Fuel Injector Patternation Evaluation in Advanced Liquid-Fueled, High Pressure, Gas Turbine Combustors, Using Nonintrusive Optical Diagnostic Techniques

Planar laser-induced fluorescence (PLIF) imaging and planar Mie scattering are used to examine the fuel distribution pattern (patternation) for advanced fuel injector concepts in kerosene burning, high pressure gas turbine combustors. Three diverse fuel injector concepts for aerospace applications were investigated under a broad range of operating conditions. Fuel PLIF patternation results are contrasted with those obtained by planar Mie scattering. Further comparison is also made for one injector with data obtained through phase Doppler measurements. Differences in spray patterns for diverse conditions and fuel injector configurations are readily discernible. An examination of the data has shown that a direct determination of the fuel spray angle at realistic conditions is also possible. The results obtained in this study demonstrate the applicability and usefulness of these nonintrusive optical techniques for investigating fuel spray patternation under actual combustor conditions

Imaging Fluorescent Combustion Species in Gas Turbine Flame Tubes: On Complexities in Real Systems

Planar laser-induced fluorescence (PLIF) is used to visualize the flame structure via OH, NO, and fuel imaging in kerosene- burning gas turbine combustor flame tubes. When compared to simple gaseous hydrocarbon flames and hydrogen flames, flame tube testing complexities include spectral interferences from large fuel fragments, unknown turbulence interactions, high pressure operation, and the concomitant need for windows and remote operation. Complications of these and other factors as they apply to image analysis are considered. Because both OH and gas turbine engine fuels (commercial and military) can be excited and detected using OH transition lines, a narrowband and a broadband detection scheme are compared and the benefits and drawbacks of each method are examined

Optical Fuel Injector Patternation Measurements in Advanced Liquid-Fueled, High Pressure, Gas Turbine Combustors

Planar laser-induced fluorescence (PLIF) imaging and planar Mie scattering are used to examine the fuel distribution pattern (patternation) for advanced fuel injector concepts in kerosene burning, high pressure gas turbine combustors. Three fuel injector concepts for aerospace applications were investigated under a broad range of operating conditions. Fuel PLIF patternation results are contrasted with those obtained by planar Mie scattering. For one injector, further comparison is also made with data obtained through phase Doppler measurements. Differences in spray patterns for diverse conditions and fuel injector configurations are readily discernible. An examination of the data has shown that a direct determination of the fuel spray angle at realistic conditions is also possible. The results obtained in this study demonstrate the applicability and usefulness of these nonintrusive optical techniques for investigating fuel spray patternation under actual combustor conditions

Comparison of Techniques for Non-Intrusive Fuel Drop Size Measurements in a Subscale Gas Turbine Combustor

In aviation gas turbine combustors, many factors, such as the degree and extent of fuel/air mixing and fuel vaporization achieved prior to combustion, influence the formation of undesirable pollutants. To assist in analyzing the extent of fuel/air mixing, flow visualization techniques have been used to interrogate the fuel distributions during subcomponent tests of lean-burning fuel injectors. Discrimination between liquid and vapor phases of the fuel was determined by comparing planar laser-induced fluorescence (PLIF) images, elastically-scattered light images, and phase/Doppler interferometer measurements. Estimates of Sauter mean diameters are made by ratioing PLIF and Mie scattered intensities for various sprays, and factors affecting the accuracy of these estimates are discussed. Mie calculations of absorption coefficients indicate that the fluorescence intensities of individual droplets are proportional to their surface areas, instead of their volumes, due to the high absorbance of the liquid fuel for the selected excitation wavelengths

Challenges to Laser-Based Imaging Techniques in Gas Turbine Combustor Systems for Aerospace Applications

Increasingly severe constraints on emissions, noise and fuel efficiency must be met by the next generation of commercial aircraft powerplants. At NASA Lewis Research Center (LeRC) a cooperative research effort with industry is underway to design and test combustors that will meet these requirements. To accomplish these tasks, it is necessary to gain both a detailed understanding of the combustion processes and a precise knowledge of combustor and combustor sub-component performance at close to actual conditions. To that end, researchers at LeRC are engaged in a comprehensive diagnostic investigation of high pressure reacting flowfields that duplicate conditions expected within the actual engine combustors. Unique, optically accessible flame-tubes and sector rig combustors, designed especially for these tests. afford the opportunity to probe these flowfields with the most advanced, laser-based optical diagnostic techniques. However, these same techniques, tested and proven on comparatively simple bench-top gaseous flame burners, encounter numerous restrictions and challenges when applied in these facilities. These include high pressures and temperatures, large flow rates, liquid fuels, remote testing, and carbon or other material deposits on combustor windows. Results are shown that document the success and versatility of these nonintrusive optical diagnostics despite the challenges to their implementation in realistic systems

How Quickly We Forget: The Duration of Persuasion Effects From Mass Communication

Scholars do not usually test for the duration of the effects of mass communication, but when they do, they typically find rapid decay. Persuasive impact may end almost as soon as communication ends. Why so much decay? Does mass communication produce any long-term effects? How should this decay color our understanding of the effects of mass communication? We examine these questions with data from the effects of advertising in the 2000 presidential election and 2006 subnational elections, but argue that our model and results are broadly applicable within the field of political communication. We find that the bulk of the persuasive impact of advertising decays quickly, but that some effect in the presidential campaign endures for at least 6 weeks. These results, which are similar in rolling cross-section survey data and county-level data on actual presidential vote, appear to reflect a mix of memory-based processing (whose effects last only as long as short-term memory lasts) and online processing (whose effects are more durable). Finally, we find that immediate effects of advertising are larger in subnational than presidential elections, but decay more quickly and more completely. [Supplementary material is available for this article. Go to the publisher's online edition of Political Communication for the following free supplemental resource(s): discussion of methodological issues; results for a alternative specifications of key models; full reports of model results.]. © 2013 Copyright Taylor & Francis Group, LLC

Politieke kennis en effecten van nieuws

Welk nieuws doet ertoe en hoeveel nieuws doet ertoe, en in welke mate hangt dit af van de politieke kennis van de ontvanger? Dit artikel beschrijft een longitudinale studie naar de verkiezingsstrijd voor het Nederlandse parlement in 2006

Howard's War on Terror: A Conceivable, Communicable and Coercive Foreign Policy Discourse

This article explores the relationship between language and political possibility. It is argued that John Howard’s language from 11 September 2001 to mid 2003 helped to enable the ‘War on Terror’ in an Australian context in three principal ways. Firstly, through contingent and contestable constructions of Australia, the world and their relationship, Howard’s language made interventionism conceivable. Secondly, emphasising shared values, mateship and mutual sacrifice in war, Howard embedded his foreign policy discourse in the cultural terrain of ‘mainstream Australia’, specifically framing a foreign policy discourse that was communicable to ‘battlers’ and disillusioned ‘Hansonites’. Thirdly, positioning alternatives as ‘un-Australian’, Howard’s language was particularly coercive, silencing potential oppositional voices

Intra-Campaign Changes in Voting Preferences: The Impact of Media and Party Communication

An increasing number of citizens change and adapt their party preferences during the electoral campaign. We analyze which short-term factors explain intra-campaign changes in voting preferences, focusing on the visibility and tone of news media reporting and party canvassing. Our analyses rely on an integrative data approach, linking data from media content analysis to public opinion data. This enables us to investigate the relative impact of news media reporting as well as party communication. Inherently, we overcome previously identified methodological problems in the study of communication effects on voting behavior. Our findings reveal that campaigns matter: Especially interpersonal party canvassing increases voters’ likelihood to change their voting preferences in favor of the respective party, whereas media effects are limited to quality news outlets and depend on individual voters’ party ambivalence