Recent design trends aim at increasing gas turbine efficiency and specific power while reducing NOx emission in the atmosphere. The latter objective is seriously threaten by the continuous increase of mean Turbine Entry Temperature (TET) that guarantees the achievement of two out of the three objectives. The reduction of pollutant emissions could be obtained using the premixed combustor technology, which main characteristic is to prevent the formation of “hot spots”. The development of such kind of combustor involves both experimental and numerical analyses. The main limit of Computational Fluid Dynamics (CFD) has been individuated in the low accuracy in the prediction of the NOx emissions using turbulence models based on the classical eddy viscosity assumption. The evaluation of the flame front relies on the correct estimation of the recirculating structures that are totally driven by fluid-dynamic parameters. Combustion chambers typically operate at low Reynolds number (lower that 100,000) in an incompressible regime, and then Large Eddy Simulation (LES) is sometimes used albeit an accurate analysis of reactive flows using LES is still computationally very expensive. For that reason hybrid LES/RANS approaches collected the interest of the scientific community: amongst them the Scale-Adaptive Simulation (SAS) approach appears to be the most promising. In this work the SAS model implemented in the commercial code ANSYS Fluent® is used to analyse the aero-thermodynamic behaviour of a premixed combustor. SAS is preliminary validated studying the flow around a square cylinder, which is a classical unsteady incompressible test case experimentally analysed by Lyn and Rodi. Data obtained using SAS and URANS are compared with each other. The numerical activity has been performed in the frame of the LaDIEs ISCRA-C project on the HPC PLX cluster, with the support of CINECA.

Hybrid LES/RANS Methods for Turbomachinery Flows: Application of SAS to a Premixed Combustor / Salvadori, S; Cappelletti, A; Carnevale, M; Martelli, F. - STAMPA. - (2012), pp. 1-9. (Intervento presentato al convegno 67° Congresso Nazionale ATI tenutosi a Trieste, Italia nel 11-14 Settembre 2012).

Hybrid LES/RANS Methods for Turbomachinery Flows: Application of SAS to a Premixed Combustor

Salvadori S;
2012

Abstract

Recent design trends aim at increasing gas turbine efficiency and specific power while reducing NOx emission in the atmosphere. The latter objective is seriously threaten by the continuous increase of mean Turbine Entry Temperature (TET) that guarantees the achievement of two out of the three objectives. The reduction of pollutant emissions could be obtained using the premixed combustor technology, which main characteristic is to prevent the formation of “hot spots”. The development of such kind of combustor involves both experimental and numerical analyses. The main limit of Computational Fluid Dynamics (CFD) has been individuated in the low accuracy in the prediction of the NOx emissions using turbulence models based on the classical eddy viscosity assumption. The evaluation of the flame front relies on the correct estimation of the recirculating structures that are totally driven by fluid-dynamic parameters. Combustion chambers typically operate at low Reynolds number (lower that 100,000) in an incompressible regime, and then Large Eddy Simulation (LES) is sometimes used albeit an accurate analysis of reactive flows using LES is still computationally very expensive. For that reason hybrid LES/RANS approaches collected the interest of the scientific community: amongst them the Scale-Adaptive Simulation (SAS) approach appears to be the most promising. In this work the SAS model implemented in the commercial code ANSYS Fluent® is used to analyse the aero-thermodynamic behaviour of a premixed combustor. SAS is preliminary validated studying the flow around a square cylinder, which is a classical unsteady incompressible test case experimentally analysed by Lyn and Rodi. Data obtained using SAS and URANS are compared with each other. The numerical activity has been performed in the frame of the LaDIEs ISCRA-C project on the HPC PLX cluster, with the support of CINECA.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2761099
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