Design of a UHBR Through Flow Nacelle for High Speed Stall Wind Tunnel Investigations

Abstract

The design of a new through flow nacelle for the Airbus XRF1 wind tunnel model is presented. The nacelle is representative of a modern UHBR turbofan engine for long range transport aircraft and was especially designed to investigate the interaction of buffet phenomena on the wing lower side, pylon and nacelle within the research unit FOR 2895. During the design process the performance of the through flow nacelle was evaluated by performing RANS simulations with the DLR TAU code using Spalart-Allmaras as well as Reynolds- Stress turbulence models. For the initial nacelle design simulations of the isolated nacelle were performed. Having obtained an initial nacelle shape, it was integrated in the XRF1 CAD model. A pylon geometry was designed and a baseline nacelle position and orientation was defined. The numerical simulations proved the configuration with nacelle and pylon shows adequate performance under cruise conditions without exhibiting unusual adverse effects on the aircraft. As intended, significant shock induced separations were observed on the wing lower side inboard of the nacelle for high speed off-design conditions with negative angles of attack allowing the investigation of buffet phenomena. The numerical results were also used to identify suitable locations for the pressure instrumentation on nacelle and pylon for the wind tunnel test at ETW.