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Dynamic characteristics and application of dual throat fluidic thrust vectoring nozzle

CHINESE JOURNAL OF AERONAUTICS 2024年第9期37卷 85-99页

作者： Xu, Buxian Hu, Dongping feng, lihao Beihang Univ Fluid Mech Key Lab Minist Educ Beijing 100191 Peoples R China Dongfang Turbine Co Ltd State Key Lab Clean & Efficient Turbomachinery Pow Dongfang Elect Corp Deyang 618000 Peoples R China

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 nozzles 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 application, 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 generated 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 degrees/% 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. (c) 2024 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY-NC-ND license (http://creativecommo

关键词： Dual throat nozzle Dynamic response characteristic Flow control Flying-wing aircraft

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Enhancing Geological Understanding and Identifying Gold Anomalies in the Ailaoshan Orogen

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Acta Geologica Sinica(English Edition) 2024年第2期98卷 441-453页

作者： ZHAO Shiyu YANG Lin SONG Yiwei DONG Yuntao feng lihao LI Huajian WU Junyu WANG Qingfei State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China Xi’an Center of Mineral Resources Survey China Geological SurveyXi’an 710010China Yunnan Gold Mining Industry Group Kunming 650299China Jiangxi Provincial Key Laboratory of Genesis and Prospect for Strategic Minerals East China University of TechnologyNanchang 330013China Frontiers Science Center for Deep-time Digital Earth China University of Geosciences(Beijing)Beijing 100083China

The Ailaoshan Orogen in the southeastern Tibet Plateau,situated between the Yangtze and Simao blocks,underwent a complex structural,magmatic,and metamorphic evolution resulting in different tectonic subzones with varying structural lineaments and elemental *** elements can conceal or reduce anomalies due to the mutual effect between different anomaly *** the whole zone into subzones based on tectonic settings,ore cluster areas,or sample catchment basins(Scb),geochemical and structural anomalies associated with gold(Au)mineralization have been identified utilizing mean plus twice standard deviations(Mean+2STD),factor analysis(FA),concentration-area(CA)modeling of stream sediment geochemical data,and lineament density in both the Ailaoshan Orogen and the individual *** FA in the divided 98 Scbs with 6 Scbs containing Au deposits can roughly ascertain unknown rock types,identify specific element associations of known rocks and discern the porphyry or skarn-type Au *** with methods of Mean+2STD and C-A model of data in the whole orogen,which mistake the anomalies as background or act the background as anomalies,the combined methods of FA and C-A in the separate subzones or Scbs works well in regional metallogenic potential *** of lineament densities with a 10-km circle diameter is not suitable to locate Au deposits because of the delineated large areas of medium-high lineament *** contrast,the use of circle diameters of 1.3 km or 1.7 km in the ore cluster scale delineates areas with a higher concentration of lineament density,consistent with the locations of known Au *** analyzing the map of faults and Au anomalies,two potential prospecting targets,Scbs 1 and 63 with a sandstone as a potential host rock for Au,have been identified in the Ailaoshan *** use of combined methods in the divided subzones proved to be more effective in improving geological understanding and identifying

关键词： minerology geochemistry gold stream sediment sample catchment basin concentration-area model lineament density Ailaoshan Orogen

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Individual influence of pitching and plunging motions on flow structures over an airfoil during dynamic stall

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Chinese Journal of Aeronautics 2020年第3期33卷 840-851页

作者： Zhenyao LI lihao feng Jinjun WANG Fluid Mechanics Key Laboratory of Ministry of Education Beihang UniversityBeijing 100083China

The individual influence of pitching and plunging motions on flow structures is studied experimentally by changing the phase lag between the geometrical angle of attack and the plunging angle of *** phase lags are chosen as the experimental parameters,while the Strouhal number,the reduced frequency and the Reynolds number are *** the motion of the airfoil,the leading edge vortex,the reattached vortex and the secondary vortex are observed in the flow *** leading edge vortex is found to be the main flow structure through the proper orthogonal *** increase of phase lag results in the increase of the leading edge velocity,which strongly influences the leading edge shear layer and the leading edge *** plunging motion contributes to the development of the leading edge shear layer,while the pitching motion is the key reason for instability of the leading edge shear *** is also found that a certain increase of phase lag,around 34.15°in this research,can increase the airfoil lift.

关键词： Dynamic stall Leading edge vortex Phase lag Pitching and plunging airfoil Vortex dynamics

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Experimental investigations on separation control and flow structure around a circular cylinder with synthetic jet

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Science China(Technological Sciences) 2007年第5期50卷 550-559页

作者： WANG JinJun feng lihao XU ChaoJun Fluid Mechanics Institute Beijing University of Aeronautics and Astronautics Beijing 100083 China Fluid Mechanics Institute Beijing University of Aeronautics and Astronautics Beijing 100083 China Fluid Mechanics Institute Beijing University of Aeronautics and Astronautics Beijing 100083 China

Circular cylinder separation control and flow structure influenced by the synthetic jet have been experimentally investigated in a water channel. The synthetic jet is- sues from a slot and ejects toward upstream from the front stagnation point of the cylinder. It has been found that, similar to the traditional synthetic jet which is po- sitioned near the separation point or inside the separation region, the present synthetic jet arrangement constitutes an efficient way to control flow separation of the circular cylinder, but with a different control mechanism. The present synthetic jet leads to an upstream displacement of the front stagnation point and the forma- tion of a vortex pair near both sides of the exit orifice. When ReU based on the synthetic jet average exit orifice velocity is about lower than 43, a closed envelope forms in front of the windward side of the cylinder during the blowing cycle of syn- thetic jet, which acts as an apparent modification for the cylinder configuration. When ReU is high enough, an open envelope forms upstream of the cylinder, and the flow around the cylinder becomes much energetic. Thus, regardless of ReU, the present synthetic jet can improve separation for flow around a circular cylinder. With regard to the leeward side, as ReU increases, the flow separation region be- hind the cylinder gradually disappears. The flow over cylinder may be fully attached when the open envelope forms upstream of the cylinder and ReU is greater than 344. Then, the flow past the cylinder will converge near the back stagnation point of the cylinder, where a new vortex pair shedding periodically is generated due to the high shear layer.

关键词： flow control, synthetic jet, flow around a cylinder, vortex structure

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Review of zero-net-mass-flux jet and its application in separation flow control

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Science China(Technological Sciences) 2008年第9期51卷 1315-1344页

作者： ZHANG Panfeng WANG JinJun feng lihao Institute of Fluid Mechanics Beijing University of Aeronautics and AstronauticsBeijing 100191China

Since the zero-net-mass-flux (ZNMF) jet was first used as a laboratory flow control method in 1990's, it has attracted much attention. The ZNMF jet has unique features such as compact actuator, no requirement for external air supply, complex piping, etc., and becomes a hot topic research subject in fluid mechanics. This review introduces the state of the art in the development of ZNMF jet in the quiescent fluid, the interaction of the ZNMF jet with the cross flow and its application in the separation flow control. The evolution of the vortex ring/pair and the spacial flow structure of the ZNMF in quicent fluid or cross flow are presented, as well as the key parameter effects. At last, the applications of ZNMF jet in the wake control of the circular cylinder, the separation control on the airfoil and the aerodynamic force or moment control on MAV/UAV are presented.

关键词： zero-net-mass-flux jet quiescent fluid cross flow separation control

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Fourier mode decomposition of PIV data.

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Science China(Technological Sciences) 2015年第11期58卷 1935-1948页

作者： MA LiQun feng lihao PAN Chong GAO Qi WANG JinJun Fluid Mechanics Key Laboratory of Education Ministry Beijing University of Aeronautics and Astronautics

The modal decomposition technique is one of the most effective methods for studying the flow dynamics in a complex flow. By rejuvenating the discrete Fourier transform(DFT), this paper proposes a Fourier mode decomposition(FMD) method for the time series of particle image velocimetry(PIV) data from the fluid field. An experimental case concerning the control of the flow around a circular cylinder by a synthetic jet positioned at the rear stagnation point is used to demonstrate the use of the FMD method. In the three different regimes where the natural shedding frequency and actuation frequency dominate respectively or simultaneously, it is found that the FMD method is capable of extracting the dynamic mode along with its amplitude and phase according to the selected characteristic frequency based on the global power spectrum. For the quasiperiodic flow phenomena presented in this particular case, the FMD method can reconstruct the original flow field using the zero-th mode and the selected mode corresponding to the characteristic frequency. Similarities and differences between the FMD method and the dynamical mode decomposition(DMD) and proper orthogonal decomposition(POD) methods are also discussed.

关键词： flow control vortex dynamics Fourier mode decomposition (FMD)

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Experimental and numerical investigation of threedimensional vortex structures of a pitching airfoil at a transitional Reynolds number

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Chinese Journal of Aeronautics 2019年第10期32卷 2254-2266页

作者： Zhenyao LI lihao feng Hamid Reza KARBASIAN Jinjun WANG Kyung Chun KIM Fluid Mechanics Key Laboratory of Education Ministry Beihang UniversityBeijing 100083China School of Mechanical Engineering Pusan National UniversityBusan 46241Republic of Korea

This research examines the vortex behaviors and aerodynamic forces in dynamic stall phenomena at a transitional Reynolds number(Re=90000)using experimental and numerical *** sinusoidal pitching motion at two different reduced frequencies is used to achieve the dynamic stall of a NACA 0012 *** leading edge vortices form and detach in the dynamic stall *** flow then quickly transitions to a full separation zone in the stall stage when the angle of attack starts to *** is discrepancy between the phaseaveraged and instantaneous flow field in that the small flow structures increased with angle of attack,which is a characteristic of the flow field at the transitional Reynolds *** interaction between the streamwise vortices in the three-dimensional numerical results and the leading edge vortex are the main contribution to the turbulent *** addition,the leading edge vortex that supplies vortex lift is more stable at higher reduced frequency,which decreases the lift fluctuation in the dynamic stall *** leading edge vortex at higher reduced frequency is strong enough to stabilize the flow,even when the airfoil is in the down-stroke phase.

关键词： DDES Dynamic stall Pitching airfoil PIV Transitional Reynolds number

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Influence of orifice-to-wall distance on synthetic jet vortex ring simpinging on a fixed wall

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Science China(Technological Sciences) 2013年第10期56卷 1798-1806页

作者： XU Yang feng lihao Fluid Mechanics Key Laboratory of Education Ministry Beijing University of Aeronautics and Astronautics

Two-dimensional particle image velocimetry (PIV) is used to investigate the influence of the orifice-to-wall distance on synthetic jet vortex rings impinging on a fixed wall. Both evolutions of vortical structures and statistical characteristics of flow fields at different orifice-to-wall distances are presented. It is found that different orifice-to-wall distances have different effects in terms of the vortex strength and impinging speed when the vortex rings are approaching the wall. The secondary vortex ring can be observed within the shear layer only when the dimensionless orifice-to-wall distance is close to or less than the dimensionless stroke length. Consequently, an appropriate orifice-to-wall distance plays a vital role in the sense of impingement effect. The statistical analysis of the flow field indicates that a wall jet forms after impingement, while both the decay rate of the maximum radial velocity and the spreading rate of the half-width decrease with the increasing orifice-to-wall distance. The non-dimensional wall jet velocity profiles at different orifice-to-wall distances all exhibit self-similar behaviors, which is consistent with the theoretical solution of the laminar wall jet.

关键词： vortex ring orifice-to-wall distance impingement wall secondary vortex statistical characteristic

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Alignment of inertialess spheroidal particles in flow-structure-dominated regions of turbulent channel flow:shape effect

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Acta Mechanica Sinica 2024年第8期40卷 45-66页

作者： Zhiwen Cui lihao Zhao Applied Mechanics Laboratory Department of Engineering MechanicsTsinghua UniversityBeijing100084China Laboratory of Flexible Electronics Technology Tsinghua UniversityBeijing100084China

The alignment of elongated fibers and thin disks is known to be significantly influenced by the presence of fluid coherent structures in near-wall turbulence(Cui et al.2021).However,this earlier study is confined to the spheroids with infinitely large or small aspect ratio,and the shape effect of finite aspect ratio on the alignment is not *** current study investigates the shape-dependent alignment of inertialess spheroids in structure-dominated regions of channel *** utilizing an ensemble-averaged approach for identifying the structure-dominated regions,we analyze the eigensystem of the linear term matrix in the Jeffery equation,which is governed by both particle shape and local fluid velocity *** contrast to earlier conventional analysis based on local vorticity and strain rate,our findings demonstrate that the eigensystem of the Jeffery equation offers a convenient,effective,and universal framework for predicting the alignment behavior of inertialess spheroids in turbulent *** leveraging the eigensystem of the Jeffery equation,we uncover a diverse effect of fluid coherent structures on spheroid alignment with different particle ***,we provide explanations for both shape-independent alignments observed in vortical-core regions and shape-dependent alignments around near-wall streamwise vortices.

关键词： Non-spherical particle Direct numerical simulation Wall turbulence Particle-laden flow

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圆和非圆湍流合成射流结构演化和质量输运的拉格朗日方法分析

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Acta Mechanica Sinica 2023年第3期39卷 115-129页

作者：王雷冯立好徐杨 Fluid Mechanics Key Laboratory of Education Ministry Beijing University of Aeronautics and AstronauticsBeijing 10191China

旋涡卷吸特性对合成射流的流动控制应用具有重要意义.为了研究湍流合成射流涡环的结构演化和瞬态卷吸特性,采用时间解析层析粒子图像测速技术,测量了相同参数下,圆形和长宽比为3的矩形合成射流的三维流场.利用拉格朗日拟序结构方法,刻... 详细信息

旋涡卷吸特性对合成射流的流动控制应用具有重要意义.为了研究湍流合成射流涡环的结构演化和瞬态卷吸特性,采用时间解析层析粒子图像测速技术,测量了相同参数下,圆形和长宽比为3的矩形合成射流的三维流场.利用拉格朗日拟序结构方法,刻画了涡环的三维拓扑变形和质量输运过程,并量化了连续涡环的卷吸特性.特别是对矩形涡环,由于涡环的对流速度沿周向分布不均匀,导致传统的移动参考系方法无法有效计算卷吸.针对该问题,采用基于有限时间李雅普诺夫指数“脊线”辨识旋涡边界的方法,估计涡泡体积,从而计算涡环的卷吸和动能转换效率.结果表明,矩形涡环能够卷吸更多的周围流质,产生比圆形涡环更大的涡旋强度;此外,矩形涡环从孔口喷出的流质中获得了更多动能,以维持涡环的轴系转换,这些特征有利于增强射流掺混.上述工作通过发展旋涡动力学的数学描述,为量化流动控制中的旋涡卷吸特性提供了重要参考.

关键词： Vortex dynamics Noncircular synthetic jet Axis switching Lagrangian coherent structures Entrainment

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