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Flow characteristics along an active jets equipped contour bump in a supersonic freestream and its potential to be applied on transonic aircraft for drag reduction: an experimental study
No full textControl of flow separation on a contour bump by jets in a Mach 1.9 free-stream: an experimental study
Get PDFFlow separation control over a three-dimensional contour bump using jet in a Mach 1.9 supersonic free-stream has been experimentally investigated using a transonic/supersonic wind tunnel. Jet total pressure in the range of 0–4 bar was blowing at the valley of the contour bump. Schlieren photography, surface oil flow visualisation and particle image velocimetry measurements were employed for flow visualisation and diagnostics. Experimental results show that blowing jet at the valley of the contour bump can hinder the formation and distort the spanwise vortices. The blowing jet can also reduce the extent of flow separation appears downstream of the bump crest. It was observed that this approach of flow control is more effective when high jet total pressure is employed. It is believed that a pressure gradient is generated as a result of the interaction between the flow downstream of the bump crest and the jet induced shock leads to the downwards flow motion around the bump valley
On the computerisation of the trims management system of a garment manufacturing company.
Get PDFby Lo Kin Wing, Andy.Thesis (M.B.A.)--Chinese University of Hong Kong, 1994.Includes bibliographical references (leave 60).ABSTRACT --- p.iiiTABLE OF CONTENT --- p.ivCHAPTERChapter I --- INTRODUCTION --- p.1Chapter II --- RESEARCH OBJECTIVES AND METHODOLOGY --- p.4Chapter III --- IMPORTANCE OF TRIMS MANAGEMENT SYSTEM IN GARMENT MANUFACUTRING --- p.10Chapter IV --- CURRENT TRIMS MANAGEMENT SYSTEM --- p.19Chapter V --- PROPOSED TRIMS MANAGEMENT SYSTEM --- p.32Chapter VI --- COST / BENEFIT ANALYSIS --- p.40APPENDIXPROPOSED DATA FLOW DIAGRAM --- p.44FILE LAYOUT --- p.45BIBlLIOGRAPHY --- p.6
Effectiveness of Flow Separation Control on Contour Bumps under a Mach 1.3 Freestream: An Experimental Study
No full textFlow separation control stragies on contour bump models under a Mach 1.3 freestream has been investigated experimentally in a transonic/supersonic wind tunnel. Surface oil flow visualisaiton, Schlieren photography, and Particle Image Velocimetries (PIV) measurements have been conducted. Flow separation, in both streamwise and spanwise directions, was observed at the valley of the plain contour bump. Usage of passive by-pass jets on contour bump show no effects in reducing the extent of flow separation in both streamwise and spanwise directions. It is observed that both spanwise and streamwise flow separation are reduced by blowing jets from the valley of the contour bump. It is believed that the jets hinder the formation of the spanwise, counter-rotating vortrices and deflect the shear layer to make the flow at the valley becomes more attach to the surface of the bump. Two active jet pressures of 1 bar and 4 bar have been employed in this study. It is observed that a higher jet pressure is more effective in achieving flow separation control in both streamwise and spanwise directions. Further investigations will be conducted to obtain surface pressure profiles on the contour bump models
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Experimental investigation of impinging shock – cavity interactions with upstream transverse jet injection
Get PDFMixing between the injected fuel and high speed free stream air is challenging at supersonic speeds. Placing cavities downstream of injection holes or slots addresses the problem of flame holding and stabilisation, however there are still open questions related to mixing enhancement, uniformity and efficiency. The present study examines experimentally the flow field interactions due to a transverse jet - cavity combination with shock impingement at supersonic speeds using PIV, Schlieren photography, and oil flow surface visualisation. The oblique shock lifts the shear layer over the cavity and combined with the instabilities generated by the transverse jet injection creates a highly complicated flowfield with numerous vortical structures. The interaction between the oblique shock and the jet leads to a relatively uniform velocity distribution within the cavity. The lifting of the shear layer is also believed to reduce the drag created by the cavity
Effects of dual jets distance on mixing characteristics and flow path within a cavity in supersonic crossflow
No full textA rectangular open cavity with upstream dual injectors at a freestream Mach number of 1.9 was investigated experimentally. To evaluate the effect of the distance between the jets, the flow characteristics were investigated using the high-speed schlieren photography, particle image velocimetry, and surface oil flow techniques. The dual jet distances of 18 and 54 mm were used. Unstable flow occurs over the cavity in all cases and is not improved by changing the distance between the dual jets. Although the distance between the dual jets does not influence the flow stability, the flow field varies decidedly depending on the dual jets distance. The enhancement of air mixing depends on the distance between the jets. A long dual jets distance was found to yield better mixing characteristics within the cavity than a short one. When the jets are further apart, the mainstream between two counter-rotating vortex pairs behind the jets flows strongly into the cavity because of the increased blow-down occurring between the vortex pairs. Additionally, a counterflow with a low velocity magnitude occurs behind the jets. Hence, mixing is enhanced within the cavity by effects of the opposed flow. When the jet pairs are closer to each other, the counter-rotating vortex pairs are in contact; as a result, the blow-down effect does not occur between them. The flow drawn into the cavity from the mainstream is supplied from the sides of the test section into the cavity
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