Design of UAV Downwash Airflow Field Detection System Based on Strain Effect Principle

Accurate measurement of the downwash flow field of plant protection unmanned aerial vehicles (UAVs) is essential for analyzing the spatial distribution of droplets. To realize on-line rapid detection of the downwash flow field of a multi-rotor UAV, a flexible polypropylene detection device based on the principle of full bridge strain effect was proposed. Its performance principle was based on the physical deformation caused by wind pressure. The Fluid Flow and Static Structural modules of ANSYS 16.0 finite element software were used to simulate one-way fluid-solid coupling interaction. The surface of the resistive strain gauge embedded in the flexible detecting structure responded well to wind speed variation, hence it was suitable for downwash airflow wind field detection. By solving the strain force on the surface of the flexible detection structure, the length and layout of the grating wire of the strain gauge on the surface of the flexible detection structure were optimized. Meanwhile at 4 m·s−1 wind speed, the output voltage at varied bridge flexible acquisition systems in the acquisition card was measured. Results indicated coefficient of variation of 3.67%, 1.63% and 1.5%, respectively, which proved the good data acquisition consistency of the system. Through calibration test, the regression equation for the relationship between output voltage and wind speed for three unique sensor signal measuring circuits was established. The determination coefficients R2 for single bridge, half bridge and full bridge circuits were 0.9885, 0.9866 and 0.9959, respectively. In conclusion, by applying the multi-rotor plant protection UAV test platform, the results indicated the maximum relative error of the wind speed at each sampling point of the system at 1.0 m altitude was below 5.61%. Simulated and measured value had an RMSE maximum error of 0.1246 m·s−1. Moreover, downwash airflow detection not only has high accuracy but also has high sensitivity. Thus, there is convenience and practicability in the plant protection offered by this approach. The rapid measurement of UAV wind field and the established two-dimensional wind field model can provide a basis for precise application of agricultural aviation.

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Numerical Analysis of Construction Ventilation of Long Railway Tunnel in Plateau Area

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.3489 ◽

2011 ◽

Vol 243-249 ◽

pp. 3489-3492

Author(s):

Bao Long Lin ◽

Xiao Yun Jia

Keyword(s):

Finite Element ◽

Numerical Analysis ◽

Wind Speed ◽

Flow Field ◽

Air Flow ◽

Railway Tunnel ◽

Finite Element Software ◽

Plateau Area ◽

The Future ◽

The Face

Based on the conditions of Guanjiao tunnel, numerical analysis of air flow field is carried out by the finite element software—CFD in this paper. The results show that when the wind speed is 11m/s, the outlet to the face is less than 50m was better; if the speed is 8m/s ~ 4m/s, the distance is less than 40m better. Under the same conditions, the face wind speed of 40m is larger than of 30m. The faster of the speed, the greater of the attenuation along the way. The best distance from duct to the face is suggested according to different wind speed, which can provide a reference for the construction ventilation of the similar projects in the future.

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Simulation of the wind fields over complex terrain with coupling of CFD and WRF

Journal of Computational Methods in Sciences and Engineering ◽

10.3233/jcm-204759 ◽

2021 ◽

pp. 1-12

Author(s):

Xiaoyu Luo ◽

Yiwen Cao

Keyword(s):

Wind Speed ◽

Wind Field ◽

Complex Terrain ◽

Civil Engineering ◽

Meteorological Data ◽

Mass Conservation ◽

Coupling Method ◽

Wind Fields ◽

Civil Structures ◽

Civil Engineers

In the field of civil engineering, the meteorological data available usually do not have the detailed information of the wind near a certain site. However, the detailed information of the wind field during typhoon is important for the wind-resistant design of civil structures. Furthermore, the resolution of the meteorological data available by the civil engineers is too coarse to be applicable. Therefore it is meaningful to obtain the detailed information of the wind fields based on the meteorological data provided by the meteorological department. Therefore, in the present study, a one-way coupling method between WRF and CFD is adopted and a method to keep the mass conservation during the simulation in CFD is proposed. It is found that using the proposed one-way coupling method, the predicted wind speed is closer to the measurement. And the curvature of the wind streamline during typhoon is successfully reproduced.

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Numerical Investigation of Thermal Flow Field of Air-Cooled Condensers for Yongshou Plant

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.248.391 ◽

2012 ◽

Vol 248 ◽

pp. 391-394

Author(s):

Wen Zhou Yan ◽

Wan Li Zhao ◽

Qiu Yan Li

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Wind Speed ◽

Power Plant ◽

Flow Field ◽

Wind Direction ◽

Rotational Speed ◽

Power Plants ◽

Thermal Flow ◽

Air Cooled Condensers

By using the computational fluid dynamics code, FLUENT, Numerically simulation is investigated for Youngshou power plant. Under the constant ambient temperature, the effects of different wind speed and wind direction on the thermal flow field are qualitatively considered. It was found that when considering about the existing and normally operating power plants, the thermal flow field is more sensitive to wind direction and wind speed. Based on the above results, three improved measures such as: increasing the wind-wall height and accelerating the rotational speed of the fans near the edge of the ACC platform and lengthen or widen the platform are developed to effectively improving the thermal flow field, and enhanced the heat dispersal of ACC.

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Unsteady Flow Analysis and Vibratory Stress Predictions for a High Work Single Stage Turbine Blade

Volume 7: Structures and Dynamics, Parts A and B ◽

10.1115/gt2012-69085 ◽

2012 ◽

Author(s):

Kurt Weber ◽

Girish Modgil ◽

Steve Gegg ◽

Shyam Neerarambam ◽

Moujin Zhang

Keyword(s):

Flow Field ◽

Strain Gauge ◽

Flow Analysis ◽

Forced Response ◽

Single Stage ◽

Turbine Stage ◽

Rotating Blade ◽

Gauge Data ◽

Unsteady Flow Analysis ◽

High Work

The flow field in High-Work Single-Stage (HWSS) turbines differs from traditional turbine flow fields. Operating at increased pressure ratios, wakes and trailing edge shocks at the exit of the vane are more likely to cause a vibratory response in the rotating blade. This flow field can produce increased excitation at harmonics that correspond to the vane passing frequency and harmonics higher than the vane passing frequency. In this paper, blade vibratory stresses in a HWSS gas turbine stage are predicted using unsteady pressures from two Rolls-Royce in-house flow codes that employ different phase lagged unsteady approaches. Hydra uses a harmonic storage approach, and the Vane/Blade Interaction (VBI) code uses a direct storage approach. Harmonic storage reduces memory requirements considerably. The predicted stress for four modes at two engine speeds are presented and are compared with rig test strain gauge data to assess and validate the predictive capability of the codes for forced response. Strain gauge data showed the need to consider harmonics higher than the fundamental vane passing frequency for the max power shaft speed and operating at the conditions. Because of this, it was a good case for validation and for comparing the two codes. Overall, it was found that, stress predictions using the Hydra flow code compare better with data. To the best of the authors’ knowledge, this paper is a first in comparing two different phase lagged unsteady approaches, in the context of forced response, to engine rig data for a High-Work Single Stage turbine.

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Numerical Simulation and Analysis on Spray Drift Movement of Multirotor Plant Protection Unmanned Aerial Vehicle

Energies ◽

10.3390/en11092399 ◽

2018 ◽

Vol 11 (9) ◽

pp. 2399 ◽

Cited By ~ 5

Author(s):

Fengbo Yang ◽

Xinyu Xue ◽

Chen Cai ◽

Zhu Sun ◽

Qingqing Zhou

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Droplet Size ◽

Wind Field ◽

Flow Model ◽

Two Phase Flow ◽

Plant Protection ◽

Three Dimensional ◽

Phase Flow ◽

Two Phase

In recent years, multirotor unmanned aerial vehicles (UAVs) have become more and more important in the field of plant protection in China. Multirotor unmanned plant protection UAVs have been widely used in vast plains, hills, mountains, and other regions, and become an integral part of China’s agricultural mechanization and modernization. The easy takeoff and landing performances of UAVs are urgently required for timely and effective spraying, especially in dispersed plots and hilly mountains. However, the unclearness of wind field distribution leads to more serious droplet drift problems. The drift and distribution of droplets, which depend on airflow distribution characteristics of UAVs and the droplet size of the nozzle, are directly related to the control effect of pesticide and crop growth in different growth periods. This paper proposes an approach to research the influence of the downwash and windward airflow on the motion distribution of droplet group for the SLK-5 six-rotor plant protection UAV. At first, based on the Navier-Stokes (N-S) equation and SST k–ε turbulence model, the three-dimensional wind field numerical model is established for a six-rotor plant protection UAV under 3 kg load condition. Droplet discrete phase is added to N-S equation, the momentum and energy equations are also corrected for continuous phase to establish a two-phase flow model, and a three-dimensional two-phase flow model is finally established for the six-rotor plant protection UAV. By comparing with the experiment, this paper verifies the feasibility and accuracy of a computational fluid dynamics (CFD) method in the calculation of wind field and spraying two-phase flow field. Analyses are carried out through the combination of computational fluid dynamics and radial basis neural network, and this paper, finally, discusses the influence of windward airflow and droplet size on the movement of droplet groups.

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Influence of Wind Speed, Wind Direction and Turbulence Model for Bridge Hanger: A Case Study

Symmetry ◽

10.3390/sym13091633 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1633

Author(s):

Yang Ding ◽

Shuang-Xi Zhou ◽

Yong-Qi Wei ◽

Tong-Lin Yang ◽

Jing-Liang Dong

Keyword(s):

Wind Speed ◽

Wind Direction ◽

Wind Field ◽

Solid Mechanics ◽

Von Mises Stress ◽

Long Span Bridges ◽

High Rise ◽

Long Span ◽

Cfd Models ◽

Von Mises

Wind field (e.g., wind speed and wind direction) has the characteristics of randomness, nonlinearity, and uncertainty, which can be critical and even destructive on a long-span bridge’s hangers, such as vortex shedding, galloping, and flutter. Nowadays, the finite element method is widely used for model calculation, such as in long-span bridges and high-rise buildings. In this study, the investigated bridge hanger model was established by COMSOL Multiphysics software, which can calculate fluid dynamics (CFD), solid mechanics, and fluid–solid coupling. Regarding the wind field of bridge hangers, the influence of CFD models, wind speed, and wind direction are investigated. Specifically, the bridge hanger structure has symmetrical characteristics, which can greatly reduce the calculation efficiency. Furthermore, the von Mises stress of bridge hangers is calculated based on fluid–solid coupling.

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Stability Analysis of Ecological Slopes Based on a 3D Finite Element Model

Advances in Materials Science and Engineering ◽

10.1155/2021/3785943 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

ZiFan Sui ◽

Weijia Yuan ◽

Wen Yi ◽

Weihuan Yang

Keyword(s):

Finite Element ◽

Root System ◽

Safety Factor ◽

Cynodon Dactylon ◽

Plant Protection ◽

Lateral Roots ◽

Plant Distribution ◽

Plant Roots ◽

Research Subjects ◽

Finite Element Software

To explore the effect of grass and shrub plant roots on the stability of soil slopes in rainy areas in the south, this article relies on the Longlang Expressway construction project. Cynodon dactylon and Magnolia multiflora were selected as research subjects. The plant distribution characteristics and mechanical properties are analyzed. This paper uses ABAQUS finite element software to construct a 3D model of the planted slope in the test section. The stress and strain on the root system and the soil were observed, and the variation law of slope stability before and after plant protection under different rainfall events was compared and analyzed. The test and simulation results show that the root content of Cynodon dactylon gradually decreases with increasing depth. Cynodon dactylon was mainly distributed in the 0–30 cm soil body, and its effect on improving the cohesion of the soil body reached 75%. Magnolia multiflora belongs to vertical roots and has a strong and longer main root with relatively developed lateral roots. Its root system passes through the sliding surface of the slope bottom, which reduces the maximum equivalent plastic stress generated inside the slope by 61%. When the total rainfall duration is unchanged, under the three rainfall intensities of small, medium, and large, herbaceous plants increase the safety factor of the soil by 1.33%, 2.08%, and 6.1%, respectively, and the roots of shrubs increase the safety factor of the soil by 3.29%, 4.08%, and 4.32%, respectively. When the rainfall intensity does not change, as the rainfall time increases, the effect of plants on the slope safety factor first gradually increases and eventually stabilizes. The research results provide a reliable theoretical basis for analyzing the effect of plant roots on soil consolidation and slope protection, and they also lay a technical foundation for the promotion and application of ecological slope protection technology.

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Analysis on the influence of sinusoidal wind on the structure of pumping unit based on dynamics of solid-fluid interaction

Journal of Mines, Metals and Fuels ◽

10.18311/jmmf/2021/28077 ◽

2021 ◽

Vol 69 (5) ◽

pp. 165

Author(s):

Zheng Liang ◽

Luo-ming Zhao ◽

Li-qin Tan

Keyword(s):

Wind Speed ◽

Wind Field ◽

Research Work ◽

Scientific Basis ◽

Wind Load ◽

Load Range ◽

Pumping Unit ◽

Stress And Deformation ◽

Fluid Interaction ◽

Field Area

China National Petroleum Corporation Dingbian oilfield is located in the wind field area of the beam pumping unit affected by the wind load, occurred several pumping unit bracket bending, beam fracturing, horsehead off and horsehead drop and other serious accidents, endanger the equipment and personnel safety. However, there is little research on the influence of beam pumping unit under wind load. Based on the dynamics of solid-fluid interaction theory and the standard k- turbulence model, this paper calculated the polished rod load range of the pumping unit according to the actual working condition of Dingbian oilfield, and established the CYJ10-4.2-53 numerical model of wind field. Under the sinusoidal variable wind speed conditions, the stress and deformation of the beam loader with different sizes of wind load on the beam loader were compared to those of the different sorts. The stress and deformation of the two different types of pumping unit were compared under the wind load. The results show that under the influence of wind load, the rig of the pumping unit bracket has a serious bending deformation, and the safety risk of the front end of the horsehead along the wind load is deformed. When the wind speed reaches 24.48m/s, the horsehead and barcket’s offset is the largest to the top dead point by the wind load, The minimum impact is affected by the wind load at the bottom dead center, The maximum offset of the horsehead and the bracket reached 8.5 mm and 2.16 mm. The research work of this paper provides a scientific basis for the improvement of safety structure for pumping unit in the wind field area.

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Bio-Inspired Flexible Sensors for Flow Field Detection

10.1007/978-3-030-79749-2_9 ◽

2021 ◽

pp. 231-245

Author(s):

Yonggang Jiang ◽

Zhiqiang Ma ◽

Dawei Shen

Keyword(s):

Flow Field ◽

Flexible Sensors ◽

Field Detection

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Three-dimensional hydrodynamics numerical of wind-driven circulations in Danjiangkou Reservoir

MATEC Web of Conferences ◽

10.1051/matecconf/201824602021 ◽

2018 ◽

Vol 246 ◽

pp. 02021

Author(s):

Jie Zhu ◽

Jin Quan ◽

Xiaohui Lei ◽

Xia Yue ◽

Yang Duan

Keyword(s):

Wind Speed ◽

Flow Field ◽

Potential Flow ◽

Flow Direction ◽

Three Dimensional ◽

Surface Flow ◽

Surface Velocity ◽

Wind Condition ◽

Reservoir Area ◽

Danjiangkou Reservoir

This paper focuses on the analysis of the flow field of Danjiangkou Reservoir under the action of wind stress. Based on the analysis of the annual wind field data of Danjiangkou Reservoir, the three-dimensional hydrodynamic model of Danjiangkou Reservoir was established. The distribution of water flow field in the reservoir area under five different wind directions and two different wind speeds was studied. The simulation results were compared with the flow field without wind. The results show that when the wind speed in the reservoir area is 3.3m/s, the surface velocity and flow direction change less under the same wind conditions as the potential flow direction. Under the wind condition opposite to the potential flow direction, the reservoir area is locally generated. The small circulation and surface flow are more disordered; when the wind speed reaches 10.0m/s, under the same wind condition as the potential flow direction, the surface velocity of the reservoir area increases significantly. Under the wind condition opposite to the direction of the potential flow, a stable counterclockwise circulation is generated, and the wind direction dominates the surface layer. seriously affecting the flow field distribution in the reservoir area. The research results in this paper can provide support for the reservoir in the formulation of emergency water pollution emergency strategy and the formulation of real-time scheduling plan.

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