CFD Modeling of Turbofan Intake Aerodynamics at Crosswind Conditions

Abstract

Crosswind flow at take-off conditions can be a critical operating point for a turbofan engine due to the occurrence of potentially significant flow separation on the intake lip, which may lead to strong unsteady loads on the blades of the fan. In the frame of the project PRESTIGE, nationally funded under the German Luftfahrtforschungsprogramm (Aerospace research program) framework, the DLR Institute of Aerodynamics and Flow Technology collaborated with Rolls-Royce Deutschland on a study to develop and improve the capabilities of modern CFD methods to support intake design and analysis approaches for these challenging flow conditions. Building both on previous collaborations as well as a full-scale engine test at crosswind conditions performed at the Rolls-Royce test site located at the NASA Stennis Space Center in Mississippi, which included the application of novel stereoscopic PIV measurements of the intake flow, the complex crosswind flowfield was studied in detail using various fidelity CFD approaches. The main focus in this paper is a high-fidelity approach with a geometrically fully modeled fan, which will provide the reference data for simpler computations using classical engine boundary conditions and an actuator disc model to represent the rotor. 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.