Numerical Simulations of Fan/Airframe Interaction with Active Flow-Control
Résumé
This paper presents a numerical study of a Ultra High Bypass Ratio turbofan (UHBR) with and without active ow control in isolated conditions. Steady and unsteady Reynolds- Averaged Navier-Stokes equations are solved on a 360° representation of the isolated engine, where the rotating fan and the outlet guide vane (OGV) are fully modelled to analyse the interaction with the airframe. Spatial and temporal resolution are discussed, and different approaches are proposed providing increasing levels of fidelity. The configuration is first investigated without control for various angles of attack at low-speed conditions. Then, the angle of attack is increased until massive ow detachment is observed, and active ow-control technique is proposed to mitigate the impact of the separated zone using ow-suction upstream of the fan. A parametric study is proposed using steady- state simulations, aiming at evaluating the most efficient configuration that allows a gain in the overall performance of the engine while limiting the costs induced by the control device. This work has been conducted in the framework of the European funded Clean Sky 2 project ASPIRE, aiming at demonstrating the ability of existing numerical and experimental methods to accurately assess the aerodynamic and acoustic performance of UHBR engines thanks to a reliable modelling of fan/airframe physical interactions.
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