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wind tunnel test of gust load alleviation for a large-scale full aircraft model

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Chinese Journal of Aeronautics 2023年第4期36卷 201-216页

作者： Dongqiang ZHAO Zhichun YANG Xianang ZENG Jinge YU Yining GAO Guoning HUANG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China AVIC The First Aircraft Institute Xi’an 710089China AVIC Aerodynamics Research Institute Harbin 150001China

wind tunnel test is an important way to test the performance of Gust Load Alleviation(GLA).At present,some component-level wind tunnel tests have been carried out in big aviation countries,but there is a lack of full aircraft model GLA tests.In this study,a set of large-scale GLA test system in low-speed wind tunnel is developed,which includes a gust generator,a five-degree-of-freedom suspension system,a full elastic aircraft model with control system,and gust load measuring devices.Two control schemes based on closed-loop feedback control and open-loop feed forward control are respectively designed and verified by the full-model GLA tests in the wind tunnel.The experimental results show that the designed gust generator can generate a stable wideband,wide-area gust wind field;the suspension support system can sustain static and dynamic stability during wind tunnel test,and enables the model moving in the horizontal,vertical,pitching,rolling and yawing directions.The results show that the closed-loop feedback control can obtain good control performance of reducing the peak values of elastic vibration response induced by gust excitation,but has little effect on suppressing the rigid body motion excited by low-frequency gust,while the open-loop feed forward control presents superior performance in allevi-ating the high-frequency elastic vibration as well as the low-frequency rigid body motion with more than 40%overall reduction rate.

关键词： Alleviation Full model Gust generator Suspension system wind tunnel

Flow field control for 2-meter high-speed free-jet wind tunnel

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Chinese Journal of Aeronautics 2023年第10期36卷 77-89页

作者： Jiayi TIAN Zhongwei LING Weijie LIU Jianhua Qin Neng XIONG China Aerodynamics Research and Development Center Mianyang 621000China

The 2-meter High-speed Free-jet wind tunnel(2 m HFWT)is China’s first large-scale open-jet trisonic wind tunnel.Compared to traditional closed high-speed wind tunnels,this wind tunnel is endowed with remarkable advantages of ample test chamber space,less interference from the tunnel wall,flexible model support mode,and adjustable continuous variation of the Mach number.Nevertheless,its unique structure makes traditional wind tunnel control methods difficult to apply and brings significant challenges to wind tunnel flow field control.In this paper,a flow field control system is designed for the 2 m HFWT by comprehensively using advanced control technologies such as neural network,gain scheduling,feedforward control,and adaptive control.Through practical application tests,it is proved that the proposed control system successfully solves the problem of high-precision flow field control under continual depletion of storage tank pressure,and realizes distinctive functions of adaptive static pressure matching and continuously varying Mach number at supersonic speed.In addition,due to the application of workflow technology,the flow field control system can flexibly adapt to the implementation of tests of different types and operation conditions,thus fully satisfying the needs of conducting various conventional and special tests in the 2 m HFWT.

关键词： Continuously varying Mach number wind tunnel Flow field control Neural network Static pressure matching Feedforward control

wind erosion from crusted playa surfaces by no saltation and with saltation:A comparison through laboratory wind tunnel experiments

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International Soil and Water Conservation Research 2023年第3期11卷 518-527页

作者： Guoming Zhang Li Li Wenjian Tang Lianyou Liu Peijun Shi Xujiao Han jiadong Dai School of National Safety and Emergency Management Beijing Normal UniversityBeijing100875China Key Laboratory of Environmental Change and Natural Disasters of Chinese Ministry of Education Beijing Normal UniversityBeijing100875China Academy of Disaster Reduction and Emergency Management Faculty of Geographical ScienceBeijing Normal UniversityBeijing100875China Changjiang River Scientific Research Institute of Changjiang Water Resources Commission Wuhan430010China

Playas are common in many arid regions and recognized as a major source of hypersaline particles.A better understanding of wind erosion on crusted playas has significant implications for land management and pollution control practices.We hypothesized that wind erosion rates of crusted playas were complicated and controlled by the interactions between playa crust and wind-induced saltation conditions.However,comparisons regarding the effects of different playa crusts on wind erosion under no saltation(NS)and with saltation(WS)conditions were lacking.In this study,laboratory wind tunnel experiments were carried out to simulate both NS and WS conditions,to investigate the erosion rates of different crust types(Salt,Takyr,and Puffic crust)at different wind speeds.Results showed that:1)Salt crust had greater crust strengths than did Takyr crust and Puffic crust;2)wind erosion rates under the WS condition were up to 60 times greater than those under the NS condition,suggesting that sand bombardment was the dominant mechanism responsible for removal of fine material from crusted playa surfaces;3)both sand bombardment rate and wind erosion rate of the playa crusts increased with increasing wind speed under the WS conditions;4)Puffic crust exhibited a greater rate of wind erosion compared to both the Takyr and Salt crusts under the Ns condition,yet tended to have a lower rate of wind erosion compared to both the Takyr and Salt crusts under the WS condition.This difference can be attributed to the fact that soft Puffic crusts are pliable and can dissipate the force of impacting grains under the Ws conditions.Our results indicated that wind erosion processes on crusted playas are complicated and are affected by wind-induced saltation and crust type,specifically crust strength and elasticityofthesurface.

关键词： Playa crust Sand bombardment wind tunnel Surface abrasion Crust strength

Effects of wind speed,underlying surface,and seed morphological traits on the secondary seed dispersal in the Tengger Desert,China

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Journal of Arid Land 2024年第4期16卷 531-549页

作者： QU Wenjie ZHAO Wenzhi YANG Xinguo WANG Lei ZHANG Xue QU Jianjun Northwest Institute of Eco-Environment and Resources Chinese Academy of SciencesLanzhou 730000China Key Laboratory of Restoration and Reconstruction of Degraded Ecosystems in Northwestern China of Ministry of Education Ningxia UniversityYinchuan 750021China University of Chinese Academy of Sciences Beijing 100049China School of Ecology and Environment Ningxia UniversityYinchuan 750021China

The maintenance of sand-fixing vegetation is important for the stability of artificial sand-fixing systems in which seed dispersal plays a key role.Based on field wind tunnel experiments using 11 common plant species on the southeastern edge of the Tengger Desert,China,we studied the secondary seed dispersal in the fixed and semi-fixed sand dunes as well as in the mobile dunes in order to understand the limitations of vegetation regeneration and the maintenance of its stability.Our results indicated that there were significant variations among the selected 11 plant species in the threshold of wind speed(TWS).The TWS of Caragana korshinskii was the highest among the 11 plant species,whereas that of Echinops gmelinii was the lowest.Seed morphological traits and underlying surface could generally explain the TWS.During the secondary seed dispersal processes,the proportions of seeds that did not disperse(no dispersal)and only dispersed over short distance(short-distance dispersal within the wind tunnel test section)were significantly higher than those of seeds that were buried(including lost seeds)and dispersed over long distance(long-distance dispersal beyond the wind tunnel test section).Compared with other habitats,the mobile dunes were the most difficult places for secondary seed dispersal.Buried seeds were the easiest to be found in the semi-fixed sand dunes,whereas fixed sand dunes were the best sites for seeds that dispersed over long distance.The results of linear mixed models showed that after controlling the dispersal distance,smaller and rounder seeds dispersed farther.Shape index and wind speed were the two significant influencing factors on the burial of seeds.The explanatory power of wind speed,underlying surface,and seed morphological traits on the seeds that did not disperse and dispersed over short distance was far greater than that on the seeds that were buried and dispersed over long distance,implying that the processes and mechanisms of burial and long-distance dispersal are more complex.In summar

关键词： seed dispersal seed morphological traits wind speed vegetation regeneration wind tunnel Tengger Desert

wind tunnel measurement of aerodynamic characteristics of trains passing each other on a simply supported box girder bridge

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Railway Engineering Science 2021年第2期29卷 152-162页

作者： Xiaozhen Li Yiling Tan Xiaowei Qiu Zhenhua Gong Ming Wang School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China.

The aerodynamic performance of high-speed trains passing each other was investigated on a simply supported box girder bridge,with a span of 32 m,under crosswinds.The bridge and train models,modeled at a geometric scale ratio of 1:30,were used to test the aerodynamic forces of the train,with the help of a designed moving test rig in the XNJD-3 wind tunnel.The effects of wind speed,train speed,and yaw angle on the aerodynamic coefficients of the train were analyzed.The static and moving model tests were compared to demonstrate how the movement of the train influences its aerodynamic characteristics.The results show that the sheltering effect introduced by trains passing each other can cause a sudden change in force on the leeward train,which is further influenced by the wind and running speeds.Detailed analyses related to the effect of wind and train speeds on the aerodynamic coefficients were conducted.The relationship between the change in aerodynamic coefficients and yaw angle was finally described by a series of proposed fitting formulas.

关键词： Aerodynamic coefficient Two trains passing each other Simply supported box girder bridge wind tunnel

wind tunnel experiments on dust emissions from different landform types

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Journal of Arid Land 2018年第4期10卷 548-560页

作者： WU Wei YAN Ping WANG Yong DONG Miao MENG Xiaonan JI Xinran Faculty of Geographical Science Beijing Normal University State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University

The measurement and assessment of dust emissions from different landforms are important to understand the atmospheric loading of PM10 （particulate matter ≤10 μm aerodynamic diameter） and to assess natural sources of dust; however, the methodology and technique for determining the dust still present significant research challenges. In the past, specialized field observation and field wind tunnel studies have been used to understand the dust emission. A series of wind tunnel tests were carried out to identify natural sources of dust and measure the magnitudes of dust emissions from different landforms. The method used in this study allowed the measurement of the PM10 emission rate using a laboratory based environmental boundary layer wind tunnel. Results indicated that PM10 emissions demonstrated strong temporal variation and were primarily driven by aerodynamic entrainment. Sand dunes, playa, and alluvial fans had the largest dust emission rates （0.8-5.4 mg/（me.s）） while sandy gravel, Gobi desert and abandoned lands had the lowest emission rates （0.003-0.126 mg/（m2.s））. Dust emissions were heavily dependent on the surface conditions, especially the availability of loose surface dust. High dust emissions were a result of the availability of dust- particle materials for entrainment while low dust emissions were a result of surface crusts and gravel cover. Soil surface property （surface crusts and gravel cover） plays an important role in controlling the availability of dust-sized particles for entrainment. The dust emission rate depended not only on the surface conditions but also on the friction velocity. The emission rate of PM10 varies as a power function of the friction velocity. Although dynamic abrasion processes have a strong influence on the amount of dust entrainment, aerodynamic entrainment may provide an important mechanism for dust emissions. Large volumes of dust entrained by aerodynamic entrainment cannot only occur at low shear velocity without saltation, but may dominate the entrainment process in man

关键词： emission rates PMIO fugitive dust landforms wind tunnel dust dynamics

wind tunnel experimental study on droplet drift reduction by a conical electrostatic nozzle for pesticide spraying

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International Journal of Agricultural and Biological Engineering 2017年第3期10卷 87-94页

作者： Zhang Wei Hou Yongrui Liu Xin Lian Qi Fu Xiaoming Zhang Bo Wang Haiyang Wang Yingqian College of Information Technology Heilongjiang Bayi Agricultural UniversityDaqing 163319China College of Engineering Heilongjiang Bayi Agricultural UniversityDaqing 163319China

Droplet drift wastes pesticide,pollutes the environment,and has become one of the focus issues of agricultural crop protection.Electrostatic spray technology reduces drift to a certain degree.In order to investigate the droplet drift pattern of a conical electrostatic nozzle,the droplet drift mass center distance was defined as an experimental index and used to conduct experimental wind tunnel studies on droplet drift.A mathematical model of the droplet drift mass center distance versus electrostatic voltage and wind speed was created via the regression method.The test results showed that the electrostatic voltage had an insignificant effect on droplet drift,the wind speed and its interaction with the electrostatic voltage had significant effects on droplet drift.When the wind speed was less than 3 m/s and stable,the crop adsorbability of a droplet had a dominant effect on the droplet drift;the droplet drift decreased with the increase of electrostatic voltage.When the wind speed exceeded 3 m/s and was stable,the reduced droplet particle size had a dominant effect on droplet drift,where droplet drift increased as the electrostatic voltage increased.When the wind speed was 0 m/s and the electrostatic voltage was 12 kV,the minimum droplet drift mass center distance was 35.5 mm,which was 56 mm less than that of conventional nozzle droplet drift.Therefore,a conical electrostatic nozzle is inapplicable for operation in an environment where wind speeds exceed 3 m/s.This study provides a reference for optimizing operational parameters of conical electrostatic nozzles and improving the anti-drift capability of droplets.

关键词： pesticide spraying conical electrostatic nozzle droplet drift wind tunnel experimental study electrostatic sprayer

Remote-controlled flexible pose measurement system and method for a moving target in wind tunnel

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Chinese Journal of Aeronautics 2018年第1期31卷 89-98页

作者： Wei LIU Xin MA Ling CHEN Zhenyuan JIA Weixiao LIU Xiao LI Jiakun ZHANG Jiwen LU Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education Dalian University of Technology Dalian 116024 China

The measurement of position and attitude parameters for the isolated target from a highspeed aircraft is a great challenge in the field of wind tunnel simulation technology. This paper proposes a remote-controlled flexible pose measurement system in wind tunnel conditions for the separation of a target from an aircraft. The position and attitude parameters of a moving object are obtained by utilizing a single camera with a focal length and camera orientation that can be changed based on different measurement conditions. Using this proposed system and method, both the flexibility and efficiency of the pose measurement system can be enhanced in wind tunnel conditions to meet the measurement requirements of different objects and experiments, which is also useful for the development of an intelligent position and attitude measurement system. The position and the focal length of the camera also can be controlled remotely during measurements to enlarge both the vertical and horizontal measurement range of this system. Experiments are conducted in the laboratory to measure the position and attitude of moving objects with high flexibility and efficiency, and the measurement precision of the measurement system is also verified through experiments.

关键词： High-speed motion Machine vision Pose measurement Remote-controlled flexible wind tunnel

An experimental system for release simulation of internal stores in a supersonic wind tunnel

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Chinese Journal of Aeronautics 2017年第1期30卷 186-195页

作者： Liu Wei Ma Xin Jia Zhenyuan Lu Wenbo Wang Zhengqu Chen Ling Liu Weixiao Lu Jiwen Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education Dalian University of Technology Dalian 116024 China AVIC Aerodynamics Research Institute Shenyang 110034 China

Aerodynamic parameters obtained from separation experiments of internal stores in a wind tunnel are significant in aircraft designs. Accurate wind tunnel tests can help to improve the release stability of the stores and in-flight safety of the aircrafts in supersonic environments.A simulative system for free drop experiments of internal stores based on a practical project is provided in this paper. The system contains a store release mechanism, a control system and an attitude measurement system. The release mechanism adopts a six-bar linkage driven by a cylinder, which ensures the release stability. The structure and initial aerodynamic parameters of the stores are also designed and adjusted. A high speed vision measurement system for high speed rolling targets is utilized to measure the pose parameters of the internal store models and an optimizing method for the coordinates of markers is presented based on a priori model. The experimental results show excellent repeatability of the system, and indicate that the position measurement precision is less than0.13 mm, and the attitude measurement precision for pitch and yaw angles is less than 0.126°, satisfying the requirements of practical wind tunnel tests. A separation experiment for the internal stores is also conducted in the FL-3 wind tunnel of China Aerodynamics Research Institute.

关键词： Binocular vision system Pose measurement Release mechanism wind tunnel