Aero-Structural Wind Tunnel Experiments with Elastic Wing Models at High Reynolds Numbers (HIRENASD - ASDMAD)

Abstract

The SFB 401 Flow Modulation and Fluid-Structure Interaction at Airplane Wings at RWTH Aachen has first performed experiments in the European Transonic Windtunnel (ETW) with a swept elastic clean wing model in its central project High Reynolds Number Aero-Structural Dynamics (HIRENASD). Mach numbers were in the transonic regime. The model has been excited for vibration applying span-wise acting interior force couples in the wing root region. The structure is made from linear elastic material and consists of the wing model and its suspension in the wind tunnel. In the follower project ASDMAD the model has been shortened in the tip range to be equipped and tested in ETW in succession with two different winglets. Data from one series of experiments is already available and is used to compare with HIRENASD results for corresponding wind tunnel conditions. In the HIRENASD project, the analysis of the raw data for quasi-stationary tests brought to light weak upstream running pressure waves behind shocks or even upstream running shocks forming from steepening compression waves when the transonic regime is still being established. This phenomenon was not observed as clearly in the data from the ASDMAD experiments. For excited vibration the results are more comparable. A convincing argument was elaborated from the HIRENASD data, why artificial transition in aero-elastic experiments at low Reynolds number cannot replace experiments at realistic Reynolds numbers.