| The aerodynamic performance of heavy-lift helicopter rotor is a critical technology in development of the heavy-lift helicopter technology. Its research is significant.Many blades are used in heavy-lift helicopter, leading to largely increased interactions between blades and vortex. The bound vortex wake of the elements and their interactions with rotor wake can be reflected more adequately in the blade aerodynamic model based on the lifting surface / vortex lattice method. Therefore, the lifting surface theory can improve the calculation accuracy of greatly changed induced velocity and airloads when the condition of increasing blade/vortex interactions.In this thesis, the prescribed wake model of heavy-lift helicopter in hover and forward flight has been developed based on lifting surface / vortex lattice method. In hover, the inflow is added to the hover wake model by using the recirculation mechanism, the comparisons between the case studies and experimental data verified the developed model. The hover wake model of the heavy-lift helicopter was used to calculate the effects of number of blades, aspect ratio, linear blade twist and double linear blade twist on the hover aerodynamic performance of rotor, emphasizing the effects of double linear blade twist. In forward flight, blade airloads, flight power and rotor lift-to-drag ratio were calculated using the forward flight model. The comparisons between the numerical results and the experimental data of medium helicopters verified the developed model, then the heavy-lift helicopter forward flight performance was calculated. The forward flight wake model was used to calculate the effects of blade tip, linear blade twist and double linear blade twist on the forward aerodynamic performance, emphasizing the effects of double linear blade twist. The characteristics of heavy-lift helicopter hover performance, forward flight performance and the effects of blade parameters on heavy-lift helicopter performance were obtained. |
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