04.2 - Aerostructures Design, Structural Dynamics, Aeroelasticity
REDUCED ORDER MODELLING OF UNSTEADY AERODYNAMICS FOR GROUND FLUTTER TEST SYSTEM
W.-Z. Feng¹, J.-H. Zhang¹, Z.-H. Liang¹, W. Qian¹; ¹Dalian University of Technology, China
Ground Flutter Test (GFT) technique is a recently developed flutter test technique for carrying out flutter test on full scale aircraft configures based on GVT devices and an efficient Reduce Order Model (ROM) of unsteady aerodynamics. The key techniques of GFT system are the loading of equivalent unsteady aerodynamic force by using electromagnetic shakers and the convergence of continuously distributed aerodynamic force into equivalent concentrated forces. In this paper, an equivalent ROM of unsteady aerodynamic force on several concentrated points are developed based frequency domain unsteady aerodynamic theory and surface spline interpolation technique. The genetic optimization algorithm is used to search the optimized location of concentrated points for the best fits of equivalent unsteady aerodynamic forces. Then, the minimum state method in rational function fitting is used to transform the frequency domain ROM of aerodynamic force into time domain. A real-time simulation of GFT system is carried out based the presented ROM model and Simulink units of other physical devices used in GFT system. Flutter phenomenon appears in flutter test using GFT system. The frequency domain and time domain validation of equivalent unsteady aerodynamics are carried out using equivalent unsteady aerodynamics for flutter calculation. The results show that frequency domain error does not exceed 5% and the time domain error does not exceed 8%. Which validates correctness of the present method.