A 2D Validation Experiment for Dynamic High-Lift System Aerodynamics

Abstract

AbstractThe feasibility of laminar flow control technology for future wing is bound to the development of a leading edge high-lift system that complies with the requirements on smooth surfaces to enable maintaining the laminar boundary layer flow, such as a Krueger flap. Although in principle the aerodynamic performance of a Krueger flap is known, the unsteady behaviour of the flow during deployment and retraction is completely unknown. This is as even more important as during deployment the Krueger flap is exposed to highly unfavourable positions perpendicular to the flow. To mitigate the risk of unfavourable aircraft behaviour, it is therefore expected that a Krueger flap has to be deflected significantly fast and may trigger unsteady aerodynamic effects. Within the European H2020 project UHURA (Unsteady High-Lift Aerodynamics—Unsteady RANS Validation), currently a wind tunnel test is conducted incorporating the vented foldable bull nose Krueger flap. A wind tunnel model based on the DLR-F15 airfoil has been designed and manufactured that features a part span and a full span Krueger device, which can be actuated at high deflection rates up to 360°/s. First wind tunnel tests have been conducted at the ONERA L1 wind tunnel in Lille in October 2020. The tests included the measurements of internal forces, steady and unsteady pressures, as well as phase-locked Particle Image Velocimetry (PIV) to achieve high quality validation data for comparison with numerical methods.KeywordsAerodynmamicsHigh-lift systemKrueger flapUnsteady flowWind tunnel test