On the experiment of receptances of rotating rotor model

Avoiding resonance is the basic requirement to keep a helicopter in a low vibration level, so it is of importance to determine the natural frequencies of the coupled rotor-fuselage system. In order to attain the aim, the receptances of the fuselage and the rotor must be known respectively. The former may be relatively easy to get, such as using the Finite Element Method. However, at present there is no good method which can perfectly determine the receptances of a rotating rotor, and there is much difficulty in direct measurement from the real rotor in rotation. Before this paper, the authors have developed a method to calculate the receptances of a rotating rotor. In this paper, a rotating rotor model is designed and a program is presented to test the receptances of the rotating rotor model. The testing results are given. The results show that the in-plane receptances couple each other in the orthogonal directions, and furthermore they will couple the receptances of fuselage in the coupled rotor-fuselage system. The comparisons between experimental results and theoretical results attest to the feasibility of the approach and the correctness of the formulas deduced by ourselves.