Effect of Atomization Quality on Lean Blow-Out Limits and Acoustic Oscillations in a Swirl Stabilized Burner
TL;DR: In this paper, the influence of atomization quality on lean blowout limits and acoustic oscillations in a swirl stabilized burner with simplex atomizer was highlighted, and experiments were conducted with a simplex-based atomizer.
Abstract: The present experimental work highlights the influence of atomization quality on lean blow-out (LBO) limits and acoustic oscillations in a swirl stabilized burner with simplex atomizer. With decrea...
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01 Dec 1988
TL;DR: In this paper, the basic processes in Atomization are discussed, and the drop size distributions of sprays are discussed.Preface 1.General Considerations 2.Basic Processes of Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.AtOMizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index
Abstract: Preface 1.General Considerations 2.Basic Processes in Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.Atomizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index
1,214 citations
TL;DR: In this paper, spray atomization characteristics of pre-filming airblast nozzles developed for use in aviation gas turbine combustors were experimentally investigated for different air to liquid ratios (ALR) and air pressure differences (ΔP (%)).
20 citations
29 Jan 2011
TL;DR: In this article, the authors present some very unique operating characteristics of a kerosene-fueled diffusion type combustor undergoing limit-cycle oscillations and show that combustor instability depends on the characteristics of the fuel spray.
Abstract: Thermoacoustic instabilities in combustors have remained a topic of investigation for over a few decades due to the challenges it posses to the operation of low emission gas turbines. For combustors burning liquid fuel, understanding the cause-andeffect relationship between spray combustion dynamics and thermoacoustic oscillations is imperative for the successful development of any control methodology for its mitigation. The paper presents some very unique operating characteristics of a kerosene-fueled diffusion type combustor undergoing limit-cycle oscillations. Combustor stability limits were mapped using three different-sized injectors. The results show that combustor instability depends on the characteristics of the fuel spray. A simple analytic analysis is also reported in support of a plausible explanation for the unique combustor behavior. The study indicates that high amplitude acoustic pressure in the combustor may cause secondary breakdown of fuel droplets resulting in premixed pre-vaporized type burning of the diffusion type combustor. Keywords—Secondary droplet breakup, Spray dynamics, Taylor Analogy Breakup Model, Thermoacoustic instabilities.
5 citations
TL;DR: In this article, a new and special aerodynamic "swing" phenomenon of static pressure (or pressure drops across combustor liner) and low frequency pressure oscillations (50 Hz∼180 Hz) were observed in the tests and discussed in detail.
5 citations
TL;DR: Peiffer et al. as mentioned in this paper evaluated nearly twenty alternative jet fuels across approximately a dozen rigs to evaluate the relative ignition and lean blowout performance for fuels with different compositions and properties.
Abstract: The current process for qualification of sustainable alternative jet fuels requires thousands of gallons of fuel and multiple levels of testing, which can take years to complete. To streamline this process, nearly twenty fuels were evaluated across approximately a dozen rigs to evaluate the relative ignition and lean blowout performance for fuels with different compositions and properties. Eight of nine rigs at ambient and elevated temperature conditions showed correlations with the derived cetane number for lean blowout. The remaining rig, the combustor of an auxiliary power unit, correlated most strongly with physical properties and a reference rig at chilled temperatures. In congregate, these lean blowout results illuminated two distinct regimes controlled by either the ease at which a spray breaks up or a fuel auto-ignites at a given operating condition. Similarly, multiphase ignition performance across rigs showed similar correlations to fuel properties. Here it is shown that (1) spray break-up and chemical processes timescales determine relative fuel performance trends across nearly 10 rigs, (2) a reference rig, such as the Referee Rig, can capture fuel performance trends of all rigs and engines evaluated to date by tailoring the inlet air and fuel temperatures, and (3) the Referee Rig is a viable tool for screening and evaluating sustainable alternative fuel candidates. References: [1] Peiffer, E.E., Heyne, J.S., and Colket, M., “Sustainable Aviation fuels Approval Streamlining: Auxiliary Power Unit Lean Blowout Testing,” AIAA Journal, Vol. 57, No. 11, November 2019, pp. 1-9
4 citations
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Book•
01 Dec 1988
TL;DR: In this paper, the basic processes in Atomization are discussed, and the drop size distributions of sprays are discussed.Preface 1.General Considerations 2.Basic Processes of Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.AtOMizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index
Abstract: Preface 1.General Considerations 2.Basic Processes in Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.Atomizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index
1,214 citations
TL;DR: In this paper, the authors investigated the mechanisms responsible for combustion instabilities and found that combustors operating in a lean, premixed (LP) mode of combustion are highly sensitive to variations in the equivalence ratio (O) of the mixture that enters the combustor.
Abstract: There has been increased demand in recent years for gas turbines that operate in a lean, premixed (LP) mode of combustion in an effort to meet stringent emissions goals. Unfortunately, detrimental combustion instabilities are often excited within the combustor when it operates under lean conditions, degrading performance and reducing combustor life. To eliminate the onset of these instabilities and develop effective approaches for their control, the mechanisms responsible for their occurrence must be understood. This paper describes the results of an investigation of the mechanisms responsible for these instabilities. These studies found that combustors operating in a LP mode of combustion are highly sensitive to variations in the equivalence ratio (O) of the mixture that enters the combustor. Furthermore, it was found that such O variations can be induced by interactions of the pressure and flow oscillations with the reactant supply rates. The O perturbations formed in the inlet duct (near the fuel injector) are convected by the mean flow to the combustor where they produce large amplitude heat release oscillations that drive combustor pressure oscillations. It is shown that the dominant characteristic time associated with this mechanism is the convective time from the point of formation of the reactive mixture at the fuel injector to the point where it is consumed at the flame. Instabilities occur when the ratio of this convective time and the period of the oscillations equals a specific constant, whose magnitude depends upon the combustor design, Significantly, these predictions are in good agreement with available experimental data, strongly suggesting that the proposed mechanism properly accounts for the essential physics of the problem. The predictions of this study also indicate, however, that simple design changes (i.e., passive control approaches) may not, in general, provide a viable means for controlling these instabilities, due to the multiple number of modes that may be excited by the combustion process.
351 citations
TL;DR: In this article, the impact of fuel composition on the operability of lean premixed gas turbine combustors is discussed, and the underlying processes that must be considered when evaluating how a given combustor's operability will be affected as fuel composition is varied.
Abstract: This paper addresses the impact of fuel composition on the operability of lean premixed gas turbine combustors. This is an issue of current importance due to variability in the composition of natural gas fuel supplies and interest in the use of syngas fuels. Of particular concern is the effect of fuel composition on combustor blowout, flashback, dynamic stability, and autoignition. This paper reviews available results and current understanding of the effects of fuel composition on the operability of lean premixed combustors. It summarizes the underlying processes that must be considered when evaluating how a given combustor’s operability will be affected as fuel composition is varied.Copyright © 2006 by ASME
279 citations
TL;DR: In this article, an experimental study of the mechanism of unstable combustion in a coaxial, optically accessible, bluff-body-stabilized dumpcombustor with natural gas and fuel was performed.
Abstract: Results from an experimental study of the mechanism of unstable combustion in a coaxial, optically accessible, bluff-body-stabilizeddumpcombustorwithnaturalgasasthefuelarereported.Aparametricstudywasperformed to investigate the effects of equivalence ratio, inletvelocity, inlet fuel distribution, inlet swirl, and centerbody recess oncombustionstability. It wasfoundthatall of theseparametershadan effectonthestability characteristicsofthis combustor.Atselectedunstableoperatingconditions,phase-resolvedCHchemiluminescenceimageswerecaptured to study the heat-release structure during one period of pressure oscillation. The e ame‐ e owe eld interaction that is depicted in these images indicates that e ame‐ vortex interactions, and the resultant e ame area changes, play a signie cant role in the instabilities that occur when there is no swirl. A simple analysis of these images, however, showedthate uctuatinge ameareaandequivalenceratioe uctuationsbothcontributetotheheatreleasee uctuations that drive the instability. Unstable combustion with swirl appears to be fundamentally different from unstable combustion without swirl in that instabilities with swirl occur near lean blowout and appear to be associated with repeated detaching and reattaching of the e ame from the centerbody.
206 citations
"Effect of Atomization Quality on Le..." refers background in this paper
...…of combustion system shifts from stoichiometric to leaner conditions, significant increase in acoustic oscillations were reported in both premixed and non-premixed combustors by many researchers Keith et al. (1998); Venkataraman et al. (1999); Cohen et al. (1999); Tongxun and Gutmark (2007b)....
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...Venkataraman et al. (1999) explained that higher sound levels and oscillation amplitudes occur at leaner operating conditions, due to the local detachment and reattachment of flame from the swirler exit....
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TL;DR: In this paper, the effects of fuel properties on the performance and reliability of several gas turbine combustors, including J79-17A, J 79-17C (Smokeless), F101, TF41, TF39, J85, TF33, and F100, were analyzed.
Abstract: An analytical study is made of the substantial body of experimental data acquired during recent Wright-Patterson Aero Propulsion Laboratory sponsored programs on the effects of fuel properties on the performance and reliability of several gas turbine combustors, including J79-17A, J79-17C (Smokeless), F101, TF41, TF39, J85, TF33, and F100. Quantitative relationships are derived between certain key aspects of combustion, notably combustion efficiency, lean blowout limits and lean light-off limits, and the relevant fuel properties, combustor design features, and combustor operating conditions. It is concluded that combustion efficiency, lean blowout limits, and lean lightoff limits are only slightly dependent on fuel chemistry, but are strongly influenced by the physical fuel properties that govern atomization quality and spray evaporation rates.
127 citations
"Effect of Atomization Quality on Le..." refers background or methods in this paper
...In addition to the three time scales (evaporation time, mixing time and reaction time) used by Lefebvre (1985), three more time scales (for droplet residence, duct acoustics and gas flow residence) are considered in the development of present correlation....
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...This approach has also been followed by Lefebvre (1985) for studying lean blowout conditions....
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...Mixing time of air flow (Tmix, air) Mixing time of air flow (Lefebvre, 1985) is defined as the time required for the air flow to mix with the gas in the burner for flame stabilization, which is related to the mixing rate of burner by Eq....
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...In spray combustion systems, atomization and vaporization processes exert significant influence on the combustion characteristics and lean blow-out (LBO) limits of gas turbine combustors Polymeropoulos and Das (1975); Ballal and Lefebvre (1980); Lefebvre (1985)....
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...In addition to the three time scales (evaporation time, mixing time and reaction time) used by Lefebvre (1985), three more time scales (droplet residence time, duct acoustics and residence time of gas flow) are considered in the development of present correlation....
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