Lean Blowout with a High Pressure Well Stirred Reactor

Weak extinction data obtained from an experimental apparatus designed to simulate the characteristics of practical afterburner combustion systems are presented. The apparatus supplies mixtures of varied composition (equivalence ratio and degree of vitiation), temperature and velocity to Vee-gutter flame holders of various widths and shapes similar to those found in jet engine systems. The fuel employed is a liquid hydrocarbon whose chemical composition and physical properties correspond to those of aviation kerosine, JP5. An equation for predicting weak extinction limits which accounts for upstream vitiation and the chemical characteristics of the fuel is derived from stirred reactor theory. The correlation between the predictions and experimental results indicates that the stirred reactor approach can provide a framework for predicting the lean blowout limits of practical flameholders over wide ranges of engine operating conditions.

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Modeling of Local Extinction in Turbulent Flames

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2816591 ◽

1996 ◽

Vol 118 (2) ◽

pp. 292-307

Author(s):

D. G. Sloan ◽

G. J. Sturgess

Keyword(s):

Predictive Accuracy ◽

Turbulent Flames ◽

Lean Blowout ◽

Stirred Reactor ◽

Kinetic Mechanisms ◽

Global Extinction ◽

Lifted Flames ◽

Eddy Structures ◽

Fast Chemistry ◽

Computational Fluid Dynamics Cfd

The Eddy Dissipation Concept (EDC), proposed by Magnussen (1985), advances the concept that the reactants are homogeneously mixed within the fine eddy structures of turbulence and that the fine structures may therefore be regarded as perfectly stirred reactors (PSRs). To understand more fully the extent to which such a subgrid scale stirred reactor concept could be applied within the context of a computational fluid dynamics (CFD) calculation to model local or global extinction phenomena: (1) Various kinetic mechanisms are investigated with respect to CPU penalty and predictive accuracy in comparisons with stirred reactor lean blowout (LBO) data and (2) a simplified time-scale comparison, extracted from the EDC model and applied locally in a fast-chemistry CFD computation, is evaluated with respect to its capabilities to predict attached and lifted flames. Comparisons of kinetic mechanisms with PSR lean blowout data indicate severe discrepancies in the predictions with the data and with each other. Possible explanations are delineated and discussed. Comparisons of the attached and lifted flame predictions with experimental data are presented for some benchscale burner cases. The model is only moderately successful in predicting lifted flames and fails completely in the attached flame case. Possible explanations and research avenues are reviewed and discussed.

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Emissions Performance of the Macrolaminate Premixer Tested Under Simulated Engine Conditions

Volume 2: Turbo Expo 2003 ◽

10.1115/gt2003-38010 ◽

2003 ◽

Cited By ~ 1

Author(s):

Adel Mansour ◽

Michael A. Benjamin

Keyword(s):

Pressure Drop ◽

Flame Temperature ◽

Operating Conditions ◽

Inlet Temperature ◽

Nox Formation ◽

Pressure Drops ◽

Lean Blowout ◽

Stirred Reactor ◽

Pressure Swirl ◽

High Degree

Single injector, high pressure, rig evaluation of the prototype Parker macrolaminate dual fuel premixer (previously tested at NETL, see Mansour et al., 2001) [1] with pressure swirl macrolaminate atomizers was conducted under simulated engine operating conditions running on No. 2 diesel fuel (DF2). Emissions, oscillations and lean blowout (LBO) performance on liquid fuel at high, part and no load operating points (pressures of 160, 100, 120 psig, and inlet temperatures of 690, 570, 590°F, respectively) and various pressure drops (ΔP/P) and air fuel ratio conditions were investigated. The results indicate that the Parker premixer design has the potential to reduce the DF2 NOX emission to below 15 ppmv, 15% O2. At simulated high load conditions with a nominal flame temperature (TPZ) of 2700°F, the NOX and CO emissions are approximately 10 and 2.5 ppmv at 15% O2, respectively. These results compare extremely favorable to existing commercially available premixer technologies tested under similar rig operating conditions. More importantly, the NOX yield for the Parker Macrolaminate premixer appears to be independent of operating conditions (from high to no load and various pressure drop conditions). Variations in combustor pressure, inlet temperature (T2) and residence time (τ) or pressure drop (ΔP/P) does not seem to have an effect on the formation of NOX. According to Leonard and Stegmaier (1993) [2], insensitivity of NOX formation to operating conditions is a good indication of high degree of premixing. Additionally, the premixer NOX data is only 1 to 2 ppmv higher than the jet stirred reactor (JSR) results (ran at T2 = 661°F, PCD = 14.7 psi and TPZ = 2762°F with similar DF2) of Lee et al., 2001 [3], further confirming the quality of premixing achieved. Combustion driven oscillations was not investigated by tuning the rig so that oscillations would not be a factor.

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Study of n-heptane oxidation by using a high-pressure jet stirred reactor at 100 atm

10.2514/6.2022-0815 ◽

2022 ◽

Author(s):

Hao Zhao ◽

Chao Yan ◽

Ziyu Wang ◽

Yiguang Ju

Keyword(s):

High Pressure ◽

Stirred Reactor

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Characterization of NOx, N2O, and CO for Lean-Premixed Combustion in a High-Pressure Jet-Stirred Reactor

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/96-gt-128 ◽

1996 ◽

Cited By ~ 5

Author(s):

Robert C. Steele ◽

Jon H. Tonouchi ◽

David G. Nicol ◽

David C. Horning ◽

Philip C. Malte ◽

...

Keyword(s):

High Pressure ◽

Computational Models ◽

Chemical Reactor ◽

Reactor Model ◽

N2o Formation ◽

Nox Formation ◽

Lean Premixed Combustion ◽

Stirred Reactor ◽

Lean Premixed ◽

In Series

A high-pressure jet-stirred reactor (HP-JSR) has been built and applied to the study of NOx and N2O formation and CO oxidation in lean-premixed (LPM) combustion. The measurements obtained with the HP-JSR provide information on how NOx forms in lean-premixed, high-intensity combustion, and provide comparison to NOx data published recently for practical LPM combustors. The HP-JSR results indicate that the NOx yield is significantly influenced by the rate of relaxation of super-equilibrium concentrations of the O-atom. Also indicated by the HP-JSR results are characteristic NOx formation rates. Two computational models are used to simulate the HP-JSR, and to provide comparison to the measurements. The first is a chemical reactor model (CRM) consisting of two perfectly-stirred reactors (PSRs) placed in series. The second is a stirred reactor model with finite rate macromixing (i.e., recirculation) and micromixing. The micromixing is treated by either coalescence-dispersion (CD) or interaction-by-exchange-with-the-mean (IEM) theory. Additionally, a model based on one-dimensional gas dynamics with chemical reaction is used to assess chemical conversions within the gas sample probe.

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Modeling of Local Extinction in Turbulent Flames

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/94-gt-433 ◽

1994 ◽

Cited By ~ 4

Author(s):

David G. Sloan ◽

Geoffrey J. Sturgess

Keyword(s):

Predictive Accuracy ◽

Turbulent Flames ◽

Lean Blowout ◽

Stirred Reactor ◽

Kinetic Mechanisms ◽

Global Extinction ◽

Lifted Flames ◽

Eddy Structures ◽

Fast Chemistry ◽

Computational Fluid Dynamics Cfd

The Eddy Dissipation Concept (EDC), proposed by Magnussen (1985), advances the concept that the reactants are homogeneously mixed within the fine eddy structures of turbulence and that the fine structures may therefore be regarded as perfectly stirred reactors (PSRs). To understand more fully the extent to which such a sub-grid scale stirred reactor concept could be applied within the context of a computational fluid dynamics (CFD) calculation to model local or global extinction phenomena: (1) various kinetic mechanisms are investigated with respect to CPU penalty and predictive accuracy in comparisons with stirred reactor lean blowout (LBO) data and (2) a simplified time-scale comparison, extracted from the EDC model and applied locally in a fast-chemistry CFD computation is evaluated with respect to its capabilities to predict attached and lifted flames. Comparisons of kinetic mechanisms with PSR lean blowout data indicate severe discrepancies in the predictions with the data and with each other. Possible explanations are delineated and discussed. Comparisons of the attached and lifted flame predictions with experimental data are presented for some benchscale burner cases. The model is only moderately successful in predicting lifted flames and fails completely in the attached flame case. Possible explanations and research avenues are reviewed and discussed.

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Combustor Stability and Emissions Research Using a Well Stirred Reactor

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/95-gt-109 ◽

1995 ◽

Author(s):

J. Zelina ◽

D. R. Ballal

Keyword(s):

High Efficiency ◽

Flame Temperature ◽

Combustion Efficiency ◽

Combustion Stability ◽

Lean Blowout ◽

Stirred Reactor ◽

Wide Range ◽

The Future ◽

Performance And Emissions ◽

Industrial Gas Turbine

The design and development of low-emissions, lean premixed aero or industrial gas turbine combustors is very challenging because it entails many compromises. To satisfy the projected CO and NOx emissions regulations without relaxing the conflicting requirements of combustion stability, efficiency, pattern factor, relight (for aero combustor) or off-peak loading (for industrial combustor) capability demands great design ingenuity. The well stirred reactor (WSR) provides a laboratory idealization of an efficient and highly compact advanced combustion system of the future that is capable of yielding global kinetics of value to the combustor designers. In this paper, we have studied the combustion performance and emissions using a toroidal WSR. It was found that the toroidal WSR was capable of peak loading almost twice as high as that for a spherical WSR and also yielded a better fuel-lean performance. A simple analysis based upon WSR theory provided good predictions of the WSR lean blowout limits. The WSR combustion efficiency was 99 percent over a wide range of mixture ratios and reactor loading. CO emissions reached a minimum at a flame temperature of 1600K and NOx increased rapidly with an increase in flame temperature, moderately with increasing residence time, and peaked at or slightly on the fuel-lean side of the stoichiometric equivalence ratio. Finally, emissions maps of different combustors were plotted and showed that the WSR has the characteristics of an idealized high efficiency, low emissions combustor of the future.

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