustor Design With Multihole Premixer-Prevaporizer." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53203.

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A low NOx emission combustor design was presented in this paper. The design features the premixer-prevaporizer tube with multihole and two stages arranged radially in line, with the outer stage being pilot stage and inner stage being main stage. The multihole premixer and prevaporizer is a part of main stage. The results of NOx emission were provided and also compared with the baseline design that the premixer and prevaporizer tube without multihole. The double swirler prefilming airblast atomizer was installed in the premixed prevaporized duct entrance. The mean drop size and radial fuel flux distribution were measured to determine proper configurations of the multihole premixer-prevaporizer. NOx emission investigations were carried out using a test combustor with one pilot stage and one main stage under the operating condition of high inlet temperature (800K) and inlet air pressure was atmospheric pressure. The experiment results demonstrated large NOx emissions reduction of the multihole premixer-prevaporizer compared with the baseline design. The more even fuel-air mixing, which was gained by the multiple jets, intensified the fuel and air mixing within the premixer-prevaporizer, resulted in the large reduction of NOx emission. The configurations of multihole premixer-prevaporizer had great influence on NOx emissions reduction.
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Chishty, Wajid A., and Ibrahim Yimer. "Optimizing Mixing for Maximum Damping of Fuel-Air Ratio Oscillations in Gas Turbine Premixers." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50454.

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An analytical model based on advection-diffusion volume is analyzed with the objective to investigate the limits of achievable damping in fuel-air ratio oscillations over the range of frequencies at which combustor thermoacoustic instabilities are normally encountered. Results show that there exists an optimum degree of diffusion that will allow maximum damping in fuel-air ratio fluctuations. The upper bound on damping is found to be dependent on a constant value of a new non-dimensional number, defined as a ratio between Peclet Number and Strouhal Number. The analysis presented here is considered useful to evaluate the extent of damping that is inherently obtainable in practical premixers. Also presented are the results of experimental investigations, which were conducted to verify the analytically predicted behavior of premixers. The measurements were performed over a selected range of frequencies using a premixer configuration with square cross section and with fuel jet issuing in a co-flowing bulk air stream. The effects of modulation amplitude and frequency, and pressure drop across the premixer on the damping effectiveness of the premixer were examined. Results show that for the test conditions considered, the modulation amplitude has a profound effect on the premixer performance, whereas pressure drop effects are insignificant.
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Nazukin, Vladislav A., and Valery G. Avgustinovich. "Development of Requirements for Numerical Modeling of the Premixer Aerodynamic." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57529.

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The premixer is the most important part of DLN/DLE gas turbine combustion chambers because it is responsible for velocity and fuel concentration fields at the flametube inlet. Most currently used premixers were developed using long expensive experimental research efforts. At present, progress in high performance computing allows application of a new approach to the development process utilizing extensive numerical simulation up to the first tests of combustion chamber. However, it is necessary to be sure that the most important processes which take place inside premixers and downstream such as interaction of vane wakes with the main flow, fuel/air mixing, vortex breakdown and vortical structures generation are correctly predicted. In other words, verified methodology of the aerodynamic design of the premixers is required. The present work continues the previously performed analysis of non-reacting swirling flow inside premixers and it is directed towards more accurate determination the effect of different computational model parameters on the results of numerical simulation. In the first phase of this work, results of uncompressible swirling flow measurements were used. The effect of premixer geometry (full or simplified), grid resolution, turbulence model (k-e RNG, SST, SSG RSM, DES, SAS), number of timesteps and initial conditions on time-averaged flow parameters as well as flow structures such as precessing core were assessed. Some interesting features were found as the result of this work. For example, simplification of premixer geometry slightly effects on the results of RANS computations and entirely changes precessing core structure obtained in URANS modeling. In the second phase of this work compressible swirling flow measurements were used to compare the ability of DES and SST turbulence models to predict velocity and velocity fluctuation fields as well as vortical structures in a swirling flow. As the result of this work the main requirements for the computational fluid dynamics analysis of premixer aerodynamic were developed and validated. They specify parameters of computational model depending on the target flow parameters.
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Joshi, Narendra D., Michael J. Epstein, Susan Durlak, Steven Marakovits, and Paul E. Sabla. "Development of a Fuel Air Premixer for Aero-Derivative Dry Low Emissions Combustors." In ASME 1994 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/94-gt-253.

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An experimental program was conducted to develop premixer concepts for use in GE’s aero-derivative Marine and Industrial gas turbine engines such as the LM 1600, 2500 and 6000. These engines operate typically at pressure ratios up to 30:1. Extensive tests in 1 and 2 cup test combustors were carried out to evaluate the Double Annular Counter-Rotating Swirler (DACRS) premixers at test conditions representative of the above mentioned engines. These tests also help establish combustor design parameters. Single digit NOx emissions were measured at engine operating conditions with the DACRS II and III premixers. Premixer interactions and their effects on Lean Blow Out were also studied.
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Versailles, Philippe, Wajid Ali Chishty, and Huu Duc Vo. "Application of Dielectric Barrier Discharge to Improve the Flashback Limit of a Lean Premixed Dump Combustor." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45161.

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In recent years, lean-premixed (LP) combustors have been widely studied due to their potential to reduce NOx emissions in comparison to diffusion type combustors. However, the fact that the fuels and oxidizers are mixed upstream of the combustion zone makes LP type of combustors a candidate for upstream flame propagation (i.e., flashback) in the premixer that is typically not designed to sustain high temperatures. Moreover, there has been a recent demand for fuel-flexible gas turbines that can operate on hydrogen-enriched fuels like Syngas. Combustors originally designed for slower kinetics fuels like natural gas can potentially encounter flashback if operated with faster burning fuels like those containing hydrogen as a constituent. There exists a clear need in fuel-flexible lean-premixed combustors to control flashback that will not only prevent costly component damage but will also enhance the operability margin of engines. A successful attempt has been made to control flashback in an atmospheric LP combustor, burning natural gas-air mixtures, via the application of Dielectric Barrier Discharge (DBD). A low-power DBD actuator was designed, fabricated and integrated into a premixer made out of quartz. The actuator was tuned to produce a low magnitude ionic wind with an intention to modify the velocity profile in the premixer. Flashback conditions were created by decreasing the air flow rate while keeping the fuel flow rate constant. Within this experimental setup, flashback happened in the core flow along the axis of the cylindrical premixer. Results show that the utilization of the DBD delays the occurrence of flashback to higher equivalence ratios. Improvements as high as about 5% of the flashback limit have been obtained without compromising the blowout limit. It is anticipated that this novel application of DBD will lead to future demonstrations of the concept under realistic gas turbine operating conditions.
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Chishty, Wajid A., Joan Boulanger, and Sangsig Yun. "Experimental and Numerical Investigation of Spatial and Temporal Dispersion of Forced Fuel Oscillations." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12595.

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In lean premixed combustors of gas turbine engines, fuel-air mixing is considered vital for controlling pollutant emissions as well as combustion instability. Enhancement in mixing may be obtained by modulating the fuel flow rate. Modulation of fuel flow is also a useful technique to actively control combustion instabilities arising from the pressure oscillations in the combustor and thrust augmenters. Effectiveness of the forced oscillations depends on the level of dispersion present in the system. Knowledge of dispersion levels is also important in determining the degree of mixing and therefore, the effectiveness of a premixer. This paper presents the experimental efforts undertaken to study the spatial and temporal dispersion of fuel flow rate oscillation introduced at the premixer inlet. Effects of oscillation amplitude and frequency are investigated at different bulk flow rates and at various locations in the premixer. Also presented is a review of the in-house numerical work done towards this end, using three computational methods. Results show that the degree of dispersion in fuel flow rate oscillations depends on modulation amplitude and frequency as well as advective velocity of the bulk flow.
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Reports on the topic "Premixer"

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Benjamin P. Lacy, Keith R. McManus, Balachandar Varatharajan, and Biswadip Shome. Premixer Design for High Hydrogen Fuels. Office of Scientific and Technical Information (OSTI), December 2005. http://dx.doi.org/10.2172/889756.

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Lewis, Elliot Sullivan, and Vincent G. McDonell. Development of Criteria for Flameholding Tendencies within Premixer Passages for High Hydrogen Content Fuels. Office of Scientific and Technical Information (OSTI), December 2014. http://dx.doi.org/10.2172/1172979.

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Libby, P. A. Premixed turbulent combustion. Office of Scientific and Technical Information (OSTI), January 1991. http://dx.doi.org/10.2172/6065676.

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Sivashinsky, G. I. Studies in premixed combustion. Office of Scientific and Technical Information (OSTI), January 1992. http://dx.doi.org/10.2172/7305286.

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D. J. Seery. Lean Premixed Combustion/Active Control. US: United Technologies Corp, February 2000. http://dx.doi.org/10.2172/898338.

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Janus, M. C., and G. A. Richards. A model for premixed combustion oscillations. Office of Scientific and Technical Information (OSTI), March 1996. http://dx.doi.org/10.2172/379049.

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Santavicca, Domenic A. Combustion Instabilities in Lean Premixed Combustors. Fort Belvoir, VA: Defense Technical Information Center, July 2001. http://dx.doi.org/10.21236/ada400629.

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Najm, H. N. Confined superadiabatic premixed flame-flow interaction. Office of Scientific and Technical Information (OSTI), December 1995. http://dx.doi.org/10.2172/661463.

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Schefer, Robert W. Evaluation of NASA Lean Premixed Hydrogen Burner. Office of Scientific and Technical Information (OSTI), January 2003. http://dx.doi.org/10.2172/811192.

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Linteris, Gregory T., Marc D. Rumminger, and Valeri Babushok. Premixed carbon monoxide-nitrous oxide-hydrogen flames :. Gaithersburg, MD: National Institute of Standards and Technology, 1999. http://dx.doi.org/10.6028/nist.ir.6374.

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