Blowoff dynamics of bluff body stabilized turbulent premixed flames

Chaudhuri, Swetaprovo; Kostka, Stanislav; Renfro, Michael W.; Cetegen, Baki M.

doi:10.1016/j.combustflame.2009.10.020

Cited by 213 publications

(90 citation statements)

References 22 publications

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“…(2), it follows from Eq. (3) that each element p(σ, q) of the estimated morph matrix P is obtained as (4) where Similar to Eq. (4) and following the structures of Eq.…”

Section: ) the State Splitting Algorithmmentioning

confidence: 99%

“…They used photomultiplier tubes with CH chemiluminescence filters to capture the optical signal and characterized the signal in the vicinity of blowout. Chaudhuri et al [4] and Stohr et al [5] investigated LBO dynamics of premixed and partially premixed flames using combined particle image velocimetry/planar laserinduced fluorescence (PIV/PLIF)-based diagnostics. However, these works did not focus on developing strategies for mitigating LBO.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic Data-Driven Prediction of Lean Blowout in a Swirl-Stabilized Combustor

Sarkar

Ray

Mukhopadhyay

et al. 2015

International Journal of Spray and Combustion Dynamics

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This paper addresses dynamic data-driven prediction of lean blowout (LBO) phenomena in confined combustion processes, which are prevalent in many physical applications (e.g., landbased and aircraft gas-turbine engines). The underlying concept is built upon pattern classification and is validated for LBO prediction with time series of chemiluminescence sensor data from a laboratory-scale swirl-stabilized dump combustor. The proposed method of LBO prediction makes use of the theory of symbolic dynamics, where (finite-length) time series data are partitioned to produce symbol strings that, in turn, generate a special class of probabilistic finite state automata (PFSA). These PFSA, called D-Markov machines, have a deterministic algebraic structure and their states are represented by symbol blocks of length D or less, where D is a positive integer. The D-Markov machines are constructed in two steps: (i) state splitting, i.e., the states are split based on their information contents, and (ii) state merging, i.e., two or more states (of possibly different lengths) are merged together to form a new state without any significant loss of the embedded information. The modeling complexity (e.g., number of states) of a D-Markov machine model is observed to be drastically reduced as the combustor approaches LBO. An anomaly measure, based on Kullback-Leibler divergence, is constructed to predict the proximity of LBO. The problem of LBO prediction is posed in a pattern classification setting and the underlying algorithms have been tested on experimental data at different extents of fuel-air premixing and fuel/air ratio. It is shown that, over a wide range of fuel-air premixing, D-Markov machines with D > 1 perform better as predictors of LBO than those with D = 1.Keywords: Data-driven Dynamics, Lean Blowout, Gas Turbine Combustor, Symbolic Dynamics, Probabilistic Finite State AutomataInternational journal of spray and combustion dynamics · Volume . 7 · Number . 3 . 2015 -pages 209 -242 209 *Corresponding author email: svs5464@psu.edu; axr2@psu.edu; achintya.mukho@gmail.com; sen.swarnendu@gmail.com INTRODUCTIONUltra-lean combustion is commonly used for reduction of oxides of nitrogen (NOx) and is susceptible to thermo-acoustic instabilities and lean blowout (LBO). It is well known that occurrence of LBO could be detrimental for operations of both land-based and aircraft gas turbine engines. For example, LBO in land-based gas turbines may lead to engine shutdown and subsequent re-ignition involves loss of productivity; similarly, LBO in aircraft gas turbines may cause loss of engine thrust especially if the fuel flow is suddenly reduced during a throttling operation, or if air flow reduction takes place at a much slower rate due to the moment of inertia of the compressor. In essence, a sudden decrease in the equivalence ratio may lead to LBO in gas turbine engines, which could have serious consequences. This phenomenon calls for a real-time prediction of LBO and adoption of appropriate measures to mitigate it. It is noted...

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“…(2), it follows from Eq. (3) that each element p(σ, q) of the estimated morph matrix P is obtained as (4) where Similar to Eq. (4) and following the structures of Eq.…”

Section: ) the State Splitting Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamic Data-Driven Prediction of Lean Blowout in a Swirl-Stabilized Combustor

Sarkar

Ray

Mukhopadhyay

et al. 2015

International Journal of Spray and Combustion Dynamics

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“…Global extinction is a transient process in which the localized extinction area on the flame front gradually expands until complete extinction occurs. It has been shown recently that the blow-off transient is long relative to estimates of the residence time in the combustor and that empirical correlations of the blow-off condition do not give very accurate results [15,[37][38][39]. Therefore, in the context of turbulent combustion modeling, the following question can be posed: does a combustion model that can predict reasonably well the degree of local extinction also possesses the ability to predict the global extinction conditions and dynamics in a flame in a realistic geometry?…”

Section: Introductionmentioning

confidence: 99%

Prediction of Global Extinction Conditions and Dynamics in Swirling Non-premixed Flames Using LES/CMC Modelling

Zhang

Mastorakos

2015

Flow Turbulence Combust

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The Large Eddy Simulation (LES)/three-dimensional Conditional Moment Closure (CMC) model with detailed chemistry is applied to predict the operating condition and dynamics of complete extinction (blow-off) in swirling non-premixed methane flames. Using model constants previously selected to provide relatively accurate predictions of the degree of local extinction in the piloted jet flames Sandia D−F, the error in the blow-off air velocity predicted by LES/3D-CMC in short, recirculating flames with strong swirl for a range of fuel flow rates is within 25 % of the experimental value, which is considered a new and promising result for combustion LES that has not been applied before for the prediction of the whole blow-off curve in complex geometries. The results also show that during the blow-off transient, the total heat release gradually decreases over a duration that agrees well with experiment. The evolution of localized extinction, reactive scalars and scalar dissipation rate is analyzed. It has been observed that a consistent symptom for flames approaching blow-off is the appearance of high-frequency and high-magnitude fluctuations of the conditionally filtered stoichiometric scalar dissipation rate, resulting in an increased fraction of local extinction over the stoichiometric mixture fraction iso-surfaces. It is also shown that the blow-off time changes with the different blow-off conditions.

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“…When bluff body is used as a flame holder, the incoming fuel and oxidizer mixture is ignited by the hot combustion products recirculating in a wake structure formed behind the bluff body. This stabilization mechanism has been investigated extensively by many researchers [6][7][8][9][10][11][12]. Many studies associated with bluff body stabilization mechanism focus on premixed combustion systems, where premixed fuel and oxidizer are provided to the combustion zone and thus complex physics that controls mixing process can be neglected.…”

Section: Ppbb Burnermentioning

confidence: 99%

Application of a Central Composite Design for the Study of NOx Emission Performance of a Low NOx Burner

2015

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Abstract:In this study, the influence of various factors on nitrogen oxides (NOx) emissions of a low NOx burner is investigated using a central composite design (CCD) approach to an experimental matrix in order to show the applicability of design of experiments methodology to the combustion field. Four factors have been analyzed in terms of their impact on NOx formation: hydrogen fraction in the fuel (0%-15% mass fraction in hydrogen-enriched methane), amount of excess air (5%-30%), burner head position (20-25 mm from the burner throat) and secondary fuel fraction provided to the burner (0%-6%). The measurements were performed at a constant thermal load equal to 25 kW (calculated based on lower heating value). Response surface methodology and CCD were used to develop a second-degree polynomial regression model of the burner NOx emissions. The significance of the tested factors over their respective ranges has been evaluated using the analysis of variance and by the consideration of the coefficients of the model equation. Results show that hydrogen addition to methane leads to increased NOx emissions in comparison to emissions from pure methane combustion. Hydrogen content in a fuel is the strongest factor affecting NOx emissions among all the factors tested. Lower NOx formation because of increased excess air was observed when the burner was fuelled by pure methane, but this effect diminished for hydrogen-rich fuel mixtures. NOx emissions were slightly reduced when the burner head was shifted closer to the burner outer tube, whereas a OPEN ACCESSEnergies 2015, 8 3607 secondary fuel stream provided to the burner was found to have no impact on NOx emissions over the investigated range of factors.

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Blowoff dynamics of bluff body stabilized turbulent premixed flames

Cited by 213 publications

References 22 publications

Dynamic Data-Driven Prediction of Lean Blowout in a Swirl-Stabilized Combustor

Dynamic Data-Driven Prediction of Lean Blowout in a Swirl-Stabilized Combustor

Prediction of Global Extinction Conditions and Dynamics in Swirling Non-premixed Flames Using LES/CMC Modelling

Application of a Central Composite Design for the Study of NOx Emission Performance of a Low NOx Burner

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