Abstract:

A new analytical model is developed to analyze rotor dynamic loads.A dynamic inflow model, verified by the experiment of rotor static loads, is included to take unsteady inflow into account.In this analytical model, separation of variables is used to analyze structural response.The flapping displacement of the blade is determined by the flapping generalized displacement and normalized mode shape.Blade bending moment is calculated by force integration method.On the basis of the comprehensive dynamic calibration of a test system, rotor model test stand/rotor balance, rotor dynamic thrust due to collective pitch oscillation is experimentally investigated in hover.During the sine oscillation of collective pitch, signals from the rotor balance are acquired.The dynamic thrust is obtained from the analysis of both the signals and the frequency response function of the test system.Correlation between the prediction of analytical model and the test data is good.From the comparison of calculation with dynamic inflow and quasi steady model, it is discovered that the influence of dynamic inflow on both magnitude and phase of dynamic thrust is significant in low oscillation frequency and low collective pitch.

Key words: helicop ters, ro to rs, loads, hover test, dynam ic inflow