Gas Turbine Combustors
Reaction Design's software suite augments the use of computational fluid dynamics (CFD) for the efficient development of gas turbine combustors.
Accurately Predict Emissions
ENERGICO’s unique capability to incorporate chemical models with sufficient chemistry detail to yield a more accurate prediction of combustor emissions avoids the traditional CFD Time-to-Solution penalty. Combustor designers use ENERGICO in concert with their CFD Package of choice to understand not only the magnitude of the emissions formed, but where they are being formed and why.
- The automated implementation of parameter studies that identify the impacts of varied operating conditions and/or design changes on NOx, soot, CO and Unburned Hydrocarbons in both gaseous and liquid fueled combustors.
- The modeling of emissions behavior as a function of changes in fuel composition for conventional and alternative fuels.
- The simulation of the effects that take place in small regions of the combustor, such as those near wall cooling flows, to identify regions of CO quenching.
Combustor designers profit from CHEMKIN-PRO’s rapid simulations execution to design parameter studies that model trends in the effects of engine design variables on pollutant emissions such as NOx, CO and Unburned Hydrocarbons (UHC). The trends identified through the use of CHEMKIN-PRO simulations help guide conceptual design and answer key questions that arise during the combustor design process.
Use CHEMKIN-PRO to:
- Perform NOx, CO and UHC investigations using idealized reactor networks to simulate gas turbine combustion.
- Develop PSR and PFR reactor studies to determine the impacts of fuel composition and operating conditions on pollutant emissions.
- Develop and test detailed soot particle models for use in ENERGICO.
Assess Lean Blow Off and Extinction
ENERGICO allows combustor designers to take advantage of fuel chemistry models with proven accuracy for predicting LBO. Local conditions within the combustor have a strong impact on flame extinction. ENERGICO is able to apply extensively validated fuel models for CO and chemical time scale with sufficient detail to ensure accurate prediction of the conditions at LBO.
- Automatic calculation of the Local Damköhler number in the flame region to determine if a flame is viable based on the chemistry and mixing time-scales.
- Prediction of the onset of an increase in CO emissions (i.e.. the “knee” of the CO curve) that precedes LBO through the use of parameter studies with varied fuel/air ratios, flow splits, etc.
- Simulation of the impacts of fuel composition on flame extinction for conventional fuels, biofuels and additives
Modern gas turbine combustor designers take advantage CHEMKIN-PRO’s reduced-order models for general studies of flame extinction and LBO with different fuel/air mixing strategies, alternative fuels and/or rich/lean combustion methodologies.
With CHEMKIN-PRO designers can:
- Use the Extinction Model to simulate the effects of fuel composition and operating conditions on the flame.
- Simulate equivalence ratio and residence-time impacts on LBO using a closed homogeneous reactor.
Track Soot Particle Formation and Emissions
ENERGICO has the proven capability predict how Particulate Matter (PM, or soot) is formed in gas turbine combustors, as well as to predict the number and size of the soot particles produced. ENERGICO’s approach supports the tracking of multiple soot precursors, the nucleation of the primary soot particle and the tracking of how a particle agglomerates and oxidizes during a combustion cycle.
- Investigating the effects of operating conditions and design changes on soot particle formation.
- Identifying the impacts of varying fuel compositions on soot particle formation in gas turbine combustors.
- Predicting the number of particles emitted and average particle size in the exhaust and locally in the combustor.
- Discerning the effects of fuel-air mixing near the injector and of cooling flows as they impact soot particle formation.
Soot formation is a complex chemical and physical process that can be simulated in reduced-order reactors. CHEMKIN-PRO includes two distinct particle-tracking models that predict soot formation in idealized reactors. The Method-of Moments model enables predictions of average particle size and the Sectional Model predicts particle size distribution.
CHEMKIN-PRO enables designers to:
- Track the formation, agglomeration and oxidation of soot particles in the combustor.
- Predict the impact of fuel composition changes on particle size.
- Gain information on the particle size distribution of soot in an engine.
Liquid Fuel Simulation
ENERGICO’s reactor network approach lends itself well to liquid fueled combustor simulations by extending CFD results to incorporate detailed fuel chemistry. Liquid fuel combustion is modeled by the CFD package that determines where droplets go and where fuel is evaporated, albeit with limited chemistry accuracy. ENERGICO takes these CFD results as input and accounts for full energy balance for the droplet vaporization in the reactor network solution resulting in much more accurate predictions of combustion and emissions performance.
Use ENERGICO to:
- Investigate CO and UHC emissions at idle (7% power) for ICAO regulation compliance.
- Predict the effects of fuel-air mixing strategies on combustion and emissions.
- Model multicomponent liquid fuel combustion in both Lean Direct Injected (LDI) and Rich Burn, Quick Mix, Lean Burn (RQL) gas turbine combustors.
Investigate Fuel Flexibility
Engine designers take advantage of ENERGICO’s simulation of combustion behavior to investigate the impacts of using alternative fuels or fuels that have variable compositions, such as gasifier syngas. ENERGICO’s reactor network approach allows the use of sufficient chemistry detail to accurately model the effects of fuel composition on NOx, CO, and PM (soot particle) formation, as well as LBO performance.
- Automated creation of parameter study simulations to investigate the impact of biofuel additives on ignition, flame propagation and emissions performance.
- Modeling of combustor emissions changes when switching from Jet-A to alternative jet fuels.
- Investigation of the effects of using heavier hydrocarbon gaseous fuel components (such as those found in Liquefied Natural Gas) in place of pure methane or natural gas.
The ever-widening fuels landscape presents a challenge to combustor designers that can be addressed through the use of virtual Design of Experiment (DoE) studies in CHEMKIN-PRO. Biofuel and fuel additive impacts on combustion and emissions performance can be calculated using CHEMKIN-PRO’s automated Parameter Study capability.
- Simulation of ignition-delay impacts due to variations in the compositions of commonly used fuels, including natural gas, syngas, Jet-A and biofuels.
- Flame propagation comparisons between conventional and alternative fuels using the Flame Speed Calculator.
- Generation of laminar flame-speed libraries that can be used as the basis for turbulent flame propagation models in CFD.
Model Fuel Efficiency
Computational Fluid Dynamics (CFD) is the dominant tool for simulation of combustion in gas turbines. However, CFD often falls short in the prediction of critical performance metrics including pollutant emissions and the effects of fuel composition on combustion efficiency, even after extensive model calibration and adjustment. Because most CFD software cannot include adequate detail in fuel models, it also cannot accurately predict key phenomena. In most cases, the models must be severely reduced in order to achieve a reasonable Time-to-Solution. Gas turbine combustor designers use ENERGICO, which augments the benefits of CFD by enabling rapid calculations using accurate fuel combustion models that are often too detailed to be run directly in CFD.
With ENERGICO, designers can:
- Couple CFD flow modeling with accurate simulations of the effects of fuel chemistry.
- Investigate the effects of operating conditions for increased efficiency and emissions reduction, such as higher inlet pressures and exit temperatures.
- Accurately simulate combustion of emissions neutral fuels, such as biofuel.
Gas turbine combustor developers are continually under pressure to reduce fuel consumption and improve the efficiency of their engine designs. Engineers use CHEMKIN-PRO’s reduced-order models to perform scoping studies, set up virtual Design of Experiments (DoE) simulations and parameter sensitivity studies to direct conceptual design. CHEMKIN‑PRO’s rapid Time-To-Solution enables sophisticated investigations into the effects of fuel composition on combustion and emissions, including:
- The impact of fuel composition for conventional and biofuels on ignition delay.
- The impacts of flame propagation in the combustor.
- The impacts of varying fuel compositions (or using different kinetic mechanisms) on the accuracy of performance predictions for given combustor simulations.
Selecting the optimum fuel surrogate components and reducing the complexity of the fuel model for desired accuracy of specific simulation targets is easy with Reaction Workbench, an optional extension to CHEMKIN-PRO. The Surrogate Blend Optimizer in Reaction Workbench automatically determines the correct compositions of a multicomponent fuel to match desired fuel properties and merges the components to form a “master” fuel mechanism. Reaction Workbench can then take advantage of a series of well-proven mechanism reduction techniques to create the minimum- sized mechanism necessary to generate the desired simulation results.
Fuels Engineers use Reaction Workbench to:
- Create multicomponent surrogate blend models for fuels such as Jet-A, JP-8, diesel and biofuels for use in ENERGICO, FORTÉ or CHEMKIN-PRO.
- Reduce a fuel mechanism’s complexity and its associated simulation runtime requirement while maintaining specific accuracy targets for attributes such as flame speed, ignition delay, emissions and/or particle matter formation.
Investigate Aftertreatment Solutions
Combined-cycle gas turbine power plants use Selective Catalytic Reduction (SCR) aftertreatment systems to reduce NOx emissions and meet compliance on strict environmental regulations. Gas turbine system power plant designers use CHEMKIN-PRO to simulate the effectiveness of NOx reduction in SCR aftertreatment systems.
- Simulation of SCR system NOx reduction using ammonia injection across a catalyst surface.
- Investigation of the impact of honeycomb catalyst geometry and operating conditions on reduction of NOx.