Acoustic Sensing and Mitigation of Lean Blow Out in Premixed Flames

Prakash, Shashvat; Nair, Satish; Muruganandam, Thiruchenode; Neumeier, Yedidia; Lieuwen, Timothy C.; Seitzman, Jerry M.; Zinn, B. T.

doi:10.2514/6.2005-1420

Cited by 19 publications

(10 citation statements)

References 7 publications

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“…Several methods have been used to achieve stabilization in combustion systems, such as pilot flames, oxygen-rich coflows, bluff bodies, and swirling flows. Pilot flames are routinely used to stabilize laboratory scale, nonpremixed [1], [2], and premixed [3]- [5] flames. A pure oxygen coflow surrounding a jet flame was demonstrated to be successful in stabilizing laboratoryscale diffusion flames [6].…”

Section: Introductionmentioning

confidence: 99%

Plasma-Discharge Stabilization of Jet Diffusion Flames

Kim

Mungal

et al. 2006

IEEE Trans. Plasma Sci.

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Abstract-The authors examine three different types of plasma discharges in their ability to stabilize a lifted jet diffusion flame in coflow. The three discharges include a single-electrode corona discharge, an asymmetric dielectric-barrier discharge (DBD), and a repetitive ultrashort-pulsed discharge. The degree of nonequilibrium of this pulsed discharge is found to be higher than that for the DBD. Furthermore, this pulsed discharge causes the most significant improvement in the flame stability. The optimal placement of the discharge electrodes is investigated, and it is found that there is a close relation between this placement and the emission spectra, suggesting use of the emission spectra as a possible indicator of fuel/air mixture fraction. The optimal placement is mapped into mixture-fraction space by use of a fully premixed flame experiment of known mixture fraction. The result shows that the mixture fraction, which corresponds to the optimal placement, is much leaner than that of a conventional lifted jet flame.

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Section: Introductionmentioning

confidence: 99%

Plasma-Discharge Stabilization of Jet Diffusion Flames

Kim

Mungal

et al. 2006

IEEE Trans. Plasma Sci.

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“…Our studies revealed that unlike the present method, other methods in literature like those proposed by Gutmark and coworkers [13] and Lieuwen, Seitzman and coworkers [14][15][16] perform very well for L fuel = 35 cm but their performance deteriorates as the fuel inlet is moved closer towards the dump plane. These results have been presented in our earlier publications [23].…”

Section: Lbo Detectionmentioning

confidence: 61%

“…Refs. [14,15]) signals close to LBO. A comparison between the two in the same experimental setup [16] portrays optical methods as the superior choice on account of faster response time.…”

Section: Introductionmentioning

confidence: 99%

“…Mukhopadhyay et al [17] used moving kurtosis and threshold based techniques applied on combustor pressure time series for early detection of flame extinction in mathematical models of pulse combustors. Prakash et al [18,14] integrated an acoustic sensor with the combustor control system for mitigation of impending blowout. More recently, Li et al [19] reported the use of a novel tunable diode laser temperature sensor to acquire a temperature time series.…”

Section: Introductionmentioning

confidence: 99%

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Flame Color as a Lean Blowout Predictor

Chaudhari

Sahu

Ghosh

et al. 2013

International Journal of Spray and Combustion Dynamics

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The study characterizes the behavior of a premixed swirl stabilized dump plane combustor flame near its lean blow-out (LBO) limit in terms of CH* chemiluminiscence intensity and observable flame color variations for a wide range of equivalence ratio, flow rates and degree of premixing (characterized by premixing length, L fuel ). LPG and pure methane are used as fuel. We propose a novel LBO prediction strategy based solely on the flame color. It is observed that as the flame approaches LBO, its color changes from reddish to blue. This observation is found to be valid for different levels of fuel-air premixing achieved by changing the available mixing length of the air and the fuel upstream of the dump plane although the flame dynamics were significantly different. Based on this observation, the ratio of the intensities of red and blue components of the flame as captured by a color CCD camera was used as a metric for detecting the proximity of the flame to LBO. Tests were carried out for a wide range of air flow rates and using LPG and CH 4 as fuel. For all the operating conditions and both fuels tested, this ratio was found to monotonically decrease as LBO was approached. Moreover, the value of this ratio was within a small range close to LBO for all the cases investigated. This makes the ratio suitable as a metric for LBO detection at all levels of premixing.

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“…Pilot flames have been implemented in laboratory scale, nonpremixed flames [1][2] and premixed flames. [3][4][5] A pure oxygen coflow surrounding a jet flame was demonstrated in laboratory-scale diffusion flames. 6 Bluff bodies or swirl stabilization mechanisms have been used in premixed and partially premixed flames to generate a recirculation zone which preheats the reactants, resulting in increased flame stability.…”

Section: Introductionmentioning

confidence: 99%

Flame Stabilization Enhancement and NOx Production using Ultra Short Repetitively Pulsed Plasma Discharges

Kim

2006

44th AIAA Aerospace Sciences Meeting and Exhibit

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This paper examines the use of plasma discharges in flame stabilization. Three different types of plasma discharges are applied to a lifted jet diffusion flame in a coflow configuration, and evaluated for their abilities to enhance flame stabilization. A single electrode corona discharge (SECD) between a platinum electrode and the flame base is found to maintain the flame at a 20% higher coflow speed than that without the discharge. An asymmetric dielectric barrier discharge (DBD) results in flame stabilization at up to 50% higher coflow speed. The nonequilibrium properties of the DBD are characterized by a spectral line analysis and simulation of the nitrogen 2 nd positive system. Finally, an ultra short repetitively-pulsed discharge (USRD, pulse width of ~10ns) is used in an opposed platinum electrode configuration and found to increase in the stability limit by nearly tenfold. The degree of nonequilibrium of this pulsed discharge is found to be higher than that of the DBD. The stabilization process is sensitive to the positioning of the discharge in the flame flow field, and the optimal position of the discharge is mapped into mixture fraction space by comparing the emission spectra from the plasma-stabilized flame to that in a fully premixed reference flame. The result shows that the local mixture fraction at the optimal position is much leaner than that of a conventional lifted jet flame. In a second part of this study, the USRD is used to stabilize lean premixed methane flames. Nitric Oxide (NO) production is measured using probe sampling and chemiluminescence analysis. While the discharge is a potential source of NO, it is found that the flame partially consumes NO in a reburn mode. The NO production is modeled by use of PLASMAREACTOR followed by the standard PREMIX code. The modeling results show some promise in its ability to predict NO concentration. The flame structure of plasma assisted premixed combustion is also discussed. Under certain conditions, we observe a cold inner flame that has an abundance of OH radicals which have an unusually high vibrational temperature with low rotational temperature when compared to the OH found in a conventional lean premixed flame. While the role of the OH in this inner flame is not fully understood, we believe it may be important in igniting the surrounding combustible mixture.

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Acoustic Sensing and Mitigation of Lean Blow Out in Premixed Flames

Cited by 19 publications

References 7 publications

Plasma-Discharge Stabilization of Jet Diffusion Flames

Plasma-Discharge Stabilization of Jet Diffusion Flames

Flame Color as a Lean Blowout Predictor

Flame Stabilization Enhancement and NOx Production using Ultra Short Repetitively Pulsed Plasma Discharges

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