Towards understanding and prediction of strake vortices on aircraft

Kurzfassung

On modern transport aircraft the front part of the highlift system for take­off and landing, called slat, needs to have a gap where the jet engine is mounted. In this region, the flow on the main wing is more prone to flow separation. To counteract this effect, the engine nacelles are equipped with small vortex generators, called strakes. The longitudinal vortices generated by these strakes interact with the flow on the main wing upper surface and have a stabilizing effect on it. However, the physical mechanism of this vortex/boundary­ layer interaction is not yet fully understood. Moreover, for the design of new aircraft the involved flow physics need to be accurately predicted by engineering simulation methods. Thus, one goal of this project was to generate highly accurate simulation data of the flow around a simplified strake ­ an inclined Delta wing ­ by means of an academic simulation method (wall­-resolved large­-eddy simulation, LES). With these data the physical mechanisms of vortex development and wandering has been studied in detail. Besides, the data has been used to improve and validate a more efficient, but less accurate simulation method (hybrid RANS/LES) that is feasible for engineering purposes.