Wind-Tunnel Test at DNW-TWG on "Impact of Structural Damping Nonlinearity in Transonic Limit-Cycle Oscillations (LCO)"

Kurzfassung

This test report describes briefly a part of a wind-tunnel test campaign TWG200323WBAE carried out by DLR at DNW-TWG for and in cooperation with the Arizona State University (ASU) between June 30th and July 15th, 2004. This R&D activity was performed in the field of "Impact of Structural Damping Nonlinearity in Transonic Limit-Cycle Oscillations (LCO)" within a AFOSR project grant/contract no. F49620-02-1-0066, P00002. A wind-tunnel flutter experiment of the supercritical airfoil NLR 7301 at flow conditions near the transonic dip was conducted. The airfoil was nounted with two degrees-of-freedom in an adaptive solid-wall wind-tunnel, and boundary-layer transition was tripped. In the first part of the test campaign the flutter boundaries of a clean configuration, i.e. without the impact of structural nonlinearities were detected. Furthermore, limit-cycle oscillations (LCO) at the clean configuration were recorded. In the second part of the test campaign the impact of structural damping nonlinearities were investigated by recording the flutter behaviour with attached torsional friction devices provided by ASU.