Abstract:
Dynamic load due to gust exerted to helicopter rotors directly affects the structural stress and flight performance for helicopters. In order to obtain more realistic force information for helicopters in detailed design stage, a rotor-fuselage coupled aeroelastic model in the time domain is constructed. A structure model based on medium-deflection beam theory and a nonlinear dynamics model based LB model are built. In consideration of the effect of fuselage, coupled with structure and aerodynamics, this model is built to investigate the performance in hover and in forward flight with two kinds of gust. The calculation results are compared with the results of isolated rotors model. From the result of gust response calculation, it can be observed that, in hover state, when rotor suffers a downward gust, both shear force at the blade root and the thrust force coefficient decrease. The shear force of the rotor coupled with the fuselage is a little lower than the result of the isolated rotor. In the forward flight state, the shear force increases when a gust is added on the rotor. The thrust coefficient on the rotor disk for the rotor coupled with fuselage model decreases. The calculation result at the advanced ratio of 0.35 in the forward flight for the two models is different from the calculation response at the advanced ratio of 0.2. It can be concluded that the calculation result of isolated rotor is conservative. In order to provide more accurate response prediction, the fuselage coupled effect should be taken into consideration in calculation models.