Large-Eddy Simulation of a Turbulent Spray Flame Using the Flamelet Generated Manifold Approach

Andreini, Antonio; Bertini, Davide; Facchini, Bruno; Puggelli, Stefano

doi:10.1016/j.egypro.2015.11.822

Cited by 10 publications

(3 citation statements)

References 14 publications

(15 reference statements)

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“…To track the flame front propagation, a transport equation of progress variable C is solved. The model has been applied to many simple combustor-like burners [2,[13][14][15][16][17][18], but far less attention has been paid on the performance of this model in a realistic combustor. In addition, there is a lack of comparative studies on the performance of partially premixed combustion and non-premixed models in complicated flow configurations and most comparisons are only performed in a simplified burner which provides limited confidence for applying these models to realistic gas turbine combustors.…”

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confidence: 99%

Comparative study of non-premixed and partially-premixed combustion simulations in a realistic Tay model combustor

Zhang

Ghobadian

Nouri

2017

Applied Thermal Engineering

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A comparative study of two combustion models based on non-premixed assumption and partially premixed assumptions using the overall models of Zimont Turbulent Flame Speed Closure Method (ZTFSC) and Extended Coherent Flamelet Method (ECFM) are conducted through Reynolds stress turbulence modelling of Tay model gas turbine combustor for the first time. The Tay model combustor retains all essential features of a realistic gas turbine combustor. It is seen that the non-premixed combustion model fails to predict the combustion completely due to an incorrect assumption of diffusion flame scenario invoking infinitely fast chemistry in complicated flow environments while the two partially premixed combustion models accurately predict the flame pattern in the primary region of the combustor. The ZTFSC model outperformed the ECFM model by producing a better temperature agreement with the experimental result. The latter model predicts lower temperature due to the underestimation of reaction progress. Additionally, a cross-comparison of the present RSM prediction invoking ZTFSC model with LES prediction reported in the literature is conducted. The former produces more accurate species concentration and flame pattern than the latter. This is mainly due to the incorrect assumption of nonpremixed combustion used in LES prediction reported in the literature. It is interesting to find that when nonpremixed combustion model is used for both RSM and LES predictions, the LES predicts higher temperature closer to the injection nozzle of combustor than the RSM model, though the flame shape in both cases is incorrect. This is mainly due to the fact that the traditional RANS model dissipates the energy of swirling flow too fast in the primary region of the combustor. The weaker centre recirculation zone (CRZ) created by vortex breakdown recirculate less air to the area near the injection nozzle resulting in fuel rich combustion. It indicates that the temperature difference between predicted results using RSM in conjunction with ZTFC model and experimental results can be improved by using less energy dissipating turbulence models such as scale resolving simulation (SRS). 1. Introduction The advent of Gas-Turbine for military purposes tracks back to 1940s, and it is subsequently used for aviation and later for ground level power [1]. The main challenge of aviation industries nowadays is the efficiency, stability of combustion and pollutant control, such as the emission of carbon dioxide (CO2), nitrogen oxide, sulphur dioxide and etc. In order to design combustors with desired features and meet with relevant criteria, improved understanding of turbulent combustion through both realistic experimental observation and numerical simulation and validation is required. The former alone is expensive for industries before a more cost-effective numerical prediction is performed. However, the accuracy of the numerical simulation is doubtful as it is highly dependent on the turbulence and combustion models, i.e. the mixing and chemical reactions. To i...

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confidence: 99%

Comparative study of non-premixed and partially-premixed combustion simulations in a realistic Tay model combustor

Zhang

Ghobadian

Nouri

2017

Applied Thermal Engineering

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“…Indeed, turbulence has huge effects in swirling reacting flows on both chemistry, spray dynamics, and wall heat transfer. It is, therefore, recommended to adopt Scale Resolving models (SRS) to accurately address the aerothermal field in place of RANS formulations [ 16 , 17 , 18 ]. When dealing with Conjugate Heat Transfer (CHT) calculations, the use of the inherent unsteady Scale Resolving CFD models requires to manage the involved large interval of time scales.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Liner Metal Temperature of an Aeroengine Combustor with Multi-Physics Scale-Resolving CFD

Bertini

Mazzei

Andreini

2021

Entropy

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Computational Fluid Dynamics is a fundamental tool to simulate the flow field and the multi-physics nature of the phenomena involved in gas turbine combustors, supporting their design since the very preliminary phases. Standard steady state RANS turbulence models provide a reasonable prediction, despite some well-known limitations in reproducing the turbulent mixing in highly unsteady flows. Their affordable cost is ideal in the preliminary design steps, whereas, in the detailed phase of the design process, turbulence scale-resolving methods (such as LES or similar approaches) can be preferred to significantly improve the accuracy. Despite that, in dealing with multi-physics and multi-scale problems, as for Conjugate Heat Transfer (CHT) in presence of radiation, transient approaches are not always affordable and appropriate numerical treatments are necessary to properly account for the huge range of characteristics scales in space and time that occur when turbulence is resolved and heat conduction is simulated contextually. The present work describes an innovative methodology to perform CHT simulations accounting for multi-physics and multi-scale problems. Such methodology, named U-THERM3D, is applied for the metal temperature prediction of an annular aeroengine lean burn combustor. The theoretical formulations of the tool are described, together with its numerical implementation in the commercial CFD code ANSYS Fluent. The proposed approach is based on a time de-synchronization of the involved time dependent physics permitting to significantly speed up the calculation with respect to fully coupled strategy, preserving at the same time the effect of unsteady heat transfer on the final time averaged predicted metal temperature. The results of some preliminary assessment tests of its consistency and accuracy are reported before showing its exploitation on the real combustor. The results are compared against steady-state calculations and experimental data obtained by full annular tests at real scale conditions. The work confirms the importance of high-fidelity CFD approaches for the aerothermal prediction of liner metal temperature.

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“…Indeed, in swirling reacting flows turbulence has huge effects on both the chemistry and spray as well as on the wall heat fluxes. For this reason, the aerothermal field cannot be properly predicted by RANS and Scale-Resolving Simulations (SRSs) should be recommended [16][17][18]. However, the unsteady nature of SRSs requires to handle a wide range of time scales involved in Conjugate Heat Transfer (CHT) problems.…”

Section: Introductionmentioning

confidence: 99%

Multiphysics Numerical Investigation of an Aeronautical Lean Burn Combustor

Bertini

Mazzei

Andreini

et al. 2019

Volume 5B: Heat Transfer

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The importance of the combustion chamber has been underestimated for years by aeroengine manufacturers that focused their research efforts mainly on other components, such as compressor and turbine, to improve the engine performance. Nevertheless, stricter requirements on pollutant emissions have contributed to increase the interest on combustor development and, nowadays, new design concepts are widely investigated. To meet the goals of ACARE FlightPath 2050 and future ICAO-CAEP standards one of the most promising results is provided by the Lean Burn technology. As this combustion mode is based on a lean Primary Zone, the air devoted to liner cooling is restricted and advanced cooling systems must be exploited to obtain higher overall effectiveness. The pushing trends of Turbine Inlet Temperature and Overall Pressure Ratio in modern aeroengine are not supported enough by the development of materials, thus making the research branch of liner cooling increasingly relevant. In this context, Computational Fluid Dynamics is able to predict the flow field and the complex interactions between the involved phenomena, supporting the design of modern Lean Burn combustors in all stages of the process. RANS approaches provide a solution of the problem with low computational cost, but can lack in accuracy when the flow unsteadiness dominates the fluid dynamics and the strong interactions, as in aeroengine combustors. Even if steady simulations can be easily employed in the preliminary design, their inaccuracy can be detrimental for an optimized combustor design and Scale-Resolving methods should be preferred, at least, in the final stages. Unfortunately, having to deal with a multiphysics problem as Conjugate Heat Transfer (CHT) in presence of radiation, these simulations can become computationally expensive and some numerical treatments are required to handle the wide range of time and space scales in an unsteady framework. In the present work the metal temperature distribution is investigated from a numerical perspective on a full annular aeronautical lean burn combustor operated at real conditions. For this purpose, the U-THERM3D multiphysics tool was developed in ANSYS Fluent and applied on the test case. The results are compared against RANS and experimental data to assess the tool capability to handle the CHT problem in the context of scale-resolving simulations.

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Large-Eddy Simulation of a Turbulent Spray Flame Using the Flamelet Generated Manifold Approach

Cited by 10 publications

References 14 publications

Comparative study of non-premixed and partially-premixed combustion simulations in a realistic Tay model combustor

Comparative study of non-premixed and partially-premixed combustion simulations in a realistic Tay model combustor

Prediction of Liner Metal Temperature of an Aeroengine Combustor with Multi-Physics Scale-Resolving CFD

Multiphysics Numerical Investigation of an Aeronautical Lean Burn Combustor

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