| The analysis on the ducted tail rotor's flowfield and aerodynamic characteristics is a challenging subject in the field of helicopter aerodynamics. In this thesis, a numerical simulation method is established by solving the turbulent Navier-Stokes equations coupled with the momentum source model. Based on this method, the effects of different design parameters of ducted tail rotor on its flowfield and aerodynamic characteristics in hover, sideward flight and forward flight are investigated emphatically. The major research work in the thesis is as follows: As the background of the current work, the domestic and overseas research results on the aerodynamic characteristics of ducted tail rotors have been introduced briefly, and it is pointed out that the CFD method based on the momentum source model is important for the research of helicopter shroud tail rotor aerodynamic characteristics.In Chapter 2, a multi-block structured mesh generation method around the flowfield of ducted tail rotor has been established by considering the geometry characters of ducted tail rotor and the momentum source model.In Chapter 3, based on the Jameson finite volume method and the momentum source model which is used to consider the effect of rotor blades on its flow field, a numerical method suitable to solve the flowfield of helicopter ducted tail rotor has been developed.In Chapter 4, the TsAGI and FANTAIL ducted tail rotor is taken as numerical examples and the spanwise distributions of the blade section thrust and axial induced velocity are calculated. The validity of the present method is demonstrated by comparing the calculated results with available experimental data.In Chapter 5, the flowfield and aerodynamic characteristics of the helicopter ducted tail rotor with different design parameter (tip gap shroud and shroud lip radii) have been investigated respectively. Based on the above investigation, some meaningful conclusions are given.
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