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| 1 | CRISPR/Cas9-mediated base-editing system efficiently generates gain-of-function mutations in Arabidopsis显示文摘Dear Editor,The CRISPR/Cas9(clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9)system is revolutionizing genome editing due to its high efficiency,low cost,design simplicity and versatility.However,introduction of a point mutation at a desired position remains a great challenge in plant genome engineering.Currently,point mutation in plants was achieved by incorporating | Yiyu Chen Zhiping Wang Hanwen Ni Yong Xu Qijun Chen Linjian Jiang | 2017 | Science China(Life Sciences)2017，60，5： | 40 |
| 2 | CFD calculations on the unsteady aerodynamic characteristics of a tilt-rotor in a conversion mode显示文摘In order to calculate the unsteady aerodynamic characteristics of a tilt-rotor in a conversion mode, a virtual blade model(VBM) and an real blade model(RBM) are established respectively. A new multi-layer moving-embedded grid technique is proposed to reduce the numerical dissipation of the tilt-rotor wake in a conversion mode. In this method, a grid system generated abound the rotor accounts for rigid blade motions, and a new searching scheme named adaptive inverse map(AIM) is established to search corresponding donor elements in the present movingembedded grid system to translate information among the different computational zones. A dual-time method is employed to fulfill unsteady calculations on the flowfield of the tilt-rotor,and a second-order centered difference scheme considering artificial viscosity is used to calculate the flux. In order to improve the computing efficiency, the single program multiple data(SPMD)model parallel acceleration technology is adopted, according to the characteristic of the current grid system. The lift and drag coefficients of an NACA0012 airfoil, the dynamic pressure distributions below a typical rotor plane, and the sectional pressure distributions on a three-bladed Branum–Tung tilt-rotor in hover flight are calculated respectively, and the present VBM and RBM are validated by comparing the calculated results with available experimental data. Then, unsteady aerodynamic forces and flowfields of an XV-15 tilt-rotor in different modes, such as a fixed conversion mode at different tilt angles(15°, 30°, 60°) and a whole conversion mode which converses from 0° to90°, are numerically simulated by the VBM and RBM respectively. By analyses and comparisons on the simulated results of unsteady aerodynamic forces of the tilt-rotor in different modes, some meaningful conclusions about distorted blade-tip vortex distribution and unsteady aerodynamic force variation in a conversion mode are obtained, and these investigation results could provide a good foundation for tilt-rotor aircraft design in the future. | Li Peng Zhao Qijun Zhu Qiuxian | 2015 | Chinese Journal of Aeronautics2015，28，6： | 15 |
| 3 | Discovery and Significance of High CH_4 Primary Fluid Inclusions in Reservoir Volcanic Rocks of the Songliao Basin,NE China显示文摘Comparing compositions of the fluid inclusions in volcanic rocks to the contents and isotopes of the gases in corresponding volcanic reservoirs using microthermometry, Raman microspectroscopy and mass spectrum analysis, we found that: (1) up to 82 mole% methane exists in the primary inclusions hosted in the reservoir volcanic rocks; (2) high CH4 inclusions recognized in the volcanic rocks correspond to CH4-bearing CO2 reservoirs that are rich in helium and with a high 3He/4He ratio and which show reversed order of δ 13C in alkane; (3) in gas reservoirs of such abiotic methane (>80%) and a mix of CH4 and CO2, the enclosed content of CH4 in the volcanic inclusions is usually below 42 mole%, and the reversed order of δ 13C in alkane is sometimes irregular in the corresponding gas pools; (4) a glassy inclusion with a homogeneous temperature over 900°C also contains a small portion of CH4 although predominantly CO2. This affinity between gas pool and content of inclusion in the same volcanic reservoirs demonstrates that magma-originated gases, both CH4 and CO2, have contributed significantly to the corresponding gas pools and that the assumed hydrocarbon budget of the bulk earth might be much larger than conventionally supposed. | WANG Pujun HOU Qijun WANG Keyong CHEN Shumin CHENG Rihui LIU Wanzhu LI Quanlin | 2007 | Acta Geologica Sinica(English Edition)2007，81，1： | 14 |
| 4 | Experimental investigations for parametric effects of dual synthetic jets on delaying stall of a thick airfoil显示文摘A promising strategy of synthetic jet arrays(SJA) control for NACA0021 airfoil in preventing flow separation and delaying stall is investigated. Through aerodynamic forces, flowfield and velocity profiles measurements, it indicates that the synthetic jet(SJ) could enlarge the mixing of the shear layer and then enhance the stability of boundary layer, resulting in scope reduction of the flow separation zone. Furthermore, the control effects of dual jet arrays positioned at 15%c(Actuator 1) and 40%c(Actuator 2) respectively are systematically investigated with different jet parameters, such as two typical relative phase angles and various incline angles of the jet. The jet closer to the leading edge of airfoil is more advantageous in delaying the stall of airfoil, and overall,the flow control performances of jet arrays are better than those of single actuator. At the angle of attack(Ao A) just approaching and larger than the stall Ao A, jet array with 180° phase difference could increase the lift coefficient more significantly and prevent flow separation. When momentum coefficient of the jet arrays is small, a larger jet angle of Actuator 2 is more effective in improving the maximum lift coefficient of airfoil. With a larger momentum coefficient of jet array, a smaller jet angle of Actuator 2 is more effective. | Zhao Guoqing Zhao Qijun Gu Yunsong Chen Xi | 2016 | Chinese Journal of Aeronautics2016，29，2： | 14 |
| 5 | Integrated optimization analyses of aerodynamic/stealth characteristics of helicopter rotor based on surrogate model显示文摘Based on computational fluid dynamics(CFD)method,electromagnetic high-frequency method and surrogate model optimization techniques,an integration design method about aerodynamic/stealth has been established for helicopter rotor.The developed integration design method is composed of three modules:integrated grids generation(the moving-embedded grids for CFD solver and the blade grids for radar cross section(RCS)solver are generated by solving Poisson equations and folding approach),aerodynamic/stealth solver(the aerodynamic characteristics are simulated by CFD method based upon Navier–Stokes equations and Spalart–Allmaras(S–A)turbulence model),and the stealth characteristics are calculated by using a panel edge method combining the method of physical optics(PO),equivalent currents(MEC)and quasi-stationary(MQS),and integrated optimization analysis(based upon the surrogate model optimization technique with full factorial design(FFD)and radial basis function(RBF)),an integrated optimization analyses on aerodynamic/stealth characteristics of rotor are conducted.Firstly,the scattering characteristics of the rotor with different blade-tip swept and twist angles have been carried out,then time–frequency domain grayscale with strong scattering regions of rotor have been given.Meanwhile,the effects of swept-tip and twist angles on the aerodynamic characteristic of rotor have been performed.Furthermore,by choosing suitable object function and constraint condition,the compromised design about swept and twist combinations of rotor with high aerodynamic performances and low scattering characteristics has been given at last. | Jiang Xiangwen Zhao Qijun Zhao Guoqing Li Peng | 2015 | Chinese Journal of Aeronautics2015，28，3： | 12 |
| 6 | Dihydroartemisinin regulates the immune system by promotion of CD8^+T lymphocytes and suppression of B cell responses显示文摘Artemisia annua is an anti-fever herbal medicine first described in traditional Chinese medicine 1,000 years ago.Artemisinin,the extract of A.annua,and its derivatives(dihydroartemisinin(DHA),artemether,and artesunate)have been used for the treatment of malaria with substantial efficacy.Recently,DHA has also been tested for the treatment of lupus erythematosus,indicating that it may function to balance the immune response in immunocompromised individuals.In the present study,the regulatory effect of artemisinin on the murine immune system was systematically investigated in mice infected with two different protozoan parasites(Toxoplasma gondii and Plasmodium berghei).Our results revealed that the mouse spleen index significantly increased(spleen enlargement)in the healthy mice after DHA administration primarily due to the generation of an extra number of lymphocytes and CD8^+T lymphocytes in both the spleen and circulation.DHA could increase the proportion of T helper cells and CD8^+T cells,as well as decrease the number of splenic and circulatory B cells.Further,DHA could reduce the production of proinflammatory cytokines.Our study revealed that apart from their anti-parasitic activity,artemisinin and its derivatives can also actively modulate the immune system to directly benefit the host. | Ting Zhang Yiwei Zhang Ning Jiang Xu Zhao Xiaoyu Sang Na Yang Ying Feng Ran Chen Qijun Chen | 2020 | Science China(Life Sciences)2020，63，5： | 12 |
| 7 | 4 K high frequency pulse tube cryocooler used for terahertz space application显示文摘Terahertz(THz) frequency region, defined from0.1 to 10 THz, is an important frequency band for radio astronomy and atmospheric science. As NbN Superconductor-Insulator-Superconductor(SIS) mixers used for terahertz detection, which are studied by the Purple Mountain Observatory(PMO), Chinese Academy of Sciences(CAS), work at 8–10 K, and require condition of micro vibrations, its astronomical observation in aerospace is limited by suitable refrigeration method. 4 K high frequency pulse tube cryocooler developed by Key Laboratory of Space Energy Conversion Technologies(SECT), Technical Institute of Physics and Chemistry(TIPC), CAS, offers an opportunity for the application of SIS mixers. This article introduces the progress of the two-stage high frequency pulse tube cryocooler researched by TIPC. The cryocooler has reached a no load temperature of 4.5 K which is the lowest temperature for this kind of cryocooler reported so far. The successful coupling between the THz component and the high frequency pulse tube cryocooler lays a solid foundation for space detection in the terahertz band. | Jia Quan Yanjie Liu Dong Liu Kun Zhang Jingtao Liang Jing Li Qijun Yao Shengcai Shi | 2014 | Chinese Science Bulletin2014，59，27： | 12 |
| 8 | Potentiating CD8^(+) T cell antitumor activity by inhibiting PCSK9 to promote LDLR-mediated TCR recycling and signaling显示文摘Metabolic regulation has been proven to play a critical role in T cell antitumor immunity.However,cholesterol metabolism as a key component of this regulation remains largely unexplored.Herein,we found that the low-density lipoprotein receptor(LDLR),which has been previously identified as a transporter for cholesterol,plays a pivotal role in regulating CD8+T cell antitumor activity.Besides the involvement of cholesterol uptake which is mediated by LDLR in T cell priming and clonal expansion,we also found a non-canonical function of LDLR in CD8+T cells:LDLR interacts with the T-cell receptor(TCR)complex and regulates TCR recycling and signaling,thus facilitating the effector function of cytotoxic T-lymphocytes(CTLs).Furthermore,we found that the tumor microenvironment(TME)downregulates CD8+T cell LDLR level and TCR signaling via tumor cell-derived proprotein convertase subtilisin/kexin type 9(PCSK9)which binds to LDLR and prevents the recycling of LDLR and TCR to the plasma membrane thus inhibits the effector function of CTLs.Moreover,genetic deletion or pharmacological inhibition of PCSK9 in tumor cells can enhance the antitumor activity of CD8+T cells by alleviating the suppressive effect on CD8+T cells and consequently inhibit tumor progression.While previously established as a hypercholesterolemia target,this study highlights PCSK9/LDLR as a potential target for cancer immunotherapy as well. | Juanjuan Yuan Ting Cai Xiaojun Zheng Yangzi Ren Jingwen Qi Xiaofei Lu Huihui Chen Huizhen Lin Zijie Chen Mengnan Liu Shangwen He Qijun Chen Siyang Feng Yingjun Wu Zhenhai Zhang Yanqing Ding Wei Yang | 2021 | Protein & Cell2021，12，4： | 12 |
| 9 | Liquid organic hydrogen carriers显示文摘The development of efficient hydrogen storage materials is one of the biggest technical challenges for the coming 'hydrogen economy'. The liquid organic hydrogen carriers(LOHCs) with high hydrogen contents,reversibilities and moderate dehydrogenation kinetics have been considered as an alternative option supplementing the extensively investigated inorganic hydride systems. In this review, LOHCs for long distance H2 transport and for onboard application will be discussed with the focuses of the design and development of LOHCs and their hydrogenation & dehydrogenation catalyses. | Teng He Qijun Pei Ping Chen | 2015 | Journal of Energy Chemistry2015，24，5： | 11 |
| 10 | Survey of locomotion control of legged robots inspired by biological concept显示文摘Compared with wheeled mobile robots, legged robots can easily step over obstacles and walk through rugged ground. They have more flexible bodies and therefore, can deal with complex environment. Nevertheless, some other issues make the locomotion control of legged robots a much complicated task, such as the redundant degree of freedoms and balance keeping. From literatures, locomotion control has been solved mainly based on programming mechanism. To use this method, walking trajectories for each leg and the gaits have to be designed, and the adaptability to an unknown environment cannot be guaranteed. From another aspect, studying and simulating animals' walking mechanism for engineering application is an efficient way to break the bottleneck of locomotion control for legged robots. This has attracted more and more attentions. Inspired by central pattern generator (CPG), a control method has been proved to be a successful attempt within this scope. In this paper, we will review the biological mechanism, the existence evidences, and the network properties of CPG. From the en- gineering perspective, we will introduce the engineering simulation of CPG, the property analysis, and the research progress of CPG inspired control method in locomotion control of legged robots. Then, in our research, we will further discuss on existing problems, hot issues, and future research directions in this field. | WUQiDi LIU ChengJu ZHANG JiaQi CHEN QiJun | 2009 | Science in China(Series F)2009，52，10： | 11 |
| 11 | Effect of the Cutter Parameters and Machining Parameters on the Interference in Gear Slicing显示文摘Current researches have not yet found the effect law of the cutter parameters and machining parameters on the interference in gear slicing,the interference between the cutter and machined gear often happens because the appropriate cutter parameters and machining parameters cannot be set,which reduces the gear machining accuracy.The relative position between the major flank face and edge-sweeping surface,distribution law of the interference area in forming process of edge-sweeping surface,and effect law of relative positions among edge-sweeping surfaces on the interference are studied by graphical analysis.The effect law of the cutter parameters and machining parameters on the interference is found.The effect law shows that the interference in gear slicing can be controlled when the relief angle measured on the top edge and feed of every rotation are chosen respectively larger than 9°and smaller than 0.15 mm/r.An internal helical gear is sliced with the spur slice cutter and the cutter parameters and machining parameters are set based on above the effect law.The machined gear is measured in Gear Measuring Center and the detection result shows that the comprehensive accuracy reaches GB/T Class 7,where some reach GB/T Class 6.The result can meet the gear machining accuracy requirement and shows that the effect law found is valid.The problem of the interference in gear slicing is solved and the gear machining accuracy can be improved. | CHEN Xinchun LI Jia LOU Benchao SHI Jiang YANG Qijun | 2013 | Chinese Journal of Mechanical Engineering2013，26，6： | 10 |
| 12 | Parametric analyses on dynamic stall control of rotor airfoil via synthetic jet显示文摘The effects of synthetic jet control on unsteady dynamic stall over rotor airfoil are investigated numerically. A moving-embedded grid method and an Unsteady Reynolds Averaged Navier-Stokes(URANS) solver coupled with k-x Shear Stress Transport(SST) turbulence model are established for predicting the complex flowfields of oscillatory airfoil under jet control. Additionally, a velocity boundary condition modeled by sinusoidal function has been developed to fulfill the perturbation effect of periodic jet. The validity of present CFD method is evaluated by comparisons of the calculated results of baseline dynamic stall case for rotor airfoil and jet control case for VR-7 B airfoil with experimental data. Then, parametric analyses are conducted emphatically for an OA212 rotor airfoil to investigate the effects of jet control parameters(jet location, dimensionless frequency, momentum coefficient, jet angle, jet type and dual-jet) on dynamic stall characteristics of rotor airfoil. It is demonstrated by the calculated results that efficiency of jet control could be improved with specific momentum coefficient and jet angle when the jet is located near separation point of rotor airfoil. Furthermore, the dual-jet could improve control efficiency more obviously on dynamic stall of rotor airfoil with respect to the unique jet, and the influence laws of dual-jet's angles and momentum coefficients on control effects are similar to those of the unique jet. Finally,unsteady aerodynamic characteristics of rotor via synthetic jet which is located on the upper surface of rotor blade in forward flight are calculated, and as a result, the aerodynamic characteristics of rotor are improved compared with the baseline. The results indicate that synthetic jet has the capability in improving aerodynamic characteristics of rotor. | Qijun ZHAO Yiyang MA Guoqing ZHAO | 2017 | Chinese Journal of Aeronautics2017，30，6： | 10 |
| 13 | Parametric analyses for synthetic jet control on separation and stall over rotor airfoil显示文摘Numerical simulations are performed to investigate the effects of synthetic jet control on separation and stall over rotor airfoils. The preconditioned and unsteady Reynolds-averaged Navier–Stokes equations coupled with a k x shear stream transport turbulence model are employed to accomplish the flowfield simulation of rotor airfoils under jet control. Additionally,a velocity boundary condition modeled by a sinusoidal function is developed to fulfill the perturbation effect of periodic jets. The validity of the present CFD procedure is evaluated by the simulated results of an isolated synthetic jet and the jet control case for airfoil NACA0015. Then, parametric analyses are conducted specifically for an OA213 rotor airfoil to investigate the effects of jet parameters(forcing frequency, jet location and momentum coefficient, jet direction, and distribution of jet arrays) on the control effect of the aerodynamic characteristics of a rotor airfoil. Preliminary results indicate that the efficiency of jet control can be improved with specific frequencies(the best lift-drag ratio at F+= 2.0) and jet angles(40 or 75) when the jets are located near the separation point of the rotor airfoil. Furthermore, as a result of a suitable combination of jet arrays, the lift coefficient of the airfoil can be improved by nearly 100%, and the corresponding drag coefficient decreased by26.5% in comparison with the single point control case. | Zhao Guoqing Zhao Qijun | 2014 | Chinese Journal of Aeronautics2014，27，5： | 10 |
| 14 | Enhanced CH4 selectivity in CO2 photocatalytic reduction over carbon quantum dots decorated and oxygen doping g-C3N4显示文摘Graphitic carbon nitride(g-C3N4,CN)exhibits inefficient charge separation,deficient CO2 adsorption and activation sites,and sluggish surface reaction kinetics,which have been recognized as the main barriers to its application in CO2 photocatalytic reduction.In this work,carbon quantum dot(CQD)decoration and oxygen atom doping were applied to CN by a facile one-step hydrothermal method.The incorporated CQDs not only facilitate charge transfer and separation,but also provide alternative CO2 adsorption and activation sites.Further,the oxygen-atom-doped CN(OCN),in which oxygen doping is accompanied by the formation of nitrogen defects,proves to be a sustainable H^+ provider by facilitating the water dissociation and oxidation half-reactions.Because of the synergistic effect of the hybridized binary CQDs/OCN addressing the three challenging issues of the CN based materials,the performance of CO2 photocatalytic conversion to CH4 over CQDs/OCN-x(x represents the volume ratio of laboratory-used H2O2(30 wt.%)in the mixed solution)is dramatically improved by 11 times at least.The hybrid photocatalyst design and mechanism proposed in this work could inspire more rational design and fabrication of effective photocatalysts for CO2 photocatalytic conversion with a high CH4 selectivity. | Qian Li Songcan Wang Zhuxing Sun Qijun Tang Yiqiu Liu Lianzhou Wang Haiqiang Wang Zhongbiao Wu | 2019 | Nano Research2019，12，11： | 9 |
| 15 | A New Single-blade Based Hybrid CFD Method for Hovering and Forward-flight Rotor Computation显示文摘A hybrid Euler/full potential/Lagrangian wake method,based on single-blade simulation,for predicting unsteady aerodynamic flow around helicopter rotors in hover and forward flight has been developed.In this method,an Euler solver is used to model the near wake evolution and transonic flow phenomena in the vicinity of the blade,and a full potential equation(FPE) is used to model the isentropic potential flow region far away from the rotor,while the wake effects of other blades and the far wake are incorporated into the flow solution as an induced inflow distribution using a Lagrangian based wake analysis.To further reduce the execution time,the computational fluid dynamics(CFD) solution and rotor wake analysis(including induced velocity up-date) are conducted parallelly,and a load balancing strategy is employed to account for the information exchange between two solvers.By the developed method,several hover and forward-flight cases on Caradonna-Tung and Helishape 7A rotors are per-formed.Good agreements of the loadings on blade surface with available measured data demonstrate the validation of the method.Also,the CPU time required for different computation runs is compared in the paper,and the results show that the pre-sent hybrid method is superior to conventional CFD method in time cost,and will be more efficient with the number of blades increasing. | SHI Yongjie ZHAO Qijun FAN Feng XU Guohua | 2011 | Chinese Journal of Aeronautics2011，24，2： | 9 |
| 16 | Robust Navier-Stokes method for predicting unsteady flowfield and aerodynamic characteristics of helicopter rotor显示文摘A robust unsteady rotor flowfield solver CLORNS code is established to predict the complex unsteady aerodynamic characteristics of rotor flowfield. In order to handle the difficult problem about grid generation around rotor with complex aerodynamic shape in this CFD code,a parameterized grid generated method is established, and the moving-embedded grids are constructed by several proposed universal methods. In this work, the unsteady Reynolds-Averaged Navier-Stokes(RANS) equations with Spalart-Allmaras are selected as the governing equations to predict the unsteady flowfield of helicopter rotor. The discretization of convective fluxes is accomplished by employing the second-order central difference scheme, third-order MUSCL-Roe scheme, and fifth-order WENO-Roe scheme. Aimed at simulating the unsteady aerodynamic characteristics of helicopter rotor, the dual-time scheme with implicit LU-SGS scheme is employed to accomplish the temporal discretization. In order to improve the computational efficiency of holecells and donor elements searching of the moving-embedded grid technology, the ‘‘disturbance diffraction method' and ‘‘minimum distance scheme of donor elements method' are established in this work. To improve the computational efficiency, Message Passing Interface(MPI) parallel method based on subdivision of grid, local preconditioning method and Full Approximation Storage(FAS) multi-grid method are combined in this code. By comparison of the numerical results simulated by CLORNS code with test data, it is illustrated that the present code could simulate the aerodynamic loads and aerodynamic noise characteristics of helicopter rotor accurately. | Qijun ZHAO Guoqing ZHAO Bo WANG Qing WANG Yongjie SHI Guohua XU | 2018 | Chinese Journal of Aeronautics2018，31，2： | 9 |
| 17 | Genome-wide Dissection of Co-selected UV-B Responsive Pathways in the UV-B Adaptation of Qingke显示文摘Qingke (Tibetan hulless barley) has long been cultivated and exposed to long-term and strong UV-B radiation on the Tibetan Plateau, which renders it an ideal species for elucidating novel UV-B responsive mechanisms in plants. Here we report a comprehensive metabolite profiling and metabolite-based genome-wide association study (mGWAS) using 196 diverse qingke and barley accessions. Our results demonstrated both constitutive and induced accumulation, and common genetic regulation, of metabolites from different branches of the phenylpropanoid pathway that are involved in UV-B protection. A total of 90 significant mGWAS loci for these metabolites were identified in barley-qingke differentiation regions, and a number of high-level metabolite trait alleles were found to be significantly enriched in qingke, suggesting co-selection of various phenylpropanoids. Upon dissecting the entire phenylpropanoid pathway, we identified some key determinants controlling natural variation of phenylpropanoid content, including three novel proteins, a flavone C-pentosyltransferase, a tyramine hydroxycinnamoyl acyltransferase, and a MYB transcription factor. Our study, furthermore, demonstrated co-selection of both constitutive and induced phenylpropanoids for UV-B protection in qingke. | Xingquan Zeng Hongjun Yuan Xuekui Dong Meng Peng Xinyu Jing Qijun Xu Tang Tang Yulin Wang Sang Zha Meng Gao Congzhi Li Chujin Shu Zexiu Wei Wangmu Qimei Yuzhen Basang Jiabu Dunzhu Zeqing Li Lijun Bai Jian Shi Zhigang Zheng Sibin Yu Alisdair R.Fernie Jie Luo Tashi Nyima | 2020 | Molecular Plant2020，13，1： | 9 |
| 18 | Aerodynamic shape optimization for alleviating dynamic stall characteristics of helicopter rotor airfoil显示文摘In order to alleviate the dynamic stall effects in helicopter rotor, the sequential quadratic programming(SQP) method is employed to optimize the characteristics of airfoil under dynamic stall conditions based on the SC1095 airfoil. The geometry of airfoil is parameterized by the class-shape-transformation(CST) method, and the C-topology body-fitted mesh is then automatically generated around the airfoil by solving the Poisson equations. Based on the grid generation technology, the unsteady Reynolds-averaged Navier-Stokes(RANS) equations are chosen as the governing equations for predicting airfoil flow field and the highly-efficient implicit scheme of lower–upper symmetric Gauss–Seidel(LU-SGS) is adopted for temporal discretization. To capture the dynamic stall phenomenon of the rotor more accurately, the Spalart–Allmaras turbulence model is employed to close the RANS equations. The optimized airfoil with a larger leading edge radius and camber is obtained. The leading edge vortex and trailing edge separation of the optimized airfoil under unsteady conditions are obviously weakened, and the dynamic stall characteristics of optimized airfoil at different Mach numbers, reduced frequencies and angles of attack are also obviously improved compared with the baseline SC1095 airfoil. It is demonstrated that the optimized method is effective and the optimized airfoil is suitable as the helicopter rotor airfoil. | Wang Qing Zhao Qijun Wu Qi | 2015 | Chinese Journal of Aeronautics2015，28，2： | 8 |
| 19 | Numerical analysis on noise of rotor with unconventional blade tips based on CFD/Kirchhoff method显示文摘A solver is developed aiming at efficiently predicting rotor noise in hover and forward flight. In this solver, the nonlinear near-field solutions are calculated by a hybrid approach which includes the Navier-Stokes and Euler equations based on a moving-embedded grid system and adaptive grid methodology. A combination of the third-order upwind scheme and flux-difference splitting scheme, instead of the second-order center-difference scheme which may cause larger wake dissipation, has been employed in the present computational fluid dynamics (CFD) method. The sound pressure data in the near field can be calculated directly by solving the Navier-Stokes equations, and the sound propagation can be predicted by the Kirchhoff method. A harmonic expansion approach is presented for rotor far-field noise prediction, which gives an analytical expression for the integral function in the Kirchhoff formula. As a result, the interpolation process is simplified and the efficiency and accuracy of the interpolation are improved. Then, the high-speed impulsive (HIS) noise of a helicopter rotor at different tip Mach numbers and on different observers is calculated and analyzed in hover and forward flight, which shows a highly directional characteristic of the rotor HIS noise with a maximum value in the rotor plane, and the HSI noise weakens rapidly with the increasing of the directivity angle. In order to investigate the effects of the rotor blade-tip shape on its aeroacoustic characteristics, four kinds of blade tips are designed and their noise characteristics have been simulated. At last, a new unconventional CLOR-II blade tip has been designed, and the noise characteristics of the presented CLOR-II model rotor have been simulated and measured compared to the reference rotors with a rectangular or swept-back platform blade tip. The results demonstrate that the unconventional CLOR-II blade tip can significantly reduce the HSI noise of a rotor. | Wang Bo Zhao Qijun Xu Guohua Ye Liang Wang Junyi | 2013 | Chinese Journal of Aeronautics2013，26，3： | 8 |
| 20 | Current status and future of acid rain in China显示文摘As a part of the national key project of acid rain research, chemical element analysis of rainwater has been carried out based on observation of acid rain network in Chinese MeteorologicalAdministration over the years of 1992 and 1993. Samples of precipitation collected from eachacid rain station were taken according to the standard established by Chinese MeteorologicalAdministration. pH value was measured with pH meter (accuracy of 0. 01) made in | DING Guo’an, XU Xiaobing, FANG Xiumei, JIN Shaping, XU Xia, Tang Jie, LIU Qijun, WANG Shufeng and WANG Wenxing1. Chinese Academy of Meteorological Sciences, Beijing 100081, China 2. Chinese Academy of Environment Sciences, Beijing 100012, China | 1997 | Chinese Science Bulletin1997，42，24： | 8 |
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