Assessing Turbofan Modeling Approaches in the DLR TAU-Code for Aircraft Aerodynamics Investigations

Abstract

In the context of an increased focus on fuel efficiency and environmental impact, turbofan engine developments continue towards larger bypass ratio engine designs, with UltraHigh Bypass Ratio (UHBR) engines becoming a likely powerplant option for future commercial transport aircraft. These engines promise low specific fuel consumption at the engine level, but the resulting size of the nacelle poses challenges in terms of the installation on the airframe. Thus their integration on an aircraft requires careful consideration of complex engine-airframe interactions impacting performance, aeroelastics and aeroacoustics both on the airframe and the engine sides. As a partner in the EU funded Clean Sky 2 project ASPIRE, the DLR Institute of Aerodynamics and Flow Technology is contributing to an investigation of numerical analysis approaches, which draws on a generic representative UHBR engine configuration specifically designed in the frame of the project. In the present paper, project results will be discussed, which aimed at comparing various engine modeling approaches in the context of external aerodynamics focused CFD simulations with the DLR TAU-Code. The primary focus is the high-fidelity approach with a geometrically fully modeled fan stage, with an in-depth study on spatial and temporal resolution requirements, which will provide the reference data for simpler approaches using classical engine boundary conditions and, in subsequent work, actuator disc or body force models to represent the rotor and stator. The primary aim is to identify the capabilities and shortcomings of each model, develop a best-practice approach in each case and determine the best application scenarios.