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| 1 | Review of zero-net-mass-flux jet and its application in separation flow control显示文摘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. | ZHANG PanFeng WANG JinJun FENG LiHao | 2008 | Science China(Technological Sciences)2008，51，9： | 30 |
| 2 | Research of the Unity Theory Between Three-level Space Vector and Carrier-based PWM Modulation Strategy显示文摘两电平空间矢量脉宽调制(space vector pulse widthmodulation,SVPWM)与正弦脉宽调制(sinusoidal pulse widthmodulation,SPWM)存有一定的本质关系,对于三电平,在常见的8段式SVPWM序列中可以证明,SVPWM与SPWM本质上也存在某种统一。实际的SVPWM调制中,由于要考虑中点电压平衡、减少谐波等其它性能问题,一般会利用开关冗余状态得到8段以上的开关调制序列。目前的文献中还未曾有对这些情况进行统一性地验证,因此三电平SVPWM与SPWM的统一理论存在一定的不足。研究发现,可通过严格地理论推导将传统意义上的调制波分解为2个子调制波,再进行SPWM调制,可以得到与SVPWM完全吻合的序列。该文在此方法基础上深入研究了8段以上(10、12、14段)的SVPWM调制序列与SPWM的统一。经过严格地理论推导,成功实现了含任意段数的SVPWM序列与SPWM的统一。仿真结果证明了该理论的正确性。 | CHEN Juan HE Yingjie WANG Xinyu LIU Jinjun | 2013 | 中国电机工程学报2013，33，9： | 28 |
| 3 | Mushroom Poisoning Outbreaks—China,2010–2020显示文摘ABSTRACT Introduction:Mushroom poisoning was the leading cause of foodborne disease outbreaks and outbreak-associated deaths in China.Mushroom poisoning outbreak surveillance can provide insight into the epidemiological characteristics of mushroom poisonings and guide policymaking and health education to reduce illnesses and deaths.Methods:Foodborne Disease Outbreak Surveillance System was upgraded in 2011 to collect foodborne disease outbreaks in China.Mushroom poisoning outbreaks during 2010–2020 were selected to analyze geographical distribution,seasonal distribution,and setting of food preparation.Results:A total of 10,036 outbreaks,which resulted in 38,676 illnesses and 788 deaths,were reported in this period.Mushroom poisonings occurred all over the country,but with highest incidence in the southwest and central China. | Weiwei Li Sara M.Pires Zhitao Liu Jinjun Liang Yafang Wang Wen Chen Chengwei Liu Jikai Liu Haihong Han Ping Fu Yunchang Guo | 2021 | China CDC weekly2021，3，24： | 18 |
| 4 | Identification of Lagrangian coherent structures in the turbulent boundary layer显示文摘Using Finite-Time Lyapunov Exponents (FTLE) method, Lagrangian coherent structures (LCSs) in a fully developed flat-plate turbulent boundary layer are successfully identified from a two-dimensional (2D) velocity field obtained by time-resolved 2D PIV measurement. The typical LCSs in the turbulent boundary layer are hairpin-like structures, which are characterized as legs of quasi-streamwise vor- tices extending deep into the near wall region with an inclination angle θ to the wall, and heads of the transverse vortex tube located in the outer region. Statistical analysis on the characteristic shape of typical LCS reveals that the probability density distribution of θ accords well with t-distribution in the near wall region, but presents a bimodal distribution with two peaks in the outer region, corresponding to the hairpin head and the hairpin neck, respectively. Spatial correlation analysis of FTLE field is im- plemented to get the ensemble-averaged inclination angle θ R of typical LCS. θ R first increases and then decreases along the wall-normal direction, similar to that of the mean value of θ. Moreover, the most probable value of θ saturates at y+=100 with the maximum value of about 24°, suggesting that the most likely position where hairpins transit from the neck to the head is located around y+=100. The ensem- ble-averaged convection velocity Uc of typical LCS is finally calculated from temporal-spatial correla- tion analysis of FTLE field. It is found that the wall-normal profile of the convection velocity Uc(y) ac- cords well with the local mean velocity profile U(y) beyond the buffer layer, evidencing that the down- stream convection of hairpins determines the transportation properties of the turbulent boundary layer in the log-region and beyond. | PAN Chong WANG JinJun ZHANG Cao | 2009 | Science China(Physics,Mechanics & Astronomy)2009，52，2： | 14 |
| 5 | A single camera volumetric particle image velocimetry and its application显示文摘Volumetric particle image velocimetry(VPIV) refers to a PIV-based technique which can obtain full velocity components in a three-dimensional measurement volume.A new VPIV method with a single lens was developed.A three-vision prism was used to make viewing from different angles using one camera.The technique was tested and successfully applied to a three-dimensional three-component(3D3C) measurement of a zero-net-mass-flux jet flow.The accuracy of the measurement was investigated,specifically in steps of calibration,self-calibration and particle triangulation.Time sequence of a vortex ring development was presented.It was shown that the measurement has high accuracy with validation rate of velocity vector reaching about 95%.The flow with vortex ring passing the measurement volume was studied using both swirl strength and vorticity magnitude criteria.Through comparison,the swirl criterion was found to be superior to the criterion of vorticity in differentiating the rotation motion and the free shear. | GAO Qi WANG HongPing WANG JinJun | 2012 | Science China(Technological Sciences)2012，55，9： | 10 |
| 6 | Experimental investigations on separation control and flow structure around a circular cylinder with synthetic jet显示文摘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. | WANG JinJun FENG LiHao XU ChaoJun | 2007 | Science China(Technological Sciences)2007，50，5： | 9 |
| 7 | Characteristics of Early Eocene radiolarian assemblages of the Saga area,southern Tibet and their constraint on the closure history of the Tethys显示文摘Quantitative analysis of Early Eocene radiolarian assemblages discovered in the sedimentary mélange (accretionary prism) of the Saga area,southern Tibet provides new information to constrain the timing of Tethys closure and the initial collision of India and Eurasia. The radiolarian species of Saga include Amphisphaera coronata (Ehrenberg),Buryella hannae Bak & Barwicz-Piskorz,Buryella clinata Foreman,Buryella tetradica Foreman,Calocycloma ampulla (Ehrenberg),Lamptonium fabaeforme constrictum Riedel and Sanfilippo,Lamptonium pennatum Foreman,Lithomespilus coronatus Squinabol and Lamptonium (?) colymbus Foreman. The adequate and reliable correlation of these radiolarians specimens indicates that the assemblage is of Early Eocene in age. The age and depositional envi-ronment of these radiolarians testify that deep ocean basins existed between India Plate and Asia Plate during the Early Eocene. The complete closure of Tethys must have taken place at least after the Early Eocene. | LI YaLin WANG ChengShan HU XiuMian M. Bak WANG JinJun CHEN Lei | 2007 | Chinese Science Bulletin2007，52，15： | 9 |
| 8 | Evaluating the accuracy performance of Lucas-Kanade algorithm in the circumstance of PIV application显示文摘Lucas-Kanade(LK) algorithm, usually used in optical flow filed, has recently received increasing attention from PIV community due to its advanced calculation efficiency by GPU acceleration. Although applications of this algorithm are continuously emerging,a systematic performance evaluation is still lacking. This forms the primary aim of the present work. Three warping schemes in the family of LK algorithm: forward/inverse/symmetric warping, are evaluated in a prototype flow of a hierarchy of multiple two-dimensional vortices. Second-order Newton descent is also considered here. The accuracy & efficiency of all these LK variants are investigated under a large domain of various influential parameters. It is found that the constant displacement constraint, which is a necessary building block for GPU acceleration, is the most critical issue in affecting LK algorithm's accuracy, which can be somehow ameliorated by using second-order Newton descent. Moreover, symmetric warping outbids the other two warping schemes in accuracy level, robustness to noise, convergence speed and tolerance to displacement gradient, and might be the first choice when applying LK algorithm to PIV measurement. | PAN Chong XUE Dong XU Yang WANG JinJun WEI RunJie | 2015 | Science China(Physics,Mechanics & Astronomy)2015，58，10： | 9 |
| 9 | Accurate measurement of wall skin friction by single-pixel ensemble correlation显示文摘The present work deals with accurately estimating wall-skin friction from near-wall mean velocity by means of PIV measurement.The estimation accuracy relies on the spatial resolution and the precision of the resolved velocity profile inside the viscous sublayer,which is a big challenge for conventional window-based correlation method(K?hler C J,et al.Exp Fluids,2012,52:1641–1656).With the help of single-pixel ensemble correlation,the ensemble-averaged velocity vector can be resolved at significant spatial resolution,thus improving the measurement accuracy.To demonstrate the feasibility of this single-pixel ensemble correlation method,we first study the velocity estimation precision in a case of steady near-wall flow.Synthetic particle images are used to investigate the effect of different image parameters.It is found that the velocity RMS-uncertainty level of the single-pixel ensemble correlation method can be equivalent to the conventional window correlation method once the effective particle number used for the ensemble correlation is large enough.Furthermore,a canonical turbulent boundary layer is synthetically simulated based on velocity statistics resolved by previous Direct Numerical Simulation(DNS)work(Schlatter P,et al.J Fluid Mech,2010,659:116–126).The relative error of wall skin friction coefficient is shown to be one-order smaller than that of the window correlation method.And the optimization strategy to further minimize the measurement uncertainty is discussed in the last part. | SHEN JunQi PAN Chong WANG JinJun | 2014 | Science China(Physics,Mechanics & Astronomy)2014，57，7： | 8 |
| 10 | Adsorption and desorption of herbicide monosulfuron-ester in Chinese soils显示文摘Monosulfuron-ester is a new,low rate,sulfonylurea herbicide that is being promoted for annual broadleaf and gramineal weed control;however,there is a lack of published information on its behavior in soils.The adsorption and desorption of monosulfuronester by seven type soils were measured using a batch equilibrium technique.The results showed that the Freundlich equation fitted its adsorption and desorption well,and the Freundlich constant values (K f-ads ) ranged from 0.88 to 5.66.Adsorption isotherms were nonlinear with 1/n f-ads values < 1.Soil pH,organic matter (OM),and clay content were the main factors influencing its adsorption and desorption.Adsorption and desorption were negatively correlated with pH 4.0–8.0 while positively correlated with OM and clay content.The adsorption of monosulfuron-ester was mainly a physical process,because its free energy (?G) in seven soils was less than 40 kJ/mol.Monosulfuron-ester adsorption by three soils increased with increasing CaCl 2 concentration using CaCl 2 as a background electrolyte.Monosulfuron-ester desorption was hysteretic in all tested soils. | Chunxian Wu Suzhi Zhang Guo Nie Zhongming Zhang Jinjun Wang | 2011 | Journal of Environmental Sciences2011，23，9： | 8 |
| 11 | A pigeon-inspired optimization algorithm for many-objective optimization problems显示文摘Dear editor,Swarm intelligence optimization algorithms are inspired by the behaviour of biological groups in nature. Such algorithms have the advantages of a clear structure, simple operation, comprehensible principles, strong parallelism, effective search abilities, and strong robustness. They can effectively solve difficult problems that traditional methods cannot. | Zhihua CUI Jiangjiang ZHANG Yechuang WANG Yang CAO Xingjuan CAI Wensheng ZHANG Jinjun CHEN | 2019 | Science China(Information Sciences)2019，62，7： | 6 |
| 12 | Fourier mode decomposition of PIV data.显示文摘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. | MA LiQun FENG LiHao PAN Chong GAO Qi WANG JinJun | 2015 | Science China(Technological Sciences)2015，58，11： | 6 |
| 13 | Effect of drag reducing riblet surface on coherent structure in turbulent boundary layer显示文摘The characteristics of turbulent boundary layer over streamwise aligned drag reducing riblet surface under zero-pressure gradient are investigated using particle image velocimetry. The formation and distribution of large-scale coherent structures and their effect on momentum partition are analyzed using two-point correlation and probability density function. Compared with smooth surface, the streamwise riblets reduce the friction velocity and Reynolds stress in the turbulent boundary layer, indicating the drag reduction effect. Strong correlation has been found between the occurrence of hairpin vortices and the momentum distribution. The number and streamwise length scale of hairpin vortices decrease over streamwise riblet surface. The correlation between number of uniform momentum zones and Reynolds number remains the same as smooth surface. | Guangyao CUI Chong PAN Di WU Qingqing YE Jinjun WANG | 2019 | Chinese Journal of Aeronautics2019，32，11： | 6 |
| 14 | Numerical investigation on synthetic jet flow control inside an S-inlet duct显示文摘The high degree of centerline curvature and cross-stream pressure gradient in S-inlet ducts gives rise to boundary layer separation and secondary flows,which result in poor pressure recovery and non-uniform flow in the outlet interface with the engine.The flowfield in ducts is three-dimensional due to the existence of secondary flow,so ordinary two-dimensional actuations have poor effect on reforming the flow.Synthetic jet actuations extended in different spanwise positions were employed to manipulate the flow,and compared with the two-dimensional actuation.The interaction mechanics between flow separation and secondary flow was studied at first.It was found that the secondary flow enhanced or weakened flow separation depending on the spanwise position of synthetic jet actuators.Moreover,the flow separation enhanced the secondary flow,thus causing lower pressure recovery and flow distortion in the duct outlet.The actuators located at different spanwise positions will weaken the secondary flows by improving the flow separation to get energetic and uniform main flow. | CHEN ZhanJun WANG JinJun | 2012 | Science China(Technological Sciences)2012，55，9： | 5 |
| 15 | Recent development of vortex ring impinging onto the wall显示文摘It has been more than one hundred years for the study on vortex structure,which is a very important flow structure in the fluid mechanics.Recently,the interaction between vortex ring and solid wall has attracted more and more attentions,for not only it is a very common phenomenon in the engineering,but also it could benefit the understanding of the mechanism of interaction between the vortex and the boundary layer.The interaction between the vortex ring and the wall is reviewed in this paper,including the evolution of vortex ring,the mechanics of vortex ring azimuthal instabilities,the achievements of synthetic vortex ring impinging onto the solid wall,its potential application to heat transfer,and the influence of vortex ring compression.Besides,the latest results of vortex ring impinging onto porous wall are presented,and the future possible investigation direction on this issue is suggested. | XU Yang WANG JinJun | 2013 | Science China(Technological Sciences)2013，56，10： | 5 |
| 16 | Numerical simulation of Gurney flap on SFYT15thick airfoil显示文摘A two-dimensional steady Reynolds-averaged Navier–Stokes(RANS) equation was solved to investigate the effects of a Gurney flap on SFYT15 thick airfoil aerodynamic performance. This airfoil was designed for flight vehicle operating at 20 km altitude with freestream velocity of 25 m/s. The chord length(C) is5 m and the Reynolds number based on chord length is Re = 7.76 × 105. Gurney flaps with the heights ranging from 0.25%C to 3%C were investigated. The shear stress transport(SST) k-ω turbulence model was used to simulate the flow structure around the airfoil. It is showed that Gurney flap can enhance not only the prestall lift but also lift-to-drag ratio in a certain range of angles of attack. Specially, at cruise angle of attack(α = 3°), Gurney flap with 0.5%C height can increase lift-to-drag ratio by 2.7%, and lift coefficient by 12.9%, respectively. Furthermore, the surface pressure distribution, streamlines and trailing-edge flow structure around the airfoil are illustrated, which are helpful to understand the mechanisms of Gurney flap on airfoil aerodynamic performance. Moreover, it is found that the increase of airfoil drag with Gurney flap can be attributed to the increase of pressure drag between the windward and the leeward sides of Gurney flap itself. | Xi He Jinjun Wang Muqing Yang Dongli Ma Chao Yan Peiqing Liu | 2016 | Theoretical & Applied Mechanics Letters2016，6，6： | 5 |
| 17 | Effects of sinusoidal leading edge on delta wing performance and mechanism显示文摘Lift and drag characteristics of delta wings with low swept angle and various sinusoidal leading edges(SLE) were investigated in a wind tunnel.Three amplitudes and three wavelengths of SLE were tested.It is revealed that,in comparison with the baseline case,when the leading-edge amplitude A?5%C(root chord length of a delta wing),the stall of the delta wing can be delayed without penalty on the maximum lift coefficient;meanwhile,the lift-to-drag ratio was kept nearly unchanged.These are beneficial to aircraft maneuverability and agility.Surface oil and hydrogen-bubble flow visualization experiments were further conducted to provide a general view of the underlying flow mechanism of SLE on delta wings.It was found that,for the flow over delta wing with SLE,vortices were generated from every crest of SLE,in contrast to the dual leading-edge vortex structure generated from the apex of the base wing.At high angle of attack,the breakdown of those vortices originating from the crests of SLE may provide additional turbulent kinetic energy to the flow,resulting in the increase of the flow reattachment region on the leeward side,therefore the stall can be delayed. | CHEN Huang PAN Chong WANG JinJun | 2013 | Chinese Science Bulletin2013，58，7： | 4 |
| 18 | Mesocrystalline TiO2/sepiolite composites for the effective degradation of methyl orange and methylene blue显示文摘 | Ruirui LIU Zhijiang JI Jing WANG Jinjun ZHANG | 2018 | Frontiers of Materials Science2018，12，3： | 4 |
| 19 | Photooxidation of arsenic(Ⅲ) to arsenic(Ⅴ) on the surface of kaolinite clay显示文摘As one of the most toxic heavy metals, the oxidation of inorganic arsenic has drawn great attention among environmental scientists. However, little has been reported on the solar photochemical behavior of arsenic species on top-soil. In the present work, the influencing factors(p H, relative humidity(RH), humic acid(HA), trisodium citrate, and additional iron ions) and the contributions of reactive oxygen species(ROS, mainly HOUand HO2U/O2U-) to photooxidation of As(Ⅲ) to As(Ⅴ) on kaolinite surfaces under UV irradiation(λ = 365 nm)were investigated. Results showed that lower p H facilitated photooxidation, and the photooxidation efficiency increased with the increase of RH and trisodium citrate.Promotion or inhibition of As(Ⅲ) photooxidation by HA was observed at low or high dosages, respectively. Additional iron ions greatly promoted the photooxidation, but excessive amounts of Fe2+competed with As(Ⅲ) for oxidation by ROS. Experiments on scavengers indicated that the HOUradical was the predominant oxidant in this system.Experiments on actual soil surfaces proved the occurrence of As(Ⅲ) photooxidation in real topsoil. This work demonstrates that the photooxidation process of As(Ⅲ) on the soil surface should be taken into account when studying the fate of arsenic in natural soil newly polluted with acidic wastewater containing As(Ⅲ). | Wei Ding Yajie Wang Yingtan Yu Xiangzhi Zhang Jinjun Li Feng Wu | 2015 | Journal of Environmental Sciences2015，27，10： | 4 |
| 20 | Effects of wing flexibility on aerodynamic performance of an aircraft model显示文摘The low-speed wind tunnel experiment is carried out on a simplified aircraft model to explore the influence of wing flexibility on the aircraft aerodynamic performance.The investigation involves the measurements of force,membrane deformation and velocity field at Reynolds number of 5.4×10^(4)-1.1×10^(5).In the lift curves,two peaks are observed.The first peak,corresponding to the stall,is sensitive to the wing flexibility much more than the second peak,which nearly keeps constant.For the optimal case,in comparison with the rigid wing model,the delayed stall of nearly5°is achieved,and the relative lift increment is about 90%.It is revealed that the lift enhanced region corresponds to the larger deformation and stronger vibration,which leads to stronger flow mixing near the flexible wing surface.Thereby,the leading-edge separation is suppressed,and the aerodynamic performance is improved significantly.Furthermore,the effects of sweep angle and Reynolds number on the aerodynamic characteristics of flexible wing are also presented. | Qinfeng GUO Xi HE Zhuo WANG Jinjun WANG | 2021 | Chinese Journal of Aeronautics2021，34，9： | 4 |
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