58945 - Multi-Objective Optimization of Aero Engine Combustor Adopting an Integrated Procedure for Aero-Thermal Preliminary Design 

The preliminary design of an aero engine combustor is a multidisciplinary process which involves an extensive and systematic analysis of the design space. Common practice in its exploration is represented by simulation driven approaches, in which several design configurations are numerically analyzed with respect to product’s requirements. This may lead, however, to heterogeneous models interacting each other, sharing miscellaneous information within the process. Moreover, iterative and user-defined approaches result inefficient when multiple and conflicting requirements are in place. In this context, to rely on integrated design methodologies has been demonstrated to be beneficial. Adopting it in a structured approach to design can bring further advantage in deriving an optimal configuration.

In this paper will be presented the application of the Combustor Design System Integration (DSI), a design methodology already described in the context of previous works, to the definition of an optimal combustor preliminary configuration. For doing this, the DSI tools have been included in a dedicated framework to drive the design process. Given a combustor technology suitable for emission reduction, the multi-objective optimization problem has been defined by targeting, at combustor’s exit, an optimal distribution for temperature profiles and patterns. Dilution ports characteristics, such as holes number and dimension as well as the axial position of the row have been selected as design variables. The DSI capabilities, aimed at easing and streamlining the process from the CAD generation step to the post-processing of CFD results, were exploited to guarantee a water-tight design process and minimize the user effort. A proper CFD domain for RANS, constituted by the flame tube region extended to the dilution ports feeding, was adopted for imposing the air split designed for the combustor. With respect to a “complete” combustor sector, this allows a reduction in computational effort while still being representative for its aero-thermal behavior. The optimization task was so carried out through a Response Surface Method (RSM), in which multiple, relevant combustor configurations so called “test points” were simulated and the CFD result elaborated to build a meta-model of the combustor itself.  Always relying on the DSI tools’ capabilities, the suitability of the resulting optimize configuration has been evaluated through an “a posteriori” analysis of thermal conditions and emission levels (NOx and CO).

To support the discussion, a concept based on lean combustion technology developed by Avio Aero in the aim of the homonymous EU research project, NEWAC, have been considered as test case.