Fuel thermal stability effects on spray characteristics

Lefebvre, A. H.; Nickolaus, D.

doi:10.2514/3.23017

Cited by 6 publications

(3 citation statements)

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“…The studies carried out by Nickolaus and Lefebvre (1987) and McCaldon et al (1993) among others, have demonstrated that coke formation within fuel nozzles can have a serious adverse effect on spray pattern. Although it has long been recognized that "cleaner" fuels of low aromatics content can greatly reduce the potential for fuel coking, this has never been regarded as a practical option due to the requirements of fuel flexibility for the military and lower-cost, heavier distillate fuels for civilian and commercial applications.…”

Section: Fuel Nozzle Cokingmentioning

confidence: 99%

The Role of Fuel Preparation in Low Emissions Combustion

Lefebvre

1995

Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation;

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The attainment of very low pollutant emissions, in particular oxides of nitrogen (NOx), from gas turbines is not only of considerable environmental concern but has also become an area of increasing competitiveness between the different engine manufacturers. For stationary engines, the attainment of ultra-low NOx has become the foremost marketing issue. This paper is devoted primarily to current and emerging technologies in the development of ultra-low emissions combustors for application to aircraft and stationary engines. Short descriptions of the basic design features of conventional gas turbine combustors and the methods of fuel injection now in widespread use are followed by a review of fuel spray characteristics and recent developments in the measurement and modeling of these characteristics. The main gas turbine generated pollutants and their mechanisms of formation are described, along with related environmental risks and various issues concerning emissions regulations and recently-enacted legislation for limiting the pollutant levels emitted by both aircraft and stationary engines. The impact of these emissions regulations on combustor and engine design are discussed first in relation to conventional combustors and then in the context of variable-geometry and staged combustors. Both these concepts are founded on emissions reduction by control of flame temperature. Basic approaches to the design of “dry” low NOx and ultra-low NOx combustors are reviewed. At the present time lean, premix, prevaporize, combustion appears to be the only technology available for achieving ultra-low NOx emissions from practical combustors. This concept is discussed in some detail, along with its inherent problems of autoignition, flashback, and acoustic resonance. Attention is also given to alternative methods of achieving ultra-low NOx emissions, notably the rich-bum, quick-quench, lean-burn and catalytic combustors. These concepts are now being actively developed, despite the formidable problems they present in terms of mixing and durability. The final section reviews the various correlations which are now being used to predict the exhaust gas concentrations of the main gaseous pollutant emissions from gas turbine engines. Comprehensive numerical methods have not yet completely displaced these semi-empirical correlations but are nevertheless providing useful insight into the interactions of swirling and recirculating flows with fuel sprays, as well as guidance to the combustion engineer during the design and development stages. Throughout the paper emphasis is placed on the important and sometimes pivotal role played by the fuel preparation process in the reduction of pollutant emissions from gas turbines.

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Section: Fuel Nozzle Cokingmentioning

confidence: 99%

The Role of Fuel Preparation in Low Emissions Combustion

Lefebvre

1995

Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation;

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“…For example, detailed measurements made with simplex, duplex, dual-orifice, and pure airblast atomizers show similar dynamic structures in radial distributions of mean droplet diameter, velocity, and liquid volume flux. Extensive studies have been made (33,34) on the spray dynamics associated with pressure swirl atomizers. Based on these studies, some common features were observed.…”

Section: Spraysmentioning

confidence: 99%

“…Using equations 9 and 10, the estimated Sauter mean diameters agree quite well with experimental data obtained for a wide range of atomizer designs. Note that the two constants in equation 11 differ from those shown in Lefebvre's equation (34). These constants have been changed to fit a wide range of experimental data.…”

Section: Spray Correlationsmentioning

confidence: 99%

Sprays

Lipp

2006

Kirk-Othmer Encyclopedia of Chemical Technology

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Sprays are widely used in many industrial processes. In more recent years, the subject of liquid atomization has developed from a position of minor importance into a broad and significant technology. This article summarizes information and covers such topics as liquid atomizers, physics of atomization, spray characterization, instrumentation, and industrial applications. Atomizers have been summarized according to their sources of energy, distinct design features, and applications. Discussion of the physics of atomization is divided into three different regimes: internal flow, liquid breakup, and droplet dispersion. Spray characterization focuses on the explanation of common spray parameters, typical spray dynamic structures, effect of variables, and correlation techniques. Because of its important role, spray instrumentation is also discussed, along with an overview of representative optical and nonoptical techniques. Specific examples of industrial spray applications are cited and general comments are made regarding the methods selection of liquid atomizers and concerns related to their operation.

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Energy considerations in spraying process of a spill-return pressure-swirl atomizer

Jedelský

Jícha

2014

Applied Energy

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Fuel thermal stability effects on spray characteristics

Cited by 6 publications

References 1 publication

The Role of Fuel Preparation in Low Emissions Combustion

The Role of Fuel Preparation in Low Emissions Combustion

Sprays

Energy considerations in spraying process of a spill-return pressure-swirl atomizer

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