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| 1 | Design concept of three-dimensional section controllable internal waverider hypersonic inlet显示文摘A new hypersonic inlet named three-dimensional section controllable internal waverider inlet is presented in this paper to achieve the goal of section shape geometric transition and complete capture of the upstream mass. On the basis of the association between hypersonic waverider airframe and streamtraced hypersonic inlet, the waverider concept is extended to yield results for the internal flows, namely internal waverider concept. It is proven theoretically that not osculating cones but osculating axisymmetric theory is appropriate for the design of section controllable internal waverider inlet. And two design methods out of the internal waverider concept are proposed subsequently to construct two inlets with specific section shape request, triangle to ellipse and rectangle to ellipse ones. The calculation results show that the inlets are capable of keeping their shock structures and the main flow characteristics exactly as their derived flowfield. Further, the inlets successfully capture all the upstream mass despite their complicated cross-section transitions. It is believed that the concept proposed ex- plores a new way of designing three-dimensional hypersonic inlets with special demand of section shape transition. However, the detailed flow characteristic and the performance of the internal waverider inlets are still under investigation. | YOU YanCheng LIANG DeWang | 2009 | Science China(Technological Sciences)2009，52，7： | 24 |
| 2 | Target-enclosing affine formation control of two-layer networked spacecraft with collision avoidance显示文摘This paper addresses a target-enclosing problem for multiple spacecraft systems by proposing a two-layer affine formation control strategy. Compared with the existing methods,the adopted two-layer network structure in this paper is generally directed, which is suitable for practical space missions. Firstly, distributed finite-time sliding-mode estimators and formation controllers in both layers are designed separately to improve the flexibility of the formation control system. By introducing the properties of affine transformation into formation control protocol design,the controllers can be used to track different time-varying target formation patterns. Besides, multilayer time-varying encirclements can be achieved with particular shapes to surround the moving target. In the sequel, by integrating adaptive neural networks and specialized artificial potential functions into backstepping controllers, the problems of uncertain Euler-Lagrange models, collision avoidance as well as formation reconfiguration are solved simultaneously. The stability of the proposed controllers is verified by the Lyapunov direct method. Finally, two simulation examples of triangle formation and more complex hexagon formation are presented to illustrate the feasibility of the theoretical results. | Yang XU Delin LUO Dongyu LI Yancheng YOU Haibin DUAN | 2019 | Chinese Journal of Aeronautics2019，32，12： | 9 |
| 3 | Affine formation maneuver tracking control of multiple second-order agents with time-varying delays显示文摘This paper considers an affine maneuver tracking control problem for leader-follower type second-order multi-agent systems in the presence of time-varying delays, where the interaction topology is directed. Using the property of the affine transformation,this paper gives the sufficient and necessary conditions of achieving the affine localizability and extends it to the second-order condition. Under the(n + 1)-reachable condition of the given n-dimensional nominal formation with n + 1 leaders, a formation of agents can be reshaped in arbitrary dimension by only controlling these leaders. When the neighboring positions and velocities are available, a formation maneuver tracking control protocol with time-varying delays is constructed with the form of linear systems, where the tracking errors of the followers can be specified. Based on Lyapunov-Krasovskii stability theory, sufficient conditions to realize affine maneuvers are proposed and proved, and the unknown control gain matrix can be solved only by four linear matrix inequalities independent of the number of agents. Finally, corresponding simulations are carried out to verify the theoretical results, which show that these followers can track the time-varying references accurately and continuously. | XU Yang LI DongYu LUO DeLin YOU YanCheng | 2019 | Science China(Technological Sciences)2019，62，4： | 5 |
| 4 | Numerical investigation of dynamic stall suppression of rotor airfoil via improved co-flow jet显示文摘The decrease in aerodynamic performance caused by the shock-induced dynamic stall of an advancing blade and the dynamic stall of a retreating blade at low speed and high angles of attack limits the flight speed of a helicopter.However,little research has been carried on the flow control methods employed to suppress both the dynamic stall induced by a shock wave and the dynamic stall occurring at high angles of attack.The dynamic stall suppression of a rotor airfoil by Co-Flow Jet(CFJ)is numerically investigated in this work.The flowfield of the airfoil is simulated by solving Reynolds Averaged Navier-Stokes equations based on the sliding mesh technique.Firstly,to improve the effect of a traditional CFJ on suppressing rotor airfoil shock-induced dynamic stall,an improved CFJ—a CFJ-sloping slot is proposed.Research shows that the CFJsloping slot suppresses the shock-induced dynamic stall more effectively than a traditional CFJ.Moreover,the improved CFJ can also suppress the dynamic stall of rotor airfoil at low speed and high angles of attack.The improved CFJ proposed in this paper is an effective flow control method that simultaneously suppresses the dynamic stall of the advancing and retreating blades.The mechanism of the improved CFJ in suppressing the dynamic stall of the rotor airfoil is studied,and a comparison is made between the improved CFJ and the traditional CFJ in terms of dynamic stall suppression at high and low speed.Finally,the effect of improved CFJ parameters(the jet momentum coefficient,the position of the injection/suction slot,and the size of the injection/suction slot)on shock-induced dynamic stall suppression is analyzed. | Jiaqi LIU Rongqian CHEN Yancheng YOU Zheyu SHI | 2022 | Chinese Journal of Aeronautics2022，35，3： | 3 |
| 5 | New advances in multiple autonomous aerial robots formation control technology显示文摘Autonomous aerial robotics has become a hot direction ofresearch inside the community of robotics and control. Theprimary problem addressed by formation control is to steermultiple aerial robots to form desired geometric patterns and,at the same time, realize desired collective swarming behaviorsin a decentralized or distributed manner. In contrast toground vehicles, aerial robots have the ability to work inthree-dimensional (3D) airspace. Equipped with electric orhydraulic motors, the vertical take-off and landing (VTOL)capability is a typical performance of aerial robots. Formationcontrol technology for such aerial robots is incessantlyspringing up to satisfy the requirements of highly intelligentautonomous systems, which affects both military and civilareas, including missile defense, battlefield surveillance,satellite network construction, fire suppression, power gridinspection, commercial show, etc. [1–5]. Such a problem ofmultiple aerial robots formation control is exceptionallychallenging to analyze if practical constraints such as complexdynamics, motion constraints, and imperfect measurementsare incorporated. | XU Yang LUO DeLin YOU YanCheng DUAN HaiBin | 2019 | Science China(Technological Sciences)2019，62，10： | 3 |
| 6 | Affine transformation based formation maneuvering for discrete-time directed networked systems显示文摘For the tracking control problems of affine formation maneuvers with discrete leader-following multi-agent systems, various distributed control schemes based on the directed graphs are designed in this paper. Consider the single and double-integrator models, different types of formation maneuvers can be achieved subject to the states of leaders with the novel characteristic of affine localizability. Meanwhile, the properties of affine transformation and signed Laplacian are introduced, which simplify the structures of controllers with distinct constraints to a great extent. Moreover, the convergence analysis of proposed protocols is proven. Static, constant and time-varying target formations can be tracked successfully. In the end, corresponding numerical simulations are carried out to certify the validity of theoretical results. | XU Yang LUO DeLin YOU YanCheng DUAN HaiBin | 2020 | Science China(Technological Sciences)2020，63，1： | 3 |
| 7 | Evaluation of Turbulence Models in Predicting Hypersonic and Subsonic Base Flows Using Grid Adaptation Techniques显示文摘The flows behind the base of a generic rocket, at both hypersonic and subsonic flow conditions, are numerically studied. The main concerns are addressed to the evaluation of turbulence models and the using of grid adaptation techniques. The investiga- tion focuses on two configurations, related to hypersonic and subsonic experiments. The applicability tests of different turbulence models are conducted on the level of two-equation models calculating the steady state solution of the Reynolds-averaged Navier-Stokes(RANS) equations. All used models, the original Wilcox k-ω, the Menter shear-stress transport (SST) and the explicit algebraic Reynolds stress model(EARSM) formulation, predict an asymmetric base flow in both cases caused by the support of the models. A comparison with preliminary experimental results indicates a preference for the SST and EARSM results over the results from the older k-ω model. Sensitivity studies show no significant influence of the grid topology or the location of the laminar to turbulent transition on the base flow field, but a strong influence of even small angles of attack is reported from the related experiments. | YOU Yancheng BUANGA Bjorn HANNEMANN Volker LUDEKE Heinrich | 2012 | Chinese Journal of Aeronautics2012，25，3： | 1 |
| 8 | Numerical Simulation of Aerodynamic Characteristics of Helicopter Rotor with Tip Slots显示文摘Effects of tip slots on the aerodynamic characteristics of helicopter rotor were investigated numerically by solving three-dimensional Navier-Stokes equations based on unstructured overset grids algorithm.Improved delayed detached eddy simulation (IDDES) based on the Spalart-Allmaras turbulence model and adaptive grid refinement technique were employed.Several slots in the rotor blade tip were designed on the base of Caradonna-Tung rotor to study the effect of tip slots.Numerical results show that tip slots are able to introduce the airflow from the leading edge and turn it in the spanwise direction to be ejected out of the face at the rotor blade tip,which can reduce the strength of the rotor blade tip vortex and accelerate the dissipation process.Although tip slots may lead to the decrease of airfoils' lift coefficient at the root of the rotor blade,it can increase the lift coefficient of airfoils at the rotor blade tip,so the lift of the rotor with tip slots is almost the same as that of the rotor without tip slots.In addition,tip slots can also reduce the intensity of the tip shock wave,which is beneficial to reduce the wave drag of the rotor. | Chen Rongqian Wang Xu Cheng Qiyou Zhu Chengxiang You Yancheng | 2018 | Transactions of Nanjing University of Aeronautics and Astronautics2018，35，6： | 1 |
| 9 | Nonlinear adaptive flight control system:Performance enhancement and validation显示文摘The problem of decreasing stability margins in L1 adaptive control systems is discussed and an out-of-loop L1 adaptive control scheme based on Lyapunov’s stability theorem is proposed.This scheme enhances the effectiveness of the adaptation,which ensures that the system has suffi-cient stability margins to achieve the desired performance under parametric uncertainty,additional delays,and actuator faults.The stability of the developed control system is demonstrated through a series of simulations.Compared with an existing control scheme,the constant adjustment of the sta-bility margins by the proposed adaptive scheme allows their range to be extended by a factor of 4–5,bringing the stability margin close to that of variable gain PD control with adaptively scheduled gains.The engineered practicability of adaptive technology is verified.A series of flight tests verify the practicability of the designed adaptive technology.The results of these tests demonstrate the enhanced performance of the proposed control scheme with nonlinear parameter estimations under insufficient stability margins and validate its robustness in the event of actuator failures. | Yue FENG Zonghua SUN Liaoni WU Yongshun WANG Bin XI Weng Khuen HO Yancheng YOU | 2023 | Chinese Journal of Aeronautics2023，36，4： | 1 |
| 10 | Iniection and mixing in a scramjet combustor: DES and RANS studies 显示文摘 | YOU Yancheng Luedeke H Hannemann K | 2013 | Proceedings of the Combustion Institute2013，34，2： | 1 |
| 11 | On the flow physics of a low momentum flux ratio jet in a supersonic turbulent crossflow显示文摘 | YOU Yancheng IAideke H Hannemann K | 2012 | Enrophysics Letters2012，97，2： | 1 |
| 12 | Quasi-linear analysis of dispersion relation preservation for nonlinear schemes显示文摘In numerical simulations of complex flows with discontinuities,it is necessary to use nonlinear schemes.The spectrum of the scheme used has a significant impact on the resolution and stability of the computation.Based on the approximate dispersion relation method,we combine the corresponding spectral property with the dispersion relation preservation proposed by De and Eswaran(J Comput Phys 218:398-416,2006)and propose a quasi-linear dispersion relation preservation(QL-GRP)analysis method,through which the group velocity of the nonlinear scheme can be determined.In particular,we derive the group velocity property when a high-order Runge-Kutta scheme is used and compare the performance of different time schemes with QL-GRP.The rationality of the QL-GRP method is verified by a numerical simulation and the discrete Fourier transform method.To further evaluate the performance of a nonlinear scheme in finding the group velocity,new hyperbolic equations are designed.The validity of QL-GRP and the group velocity preservation of several schemes are investigated using two examples of the equation for one-dimensional wave propagation and the new hyperbolic equations.The results show that the QL-GRP method integrated with high-order time schemes can determine the group velocity for nonlinear schemes and evaluate their performance reasonably and efficiently. | Fengyuan Xu Pan Yan Qin Li Yancheng You | 2022 | Advances in Aerodynamics2022，4，1： | 0 |
| 13 | Robust gain-scheduled missile autopilot design based on multifrequency extended state observers显示文摘This paper describes the design and implementation of a three-axis acceleration control autopilot for an asymmetric tail-controlled,skid-to-turn tactical missile.In an earlier flight test,degraded autopilot performance was attributed to multiple disturbances and uncertainties and the presence of hidden coupling terms,giving rise to a miss distance of greater than 20 m.To address these issues,the missile dynamics are decomposed into the angular rate dynamics as fast and the acceleration dynamics as slow subsystem using the singular perturbation theory to analyze a multi-time-scale property.Multifrequency extended state observers are then incorporated into the gain scheduling technique to attenuate disturbances,thus enhancing the control performance significantly.In the proposed engineering/practical design framework for missile autopilot,simple,conventional,and explicit tuning rules are provided.And the proposed control scheme can achieve input-to-state stability across the entire flight envelope under unknown but bounded disturbances.The advantages of the method over existing benchmark approaches are shown through nonlinear numerical simulations.This is supported by evidence from a new flight test result with a miss distance of only 2 m. | Zonghua SUN Liaoni WU Yancheng YOU | 2023 | Chinese Journal of Aeronautics2023，36，12： | 0 |
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