Based on investigations into the flow field of ducted fan aircrafts,structural parameters of duct are quantified.A three-dimensional model is established for numerical simulation,and adaptive Cartesian grid is used to...Based on investigations into the flow field of ducted fan aircrafts,structural parameters of duct are quantified.A three-dimensional model is established for numerical simulation,and adaptive Cartesian grid is used to mesh the model in order to improve calculation speed and solution accuracy.Three-dimensional Navier-Stokes equations are brought in to analyze different duct styles.Generalization of simulation results leads to several conclusions in duct aerodynamics to help design ducted fan aircrafts.展开更多
A novel coaxial ducted fan structure aircraft is proposed to enable the aircraft near vertical walls at high altitudes.The state space equation of the system can be obtained by correlation deduction and identification...A novel coaxial ducted fan structure aircraft is proposed to enable the aircraft near vertical walls at high altitudes.The state space equation of the system can be obtained by correlation deduction and identification of the whole prototype model.Based on the duct test bench experiment and computational fluid dynamics(CFD)simulation analysis,the expressions between the different distances dWE from the rotor center of the prototype to the wall and the thrust,reaction torque,and tilting moment of the system under hovering conditions are obtained.The influence of the wall effect of the prototype is incorporated into the system model to analyze the relationship between distance dWE and the comprehensive controllability of the system.The results show that the system comprehensive controllability vector of other channels changes little with the decrease of the distance dWE,and only the controllability vector of the rolling channel increases significantly.At the same time,the tilting moment also increases significantly,which strengthens the tendency of the prototype to tilt towards the wall.展开更多
This paper is concerned with the robust adaptive fault-tolerant control of a tandem coaxial ducted fan aircraft under system uncertainty, mismatched disturbance, and actuator saturation.For the proposed aircraft, comp...This paper is concerned with the robust adaptive fault-tolerant control of a tandem coaxial ducted fan aircraft under system uncertainty, mismatched disturbance, and actuator saturation.For the proposed aircraft, comprehensive controllability analysis is performed to evaluate the controllability of each state as well as the margin to reject mismatched disturbance without any knowledge of the controller. Mismatched disturbance attenuation is ensured through a structured Hinfinity controller tuned by a non-smooth optimization algorithm. Embedded with the H-infinity controller, an adaptive control law is proposed in order to mitigate matched system uncertainty and actuator fault. Input saturation is also considered by the modified reference model. Numerical simulation of the novel ducted fan aircraft is provided to illustrate the effectiveness of the proposed method. The simulation results reveal that the proposed adaptive controller achieves better transient response and more robust performance than classic Model Reference Adaptive Control（MRAC） method, even with serious actuator saturation.展开更多
文摘Based on investigations into the flow field of ducted fan aircrafts,structural parameters of duct are quantified.A three-dimensional model is established for numerical simulation,and adaptive Cartesian grid is used to mesh the model in order to improve calculation speed and solution accuracy.Three-dimensional Navier-Stokes equations are brought in to analyze different duct styles.Generalization of simulation results leads to several conclusions in duct aerodynamics to help design ducted fan aircrafts.
基金Supported by the National Key Research and Development Project(2020YFC1512500)。
文摘A novel coaxial ducted fan structure aircraft is proposed to enable the aircraft near vertical walls at high altitudes.The state space equation of the system can be obtained by correlation deduction and identification of the whole prototype model.Based on the duct test bench experiment and computational fluid dynamics(CFD)simulation analysis,the expressions between the different distances dWE from the rotor center of the prototype to the wall and the thrust,reaction torque,and tilting moment of the system under hovering conditions are obtained.The influence of the wall effect of the prototype is incorporated into the system model to analyze the relationship between distance dWE and the comprehensive controllability of the system.The results show that the system comprehensive controllability vector of other channels changes little with the decrease of the distance dWE,and only the controllability vector of the rolling channel increases significantly.At the same time,the tilting moment also increases significantly,which strengthens the tendency of the prototype to tilt towards the wall.
文摘This paper is concerned with the robust adaptive fault-tolerant control of a tandem coaxial ducted fan aircraft under system uncertainty, mismatched disturbance, and actuator saturation.For the proposed aircraft, comprehensive controllability analysis is performed to evaluate the controllability of each state as well as the margin to reject mismatched disturbance without any knowledge of the controller. Mismatched disturbance attenuation is ensured through a structured Hinfinity controller tuned by a non-smooth optimization algorithm. Embedded with the H-infinity controller, an adaptive control law is proposed in order to mitigate matched system uncertainty and actuator fault. Input saturation is also considered by the modified reference model. Numerical simulation of the novel ducted fan aircraft is provided to illustrate the effectiveness of the proposed method. The simulation results reveal that the proposed adaptive controller achieves better transient response and more robust performance than classic Model Reference Adaptive Control（MRAC） method, even with serious actuator saturation.
