1,720,957 research outputs found
THE EFFECTS OF THE PLANFORM SHAPE ON DRAG POLAR CURVES OF WINGS: FLUID-STRUCTURE INTERACTION ANALYSES RESULTS
No full textThe paper shows preliminary results of aeroelastic analyses of two half-wing models, having curved and swept planform, carried out at the Aerospace Section of the Department of Civil and Industrial Engineering of Pisa University. The curved planform causes a variable angle of sweep along the wing span, so, as demonstrated in previous papers regarding rigid models of wings, in the transonic flight conditions wave drag effects are strongly reduced. The present numerical comparison, between curved and traditional swept wing, includes the effects of structure’s deformability (the wings have the same aspect ratio). The effects of the planform shape on drag polar curves are confirmed (for fixed values of Lift Coefficient (CL) the reduction of Drag Coefficient (CD) reaches 7%-10%). Moreover the curved planform configuration improves the wing’s aeroelastic behavior: in the paper some results obtained by using Star-CCM+® 6.04.14 and Abaqus® 6.11 in “co-simulation” are summarized. As an example, adopting similar wing box metallic structures for the two half-wing models, for a fixed value of CL the reaction moments and stress values at the root of the curved wing are reduced by about 5÷8% with respect the data obtained for the traditional swept wing at the same flight conditions
A comparison of the drag polar curves of wings using the fluid-structure interaction analyses
No full textThe paper shows preliminary results of aeroelastic analyses of two half-wing models, having curved and swept planform, carried out at the Aerospace Unit of the Department of Civil and Industrial Engineering of Pisa University. For a wing with a curved planform, as demonstrated in previous papers regarding rigid models of wings, the wave drag effects are strongly reduced in the transonic flight conditions. In the paper some results obtained by using Star-CCM+® 6.04.14 and Abaqus® 6.11 in “co-simulation” are summarized: for this reason the present numerical comparison, between a curved wing and a swept wing, includes the effects of structure’s deformability (the wings have the same aspect ratio). The beneficial effects of the planform shape on drag polar curves are confirmed (for fixed values of Lift Coefficient (CL) the reduction of Drag Coefficient (CD) reaches 7%-10%). Moreover the curved planform configuration improves the wing’s aeroelastic behavior: as an example, adopting similar wing box metallic structures for the two half-wing models, for a fixed value of CL the reaction moments and stress values at the root of the curved wing are reduced by about 5%÷8% with respect the data obtained for the swept wing at the same flight conditions
Fluid-Structure Interaction Analyses of Wings with Curved Planform: Preliminary Aeroelastic Results
No full textThe paper shows preliminary results of aeroelastic analyses of two half-wing models, having curved and swept planform, carried out at the Aerospace Unit of the Department of Civil and Industrial Engineering of Pisa University. For a wing with a curved planform, as demonstrated in previous papers regarding rigid models of wings, the wave drag effects are strongly reduced in the transonic flight conditions.
In the paper some results obtained by using Star-CCM+® 6.04.14 and Abaqus® 6.11 in “co-simulation” are summarized: for this reason the present numerical comparison, between a curved wing and a swept wing, includes the effects of structure’s deformability (the wings have the same aspect ratio). The beneficial effects of the planform shape on drag polar curves are confirmed.
Moreover the curved planform configuration improves the wing’s aeroelastic behavior: for a fixed value of CL the reaction moments and stress values at the root of the curved wing are reduced by about 5%÷8% with respect the data obtained for the swept wing at the same flight conditions.
Finally, preliminary numerical analyses carried out at high angles of attack show that, as expected, the centers of pressure of the wings move forward with percentage variation of their longitudinal positions that are quite similar. These results indicate that the curved planform shape does not change in a drastic fashion the performances of a wing when the stall condition are reached
CURVED PLANFORM WINGS WITH A HIGH ASPECT RATIO FOR AIRCRAFTS OPERATING IN THE TRANSONIC REGIME
Full text linkThe present invention concerns an innovative
wing (1) specific for an aircraft operating in the
transonic regime and comprising:
- A root section ;
- A tip section and;
- A leading edge for connecting the root section to the tip section.
In accordance with the invention, the curved leading edge is configured according to a line by
which locally the angle (Λ) formed by the forwarding direction of the wing and the perpendicular to the
tangent of the leading edge increases progressively from the root section to the tip section of the wing.
In such a way, the speed component (Vu) of the asymptotic flow orthogonal to the leading edge decreases
progressively from the root section to the tip section, thus reducing the local Mach number progressively
HIGH ASPECT RATIO WING WITH CURVED PLANFORM: CFD AND FE ANALYSES
No full textModern configurations of aircraft deal with a high performance design of lifting systems especially oriented to reduction of weight, aerodynamic drag and fuel consumption. The paper shows preliminary results of aerodynamic and structural analyses of a high aspect ratio wing with curved planform, carried out at the Department of Aerospace Engineering of the University of Pisa. In transonic flight condition (high subsonic), for curved planform wing, the wave drag effects are significantly reduced. A numerical comparison, carried out using the FLUENT® code, between curved and traditional swept wing, both designed with the same supercritical airfoil, shows a drag coefficient reduction of 4% and more for asymptotic Mach numbers greater than 0.85. The B787 aircraft’s wing planform has been assumed as reference geometry to carry out the numerical analyses. The curved planform configuration also improves the aeroelastic behaviour of the wing: some preliminary results obtained using the NASTRAN® code are summarized in the paper
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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