The reduction of pollutant emissions is one of the key issues of future aero engine combustor design. Therefore low emission combustor design rules have been developed over the last years and are still being improved. To use this knowledge more effectively the preliminary combustor design system PRECODES has been developed in the framework of the European research project INTELLECT D.M. (Integrated Lean Low Emission Combustion Design Methodology). Designing a new combustion chamber requires a lot of know-how in terms of combustion modelling, aerothermal calculations and cooling technology. In PRECODES this knowhow is provided by state-of-the-art Rolls-Royce design rules, which are implemented in an EXCEL database. Based on a set of performance parameters, the combustor layout process is performed automatically using this database. That includes the combustor sizing, the cooling layout and the distribution of the mixing air in order to achieve a low emission combustion process. The database provides two parametric CAD models with the required information. The first parametric model is relatively complex including the flame tube, the prediffuser, the cowl, the metering panel, the heatshield and the casing and is therefore only used for visualisation purposes. The second CAD model is a generic model of the flame tube providing the basis for the automatic mesh generation and CFD analysis. For this purpose the CAD geometry is transferred to the commercial grid generator ICEM-CFD via the ICEM internal direct CAD interface. Based on the CAD geometry a structured mesh is generated automatically applying an ICEM-CFD script, which is exported by the EXCEL based part of the system after the layout process in the database is finished. CFD simulations are also performed automatically by PRECODES, applying the commercial software FLUENT. All boundary conditions are set automatically based on a FLUENT script, which is (similar to the ICEM-CFD script) automatically exported by PRECODES after finishing the combustor layout process in the EXCEL based part of the system. By applying CFD simulations already in the preliminary combustor design phase it is possible to gain detailed information on the temperature distribution inside the combustor. Thus, very accurate estimations of the cooling requirements and the combustor emissions (particularly NOx) can be made based on the developed system. A validation of the system has been performed based on proprietary experimental and numerical BR700 engine data provided by Rolls-Royce Deutschland. Applying the same performance parameters, stability and emission requirements, a very good match in respect to the sizing, cooling and mixing air distribution was obtained utilizing the developed design system.    «

The reduction of pollutant emissions is one of the key issues of future aero engine combustor design. Therefore low emission combustor design rules have been developed over the last years and are still being improved. To use this knowledge more effectively the preliminary combustor design system PRECODES has been developed in the framework of the European research project INTELLECT D.M. (Integrated Lean Low Emission Combustion Design Methodology). Designing a new combustion chamber requires a lo...    »