The flying-wing underwater glider (UG), shaped as a blended wing body, is a new type of underwater vehicle and still requires further research. The shape layout and the configuration of the internal actuators of the f...The flying-wing underwater glider (UG), shaped as a blended wing body, is a new type of underwater vehicle and still requires further research. The shape layout and the configuration of the internal actuators of the flying-wing UG are different from those of "legacy gliders" which have revolving bodies, and these two factors strongly affect the dynamic performance of the vehicle. Considering these differences, we propose a new configuration of the internal actuators for the flying-wing UG and treat the flying-wing UG as a multi-body system when establishing its dynamic model. In this paper, a detailed dynamic model is presented using the Newton-Euler method for the flying-wing UG. Based on the full dynamic model, the effect of the internal actuators on the steady gliding motion of vehicle is studied theoretically, and the relationship between the state parameters of the steady gliding motion and the controlled variables is obtained by solving a set of equilibrium equations. Finally, the behaviors of two classical motion modes of the glider are analyzed based on the simulation. The simulation results demonstrate that the motion performance of the proposed flying-wing UG is satisfactory.展开更多
Fluidic Thrust Vectoring(FTV)is used for the yaw attitude control of tailless flying wing,which can significantly improve stealth performance,maneuverability and lateral/heading maneuverability.The FTV control scheme ...Fluidic Thrust Vectoring(FTV)is used for the yaw attitude control of tailless flying wing,which can significantly improve stealth performance,maneuverability and lateral/heading maneuverability.The FTV control scheme of co-directional secondary flow was designed based on a 30 kgf thrust turbojet engine,an equivalent rudder deflection control variable of Mass Flow Combination(MFC)was proposed,and a control model was established to form a FTV control system scheme,which was integrated with the flight control system of a 100 kg tailless flying wing with medium aspect ratio to achieve closed-loop control of the yaw attitude based on FTV.The heading stability augmentation and maneuvering control characteristics and time response characteristics of tailless flying wing by FTV were quantitatively studied through virtual flight test in a wind tunnel at a wind speed of 35 m/s.The results show that the control strategy based on MFC achieves bidirectional continuous and stable control of thrust vector angle in a range of±11°,and the thrust vector angle varies monotonically with MFC;the co-directional FTV realizes bidirectional continuous and stable control of the yaw attitude of tailless flying wing,without longitudinal/lateral coupling moment.The increment of the maximum yawing moment coefficient is 0.0029,the maximum yaw rate is 7.55(°)/s,and the response time of the yaw rate of the vectoring nozzle actuated by the secondary flow is about 0.06 s,which satisfies the heading stability augmentation and maneuvering control response requirements of the aircraft with statically unstable heading,and provides new control means for the heading rudderless attitude control of tailless flying wing.展开更多
For different flight phases in an overall flight mission,different control and allocation preferences should be pursued considering lift,drag or maneuverability characteristics.The multi-objective flight control alloc...For different flight phases in an overall flight mission,different control and allocation preferences should be pursued considering lift,drag or maneuverability characteristics.The multi-objective flight control allocation problem for a multi-phase flight mission is studied.For an overall flight mission,different flight phases namely climbing,cruise,maneuver and gliding phases are defined.Firstly,a multi-objective control allocation problem considering drag,lift or control energy preference is constructed.Secondly,considering different control preferences at different flight phases,the analytic hierarchical process method is used to construct a comprehensive performance index from different objectives such as lift or drag preferences.The active set based dynamic programming optimization method is used to solve the real-time optimization problem.For the validation,the Innovative Control Effector(ICE)tailless aircraft nonlinear model and the angular acceleration measurements based adaptive Incremental Backstepping(IBKS)are used to construct the validation platform.Finally,an overall flight mission is simulated to demonstrate the efficiency of the proposed multi-phase and multi-objective flight control allocation method.The results show that the comprehensive performance index for different phases,which are determined from the Analytic Hierarchy Process(AHP)method,can suitably satisfy the preference requirements for different flight phases.展开更多
Thrust vectoring technology plays an important role in improving the maneuverability of aircraft.In order to overcome the disadvantages of mechanical thrust vectoring nozzles,such as complications of structure and sig...Thrust vectoring technology plays an important role in improving the maneuverability of aircraft.In order to overcome the disadvantages of mechanical thrust vectoring nozzles,such as complications of structure and significant increases in weight and cost,fluidic thrust vectoring noz-zles are proposed.Dual Throat fluidic thrust vectoring Nozzle(DTN)has received wide attention due to its excellent thrust vectoring efficiency and minimal thrust loss.In this study,three-dimensional unsteady numerical simulations of a single axisymmetric DTN are conducted first to analyze its dynamic response.Then the pitch and yaw control characteristics of DTN equipped on a flying-wing aircraft are investigated.It is found that the dynamic response will experience three stages:rapid-deflecting stage,oscillating stage,and steady stage.A complete recirculation zone forms at the end of the rapid-deflecting stage,which pushes the primary flow to attach to the wall opposite the secondary injection.Meanwhile,the exhaust flow is deflected.In terms of DTN's appli-cation,the DTN equipped on the flying-wing aircraft is capable of providing effective pitch and yaw moments at all angles of attack and Mach numbers.In addition,continuous pitch and yaw moments can be obtained by adjusting the secondary mass flow ratios.The control moment is gen-erated due to the asymmetrical pressure distribution of nozzle surface,which is mainly contributed by the pressure decrease on the secondary injection surface.Moreover,the DTN equipped on the flying-wing aircraft has a relatively high thrust vectoring efficiency of around 5°/%and a thrust coefficient of around 0.95 when nozzle pressure ratio equals 4.These results provide an important theoretical basis for the practical application of DTN.展开更多
文摘The flying-wing underwater glider (UG), shaped as a blended wing body, is a new type of underwater vehicle and still requires further research. The shape layout and the configuration of the internal actuators of the flying-wing UG are different from those of "legacy gliders" which have revolving bodies, and these two factors strongly affect the dynamic performance of the vehicle. Considering these differences, we propose a new configuration of the internal actuators for the flying-wing UG and treat the flying-wing UG as a multi-body system when establishing its dynamic model. In this paper, a detailed dynamic model is presented using the Newton-Euler method for the flying-wing UG. Based on the full dynamic model, the effect of the internal actuators on the steady gliding motion of vehicle is studied theoretically, and the relationship between the state parameters of the steady gliding motion and the controlled variables is obtained by solving a set of equilibrium equations. Finally, the behaviors of two classical motion modes of the glider are analyzed based on the simulation. The simulation results demonstrate that the motion performance of the proposed flying-wing UG is satisfactory.
文摘Fluidic Thrust Vectoring(FTV)is used for the yaw attitude control of tailless flying wing,which can significantly improve stealth performance,maneuverability and lateral/heading maneuverability.The FTV control scheme of co-directional secondary flow was designed based on a 30 kgf thrust turbojet engine,an equivalent rudder deflection control variable of Mass Flow Combination(MFC)was proposed,and a control model was established to form a FTV control system scheme,which was integrated with the flight control system of a 100 kg tailless flying wing with medium aspect ratio to achieve closed-loop control of the yaw attitude based on FTV.The heading stability augmentation and maneuvering control characteristics and time response characteristics of tailless flying wing by FTV were quantitatively studied through virtual flight test in a wind tunnel at a wind speed of 35 m/s.The results show that the control strategy based on MFC achieves bidirectional continuous and stable control of thrust vector angle in a range of±11°,and the thrust vector angle varies monotonically with MFC;the co-directional FTV realizes bidirectional continuous and stable control of the yaw attitude of tailless flying wing,without longitudinal/lateral coupling moment.The increment of the maximum yawing moment coefficient is 0.0029,the maximum yaw rate is 7.55(°)/s,and the response time of the yaw rate of the vectoring nozzle actuated by the secondary flow is about 0.06 s,which satisfies the heading stability augmentation and maneuvering control response requirements of the aircraft with statically unstable heading,and provides new control means for the heading rudderless attitude control of tailless flying wing.
基金co-supported by the National Natural Science Foundation of China(No.11502008)Aeronautical Science Foundation of China(Nos.2017ZA51002,20185702003)the Fundamental Research Funds for the Central Universities of China(No.YWF-19-BJ-J-280)。
文摘For different flight phases in an overall flight mission,different control and allocation preferences should be pursued considering lift,drag or maneuverability characteristics.The multi-objective flight control allocation problem for a multi-phase flight mission is studied.For an overall flight mission,different flight phases namely climbing,cruise,maneuver and gliding phases are defined.Firstly,a multi-objective control allocation problem considering drag,lift or control energy preference is constructed.Secondly,considering different control preferences at different flight phases,the analytic hierarchical process method is used to construct a comprehensive performance index from different objectives such as lift or drag preferences.The active set based dynamic programming optimization method is used to solve the real-time optimization problem.For the validation,the Innovative Control Effector(ICE)tailless aircraft nonlinear model and the angular acceleration measurements based adaptive Incremental Backstepping(IBKS)are used to construct the validation platform.Finally,an overall flight mission is simulated to demonstrate the efficiency of the proposed multi-phase and multi-objective flight control allocation method.The results show that the comprehensive performance index for different phases,which are determined from the Analytic Hierarchy Process(AHP)method,can suitably satisfy the preference requirements for different flight phases.
基金supported by the National Natural Science Foundation of China (Nos.U2141253 and 11721202).
文摘Thrust vectoring technology plays an important role in improving the maneuverability of aircraft.In order to overcome the disadvantages of mechanical thrust vectoring nozzles,such as complications of structure and significant increases in weight and cost,fluidic thrust vectoring noz-zles are proposed.Dual Throat fluidic thrust vectoring Nozzle(DTN)has received wide attention due to its excellent thrust vectoring efficiency and minimal thrust loss.In this study,three-dimensional unsteady numerical simulations of a single axisymmetric DTN are conducted first to analyze its dynamic response.Then the pitch and yaw control characteristics of DTN equipped on a flying-wing aircraft are investigated.It is found that the dynamic response will experience three stages:rapid-deflecting stage,oscillating stage,and steady stage.A complete recirculation zone forms at the end of the rapid-deflecting stage,which pushes the primary flow to attach to the wall opposite the secondary injection.Meanwhile,the exhaust flow is deflected.In terms of DTN's appli-cation,the DTN equipped on the flying-wing aircraft is capable of providing effective pitch and yaw moments at all angles of attack and Mach numbers.In addition,continuous pitch and yaw moments can be obtained by adjusting the secondary mass flow ratios.The control moment is gen-erated due to the asymmetrical pressure distribution of nozzle surface,which is mainly contributed by the pressure decrease on the secondary injection surface.Moreover,the DTN equipped on the flying-wing aircraft has a relatively high thrust vectoring efficiency of around 5°/%and a thrust coefficient of around 0.95 when nozzle pressure ratio equals 4.These results provide an important theoretical basis for the practical application of DTN.
