Numerical Analysis on Interactional Field Among Tilt-rotor/wing/fuselage
|School||Nanjing University of Aeronautics and Astronautics|
|Keywords||tilt-rotor aircraft transition state momentum source flowfield CFD|
The simulation on the tilt-rotor/wing/fuselage interactional flowfield of tilt-rotor aircraft is a challenging and important subject in the field of Helicopter Aerodynamics. In this thesis, a numerical simulation method for the tilt-rotor/wing/fuselage interactional flowfield has been established by presenting a new method of adding the momentum source and solving the Euler equations coupled with the momentum source model. By this method, the characteristics of tilt-rotor aircraft flowfield in unsteady transition state are investigated. Also, investigations are conducted to simulate the flowfield of tiltrotor aircraft in quasi-steady hover and forward flight. The major research work in the thesis is as follows:In Chapter 1, as the background of the current work, the domestic and foreign research results on the flowfield and aerodynamic characteristics of tilt-rotor aircraft are introduced briefly, and the necessity of CFD method based on the momentum source model for the research of tilt-rotor aircraft flowfield is pointed out.In Chapter 2, the characteristic of different flowfield mesh is analyzed, and the V-22 tilt-rotor aircraft is taken as the numerical model. Then a mesh-generation approach around the tilt-rotor aircraft is given which is not only suitable for unsteady transition state but also quasi-steady hovering and forward flight state.In Chapter 3, a new approach of adding the momentum source is presented, the unsteady and steady Euler equation is solved, based on that, a numerical method suitable for solving the flowfield and aerodynamic characteristics of tilt-rotor aircraft in transition, hover and forward flight state is developed, and the computer code is compiled. Then, the simulation of isolated fuselage and rotor flowfield is conducted and the calculated results are compared with available experimental data to demonstrate the validity of the method.In Chapter 4, based on the above numerical simulation method, the analyses on the tilt-rotor/wing/fuselage interactional flowfield in hovering, helicopter-mode forward flight and airplane-mode forward flight state are conducted, respectively. Then the flowfield at different forward velocities are calculated and the effects of forward velocities on tilt-rotor aircraft flowfield are analyzed.In Chapter 5, the tilt-rotors/wing/fuselage interactional flowfield in transition state is calculated and analyzed, some meaningful results are obtained.