Investigation of Single Jet Combustor Using Flamelet Generated Manifold Combustion Model and Detailed Chemistry

2016 ◽  
Author(s):  
Sunil Patil ◽  
Judy Cooper ◽  
Stefano Orsino ◽  
Joseph Meadows ◽  
Richard Valdes ◽  
...  
Keyword(s):  
Natural Gas ◽  
Raman Scattering ◽  
Combustion Model ◽  
Flow Measurements ◽  
Detailed Chemistry ◽  
Flamelet Generated Manifold ◽  
Hexahedral Meshes ◽  
Chemistry Calculation ◽  
Single Jet ◽  
The Impact

Numerical simulation results of a single jet premixed combustion system at atmospheric pressure are compared against comprehensive particle image velocimetry (PIV) flow measurements and Raman scattering temperature measurements for natural gas and hydrogen fuels. The simulations were performed on hexahedral meshes with 1–5 million elements. RANS calculations were carried with the k-ε realizable turbulence model. Combustion was modeled using the Flamelet Generated Manifold model (FGM) and detailed chemistry. Both the flame position and flame liftoff predicted by the FGM were in reasonable agreement with experiments for both fuels and showed little sensitivity to heat transfer or radiation modeling. The detailed chemistry calculation predicts the temperature gradients along the jet centerline accurately and compares very closely with the Raman scattering measurements. The much closer agreement of the jet axial velocity and temperature profiles with experimental values, coupled with the significantly protracted presence of intermediates in the detailed chemistry predictions, indicates that the impact of nonequilibrium intermediates on very lean natural gas flames is significant.

Investigation of Single-Jet Combustor Near Lean Blowout Conditions Using Flamelet-Generated Manifold Combustion Model and Detailed Chemistry

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Sunil Patil ◽  
Judy Cooper ◽  
Stefano Orsino ◽  
Joseph Meadows ◽  
Richard Valdes ◽  
...  
Keyword(s):  
Natural Gas ◽  
Raman Scattering ◽  
Navier Stokes ◽  
Combustion Model ◽  
Flow Measurements ◽  
Detailed Chemistry ◽  
Flamelet Generated Manifold ◽  
Chemistry Calculation ◽  
Single Jet ◽  
The Impact

Numerical simulation results of a single-jet premixed combustion system at atmospheric pressure are compared against comprehensive particle image velocimetry (PIV) flow measurements and Raman scattering temperature measurements for natural gas and hydrogen fuels. The simulations were performed on hexahedral meshes with 1–5 × 106 elements. Reynolds-averaged Navier–Stokes (RANS) calculations were carried out with the k–ε realizable turbulence model. Combustion was modeled using the flamelet-generated manifold model (FGM) and detailed chemistry. Both the flame position and flame liftoff predicted by the FGM were in reasonable agreement with experiments for both fuels and showed little sensitivity to heat transfer or radiation modeling. The detailed chemistry calculation predicts the temperature gradients along the jet centerline accurately and compares very closely with the Raman scattering measurements. The much closer agreement of the jet axial velocity and temperature profiles with experimental values, coupled with the significantly protracted presence of intermediates in the detailed chemistry predictions, indicates that the impact of nonequilibrium intermediates on very lean natural gas flames is significant.

Comparison of Temperature Fields and Emissions Predictions Using Both an FGM Combustion Model, With Detailed Chemistry, and a Simple Eddy Dissipation Combustion Model With Simple Global Chemistry

2017 ◽  
Author(s):  
Pierre Q. Gauthier
Keyword(s):  
Mixture Fraction ◽  
Temperature Fields ◽  
Combustion Model ◽  
Detailed Chemistry ◽  
Combustion Modeling ◽  
Flamelet Generated Manifold ◽  
Wide Range ◽  
Turbulence Effects ◽  
Air Chemistry ◽  
Dissipation Model

The detailed modeling of the turbulence-chemistry interactions occurring in industrial flames has always been the leading challenge in combustion Computational Fluid Dynamics (CFD). The wide range of flame types found in Industrial Gas Turbine Combustion systems has exacerbated these difficulties greatly, since the combustion modeling approach must be able to predict the flames behavior from regions of fast chemistry, where turbulence has no significant impact on the reactions, to regions where turbulence effects play a significant role within the flame. One of these combustion models, that is being used more and more in industry today, is the Flamelet Generated Manifold (FGM) model, in which the flame properties are parametrized and tabulated based on mixture fraction and flame progress variables. This paper compares the results obtained using an FGM model, with a GRI-3.0 methane-air chemistry mechanism, against the more traditional Industrial work-horse, Finite-Rate Eddy Dissipation Model (FREDM), with a global 2-step Westbrook and Dryer methane-air mechanism. Both models were used to predict the temperature distributions, as well as emissions (NOx and CO) for a conventional, non-premixed, Industrial RB211 combustion system. The object of this work is to: (i) identify any significant differences in the predictive capabilities of each model and (ii) discuss the strengths and weakness of both approaches.

scholarly journals CFD analysis of the combustion in the BERL burner fueled with a hydrogen-natural gas mixture

2020 ◽  
Vol 197 ◽  
pp. 10002
Author(s):  
Tommaso Capurso ◽  
Vito Ceglie ◽  
Francesco Fornarelli ◽  
Marco Torresi ◽  
Sergio M. Camporeale
Keyword(s):  
Natural Gas ◽  
Power Plants ◽  
Renewable Energy Sources ◽  
Thermal Power ◽  
Ghg Emissions ◽  
Combustion Model ◽  
Gas Mixture ◽  
Low Carbon ◽  
Radial Temperature ◽  
The Impact

The regulatory restrictions, currently acting, impose a significant reduction of the Greenhouse Gas (GHG) emissions. After the coal-to-gas transition of the last decades, the fossil fuel-to-renewables switching is the current perspective. However, the variability of energy production related to Renewable Energy Sources requires the fundamental contribution of thermal power plants in order to guaranty the grid stability. Moving toward a low-carbon society, the industry is looking at a reduction of high carbon content fuels, pointing to Natural Gas (NG) and more recently to hydrogen-NG mixtures. In this scenario, a preliminary study of the BERL swirled stabilized burner is carried out in order to understand the impact of blending natural gas with hydrogen on the flame morphology and CO emissions. Preliminary 3D CFD simulations have been run with the purpose to assess the best combination of combustion model (Non Premixed and Partially Premixed Falmelets), turbulence model (Realizable k ɛ and the Reynolds Stress equation model) and chemical kinetic mechanism (GriMech3.0, GriMech 1.2 and Frassoldati). The numerical results of the BERL burner fueled with natural gas have been compared with experimental data in terms of flow patterns, radial temperature profiles, O2, CO and CO2 concentrations. Finally, a 30% hydrogen in natural gas mixture has been considered, keeping fixed the thermal power output of the burner and the global equivalence ratio.

Modeling of Pollutant Formation in Gas Turbine Combustors Using Fast Reactor Network Model

2020 ◽  
Author(s):  
Piyush Thakre ◽  
Ivana Veljkovic ◽  
Vincent Lister ◽  
Graham Goldin
Keyword(s):  
Gas Turbine ◽  
Network Model ◽  
Chemical Mechanism ◽  
Combustion Model ◽  
Detailed Chemistry ◽  
Pollutant Formation ◽  
Flamelet Generated Manifold ◽  
Temperature Solution ◽  
Reactor Network ◽  
Industrial Gas Turbine

Abstract We present a robust, fast, and highly-automated Reactor Network model within a single simulation framework in Simcenter STAR-CCM+. An industrial gas turbine combustor operating at 3 bar is numerically investigated using the GRI 3.0 chemical mechanism. A baseline CFD solution with RANS and Flamelet Generated Manifold combustion model was used to create the network of reactors. A number of model variations have been investigated, such as the use of constant pressure vs. perfectly stirred reactors. Two options for the temperature solution are considered, namely temperature mapped from the CFD solution and temperature computed from an equation of state. Different numbers of reactors are investigated to understand the overall sensitivity on the key combustion results. It was found that with appropriate clustering variables, using a few thousand reactors provide a reasonable representation of the species fields. The simulation results are compared with the available experimental data for the combustor. The NOx and CO emissions predictions with the Reactor Network model perform better than the baseline CFD model. The Reactor Network model was about ∼3 orders of magnitude faster than a detailed chemistry CFD of the same combustor.

Numerical and Experimental Investigation on an Effusion-Cooled Lean Burn Aeronautical Combustor: Aerothermal Field and Emissions

2018 ◽  
Author(s):  
L. Mazzei ◽  
S. Puggelli ◽  
D. Bertini ◽  
A. Andreini ◽  
B. Facchini ◽  
...  
Keyword(s):  
Combustion Process ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Flame Spray ◽  
Lean Burn ◽  
Flamelet Generated Manifold ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
The Impact

Lean burn combustion is increasing its popularity in the aeronautical framework due to its potential in reducing drastically pollutant emissions (NOx and soot in particular). Its implementation however involves significant issues related to the increased amount of air dedicated to the combustion process, demanding the redesign of injection and cooling systems. Also the conditions at the combustor exit are a concern, as high turbulence, residual swirl and the impossibility to adjust the temperature profile with dilution holes determine a harsher environment for nozzle guide vanes. This work describes the final stages of the design of an aeronautical effusion-cooled lean burn combustor. Full annular tests were carried out to measure temperature profiles and emissions (CO and NOx) at the combustor exit. Different operating conditions of the ICAO cycle were tested, considering Idle, Cruise, Approach and Take-Off. Scale-adaptive simulations with the Flamelet Generated Manifold combustion model were performed to extend the validation of the employed CFD methodology and to reproduce the experimental data in terms of RTDF/OTDF profiles as well as emission indexes. The satisfactory agreement paved the way to an exploitation of the methodology to provide a deeper understanding of the flow physics within the combustion chamber, highlighting the impact of the different operating conditions on flame, spray evolution and pollutant formation.

Numerical Analysis of the Combustion Process in Dual-Fuel Engines With Direct Injection of Natural Gas

2018 ◽  
Author(s):  
Michael Jud ◽  
Christoph Wieland ◽  
Georg Fink ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
Direct Injection ◽  
Computing Time ◽  
Combustion Process ◽  
Gas Jet ◽  
Combustion Model ◽  
Dual Fuel ◽  
Detailed Chemistry ◽  
Geometric Configurations ◽  
Temperature Levels

An efficient computational fluid dynamics model for predicting high pressure dual-fuel combustion is one of the most essential steps in order to improve the concept, to reduce the number of experiments and to make the development process more coste-efficient. For Diesel and natural gas such a model developed by the authors is first used to analyze the combustion process with respect to turbulence chemistry interaction and to clarify the question whether the combustion process is limited by chemistry or the mixing process. On the basis of these findings a reduced reaction mechanism is developed in order to save up to 35% of computing time. The prediction capability of the modified combustion model is tested for different gas injection timings representing different degrees of premixing before ignition. Compared to experimental results from a rapid compression expansion machine, the shape of heat release rate, the ignition timing of the gas jet and the burnout are well predicted. Finally, misfiring observed at different geometric configurations in the experiment are analyzed with the model. It is identified that in these geometric configurations at low temperature levels the gas jet covers the preferred ignition region of the diesel jet. Since the model is based on the detailed chemistry approach, it can in future also be used for other fuel combinations or for predicting emissions.

An Assessment of Flamelet Generated Manifold Combustion Model for Predicting Combustor Performance

2015 ◽  
Author(s):  
Samir Rida ◽  
Saugata Chakravorty ◽  
Jaydeep Basani ◽  
Stefano Orsino ◽  
Naseem Ansari
Keyword(s):  
Combustion Model ◽  
Ansys Fluent ◽  
Flamelet Model ◽  
Eddy Simulation ◽  
Primary Zone ◽  
Flamelet Generated Manifold ◽  
Flame Shape ◽  
Partially Premixed ◽  
Partially Premixed Flame ◽  
The Impact

In Rich-Quench-Lean design of aircraft gas turbine combustors, primary zone mixing is critical for emissions, flame shape, and heat transfer. From a modeling perspective, the primary zone flow prediction is largely impacted by the fidelity of the mixing model and the type of combustion model used. The assumption that fuel spray burns in a diffusion flame or in a partially premixed flame has an impact on the combustor’s performance parameters. In this paper, we compare the non-premixed steady diffusion flamelet model with the partially premixed flamelet generated manifold model for several Honeywell combustors using the commercial CFD code ANSYS FLUENT. The validations are made in the context of Large Eddy Simulation and the time averaged CFD results are compared with rig data highlighting the impact of the combustion models on combustor performance. Results show that the flamelet generated manifold combustion model provides a more realistic lifted flame shape that is not in contact with the fuel nozzle.

scholarly journals Raman scattering in high-refractive-index nanostructures

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Søren Raza ◽  
Anders Kristensen
Keyword(s):  
Raman Spectroscopy ◽  
Refractive Index ◽  
Raman Scattering ◽  
Bound States ◽  
Stimulated Raman Scattering ◽  
Dielectric Materials ◽  
High Refractive Index ◽  
Surface Enhanced Raman Spectroscopy ◽  
Raman Enhancement ◽  
The Impact

AbstractThe advent of resonant dielectric nanomaterials has provided a new path for concentrating and manipulating light on the nanoscale. Such high-refractive-index materials support a diverse set of low-loss optical resonances, including Mie resonances, anapole states, and bound states in the continuum. Through these resonances, high-refractive-index materials can be used to engineer the optical near field, both inside and outside the nanostructures, which opens up new opportunities for Raman spectroscopy. In this review, we discuss the impact of high-refractive-index nano-optics on Raman spectroscopy. In particular, we consider the intrinsic Raman enhancement produced by different dielectric resonances and their theoretical description. Using the optical reciprocity theorem, we derive an expression which links the Raman enhancement to the enhancement of the stored electric energy. We also address recent results on surface-enhanced Raman spectroscopy based on high-refractive-index dielectric materials along with applications in stimulated Raman scattering and nanothermometry. Finally, we discuss the potential of Raman spectroscopy as a tool for detecting the optical near-fields produced by dielectric resonances, complementing reflection and transmission measurements.

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