1,720,965 research outputs found
Numerical analysis of swirl number effects on fuel-waste oil in case of mild combustion
No full textThe paper analyses some aspects concerning the mixing, the evaporation and then the combustion of a waste-oil spray in a combustion chamber at different oxidant injection conditions. A CFD commercial code has been used for the simulations, together with some routines ad hoc made by the authors. Results are presented and discussed in form of diagrams of temperature, pressure and concentration distribution along the virtual furnace
Approfondimenti sul bruciatore trapped-vortex. Analisi di sensibilità e scalatura del prototipo
Full text linkNel report in oggetto viene approfondito lo studio sul nuovo bruciatore trapped-vortex alimentato a syngas. È importante infatti valutare sia gli effetti della variazione dei principali parametri operativi, nonché indagare su quali sono gli effetti di scala sul prototipo. Altrettanto interessante è studiarne il comportamento in regime dinamico attraverso una Large Eddy Simulation (LES), allo scopo di verificare la stabilità del vortice intrappolato. Nelle pagine seguenti viene innanzitutto ripreso e descritto il principio di funzionamento del prototipo, passando poi alla vera e propria analisi di sensibilità alle grandezze operative del sistema. Successivamente vengono descritti i diversi criteri di scalabilità e riportati i risultati nel caso di un bruciatore di potenza sia raddoppiata che dimezzata. Vengono infine riportati i risultati dell’analisi LES
About the use of compact schemes approach for the modelling of fuel pulverization phenomenon
No full textIn recent times the studies related to the analysis about industrial combustion processes has known a rapid growth, moreover due to the energy demand for productive activities worldwide. Therefore, to reduce contaminants emissions and to improve the gains in the related processes oriented to the energy production, the sectorial studies on combustion are knowing enormous progress with the auxilium of new survey instruments. Actually the computational fluid dynamics (CFD) is a valuable tool for technical support in carrying out the experimental studies on combustion and related methods of process, in fact even the flame stability issue or the mixing and diffusion questions with reacting flows need to have been submitted by accurate numerical problem solving approach. In this particular case, where the fuel is present in liquid state, according with the point of view to make feasible a combustion process, it needs that the fluid has to be previously reduced in sufficiently little part (droplets) which are able to be easily combined with the air in same mixing ratio to determine ignition conditions. Since in the practice there are effected several operations to increase the contact surface among combustible and combustive gas in order to optimise both the mass exchange process, both energy one among these two phases, these operations are very difficult to realize completely because the fluid is initially in forms compacts due to a resistance of viscous nature. It's well known that this phenomenology is strongly influenced by some disturbs, like the pressure fluctuations, conferred to the liquid jet and conditioned by the local turbulence and the gaseous properties within the flow is injected. The introduced work has focused its effort in the development of an ad hoc adopted numerical procedure to the particular fluid dynamic situation in examination by the recourse to numerical tools with spectral-like characteristics those provide to guarantee the validity of the NS equations and, meanwhile, don't modify the physical-chemical ownership of the mixture
Urban Pollution: Computational approaches for the modelling of pollution transport on local scale
No full textUrban Pollution: Computational approaches for the modelling of pollution transport on local scale
No full textSpecifiche tecniche relative alla realizzazione del bruciatore trapped-vortex ed alle modifiche dell'impianto MICOS
Full text linkNel presente report si riportano le dimensioni geometriche definitive e le specifiche del nuovo bruciatore trapped-vortex alimentato a syngas. Vengono inoltre descritte alcune modifiche da apportare all’impianto MICOS su cui il prototipo verrà testato, per garantire le nuove condizioni operative. Sarà infatti necessario predisporre e regolare in maniera indipendente, due linee per l’aria (primaria + secondaria) ed una per il combustibile. Ciascuna di queste tre linee dovrà dividersi in due parti uguali in modo da alimentare le due serie di fori contrapposte sulle due piastre forate del bruciatore. La temperatura dell’aria deve essere di circa 700K. Sarà pertanto necessario dotare l’impianto di un sistema di preriscaldamento di tutta l’aria addotta, in un range 400-800K, allo scopo di avere un certo margine di manovra. Nella sperimentazione si indagherà, tra le altre cose, sull’effetto prodotto dall’utilizzo di diversi rapporti aria/syngas e sull’effetto delle velocità in ingresso sulla fluidodinamica, sul campo termico e sulle reazioni chimiche. Le piastre forate destra e sinistra, dovranno pertanto essere sostituibili al fine di variare il numero e/o le dimensioni dei fori. Le pareti laterali del combustore saranno realizzate in quarzo in modo da permettere l’accesso ottico, al fine di effettuare misure che prevedono l’uso di apparecchiature laser. L’alimentazione del combustibile sarà effettuata mediante bombole
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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