Assessing Model Dynamics within the Critical Alpha Range

Abstract

The European Transonic Windtunnel (ETW) is Europe’s unique testing facility for high Reynolds number testing, enabling the aircraft manufactures to test their designs under real flight Reynolds and Mach numbers at defined aeroelastic conditions. Driven by the increasing demand for flight Reynolds number wind tunnel testing up to the boundaries of the flight envelope and beyond, the European Transonic Windtunnel has enhanced its productivity for this type of testing by improving its capabilities to assess the model dynamics. This is on one side essential to provide more valuable data for the clients and on the other hand to secure ETW’s high safety standards for tunnel and model. Serving clients needs to test up to and even beyond the buffet onset while ensuring the mechanical model integrity is challenging. Test conditions at high Reynolds numbers and critical alpha values around the lift breakdown combine high steady loads with the risk of occurring model dynamics such that appropriate risk mitigation measures are vital. The present paper discusses a setup for tests including the critical alpha range, describing the availability of specific instrumentation for such test campaigns, the data acquisition and processing possibilities as well as the applied safety measures. Results of a recent test campaign are used to illustrate the described capabilities.