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Aerodynamic optimization of an adaptive flap for next-generation green aircraft

Chinese Journal of Aeronautics 2024年第2期37卷 100-122页

作者： Tianlong LIN Rosario PECORA Danilo CILIBERTI Wei XIA Shuling HU State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China deparment of Industrial engineering Aerospace DivisionUniversity of Naples"FEDERICO II"Napoli 80125Italy

Adaptive,morphing flaps are taking ever-increasing attention in civil aviation thanks to the expected benefits this technology can bring at the aircraft level in terms of high-lift performance improvement and related fuel burnt reduction per *** upon morphing capabilities,it is possible to fix a unique setting for the flap and adapt the flap shape to match the aerodynamic requirements for take-off or *** proper morphed shapes can assure better high-lift performances than those achievable by referring to a conventional ***,standing the unique flap setting for take-off and landing,a dramatic simplification of the flap deployment systems may be *** a consequence of this simplification,the deployment system can be fully hosted in the wing,thus avoiding under-wing nacelles with significantly better aerodynamics and fuel *** first step for a rational design of an adaptive flap consists in defining the target morphed shapes and the unique optimal flap setting in the take-off and landing *** this work,aerodynamic optimization analyses are carried out to determine the best flap setting and related morphed shapes in compliance with the take-off and landing requirements of a reference civil transport *** different initial conditions are adopted to avoid the optimization falling into local optima,thus obtaining four groups of optimal candidate *** comparing each candidate’s performance through 2D and 3D simulations,the optimal configuration has been selected.2D simulations show that the optimal configuration is characterized by a maximum lift increase of 31.92%in take-off and 9.04%in *** to 3D simulations,the rise in maximum lift equals 22.26%in take-off and 3.50%in *** results are finally verified through wind tunnel tests,and the aerodynamic mechanism behind the obtained improvements is explained by carefully analyzing the flow field around the flap.

关键词： Morphing wings High-lift system Adaptive flap Computational Fluid Dynamics(CFD) Wind tunnel tests

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Fast and Adaptive Multi-Agent Planning under Collaborative Temporal Logic Tasks via Poset Products

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Research 2024年第2期2024卷 81-94页

作者： Zesen Liu Meng Guo Weimin Bao Zhongkui Li deparment of Mechanics and engineering Science College of EngineeringPeking UniversityBejing 0081 China Science and Technology Commission of China aerospace Science and Technology Corporation Beijing 100048China

Efficient coordination and planning is essential for large-scale multi-agent systems that collaborate in a shared dynamic environment. Heuristic search methods or learning-based approaches often lack the guarantee on correctness and performance. Moreover, when the collaborative tasks contain both spatial and temporal requirements, e.g., as linear temporal logic (LTL) formulas, formal methods provide a verifiable framework for task planning. However, since the planning complexity grows exponentially with the number of agents and the length of the task formula, existing studies are mostly limited to small artificial cases. To address this issue, a new planning paradigm is proposed in this work for system-wide temporal task formulas that are released online and continually. It avoids two common bottlenecks in the traditional methods, i.e., (a) the direct translation of the complete task formula to the associated B點hi automaton and (b) the synchronized product between the B點hi automaton and the transition models of all agents. Instead, an adaptive planning algorithm is proposed, which computes the product of relaxed partially ordered sets (R-posets) on-the-fly and assigns these subtasks to the agents subject to the ordering constraints. It is shown that the first valid plan can be derived with a polynomial time and memory complexity with respect to the system size and the formula length. Our method can take into account task formulas with a length of more than 400 and a fleet with more than 400 agents, while most existing methods fail at the formula length of 25 within a reasonable duration. The proposed method is validated on large fleets of service robots in both simulation and hardware experiments.

关键词： hardware service system

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Bandgap adjustment of a sandwich-like acoustic metamaterial plate with a frequency-displacement feedback control method

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Applied Mathematics and Mechanics(English Edition) 2024年第10期45卷 1807-1820页

作者： Jianing LIU Jinqiang LI Ying WU School of aerospace engineering Xi’an Jiaotong UniversityXi’an 710049China College of aerospace and Civil engineering Harbin Engineering UniversityHarbin 150001China

Several types of acoustic metamaterials composed of resonant units have been developed to achieve low-frequency *** most of these structures,bandgaps are determined by their geometric configurations and material *** paper presents a frequency-displacement feedback control method for vibration suppression in a sandwich-like acoustic metamaterial *** band structure is theoretically derived using the Hamilton principle and validated by comparing the theoretical calculation results with the finite element simulation *** this method,the feedback voltage is related to the displacement of a resonator and the excitation *** applying a feedback voltage on the piezoelectric fiber-reinforced composite(PFRC)layers attached to a cantilever-mass resonator,the natural frequency of the resonator can be *** ensures that the bandgap moves in a frequency-dependent manner to keep the excitation frequency within the *** on this frequency-displacement feedback control strategy,the bandgap of the metamaterial plate can be effectively adjusted,and the vibration of the metamaterial plate can be significantly suppressed.

关键词： acoustic metamaterial Hamilton principle electromechanical coupling vibration control local resonance

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Origami multi-layer space shield for cylindrical space structure

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Chinese Journal of Aeronautics 2024年第10期37卷 294-312页

作者： Ji-Hun CHA Ji-Sub NOH Sarath Kumar SATHISH KUMAR Dohyeon JIN Dae-Young LEE Chun-Gon KIM Department of aerospace engineering Chosun UniversityGwangju 61452Republic of Korea Department of aerospace and Software engineering Gyeongsang National UniversityGyeongsangnam-do 52828Republic of Korea Department of aerospace engineering Seoul National UniversitySeoul 08826Republic of Korea Department of aerospace engineering KAISTDaejeon 34141Republic of Korea

The multidisciplinary space environment,encompassing orbital debris,cosmic radiation,and solar radiative heat,poses significant risks to spacecraft and astronauts,necessitating efficient and effective shielding solutions.A multi-layer shield with wide spacing has been proven to be an effective way to shield the spacecraft from space debris impact;however,due to the limited volume of the payload fairing,it was not feasible to apply a multi-layer shield to the spacecraft *** the origami design,the shield maintains a compact form during launch and subsequently expands in outer space to enhance *** geometric analysis,it has been confirmed that the deployable multi-layer space shield can occupy less space than conventional space shield structures while expanding into wider shield intervals and multiple *** hypervelocity impact experiments,it was confirmed that as the bumper spacing of the multi-layer space shield expands,its ballistic performance becomes superior to conventional space *** deployable multi-layer space shield can reduce not only hypervelocity impacts but also solar radiative heat using the same mechanism as multi-layer *** cosmic radiation dose analysis,it has been confirmed that the multi-layer space shield is effective in cosmic radiation shielding compared to conventional space structures.

关键词： Hybrid composite Origami Hypervelocity impact Space environment Space debris Cosmic radiation

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Numerical study of steady flow characteristics of a rear variable-area bypass injector with alternating area regulator

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Chinese Journal of Aeronautics 2024年第5期37卷 180-198页

作者： Runfu LIU Zhenyao LI Huiliu ZHANG Qixing WANG Yue HUANG Yancheng YOU School of aerospace engineering Xiamen UniversityXiamen 361000China

The mixing effectiveness of the airflow between the inner and outer bypass inlets of a Rear Variable-Area Bypass Injector(RVABI)is the key to the afterburner performance of variable cycle *** paper describes an optimized RVABI design based on an alternating area regulator to improve the velocity/temperature uniformity of the incoming flow at the *** with a classical RVABI,numerical simulations show that the proposed alternating RVABI performs better in terms of thermal mixing efficiency and total pressure loss in different variable cycle engine *** the increasing air contact area between the inner and outer bypass of alternating structure RVABI,and a larger streamwise vortex in the inner bypass inlet due to the proposed alternating lobe structure in the RVABI contribute to the significantly increase of mixing ***,the alternating regulator induces strong streamwise vortex,which helps to improve the airflow mixing with its vortex-induced *** interaction between the streamwise vortex and azimuthal vortex further promises the velocity/temperature uniformity after the *** the increase of alternating lobe’s height ratio,the covering area of the streamwise vortex and the azimuthal vortex is enlarged,which further enhances the thermal mixing efficiency of the *** design gives an insight into the future design and optimization of RVABI.

关键词： Alternating area regulator Lobed mixer Variable cycle engine Rear Variable-Area Bypass Injector(RVABI) Streamwise vortex

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Multidisciplinary design optimization of a dual-spin guided vehicle

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Defence Technology（防务技术） 2024年第7期37卷 133-148页

作者： Jalal Karimi Mohammad Reza Rajabi Seyed Hossein Sadati Seyed Mahid Hosseini Department of aerospace engineering Malek Ashtar University of TechnologyTehranIran

In this research,a Multidisciplinary Design Optimization approach is proposed for the dual-spin guided flying projectile design considering external and internal parts of the body as design *** this way,a parametric formulation is *** related disciplines,including structure,aerodynamics,guidance,and control are *** total mass,maximum aerodynamic control effectiveness,minimum miss distance,maximum yield stress in all subsystems,controllability and gyroscopic stability constraints are some of objectives/constraints taken into *** problem is formulated in All-At-Ones Multidisciplinary Design Optimization approach structure and solved by Simulated Annealing and minimax *** optimal configurations are evaluated in various *** resulted optimal configurations have met all design objectives and constraints.

关键词： Flying projectile optimal design All-at-ones multidisciplinary optimization Structure discipline Guidance and control discipline Aerodynamic discipline

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Full lifetime demonstration of a Micro-Cathode-Arc thruster evolution characteristics

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Chinese Journal of Aeronautics 2024年第6期37卷 38-49页

作者： Zhe ZHANG Zijing ZHAO Xiangyang LIU Ningfei WANG School of aerospace engineering Beijing Institute of TechnologyBeijing 100081China

Ground lifetime test is the most crucial experiment to assess the performance,*** flight qualification of electric propulsion,and it can bring new insights for understanding the operation *** work demonstrates a full lifetime test of 140000 cycles on a Micro-Cathode-Arc Thruster(μCAT)with 160μs charging time and 86 mJ charging energy.A four-probe resistivity measurement method is utilized to investigate variations in the conductive film thickness and resistivity throughout the thruster *** film parameters show that the lifetime of theμCAT can be divided into three *** the initial stage,the film thickness decreases by 1.2μm and the resistivity increases significantly due to the high discharge intensity and intense film ablation;In the steady stage,the change of the film thickness is within 5%,and the resistivity of the film increases slowly from 0.050Ω·mm to 0.223Ω·*** the end stage,the resistivity exponentially increases from 0.223Ω·mm to 1.176Ω·mm,with the increase accounting for 81%,ultimately resulting in the failure of the thruster open ***,the evolution of discharge parameters,and the variation of plume parameters are measured throughout the *** discharge characteristics also show significant differences in the duration of voltage and current in these three *** results of plume shape and plasma parameters are also well con-sistent with the discharge parameters and film *** results suggest that,for evaluating the steady stage lifetime of thrusters,the film thickness is the best indicator compared to the variations in resistivity and voltage-current *** the end stage,the plasma plume *** duration,and plume parameters can conveniently and clearly characterize the thruster failures and irregularity.

关键词： Electric propulsion Lifetime test Micro-Cathode-Arc Thruster(uCAT) Conductive film Discharge characteristics Plasma parameters

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A method to determine the bonded-particle model parameters for simulation of ores

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Particuology 2024年第3期86卷 24-38页

作者： Shuwei Wu Guoqiang Wang Longfei Fan Wei Guan Jianbo Guo Zhengbin Liu Yukuan Wang School of Mechanical and aerospace engineering Jilin UniversityChangchun130025China

The bonded-particle model(BPM)is commonly used in the numerical analysis of ore *** improve the accuracy of simulating the mechanical process of ore process of ore crushing in a crusher,the parameters of the BPM for the ore must be *** this study,a calibration method was proposed for the scientific determination of the parameters of the BPM for ore undergoing uniaxial ***,physical tests and simulations were conducted to determine the mechanical response(uniaxial compressive strength and macroscopic stiffness)of ore during uniaxial ***,the sensitivity of the mechanical response to the values of microscopic parameters was tested using a Plackett-Burman ***,the microscopic parameters with the greatest impact on the response were identified,and the range of parameters that met the target response was determined using a steepest ascent design;Second,a second-order model of the mechanical response was established using the sensitive parameters by combining a Box-Behnken design with response surface methodology to obtain the optimal BPM *** tests showed that the normal stiffness per unit area,critical shear stress,and bonded disk radius had significant effects on the uniaxial compressive strength(UCS)and macroscopic stiffness(MS).To verify the validity of the proposed calibration method,laboratory tests were *** consistency of the simulation results with experimental results indicated that response surface methodology with the Plackett-Burman design,steepest ascent design,and Box-Behnken design can be an effective method for calibrating the BPM of ores.

关键词： Bonded-particle model Discrete element method Calibration method Design of experiment Uniaxial compression test

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Initial costates derived by near-optimal reference sequence and least-squares method

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Chinese Journal of Aeronautics 2024年第5期37卷 377-391页

作者： Shaozhao LU Yao ZHANG Quan HU School of aerospace engineering Beijing Institute of TechnologyBeijing 100081China

In this paper,we present a novel initial costates solver for initializing time-optimal trajectory problems in relative motion with continuous low *** proposed solver consists of two primary components:training a Multilayer Perceptron(MLP)for generating reference sequence and Time of Flight(TOF)to the target,and deriving a system of linear algebraic equations for obtaining the initial *** overcome the challenge of generating training samples for the MLP,the backward generation method is proposed to obtain five different training *** training database and sample form are determined by analyzing the input and output correlation using the Pearson correlation *** best-performing MLP is obtained by analyzing the training results with various hyper-parameter combinations.A reference sequence starting from the initial states is obtained by integrating forward with the near-optimal control vector from the output of ***,a system of linear algebraic equations for estimating the initial costates is derived using the reference sequence and the necessary conditions for *** results demonstrate that the proposed initial costates solver improves the convergence ratio and reduce the function calls of the shooting ***,Monte-Carlo simulation illustrates that the initial costates solver is applicable to different initial velocities,demonstrating excellent generalization ability.

关键词： Relative motion Expanding training database Multilayer perceptron Initial costates Least-squares method

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Conceptual design and configurations selection of S/H-UAVs based on Q-rung dual hesitant double layer FQFD

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Chinese Journal of Aeronautics 2024年第9期37卷 193-205页

作者： Dun YANG Li LIU Wencan BAI Weiyong TIAN School of aerospace engineering Beijing Institute of TechnologyBeijing 100081China

For the conceptual design phase of Unmanned Aerial Vehicles(UAVs),a process for conceptual design and configuration selection of Solar/Hydrogen powered UAVs(S/H-UAVs)is *** design requirements of S/H-UAVs were analyzed *** proposed process used Fuzzy Quality Function Deployment(FQFD)to establish logical and quantitative ***,in order to appropriately describe the hesitancy of experts while making decision,it used Q-Rung Dual Hesitant Fuzzy Sets(QRDHFS)to score the *** addition,a decision-making framework is proposed to perform a logical selection of typical layouts based on defuzzi-fication method and Technique for Order Preference by Similarity to the Ideal Solution(TOPSIS).The present process has been applied for S/*** resulting set of design requirements con-sists of three categories:Mission Requirements(MRs),engineering Characteristics(ECs)and Tech-nical Indicators(TIs).Four typical layouts of S/H-UAVs were sorted and *** performance of four typical layouts were evaluated and the Strut-Braced Wing(SBW)with external hydrogen storage was selected as the best layout for S/H-UAVs.

关键词： Hybrid powered UAV Conceptual design Q-Rung Dual Hesitant Fuzzy Set(QRDHFS) Quality function deployment Strut-braced wing

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