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Recent advance in nonlinear aeroelastic analysis and control of the aircraft

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Chinese Journal of Aeronautics 2014年第1期27卷 12-22页

作者： xiang jinwu Yan Yongju Li Daochun School of Aeronautic Science and Engineering Beihang University

A review on the recent advance in nonlinear aeroelasticity of the aircraft is presented in this paper. The nonlinear aeroelastic problems are divided into three types based on different research objects, namely the two dimensional airfoil, the wing, and the full aircraft. Different non- linearities encountered in aeroelastic systems are discussed firstly, where the emphases is placed on new nonlinear model to describe tested nonlinear relationship. Research techniques, especially new theoretical methods and aeroelastic flutter control methods are investigated in detail. The route to chaos and the cause of chaotic motion of two-dimensional aeroelastic system are summarized. Var- ious structural modeling methods for the high-aspect-ratio wing with geometric nonlinearity are dis- cussed. Accordingly, aerodynamic modeling approaches have been developed for the aeroelastic modeling of nonlinear high-aspect-ratio wings. Nonlinear aeroelasticity about high-altitude long- endurance （HALE） and fight aircrafts are studied separately. Finally, conclusions and the chal- lenges of the development in nonlinear aeroelasticity are concluded. Nonlinear aeroelastic problems of morphing wing, energy harvesting, and flapping aircrafts are proposed as new directions in the future.

关键词： Chaos Flutter control Geometric nonlinearity LCO Nonlinear aeroelasticity

Flight safety measurements of UAVs in congested airspace

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Chinese Journal of Aeronautics 2016年第5期29卷 1355-1366页

作者： xiang jinwu Liu Yang Luo Zhangping School of Aeronautic Science and Engineering Beihang University

Describing spatial safety status is crucial for high-density air traffic involving multiple unmanned aerial vehicles （UAVs） in a complex environment. A probabilistic approach is proposed to measure safety situation in congested airspace. The occupancy distribution of the airspace is represented with conflict probability between spatial positions and UAV. The concept of a safety envelope related to flight performance and response time is presented first instead of the conventional fixed-size protected zones around aircraft. Consequently, the conflict probability is performance-dependent, and effects of various UAVs on safety can be distinguished. The uncertainty of a UAV future position is explicitly accounted for as Brownian motion. An analytic approximate algorithm for the conflict probability is developed to decrease the computational consumption. The relationship between safety and flight performance are discussed for different response times and prediction intervals. To illustrate the applications of the approach, an experiment of three UAVs in formation flight is performed. In addition, an example of trajectory planning is simulated for one UAV flying over airspace where five UAVs exist. The validation of the approach shows its potential in guaranteeing flight safety in highly dynamic environment.

关键词： Airspace safety situation Conflict probability Flight conflict Navigation UAV

Aeroservoelastic modeling and analysis of a canard-configured air-breathing hypersonic vehicles

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Chinese Journal of Aeronautics 2013年第4期26卷 831-840页

作者： Zeng Kaichun xiang jinwu Li Daochun School of Aeronautic Science and Engineering Beihang University

Air-breathing hypersonic vehicles （HSVs） are typically characterized by interactions of elasticity, propulsion and rigid-body flight dynamics, which may result in intractable aeroservoelastic problem. When canard is added, this problem would be even intensified by the introduction of low-frequency canard pivot mode. This paper concerns how the aeroservoelastic stability of a canard-configured HSV is affected by the pivot stiffnesses of all-moveable horizontal tail （HT） and canard. A wing/pivot system model is developed by considering the pivot torsional flexibility, fuselage vibration, and control input. The governing equations of the aeroservoelastic system are established by combining the equations of rigid-body motion, elastic fuselage model, wing/pivot system models and actuator dynamics. An unsteady aerodynamic model is developed by steady Shock-Expansion theory with an unsteady correction using local piston theory. A baseline controller is given to provide approximate inflight characteristics of rigid-body modes. The vehicle is trimmed for equilibrium state, around which the linearized equations are derived for stability analysis. A comparative study of damping ratios, closed-loop poles and responses are conducted with varying controller gains and pivot stiffnesses. Available bandwidth for control design is discussed and feasible region for pivot stiffnesses of HT and canard is given.

关键词： Aeroservoelasticity Canard Flight dynamics Hypersonic vehicles Pivot Stability

Design and experimental study of a new flapping wing rotor micro aerial vehicle

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Chinese Journal of Aeronautics 2020年第12期33卷 3092-3099页

作者： Xin DONG Daochun LI jinwu xiang Ziyu WANG School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China

A three-wing Flapping Wing Rotor Micro Aerial Vehicle(FWR-MAV)which can perform controlled flight is introduced and an experimental study on this vehicle is presented.A mechanically driven flapping rotary mechanism is designed to drive the three flapping wings and generate lift,and control mechanisms are designed to control the pose of the FWR-MAV.A flight control board for attitude control with robust onboard attitude estimation and a control algorithm is also developed to perform stable hovering flight and forward flight.A series of flight tests was conducted,with hovering flight and forward flight tests performed to optimize the control parameters and assess the performance of the *** hovering flight test shows the ability of the FWR-MAV to counteract the moment generated by rotary motion and maintain the attitude of the FWR-MAV in space;the experiment of forward flight shows that the FWR-MAV can track the desired attitude.

关键词： Attitude estimation Flapping wing rotor Flight control Flight tests Micro aerial vehicle(MAV)

Delaying stall of morphing wing by periodic trailing-edge deflection

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Chinese Journal of Aeronautics 2020年第2期33卷 493-500页

作者： Zi KAN Daochun LI jinwu xiang Chunxiao CHENG School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China

Morphing wings can improve aircraft performance during different flight *** research has focused on steady aerodynamic characteristics of the morphing wing with a flexible trailing-edge,and the unsteady aerodynamic and stall characteristics in the deflection process of the morphing wing are worthy further *** effects of the angle of attack and deflection rate on aerodynamic characteristics were examined,and based on the aerodynamic characteristics of the morphing wing,a method was developed to delay stall by using the flexible periodic trailing-edge *** numerical results show that the lift coefficients in the deflection process are smaller than those in the static situation at small angles of attack,and that the higher the deflection rate is,the smaller the lift coefficients will *** the contrary,at large angles of attack,the lift coefficients are higher than those in the static case,and they become larger with the increase of the deflection ***,the periodic deflection of the flexible trailing-edge with a small deflection amplitude and high deflection rate can increase lift coefficients at the critical stall angle.

关键词： Aerodynamics Computational fluid dynamics Flexible structures Morphing wings Stall angle

Crashworthiness analysis of aircraft fuselage with sine-wave beam structure

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Chinese Journal of Aeronautics 2016年第2期29卷 403-410页

作者： Ren Yiru xiang jinwu Zheng Jianqiang Luo Zhangping College of Mechanical and Vehicle Engineering Hunan University Changsha 410082 China School of Aeronautic Science and Engineering Beihang University Beijing 100083 China Beijing Aeronautical Science and Technology Research Institute of COMAC Beijing 102211 China

An integrated design concept for crashworthy fuselage using sine-wave beam and strut is proposed and investigated. The finite element model of aircraft fuselage is built first. The structures above cabin floor, occupant and seat are simplified as two rigid blocks. The fuselage frame is rede- signed, and the sine-wave beam is arranged under the frame. The impact dynamic performance of the aircraft with bottom sine-wave beam structure is studied and compared with that of conven- tional type. To obtain better crashworthiness performance, different rigidity of strut is combined with the sine-wave beam bottom structure. Numerical simulation result shows that the proposed sine-wave beam bottom structure could not only dissipate more proportion of impact kinetic energy but also reduce the initial peak acceleration. The structure and rigidity of strut have great influence on the crashworthiness performance. To give a better fuselage structure, both of the strut and bottom structure should be properly integrated and designed.

关键词： Aircraft Crashworthiness Energy absorption structureSine-wave beam Strut

Aerodynamic Performance of the Locust Wing in Gliding Mode at Low Reynolds Number

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Journal of Bionic Engineering 2016年第2期13卷 249-260页

作者： jinwu xiang Jianxun Du Daochun Li Kai Liu School of Aeronautic Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China

Gliding is an important flight mode for insects because it saves energy during long distance flight without wing flapping. In this study, we investigated the influence of locust wing corrugation on the aerodynamic performance in gliding mode at low Reynolds number. Numerical simulations using two-dimensional Navier-Stokes equations are applied to study the gliding flight, which reveals the interaction between forewing and hindwing. The lift of the corrugated airfoil in a locust wing decreases from the wing root to the tip. Simulation results show that the pressure drags on the forewing and hindwing increase with an increase in wing thickness; while the lift-drag ratio of the airfoil is marginally affected by the corrugation on the airfoil. Geometric parameters analysis of the locust wing is also carried out, which includes the corrugation height, the corrugation placement and the shapes of leading and trailing edges.

关键词： biological fluid mechanics corrugated gliding flight lift and drag coefficient locust wing low Reynolds number

Aerodynamic characteristics of morphing wing withflexible leading-edge

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Chinese Journal of Aeronautics 2020年第10期33卷 2610-2619页

作者： Zi KAN Daochun LI Tong SHEN jinwu xiang Lu ZHANG School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China

The morphing wing can improve the flight performance during different ***,research has been subject to limitations in aerodynamic characteristics of the morphing wing with a flexible *** computational fluid dynamic method and dynamic mesh were used to simulate the continuous morphing of the flexible *** comparing the steady aerodynamic characteristics of morphing and conventional wings,this study examined the unsteady aerodynamic characteristics of morphing wings with upward and downward deflections of the leading-edge at different *** numerical results show that for the steady aerodynamic,the leading-edge deflection mainly affects the stall *** downward deflection of the leading-edge increases the stall angle of attack and nose-down pitching *** results are opposite for the upward *** the unsteady aerodynamic,at a small angle of attack,the transient lift coefficient of the upward deflection,growing with the increase of deflection frequency,is larger than that of the static *** transient lift coefficient of the downward deflection,decreasing with the increase of deflection frequency,is smaller than that of the static ***,at a large angle of attack,an opposite effect of deflection frequency on the transient lift coefficient was *** transient lift coefficient is larger than that of the static case when the leading edge is in the nose-up stage,and lower than that of the static one in the nose-down stage.

关键词： Aerodynamics Computational fluid dynamics Flexible leading-edge Morphing wings Stall angle

Numerical simulation of aircraft arresting process with an efficient full-scale rigid-flexible coupling dynamic model

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Chinese Journal of Aeronautics 2024年第5期37卷 586-602页

作者： Haoyuan SHAO Daochun LI Zi KAN Lanxi BI Zhuoer YAO jinwu xiang School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China Tianmushan Laboratory Hangzhou 310023China

The arresting process of carrier-based aircraft is widely recognized as a challenging task,characterized by the highest accident rate among all carrier-based aircraft *** simulation plays a crucial role in assessing the intricate responses of the arresting process,favoring the design of carrier-based *** efficient and accurate rigid-flexible coupling model for analyzing the dynamic response of the arresting process is *** combining the dynamic characteristics of airframe,landing gear,arresting hook and arresting gear system,the rigid-flexible coupling dynamic model is established to reflect the relative motion of the coupling parts and arresting *** dynamic model is verified through simulations of landing gear landing drops and by comparing the arresting simulation results with corresponding data in the US military ***,simulations of the arresting process under different off-center distance and aircraft yaw angle are conducted to obtain the dynamic response of the aircraft during the arresting *** result indicates that the rigid-flexible coupling dynamic model proposed is effective for analyzing the arresting dynamics response of carrier-based *** axial force of the arresting cable on both sides of the hook engagement point,pitch and yaw angle of aircraft are inconsistent under yaw and off-center *** analysis method and obtained results provide valuable references for assessing the dynamic responses of carrier-based aircraft during arresting process and offer valuable in-sights in the design of carrier-based aircraft.

关键词： Carrier-based aircraft Deck landing Rigid-flexible coupling dynamic model Finite element method Dynamic analysis