Convegni ATI - Accesso riservato soci CTI

Autore: A. Andreini, B. Facchini, L. Mangani, A. Asti, G.Ceccherini, R. Modi

Collana: CA - 60 - Roma 2005

Note:
In gas turbine design, the reduction of pollutant emissions is one of the driving design requirements. Especially in mature markets, authorizations to install new plants are granted provided emissions meet restrictive limits, in a wide range of ambient temperatures and loads. To meet such requirements, design techniques have to take advantage of the most recent CFD tools. This paper reports the results of a reactive 3D
numerical! study of a single-can combustor for the GE 10 gas turbine, recently updated by GE-Energy.
This work aims to evaluate the effects on the flame shape and on NOx emissions of a new pilot-system (located on the upper part of the liner. The former GE10 combustor is equipped with fuel-injecting-holes realizing purely diffusive pilot-flames. To reduce NOx emissions from the current 25 ppmvd@15%02 to less than 15 ppmvd@15%O2, the new version of the combustor is equipped with 4 swirler-burners realizing leanpremixed
pilot flames; these flames are themselves stabilized by a minimal amount of diffusive subpilot-fuel. The overall goal of this new configuration is the reduction of the fraction of fuel burnt by diffusion, lowering peak temperatures and therefore NOx emissions.
The study was performed with a detailed reactive RANS study using STAR-CDTM package. Specific combustion and NOx emissions models were employed as user defined routines. Three different ambient temperatures were simulated and the results were then compared with experimental data, resulting in reasonable agreement.
Finally, an additional simulation with an advanced combustion model, based on the laminar flamelet approach, was performed. The model is based on the G-Equation scheme but was modified to study partiallypremixed flames. A geometric procedure to solve G-Equation was implemented as add-on in STAR-CDTM code.