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Time-Domain Analysis of Body Freedom Flutter Based on 6DOF Equation

工程与科学中的计算机建模(英文) 2024年第1期138卷 489-508页

作者： Zhehan Ji Tongqing Guo Di Zhou Zhiliang Lu Binbin Lyu key laboratory of unsteady aerodynamics and flow control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing210016China High Speed aerodynamics Institute China Aerodynamics Research and Development CenterMianyang621000China

The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic ***,a high-aspect-ratio flexible flying wing is prone to body freedomflutter(BFF),which is a result of coupling of the rigid body short-periodmodewith 1st wing *** prediction of the BFF characteristics is helpful to reflect the attitude changes of the vehicle intuitively and design the active flutter suppression control *** of using the rigid body mode,this work simulates the rigid bodymotion of the model by using the six-degree-of-freedom(6DOF)equation.A dynamicmesh generation strategy particularly suitable for BFF simulation of free flying aircraft is *** accurate Computational Fluid Dynamics/Computational Structural Dynamics/six-degree-of-freedom equation(CFD/CSD/6DOF)-based BFF prediction method is ***,the time-domain CFD/CSD method is used to calculate the static equilibrium state of the *** on this state,the CFD/CSD/6DOF equation is solved in time domain to evaluate the structural response of *** combinedwith the variable stiffnessmethod,the critical flutter point of the model is *** method is applied to the BFF calculation of a flyingwing *** calculation results of the BFF characteristics of the model agree well with those fromthe modalmethod andNastran ***,the method is used to analyze the influence factors of *** analysis results show that the flutter speed can be improved by either releasing plunge constraint or moving the center ofmass forward or increasing the pitch inertia.

关键词： Body freedom flutter time-domain CFD/CSD/6DOF method dynamic mesh generation strategy aeroelasticity

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Study of flow and Heat Transfer in an Ejector-Driven Swirl Anti-Icing Chamber

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Fluid Dynamics & Materials Processing 2024年第5期20卷 989-1014页

作者： Yi Tu Yuan Wu Yu Zeng Hunan University of Arts and Sciences Hunan Key Laboratory of Distributed Electric Propulsion Vehicle Control TechnologyChangde415000China Liaoning Provincial key laboratory of Aircraft Ice Protection AVIC Aerodynamics Research InstituteShenyang110034China School of Aeronautic Science and Engineering Beihang UniversityBeijing100191China

The formation of ice on the leading edge of aircraft engines is a serious issue,as it can have catastrophic *** Swirl Anti-Icing(SAI)system,driven by ejection,circulates hot fluid within a 360°annular chamber to heat the engine inlet lip surface and prevent *** study employs a validated Computational Fluid Dynamics(CFD)approach to study the impact of key geometric parameters of this system on flow and heat transfer characteristics within the anti-icing ***,the entropy generation rate and exergy efficiency are analyzed to assess the energy utilization in the *** research findings indicate that,within the considered flow range,reducing the nozzle specific areaφfrom 0.03061 to 0.01083 can enhance the ejection coefficient by over 60.7%.This enhancement increases the air circulating rate,thereby intensifying convective heat transfer within the SAI ***,the reduction inφalso leads to a significant increase in the required bleed air pressure and a higher entropy generation rate,indicating lower exergy *** nozzle angleθnotably affects the distribution of hot and cold spots on the lip surface of the SAI ***θfrom 0°to 20°reduces the maximum temperature difference on the anti-icing chamber surface by 60 K.

关键词： Swirl anti-icing heat transfer exergy efficiency hot and cold spot aircraft engine

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高雷诺数下覆羽控制直翼型流动分离的位置影响实验

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Acta Mechanica Sinica 2024年第4期40卷 125-135页

作者：巩绪安马兴宇姜楠 Department of Mechanics School of Mechanical EngineeringTianjin UniversityTianjin300354China National key laboratory of Aerodynamic Noise control China Aerodynamics Research and Development CenterSichuan621000China National key laboratory of Science and Technology on Aerodynamic Design and Research School of AeronauticsNorthwestern Polytechnical UniversityXi’an710072China State key laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu610031China

本文在二维机翼上安装了仿生的覆羽结构,在5.0×105的雷诺数下研究它们控制前缘流动分离的效果.覆羽是指覆盖在鸟类翅膀上的多排短而柔软的带有锯齿状尖端的羽毛.它们覆盖在长而硬的飞羽边缘,使鸟的翅膀保持流线型.当流动分离发生时,这... 详细信息

本文在二维机翼上安装了仿生的覆羽结构,在5.0×105的雷诺数下研究它们控制前缘流动分离的效果.覆羽是指覆盖在鸟类翅膀上的多排短而柔软的带有锯齿状尖端的羽毛.它们覆盖在长而硬的飞羽边缘,使鸟的翅膀保持流线型.当流动分离发生时,这些柔性锯齿形的人工覆羽在来流的激励下能够自适应地变形和颤振.在风洞实验中,本文使用高时间分辨率的粒子图像测速仪(PIV)来测量机翼上表面的速度场,并使用热线风速仪来测量尾流中的高频湍流脉动.安装在20%弦长处的人工覆羽在前缘分离流的激励下会自适应地大幅翻转.安装在80%弦长处的覆羽则会被尾缘卷起的脱落涡向上抬起,并在准平衡状态下轻微摆动.这两类人工覆羽均能够有效地控制流动分离,并减小尾流的湍流脉动强度.

关键词：流动分离风洞实验分离流湍流脉动高时间分辨率热线风速仪高雷诺数锯齿形

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Fluid-structure interaction simulation for multi-body flexible morphing structures

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Chinese Journal of Aeronautics 2024年第2期37卷 137-147页

作者： Wenzhi GUO Yongtao SHUI Lu NIE Gang CHEN State key laboratory of Strength and Vibration for Mechanic Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China China Academy of Launch Vehicle Technology Beijing 100076China China Academy of Aerospace Science and Innovation Beijing 100086China Shannxi key laboratory of Service Environment and control for Flight Vehicles Xi’an Jiaotong UniversityXi’an 710049China

The multi-body flexible morphing airfoil can improve the aerodynamic characteristics based on different flight missions *** researches have focused on the unsteady aerodynamic characteristics of flexible wings under passive ***,the unsteady aerodynamic characteristics with the fluid-structure interaction effects in the multi-body active actuation process of morphing airfoil deserve further *** this paper,a fluid-structure coupled simulation method for multi-body flexible morphing airfoil with active actuation subsystem was investigated,and the aerodynamic characteristics during deformation were compared with different skin flexibility,flow field environment,actuation mode and actuation *** numerical results show that for the steady aerodynamic,the skin flexibility can improve the stability *** the unsteady process,the change trend of the transient lift coefficient and pitching moment are consistent with those of the active drive characteristics,while the instantaneous lift-drag ratio coefficient is greatly affected by the driving mode and can be improved by increasing the driving duration.

关键词： Fluid-structure interaction Multi-body dynamics modeling Flexible structures aerodynamics Morphing wings

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Gas kinetic flux solver based finite volume weighted essentially non-oscillatory scheme for inviscid compressible flows

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Applied Mathematics and Mechanics(English Edition) 2023年第6期44卷 961-980页

作者： Lan JIANG Jie WU Liming YANG Hao DONG State key laboratory of Mechanics and control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of aerodynamics Nanjing University of Aeronautics and AstronauticsNanjing 210016China key laboratory of unsteady aerodynamics and flow control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China

A high-order gas kinetic flux solver(GKFS)is presented for simulating inviscid compressible *** weighted essentially non-oscillatory(WENO)scheme on a uniform mesh in the finite volume formulation is combined with the circular function-based GKFS(C-GKFS)to capture more details of the flow fields with fewer *** from most of the current GKFSs,which are constructed based on the Maxwellian distribution function or its equivalent form,the C-GKFS simplifies the Maxwellian distribution function into the circular function,which ensures that the Euler or Navier-Stokes equations can be recovered *** improves the efficiency of the GKFS and reduces its complexity to facilitate the practical application of *** benchmark cases are simulated,and good agreement can be obtained in comparison with the references,which demonstrates that the high-order C-GKFS can achieve the desired accuracy.

关键词： circular function-based gas kinetic flux solver(C-GKFS) weighted essentially non-oscillatory(WENO)scheme compressible flow finite volume method

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A high-order scheme based on lattice Boltzmann flux solver for viscous compressible flow simulations

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Applied Mathematics and Mechanics(English Edition) 2022年第10期43卷 1601-1614页

作者： Jian QIN Jie WU Chao MA State key laboratory of Mechanics and control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China key laboratory of unsteady aerodynamics and flow control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing210016China Department of aerodynamics Nanjing University of Aeronautics and AstronauticsNanjing210016China

In this paper,a high-order scheme based on the lattice Boltzmann flux solver(LBFS)is proposed to simulate viscous compressible *** flux reconstruction(FR)approach is adopted to implement the spatial *** LBFS is employed to compute the inviscid flux by using the local reconstruction of the lattice Boltzmann equation solutions from macroscopic flow ***,a switch function is used in LBFS to adjust the magnitude of the numerical ***,it is more beneficial to capture both strong shock waves and thin boundary ***,the viscous flux is computed according to the local discontinuous Galerkin *** typical compressible viscous problems,including manufactured solution case,lid-driven cavity flow,supersonic flow around a cylinder and subsonic flow over a NACA0012 airfoil,are simulated to demonstrate the accuracy and robustness of the proposed FR-LBFS.

关键词： high-order method flux reconstruction lattice Boltzmann flux solver(LBFS) viscous compressible flow

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Investigation of control effects of end-wall selfadaptive jet on three-dimensional corner separation of a highly loaded compressor cascade

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Chinese Journal of Aeronautics 2024年第6期37卷 109-126页

作者： Hejian WANG Bo LIU Xiaochen MAO Botao ZHANG Zonghao YANG School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China The National key laboratory of Science and Technology on Aerodynamic Design and Research Xi’an 710129China Taihang laboratory Chengdu 610000China

To overcome the limitations posed by three-dimensional corner separation,this paper proposes a novel flow control technology known as passive End-Wall(EW)self-adaptive *** single EW slotted schemes(EWS1 and EWS2),alongside a combined(COM)scheme featuring double EW slots,were *** results reveal that the EW slot,driven by pressure differentials between the pressure and suction sides,can generate an adaptive jet with escalating velocity as the operational load *** high-speed jet effectively re-excites the local low-energy fluid,thereby mitigating the corner ***,the EWS1 slot,positioned near the blade leading edge,exhibits relatively low jet velocities at negative incidence angles,causing jet separation and exacerbating the corner ***,the EWS2 slot is close to the blade trailing edge,resulting in massive low-energy fluid accumulating and separating before the slot outlet at positive incidence *** contrast,the COM scheme emerges as the most effective solution for comprehensive corner separation *** can significantly reduce the total pressure loss and improve the static pressure coefficient for the ORI blade at 0°-4° incidence angles,while causing minimal negative impact on the aerodynamic performance at negative incidence ***,the corner stall is delayed,and the available incidence angle range is broadened from -10°--2°to -10°-4°.This holds substantial promise for advancing the aerodynamic performance,operational stability,and load capacity of future highly loaded compressors.

关键词： Three-dimensional corner separation End-wall adaptive jet Total pressure loss Highly loaded compressor cascade Compressors

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Numerical analysis of wind effects on aerodynamic characteristics of a ducted fan

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Chinese Journal of Aeronautics 2024年第5期37卷 263-280页

作者： Yiwei LUO Tianfu AI Yuhang HE Bin XU Yuping QIAN Yangjun ZHANG State key laboratory of Intelligent Green Vehicle and Mobility School of Vehicle and MobilityTsinghua UniversityBeijing 100084China key laboratory of Conveyance and Equipment Ministry of Education East China Jiaotong UniversityNanchang 330013China Vehicle Research Center School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

Ducted fans have been extensively used in Unmanned Aerial Vehicles(UAVs)for a variety of missions because of high efficiency,high safety and low ***,as a kind of typical meteorological condition,brings significant aerodynamic interference to the ducted fan,which seriously threatens flight stability and *** this work,the numerical simulation with the unsteady Reynolds Averaged Navier-Stokes(URANS)method and the sliding mesh technique is performed to evaluate the steady wind *** results show that the wind will lead to serious unsteady effects in the flow field,and the thrust fluctuates at the blade passing frequency of 200 *** the wind speed increases,the rotor thrust increases,the duct thrust decreases,and the total thrust changes *** instability may occur when the wind speed exceeds 8 m/*** the angle of low-speed wind increases,the rotor thrust changes little,the duct thrust increases,and the total thrust *** addition,we figure out that cases with the same crosswind ratio are similar in results,and increasing the rotating speed or fan radius is beneficial to performance improvement in *** findings are essential to the ducted fan design and UAV flight control design for stable and safe operations in wind conditions.

关键词： Unmanned Aerial Vehicle(UAV) Ducted fan Wind effect Thrust fluctuations Computational Fluid Dynamics(CFD)

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Oblique shock train motion based on schlieren image processing

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Chinese Journal of Aeronautics 2023年第3期36卷 30-41页

作者： Longsheng XUE Chuan CHENG Chengpeng WANG Lantian ZHANG Kang LI Keming CHENG College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China key laboratory of unsteady aerodynamics and flow control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China Beijing Institute of Tracking and Telecommunication Technology Beijing 100094China Aerospace System Engineering Shanghai Shanghai 201109China

In this paper,shock train motion in a Mach number 2.7 duct is studied experimentally,and large numbers of schlieren images are obtained by a high-speed *** image processing method based on Maximum Correlation Detection(MCD)is proposed to detect shock train motion from the schlieren images,based on which the key structures,e.g.,separation positions and separation shock angles on the top and bottom walls,can be analysed in *** oscillations of the shock train are generated by rhombus and ellipse shafts at various excitation *** to the analysis of MCD results,the distributions of the frequency components of shock train oscillation generated by the two shafts are distinctly different,in which the motion generated by the ellipse shaft is much smoother;shock train motion is mainly characterized by the oscillation of separation position while the separation shock strength is not so sensitive to downstream disturbance;there is a hysteresis loop relation between the downstream pressure and separation position.

关键词： Frequency components Hysteresis loop Maximum Correlation Detection(MCD) Schlieren image processing Shock train oscillation

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Time delay compensation in lateral-directional flight control systems at high angles of attack

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Chinese Journal of Aeronautics 2021年第4期34卷 1-18页

作者： Lin SHEN Da HUANG Genxing WU key laboratory of unsteady aerodynamics and flow control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China

The previous studies of time delay compensation in flight control systems are all based on the conventional aerodynamic derivative model and conducted in longitudinal motions at low angles of *** this investigation,the effects of time delay on the lateral-directional stability augmentation system in high-a regime are discussed based on theβmodel,which is proposed in our previous work and proved as a more accurate aerodynamic model to reveal the lateraldirectional unsteady aerodynamic characteristics at high angles of *** theβmodel and the quasi-steady model are used for simulating the effects of time delay on the flying qualities in high-a *** comparison between the simulation results shows that the flying qualities are much more sensitive to the mismatch of feedback gains than the state errors caused by time *** a typical adaptive controller based on the conventional dynamic derivative model and a gain-prediction compensator based onβmodel are designed to address the time delay in different *** simulation results show that the gain-prediction compensator is much simpler and more efficient at high angles of ***,the gain-prediction compensator is combined with a linearizedβmodel reference adaptive controller to compensate the adverse effects of very large time delay,which exhibits excellent performance when addressing the extreme conditions at high angles of attack.

关键词： Adaptive control Flying quality High angles of attack Time delay Yaw-roll coupling

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