Simulation And Analysis Of Smart Rotor With Dual Trailing-edge Flaps

Helicopters have been widely used in both military and civil fields due to their capabilities of vertical take-off and landing, hover, low speed forward flight and even inverted flight, while other aircrafts do not have. However the vibration problem of helicopter is much more severe due to the airflow asymmetry of rotor during forward flight, and it may have a negative effect on the application of helicopters in some extent. Rotor is the most fundamental part of rotorcraft, while it's the main source of vibration, therefore it is essential to take some measures on the blades to reduce the hub vibratory loads. The trailing-edge flap is an effective active vibration control method for helicopter, active flaps deflect according to the given control law in the same revolution as rotor blades, and it will induce additional aerodynamic loads to eliminate some of hub vibration loads.This thesis simulated a smart rotor with dual trailing-edge flaps, and the control laws of dual trailing-edge flaps were got with an optimization method. The advantages of smart rotor of dual trailing-edge flaps were verified and analyzed. Based on the achievements of this research group, a new dynamic analysis model was developed, additional aerodynamic loads of active flaps, including lift, drag and moment, were calculated utilizing Theodorsen's theory. The control law inputs were expanded in the form of Fourier series, control inputs of different frequencies including 2rev, 3rev and 4rev were studied, because these the 3rev hub load is most remarkably affected with this frequencies. Through the phase-swept analysis on control input of individual frequency, the influence of different frequencies control input on hub vibration loads was investigated, and it was found impossible to reduce the all components of hub vibration load at the same time using control of single frequency. Three different configurations of smart rotors with trailing-edge flaps were studied, and their control law of flaps was optimized using Differential Evolution optimization algorithm. The vibration reduction of smart rotors of different configurations of trailing-edge flaps was compared with each other. Results show that the smart rotor with dual trailing-edge flaps is the best one. Smart rotor with dual trailing-edge flaps can reduce all the components of hub vibration load in the same time and it is better than that with only one trailing-edge flap. Additionally, the optimization module and the hub load calculation module were coded using different programming languages. More than one optimization modules could be called by the optimization module simultaneously, computing efficiency was greatly increased, and improvement of the simulation program would be more convenient and simpler in the future research.