Computational Investigation On Interactional Aerodynamics Of Rotor Flowfield

Research on the aerodynamic interaction between the rotors and components of rotorcraft have been a very important aspect and a very challenging subject in Rotorcraft Aerodynamics. This thesis is aimed at the interaction aerodynamics problem on the rotor flowfield of a helicopter and a tilt-rotor aircraft by applying the rotor vortex theory and the panel method, and the major contributions of the author's research work are as follows:Based on the blade Weissinger-L model, rotor roll-up tip vortex model and rotor trim model, a free-wake analytical method is developed in Chapter 2 for the analysis of the rotor down wash flow field of a helicopter and a tiltrotor aircraft.Based upon the free wake model, the influence of the rotor downwash on rocket trajectories are calculated and analyzed in Chapter 3. The comparisons between the present calculations and available experimental data are made and the capability of the present method is demonstrated.In Chapter 4, the above free-wake method is improved to predict the interactional aerodynamic characteristics of twin tilt-rotors, and some new results are acquired.In Chapter 5, a new dynamic wake model is developed by employing the rotor free-wake method in chapter 2, and is used to investigate the curve distortion during the conversion of tiltrotor aircraft between helicopter flight conditions and airplane flight conditions.An analytical model combining the above rotor free-wake method with a fuselage source panel method is presented and used to investigate the interactional influence of the fuselage on its rotor in hover and forward flight in Chapter 6, and some conclusions are obtained.Finally, an iterative method coupled between rotor free wake model and lifting wing panel model is given. By the method, the aerodynamic interaction of the rotor on its wing for tilt-rotor aircraft in hover are computed and discussed.