APPLICATION OF IMPOSED MOTION METHOD FOR MODEL FLUTTER TESTS IN HIGH-SPEED WIND TUNNELS

摘要

A brief background on Frequency Response Functions (FRFs) measurement technology applied to mechanical systems on the basis of imposed motion method (kinematic excitation method) is presented herein. Shown is the possibility to use analysis to evaluate an effect of adding extra concentrated mass, stiffness and damping, in the points of application of driving forces, on the FRFs of a tested article with use of experimental FRFs of initial unmodified structure as a reference. The capabilities of the technology for flutter research are demonstrated by the example of GVT of a dynamically-scaled model of an all-movable stabilizer intended for flutter wind tunnel tests, with an electro hydraulic actuator used to impose model displacement in the driving point. The test techniques, as well as details of measuring FRFs under wind tunnel flow conditions with the use of specific multi-sine test signal for structure excitation are described. Presented are examples of measured in-flow model FRFs, and identified modal data as a function of flow parameters, including eigenfrequencies, eigendamping and eigenmodes recovered for unmodified model (free of the links imposed by the actuator) at flow speed beyond flutter boundary.