Abstract:
Based on the flight state planning, a new predetermined trimming methodology has been established to investigate the tilt-rotor/wing operational characteristics under conversion flight condition. Firstly, in order to enhance aerodynamic forces computing precision of tilt-rotor, and overcome the dependency on the test data, the two CFD models including Virtual Blade Model (VBM) and Real Blade Model (RBM) are established to simulate the unsteady flowfield of tilt-rotor in conversion mode. In the two CFD models, RANS equations are employed as government equations, and the implicit LU-SGS method is used for temporal discretization. Secondly, the two simplified aerodynamic models containing Conventional Rotor Model (CRM) and the new Momentum Actuator Disk Model (MADM) are proposed to improve the computing efficiency of trimming. Additionally, the trimming strategy has been developed based upon the CFD models and the simplified aerodynamic models for the conversion flight condition. After verifying the effectiveness of the above numerical method on calculating the aerodynamic forces of rotor and tilt-rotor, the conversion envelope of XV-15 tilt-rotor is determined by the CRM, and manipulations of XV-15 tilt-rotor in different conversion flight procedures are calculated. Finally, the RBM is employed to simulate the flowfield of XV-15 tilt-rotor in three typical states with trimming.